WorldWideScience

Sample records for fine root distribution

  1. Spatial distribution characteristics of fine roots of Populus euphratica in a desert riparian forest

    Institute of Scientific and Technical Information of China (English)

    Jianhua SI; Qi FENG; Jianlin LI; Jian ZHAO

    2008-01-01

    The soil-plant system is a very important sub-system of the soil-plant-atmosphere continuum (SPAC). The water uptake by plant roots is an important subject in the research on water transport in this SPAC and is also the most active study direction in the fields of ecology, hydrology and environment. The study of the spatial dis-tribution pattern of fine roots of plants is the basis of constructing a water absorption model of plant roots. Our study on the spatial distribution pattern of fine roots of Populus euphratica in a desert riparian forest shows that the density distribution of its root lengths can be expressed horizontally as a parabola. The fine roots are concen-trated within the range of 0-350 cm from the tree trunk and their amount accounts for 91.9% of the total root mass within the space of 0-500 cm. In the vertical dir-ection, the density distribution of the fine root lengths shows a negative exponential relation with soil depth. The fine roots are concentrated in the 0-80 cm soil layer, accounting for 96.8% of the total root mass in the 0-140 cm soil layer.

  2. Spatial distribution of fine roots of larch and ash in the mixed plantation stand

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The spatial distribution of standing fine roots in tree rows of different species in a 12-year-old mixed stand of ash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) was studied by soil core sampling in early spring, 2001. It is found that ash and larch differ greatly in their belowground biomass distribution. Ash has much higher fine root biomass density in the soil than l arch at stand level (with the max value of 4442.3 vs. 2234.9 g@m-3). Both tree species deployed more fine roots in their neighboring zone, suggesting a less in tensive competition between roots of the two species. Both fine root biomass den sity and root length density of ash in the zone between larch tree rows are greater than that of larch in zone between ash tree rows, indicating that ash is more powerful than larch in belowground competition. The spatial distribution feature of roots favors the growth of ash in the mixed stand.

  3. Interactions Between Pinus taeda (loblolly) Fine Roots and Soil Fungi: Impacts of Elevated CO2, N Availability, and Spatial Distribution of Fungi on Fine Root Persistence and Turnover

    Science.gov (United States)

    Strand, A.; Beidler, K.; McGlinn, D.; Pritchard, S. G.

    2016-12-01

    Fine root turnover represents the most significant mode of flux from plants into soil C pools. Unfortunately fine root senescence and decomposition, processes critical in turnover, are particularly understudied. For example, little is known about either the factors that influence fine-root decomposition or the fate of compounds they contain during root death. Better understanding fine root senescence and decomposition should reduce uncertainty associated with global climate models; including re-uptake of materials in dying leaves into these models has already been shown to increase their accuracy. Over 4400 individual fine-roots and 4734 rhizomorphs were tracked from initiation until disintegration over 12 years using minirhizotrons at the Duke FACE site. Image-based approaches such as minirhizotrons cannot directly assess fine-root physiological status. To assess fine-root function directly, we are now conducting manipulative experiments in P. taeda in which fine-root senescence is induced through two treatments, steam- and direct hand-girdling. Physiological status is then assessed by examining gene-expression, root anatomy and chemical composition of manipulated roots. Changing [CO2] did not change persistence times for roots, but did impact rhizomorph persistence. Both roots and rhizomorphs showed interactions between effects of N and CO2 on persistence. Most interesting is the interaction between fine-roots and rhizomorphs: fine root persistence times are reduced in the presence of rhizomorphs, but this effect depends on the amount of N available. Finally, we found experimentally inducing senescence via steam girdling to be very effective relative to hand-girdling. These results provide evidence of the importance of priming on function of soil fungi and the role of N availability on fine-root turnover. The ability to stimulate fine-root senescence provides a powerful experimental tool to examine the fates of resources contained in fine-root pools as these

  4. Species-specific fine root biomass distribution alters competition in mixed forests under climate change

    Science.gov (United States)

    Reyer, Christopher; Gutsch, Martin; Lasch, Petra; Suckow, Felicitas; Sterck, Frank; Mohren, Frits

    2010-05-01

    The importance of mixed forests in European silviculture has increased due to forest conversion policies and multifunctional forest management. Concurrently, evidences for substantial impacts of climate change on forest ecosystems accumulate. Projected drier and warmer conditions alter the water relations of tree species, their growth and ultimately their inter-specific competition in mixed stands. Process-based models are scientific tools to study the impact of climate change on and to deepen the understanding of the functioning of these systems based on ecological mechanisms. They allow for long-term, stand-level studies of forest dynamics which could only be addressed with great difficulty in an experimental or empirical setup. We used the process-based forest model 4C to simulate inter-specific competition in mixed stands of Douglas-fir (Pseudotsuga menziesii) and Common beech (Fagus sylvatica) as well as Scots pine (Pinus sylvestris) and Sessile / Pedunculate oak (Quercus petraea and Quercus robur) under a) historical climate for model verification and b) under climate change scenario realizations of the climate model STAR 2.0 in Brandenburg, Germany. Some of the climate change scenario realizations feature a substantially drier and warmer summer climate which decreases the climatic water balance during the growing season. We assumed species-specific fine root biomass distributions which feature broadleaved fine roots in deeper soil layers and coniferous fine roots in upper soil layers according to several root excavation studies from mixed stands. The stands themselves were constructed from yield tables of the contributing species. The model verification provided good results for the basal area predictions under the historical climate. Under climate change, the number of days when the tree water demand exceeded the soil water supply was higher for the coniferous species than for broadleaved species. Furthermore, after 45 simulation years the basal area

  5. Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees.

    Science.gov (United States)

    Artacho, Pamela; Bonomelli, Claudia

    2016-05-01

    Factors regulating fine-root growth are poorly understood, particularly in fruit tree species. In this context, the effects of N addition on the temporal and spatial distribution of fine-root growth and on the fine-root turnover were assessed in irrigated sweet cherry trees. The influence of other exogenous and endogenous factors was also examined. The rhizotron technique was used to measure the length-based fine-root growth in trees fertilized at two N rates (0 and 60 kg ha(-1)), and the above-ground growth, leaf net assimilation, and air and soil variables were simultaneously monitored. N fertilization exerted a basal effect throughout the season, changing the magnitude, temporal patterns and spatial distribution of fine-root production and mortality. Specifically, N addition enhanced the total fine-root production by increasing rates and extending the production period. On average, N-fertilized trees had a length-based production that was 110-180% higher than in control trees, depending on growing season. Mortality was proportional to production, but turnover rates were inconsistently affected. Root production and mortality was homogeneously distributed in the soil profile of N-fertilized trees while control trees had 70-80% of the total fine-root production and mortality concentrated below 50 cm depth. Root mortality rates were associated with soil temperature and water content. In contrast, root production rates were primarily under endogenous control, specifically through source-sink relationships, which in turn were affected by N supply through changes in leaf photosynthetic level. Therefore, exogenous and endogenous factors interacted to control the fine-root dynamics of irrigated sweet cherry trees.

  6. Comparing growth and fine root distribution in monocultures and mixed plantations of hybrid poplar and spruce

    Institute of Scientific and Technical Information of China (English)

    Lahcen Benomar; Annie DesRochers; Guy R.Larocque

    2013-01-01

    Disease prevention,biodiversity,productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations.The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones,P.balsamifera x trichocarpa (PBT) and P.maximowiczii x balsamifera (PMB),one improved family of Norway spruce (Picea glauca (PA)) and one improved family of white spruce (Picea abies (PG)) growing under different spacings in monocultures and mixed plots.The plantations were established in 2003 in Abitibi-Témiscamingue,Quebec,Canada,in a split plot design with spacing as the whole plot factor (1 × 1 m,3 × 3 m and 5 × 5 m) and mixture treatments as subplot factor (pure:PBT,PMB,PA and PG,and 1:1 mixture PBT:PA,PBT:PG,PMB:PA and PMB:PG).Results showed a beneficial effect of the hybrid poplar-spruce mixture on diameter growth for hybrid poplar clones,but not for the 5 × 5 m spacing because of the relatively young age of the plantations.Diameter growth of the spruces decreased in mixed plantings in the 1 × 1 m,while their height growth increased,resulting in similar aboveground biomass per tree across treatments.Because of the large size differences between spruces and poplars,aboveground biomass in the mixed plantings was generally less than that in pure poplar plots.Leaf nitrogen concentration for the two spruce families and hybrid poplar clone PMB was greater in mixed plots than in monocultures,while leaf nitrogen concentration of clone PBT was similar among mixture treatments.Because of its faster growth rate and greater soil resources demands,clone PMB was the only one showing an increase in leaf N with increased spacing between trees.Fine roots density was greater for both hybrid poplars than spruces.The vertical distribution of fine roots was insensitive to mixture treatment.

  7. Relation between Growth and Vertical Distribution of Fine Roots and Soil Density in the Weibei Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhong; Li Peng; Xue Wenpeng; Guo Shengwu

    2006-01-01

    The influence of woodland soil bulk density on the growth and distribution of fine root system of main planting tree species in the Weibei Loess Plateau was investigated by means of pot culture and field survey.Results indicated that in the woodland of Pinus tabulaeformis,soil bulk density increased with the depth at different sites,while in the woodland of Robinia pseudoacacia,soil bulk density was higher than that in P.tabulaeformis,and there was no clear difference across the profile.Further analysis implied that there existed negative correlations between soil bulk density and fine root length in the woodland of P.tabulaeformis.Results from pot culture indicated that although the effects of pot culture media on the free root growth and development of different tree species seedlings were different,all treated seedlings grew better in the soil matter with medium bulk density and porosity and with the biggest biomass.Bulk density of pot culture media had clear effects on the growth and development of P.tabulaeformis and R.pseudoacacia seedling roots,especially on the former,whereas it had little effect on that of Platycladus orientalis and Prunus armeniaca var.ansu,whose fine root biomass changed little in different pot culture media.

  8. Dynamics of heterorhizic root systems: protoxylem groups within the fine-root system of Chamaecyparis obtusa.

    Science.gov (United States)

    Hishi, Takuo; Takeda, Hiroshi

    2005-08-01

    To understand the physiology of fine-root functions in relation to soil organic sources, the heterogeneity of individual root functions within a fine-root system requires investigation. Here the heterogeneous dynamics within fine-root systems are reported. The fine roots of Chamaecyparis obtusa were sampled using a sequential ingrowth core method over 2 yr. After color categorization, roots were classified into protoxylem groups from anatomical observations. The root lengths with diarch and triarch groups fluctuated seasonally, whereas the tetrarch root length increased. The percentage of secondary root mortality to total mortality increased with increasing amounts of protoxylem. The carbon : nitrogen ratio indicated that the decomposability of primary roots might be greater than that of secondary roots. The position of diarch roots was mostly apical, whereas tetrarch roots tended to be distributed in basal positions within the root architecture. We demonstrate the heterogeneous dynamics within a fine-root system of C. obtusa. Fine-root heterogeneity should affect soil C dynamics. This heterogeneity is determined by the branching position within the root architecture.

  9. Fine root production at drained peatland sites

    Energy Technology Data Exchange (ETDEWEB)

    Finer, L. [Finnish Forest Research Inst. (Finland). Joensuu Research Station; Laine, J. [Helsinki Univ. (Finland). Dept. of Forest Ecology

    1996-12-31

    The preliminary results of the Finnish project `Carbon balance of peatlands and climate change` show that fine roots play an important role in carbon cycling on peat soils. After drainage the roots of mire species are gradually replaced by the roots of trees and other forest species. Pine fine root biomass reaches a maximum level by the time of crown closure, some 20 years after drainage on pine mire. The aim of this study is to compare the results of the sequential coring method and the ingrowth bag method used for estimating fine root production on three drained peatland sites of different fertility. The results are preliminary and continuation to the work done in the study Pine root production on drained peatlands, which is part of the Finnish project `Carbon cycling on peatlands and climate change`. In this study the fine root biomass was greater on the poor site than on the rich sites. Pine fine root production increased with the decrease in fertility. Root turnover and the production of field layer species were greater on the rich sites than on the poor site. The results suggested that the in growth bag method measured more root activity than the magnitude of production. More than two growing seasons would have been needed to balance the root dynamics in the in growth bags with the surrounding soil. That time would probably have been longer on the poor site than on the rich ones and longer for pine and field layer consisting of dwarf shrubs than for field layer consisting of sedge like species and birch. (11 refs.)

  10. Tree species richness affecting fine root biomass in European forests

    Science.gov (United States)

    Finér, Leena; Domisch, Timo; Vesterdal, Lars; Dawud, Seid M.; Raulund-Rasmussen, Karsten

    2016-04-01

    Fine roots are an important factor in the forest carbon cycle, contributing significantly to below-ground biomass and soil carbon storage. Therefore it is essential to understand the role of the forest structure, indicated by tree species diversity in controlling below-ground biomass and managing the carbon pools of forest soils. We studied how tree species richness would affect fine root biomass and its distribution in the soil profile and biomass above- and below-ground allocation patterns of different tree species. Our main hypothesis was that increasing tree species richness would lead to below-ground niche differentiation and more efficient soil exploitation by the roots, resulting in a higher fine root biomass in the soil. We sampled fine roots of trees and understorey vegetation in six European forest types in Finland, Poland, Germany, Romania, Italy and Spain, representing boreal, temperate and Mediterranean forests, established within the FunDivEUROPE project for studying the effects of tree species diversity on forest functioning. After determining fine root biomasses, we identified the percentages of different tree species in the fine root samples using the near infrared reflectance spectroscopy (NIRS) method. Opposite to our hypothesis we did not find any general positive relationship between tree species richness and fine root biomass. A weak positive response found in Italy and Spain seemed to be related to dry environmental conditions during Mediterranean summers. At the Polish site where we could sample deeper soil layers (down to 40 cm), we found more tree fine roots in the deeper layers under species-rich forests, as compared to the monocultures, indicating the ability of trees to explore more resources and to increase soil carbon stocks. Tree species richness did not affect biomass allocation patterns between above- and below-ground parts of the trees.

  11. Fine Root Patterning and Balanced Inorganic Phosphorus Distribution in the Soil Indicate Distinctive Adaptation of Maize Plants to Phosphorus Deficiency

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu; YU Peng; PENG Yun-Feng; LI Xue-Xian; CHEN Fan-Jun; LI Chun-Jian

    2012-01-01

    Plants have diverse strategies to cope with phosphorus (P) deficiency.To better understand how maize responds to P deficiency,a field experiment with two P levels,0 and 100 kg P2O5 ha-1 (P0 and P100,respectively),was carried out as a part of a long-term Pfertilizer field trial.Plant and soil analyses showed that P-deficient maize reduced its growth rate,increased P use efficiency,and formed more thin roots with the diameter less than 0.6 mm at jointing and silking stages,compared to the plants treated with P100.Further,there were no differences in major inorganic P fractions (Ca2-P,Ca8-P,A1-P,Fe-P,occluded P and Ca10-P) between the rhizospheric and bulk soils at each harvest,even when soil Olsen-P was only 1.38 mg kg-1.These results suggested that maize responded to P deficiency by reducing the internal P demand for growth and increasing P acquisition ability by favorable root morphological alteration at low carbon cost.

  12. Changes in arbuscular mycorrhizal associations and fine root traits in sites under different plant successional phases in southern Brazil.

    Science.gov (United States)

    Zangaro, Waldemar; de Assis, Rafael Leandro; Rostirola, Leila Vergal; de Souza, Priscila Bochi; Gonçalves, Melissa Camargo; Andrade, Galdino; Nogueira, Marco Antonio

    2008-12-01

    Fine root morphological traits and distribution, arbuscular mycorrhizal (AM) fungi, soil fertility, and nutrient concentration in fine root tissue were compared in sites under different successional phases: grass plants, secondary forest, and mature forest in Londrina county, Paraná state, southern Brazil. Soil cores were collected randomly at the 0-10- and 10-20-cm depths in three quadrants (50 m2) in each site. Plants from the different successional stages displayed high differences in fine root distribution, fine root traits, and mycorrhizal root colonization. There were increases in the concentration of nutrients both in soil and fine roots and decrease of bulk soil density along the succession. The fine root biomass and diameter increased with the succession progress. The total fine root length, specific root length, root hair length, and root hair incidence decreased with the succession advance. Similarly, the mycorrhizal root colonization and the density of AM fungi spores in the soil decreased along the succession. Mycorrhizal root colonization and spore density were positively correlated with fine root length, specific root length, root hair length, root hair incidence, and bulk density and negatively correlated with fine root diameter and concentration of some nutrients both in soil and root tissues. Nutrient concentration in root tissue and in soil was positively correlated with fine root diameter and negatively correlated with specific root length, root hair length, and root hair incidence. These results suggest different adaptation strategies of plant roots for soil exploration and mineral acquisition among the different successional stages. Early successional stages displayed plants with fine root morphology and AM fungi colonization to improve the root functional efficiencies for uptake of nutrients and faster soil resource exploration. Late successional stages displayed plants with fine root morphology and mycorrhizal symbiosis for both a lower

  13. Effects of fine root length density and root biomass on soil preferential flow in forest ecosystems

    Directory of Open Access Journals (Sweden)

    Yinghu Zhang

    2015-04-01

    Full Text Available Aim of study: The study was conducted to characterize the impacts of plant roots systems (e.g., root length density and root biomass on soil preferential flow in forest ecosystems. Area of study: The study was carried out in Jiufeng National Forest Park, Beijing, China. Material and methods: The flow patterns were measured by field dye tracing experiments. Different species (Sophora japonica Linn,Platycladus orientalis Franco, Quercus dentata Thunbwere quantified in two replicates, and 12 soil depth were applied. Plant roots were sampled in the sieving methods. Root length density and root biomass were measured by WinRHIZO. Dye coverage was implied in the image analysis, and maximum depth of dye infiltration by direct measurement. Main results: Root length density and root biomass decreased with the increasing distance from soil surface, and root length density was 81.6% higher in preferential pathways than in soil matrix, and 66.7% for root biomass with respect to all experimental plots. Plant roots were densely distributed in the upper soil layers. Dye coverage was almost 100% in the upper 5-10 cm, but then decreased rapidly with soil depth. Root length density and root biomass were different from species: Platycladus orientalis Franco > Quercus dentata Thunb > Sophora japonica Linn. Research highlights: The results indicated that fine roots systems had strong effects on soil preferential flow, particularly root channels enhancing nutrition transport across soil profiles in forest dynamics.

  14. Effects of spatiotemporal variation of soil salinity on fine root distribution in different plant configuration modes in new reclamation coastal saline field.

    Science.gov (United States)

    Jiang, Hong; Du, Hongyu; Bai, Yingying; Hu, Yue; Rao, Yingfu; Chen, Chong; Cai, Yongli

    2016-04-01

    In order to study the effects of salinity on plant fine roots, we considered three different plant configuration modes (tree stand model (TSM), shrub stand model (SSM), and tree-shrub stand model (TSSM)). Soil samples were collected with the method of soil drilling. Significant differences of electrical conductivity (EC) in the soil depth of 0-60 cm were observed among the three modes (p salinity among various soil layers and monthly variation of soil salinity were the highest in SSM and reached 2.30 and 2.23 mS/cm (EC1:5), respectively. Due to the effect of salinity, fine root biomass (FRB) showed significant differences in different soil depths (p salinity should be below 1.5 mS/cm, which was suitable for the growth of plant roots. Among the three modes, TSSM had the highest FRB, SRL, and FRLD and no obvious soil salt accumulation was observed. The results indicated that fine root biomass was affected by high salt and that TSSM had the strong effects of salt suppression and control. In our study, TSSM may be the optimal configuration mode for salt suppression and control in saline soil.

  15. Fine-root mortality rates in a temperate forest: Estimates using radiocarbon data and numerical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Riley, W.J.; Gaudinski, J.B.; Torn, M.S.; Joslin, J.D.; Hanson, P.J.

    2009-09-01

    We used an inadvertent whole-ecosystem {sup 14}C label at a temperate forest in Oak Ridge, Tennessee, USA to develop a model (Radix1.0) of fine-root dynamics. Radix simulates two live-root pools, two dead-root pools, non-normally distributed root mortality turnover times, a stored carbon (C) pool, and seasonal growth and respiration patterns. We applied Radix to analyze measurements from two root size classes (< 0.5 and 0.5-2.0 mm diameter) and three soil-depth increments (O horizon, 0-15 cm and 30-60 cm). Predicted live-root turnover times were < 1 yr and 10 yr for short- and long-lived pools, respectively. Dead-root pools had decomposition turnover times of 2 yr and 10 yr. Realistic characterization of C flows through fine roots requires a model with two live fine-root populations, two dead fine-root pools, and root respiration. These are the first fine-root turnover time estimates that take into account respiration, storage, seasonal growth patterns, and non-normal turnover time distributions. The presence of a root population with decadal turnover times implies a lower amount of belowground net primary production used to grow fine-root tissue than is currently predicted by models with a single annual turnover pool.

  16. [Response of fine roots to soil nutrient spatial heterogeneity].

    Science.gov (United States)

    Wang, Qingcheng; Cheng, Yunhuan

    2004-06-01

    The spatial heterogeneity is the complexity and variation of systems or their attributes, and the heterogeneity of soil nutrients is ubiquitous in all natural ecosystems. The scale of spatial heterogeneity varies considerably among different ecosystems, from tens of centimeters to hundred meters. Some of the scales can be detected by individual plant. Because the growth of individual plants can be strongly influenced by soil heterogeneity, it follows that the inter-specific competition should also be affected. During the long process of evolution, plants developed various plastic responses with their root system, including morphological, physiological and mycorrhizal plasticity, to maximize the nutrient acquisition from heterogeneous soil resources. Morphological plasticity, an adjustment in root system spatial allocation and architecture in response to spatial heterogeneous distribution of available soil resources, has been most intensively studied, and root proliferation in nutrient rich patches has been certified for many species. The species that do respond may have an increased rate of nutrient uptake, leading to a competitive advantage. Scale and precision are two important features employed in describing the size and foraging behavior of root system. It was hypothesized that scale and precision is negatively related, i. e., the species with high scale of root system tend to be a less precise forager. The outcomes of different research work have been diverse, far from reaching a consensus. Species with high scale are not necessarily less precise in fine root allocation, and vice versa. The proliferation of fine root in enriched micro-sites is species dependent, and also affected by other factors, such as patch attributes (size and nutrients concentration), nutrients, and overall soil fertility. Beside root proliferation in nutrient enriched patches, plants can also adapt themselves to the heterogeneous soil environment by altering other root characteristics

  17. Regional scale patterns of fine root lifespan and turnover under current and future climate.

    Science.gov (United States)

    McCormack, Luke M; Eissenstat, David M; Prasad, Anantha M; Smithwick, Erica A H

    2013-06-01

    Fine root dynamics control a dominant flux of carbon from plants and into soils and mediate potential uptake and cycling of nutrients and water in terrestrial ecosystems. Understanding of these patterns is needed to accurately describe critical processes like productivity and carbon storage from ecosystem to global scales. However, limited observations of root dynamics make it difficult to define and predict patterns of root dynamics across broad spatial scales. Here, we combine species-specific estimates of fine root dynamics with a model that predicts current distribution and future suitable habitat of temperate tree species across the eastern United States (US). Estimates of fine root lifespan and turnover are based on empirical observations and relationships with fine root and whole-plant traits and apply explicitly to the fine root pool that is relatively short-lived and most active in nutrient and water uptake. Results from the combined model identified patterns of faster root turnover rates in the North Central US and slower turnover rates in the Southeastern US. Portions of Minnesota, Ohio, and Pennsylvania were also predicted to experience >10% increases in root turnover rates given potential shifts in tree species composition under future climate scenarios while root turnover rates in other portions of the eastern US were predicted to decrease. Despite potential regional changes, the average estimates of root lifespan and turnover for the entire study area remained relatively stable between the current and future climate scenarios. Our combined model provides the first empirically based, spatially explicit, and spatially extensive estimates of fine root lifespan and turnover and is a potentially powerful tool allowing researchers to identify reasonable approximations of forest fine root turnover in areas where no direct observations are available. Future efforts should focus on reducing uncertainty in estimates of root dynamics by better understanding how

  18. The effect of tree species diversity on fine-root production in a young temperate forest.

    Science.gov (United States)

    Lei, Pifeng; Scherer-Lorenzen, Michael; Bauhus, Jürgen

    2012-08-01

    The phenomenon of overyielding in species-diverse plant communities is mainly attributed to complementary resource use. Vertical niche differentiation belowground might be one potential mechanism for such complementarity. However, most studies that have analysed the diversity/productivity relationship and belowground niche differentiation have done so for fully occupied sites, not very young tree communities that are in the process of occupying belowground space. Here we used a 5–6 year old forest diversity experiment to analyse how fine-root (tree species identity, as well as the species diversity and richness of tree neighbourhoods. Fine-root production during the first growing season after the installation of ingrowth cores increased slightly with tree species diversity, and four-species combinations produced on average 94.8% more fine-root biomass than monocultures. During the second growing season, fine-root mortality increased with tree species diversity, indicating an increased fine-root turnover in species-rich communities. The initial overyielding was attributable to the response to mixing by the dominant species, Pseudotsuga menziesii and Picea abies, which produced more fine roots in mixtures than could be expected from monocultures. In species-rich neighbourhoods, P. abies allocated more fine roots to the upper soil layer (0–15 cm), whereas P. menziesii produced more fine roots in the deeper layer (15–30 cm) than in species-poor neighbourhoods. Our results indicate that, although there may be no lasting overyielding in the fine-root production of species-diverse tree communities, increasing species diversity can lead to substantial changes in the production, vertical distribution, and turnover of fine roots of individual species.

  19. Adaptation of fine roots to annual fertilization and irrigation in a 13-year-old Pinus pinaster stand.

    Science.gov (United States)

    Bakker, M R; Jolicoeur, E; Trichet, P; Augusto, L; Plassard, C; Guinberteau, J; Loustau, D

    2009-02-01

    Effects of fertilization and irrigation on fine roots and fungal hyphae were studied in 13-year-old maritime pine (Pinus pinaster Aït. in Soland), 7 years after the initiation of the treatments. The fertilization trials consisted of a phosphorus treatment, a complete fertilizer treatment (N, P, K, Ca and Mg), and an unfertilized treatment (control). Fertilizers were applied annually and were adjusted according to foliar target values. Two irrigation regimes (no irrigation and irrigation of a set amount each day) were applied from May to October. Root samples to depths of 120 cm were collected in summer of 2005, and the biomass of small roots (diameter 2-20 mm) and fine roots (diameter fertilizer treatments reduced the size of the fine root system, especially in the top soil layers, but did not affect small roots. Compared with control treatments, fine root morphology was affected by both fertilizer treatments with the fine roots having increased specific root length/area, and irrigation tended to reinforce this finer morphology. The amount of hyphae in the mesh ingrowth bags was higher in the fertilization and irrigation treatments than in the controls, suggesting further extension of the root system (ectomycorrhizal infection) and thus of the uptake system. Irrigation had no significant effect on the size of the fine root system, but resulted in a shallower rooting system. Total root to shoot ratios were unaffected by the treatments, but fine root mass:needle mass and fine root area index:leaf area index ratios decreased with increasing nutrient supply. Overall, compared with the control fine roots, increased nutrient supply resulted in a lower fine root biomass but the dynamic fraction of the finest roots was greater. Irrigation had only limited effects on fine root size, distribution and morphology.

  20. Acclimation of fine root respiration to soil warming involves starch deposition in very fine and fine roots: a case study in Fagus sylvatica saplings.

    Science.gov (United States)

    Di Iorio, Antonino; Giacomuzzi, Valentino; Chiatante, Donato

    2016-03-01

    Root activities in terms of respiration and non-structural carbohydrates (NSC) storage and mobilization have been suggested as major physiological roles in fine root lifespan. As more frequent heat waves and drought periods within the next decades are expected, to what extent does thermal acclimation in fine roots represent a mechanism to cope with such upcoming climatic conditions? In this study, the possible changes in very fine (diameter Fagus sylvatica saplings subjected to a simulated long-lasting heat wave event and to co-occurring soil drying. For both very fine and fine roots, soil temperature (ST) resulted inversely correlated with specific root length, respiration rates and SSs concentration, but directly correlated with root mass, root tissue density and starch concentration. In particular, starch concentration increased under 28 °C for successively decreasing under 21 °C ST. These findings showed that thermal acclimation in very fine and fine roots due to 24 days exposure to high ST (∼ 28 °C), induced starch accumulation. Such 'carbon-savings strategy' should bear the maintenance costs associated to the recovery process in case of restored favorable environmental conditions, such as those occurring at the end of a heat wave event. Drought condition seems to affect the fine root vitality much more under moderate than high temperature condition, making the temporary exposure to high ST less threatening to root vitality than expected.

  1. Transitory effects of elevated atmospheric CO₂ on fine root dynamics in an arid ecosystem do not increase long-term soil carbon input from fine root litter.

    Science.gov (United States)

    Ferguson, Scot D; Nowak, Robert S

    2011-06-01

    Experimental increases in atmospheric CO₂ often increase root production over time, potentially increasing soil carbon (C) sequestration. Effects of elevated atmospheric CO₂ on fine root dynamics in a Mojave desert ecosystem were examined for the last 4.5 yr of a long-term (10-yr) free air CO₂ enrichment (FACE) study at the Nevada desert FACE facility (NDFF). Sets of minirhizotron tubes were installed at the beginning of the NDFF experiment to characterize rooting dynamics of the dominant shrub Larrea tridentata, the codominant shrub Ambrosia dumosa and the plant community as a whole. Although significant treatment effects occurred sporadically for some fine root measurements, differences were transitory and often in opposite directions during other time-periods. Nonetheless, earlier root growth under elevated CO₂ helped sustain increased assimilation and shoot growth. Overall CO₂ treatment effects on fine root standing crop, production, loss, turnover, persistence and depth distribution were not significant for all sampling locations. These results were similar to those that occurred near the beginning of the NDFF experiment but unlike those in other ecosystems. Thus, increased C input into soils is unlikely to occur from fine root litter under elevated atmospheric CO₂ in this arid ecosystem.

  2. Unresolving the "real age" of fine roots in forest ecosystems

    Science.gov (United States)

    Solly, Emily; Brunner, Ivano; Herzog, Claude; Schöning, Ingo; Schrumpf, Marion; Schweigruber, Fritz; Trumbore, Susan; Hagedorn, Frank

    2016-04-01

    Estimating the turnover time of tree fine roots is crucial for modelling soil organic matter dynamics, but it is one of the biggest challenges in soil ecology and one of the least understood aspects of the belowground carbon cycle. The methods used - ranging from radiocarbon to ingrowth cores and root cameras (minirhizotrons) - yield very diverse pictures of fine root dynamics in forest ecosystems with turnover rates reaching from less than one year to decades. These have huge implications on estimates of carbon allocation to root growth and maintenance and on the persistence of root carbon in soils before it is decomposed or leached. We will present a new approach, involving techniques to study plant anatomy, which unravels the "real age" of fine roots. For a range of forests with diverse water and nutrient limitations located at different latitudes, we investigated the annual growth rings in the secondary xylem of thin transversal sections of fine roots belonging to tree species which form distinct growth rings. In temperate forests we find mean root "ring ages" of 1-2 years while in sub-arctic forests living fine roots can also persist for several years. The robustness of these results were tested by counting the maximum yearly growth rings in tree seedlings of known age and by counting the maximum number of growth rings of fine roots grown in ingrowth cores which were kept in temperate forest soils for one and two years. Radiocarbon estimates of mean "carbon ages", which define the time elapsed since structural carbon was fixed from the atmosphere, instead average around a decade in root systems of temperate forests (mixture of newly produced and older living roots). This dramatic difference may not be related to methodological bias, but to a time lag between C assimilation and production of a portion of fine root tissues due to the storage of older carbon components. The time lag depends very likely on tree species and environmental conditions. We further

  3. Spatial distribution and morphological variations of the fine roots in walnut-wheat intercropping agroforestry ecosystem%核桃-小麦复合系统中细根的分布及形态变异研究

    Institute of Scientific and Technical Information of China (English)

    王来; 仲崇高; 蔡靖; 姜在民; 张硕新

    2011-01-01

    【目的】研究核桃(Juglans regia)-小麦(Triticum aestivum)复合系统中细根的分布格局及形态变异,为种间关系研究及农林复合系统的合理设计提供依据。【方法】以核桃、小麦单作为对照,采用根钻法取样,用WinRHIZO根系分析系统对根系形态进行分析,比较核桃-小麦复合系统与单作系统中植物细根的空间分布和形态差异。【结果】①复合系统中核桃细根根长的垂直分布重心深度为35.49 cm,比核桃单作(29.97 cm)下移了5.52 cm;水平径向的分布重心为距树干基部0.91 m,比核桃单%【Objective】 This paper studied the distribution patterns and morphological variations of fine roots in walnut(Juglans regia)-wheat(Triticum aestivum) agroforestry system to provide theoretical basis for the interspecific relationship research and management of agroforestry ecosystem.【Method】 With walnut,wheat monocropping ecosystem as control,samples were collected by soil coring method.WinRHIZO root analysis system was conducted to measure root morphology parameters.Moreover,differences of the fine roots spatial distribution and morphological variations between the agroforestry ecosystem and monocropping ecosystem were analyzed.【Result】 ①The vertical gravity center of walnut fine root length in agroforestry ecosystem is 35.49 cm,compared with that in walnut monocropping ecosystem,which is 29.97 cm,moving down 5.52 cm.The distance between the radial gravity centers of walnut fine root length and the tree in agroforestry ecosystem is 0.91 m,which is 0.08 m closer to the tree than that(0.99 m) of walnut in monocropping ecosystem.The vertical gravity center of wheat root length in agroforestry ecosystem is 18.46 cm,compared with that in wheat monocropping ecosystem,which is 26.04 cm,moving up 7.58 cm.②The total mean root length density of walnuts in agroforestry ecosystem is 83.6 cm/dm3,which is 135.6 cm/dm3 in walnut monocropping

  4. Variations of fine root diameter with root order in Manchurian ash and Dahurian larch plantations

    Institute of Scientific and Technical Information of China (English)

    WANG Xiangrong; WANG Zhengquan; HAN Youzhi; GU Jiacun; GUO Dali; MEI Li

    2007-01-01

    Fine root lifespan and turnover play an important role in carbon allocation and nutrient cycling in forest ecosystems.Fine roots are typically defined as less than 1 or 2mm in diameter.However,when categorizing roots by this diameter size,the position of an individual root on the complex lateral branching pattern has often been ignored,and our knowledge about relationships between branching order and root function thus remains limited.More recently,studies on root survivals found that longevity was remarkably different in the same branching level due to diameter variations.The objectives of this study were:(1) To examine variations of fine root diameter from the first-to fifth-orders in Fraxinus mandshurica Rupr and Larix gmelinii Rupr roots;and (2) To reveal how the season,soil nutrient,and water availability affect root diameter in different branch order in two species.This study was conducted at Maoershan Forest Research Station (45°21'-45°25'N,127°30'-127°34'E) owned by Northeast Forestry University in Harbin,northeast China.Both F.mandshurica and L.gmelinii were planted in 1986.In each plantation,fine roots of two species by sampling up to five fine root branch orders three times during the 2003 growing season from two soil depths (i.e.,0-10 and 10-20 cm)were obtained.The results showed that average diameters of fine roots were significantly different among the five branch orders.The first-order had the thinner roots and the fifth order had the thickest roots,the diameter increasing regularly with the ascending branch orders in both species.If the diameter of fine roots was defined as being smaller than 0.5 mm,the first three orders ofF.mandshurica roots and the first two orders of L.gmelinii roots would be included in the fine root population.The diameter ranges of the fine roots from first-order to fifth-order were 0.15-0.58,0.18-0.70,0.26-1.05,0.36-1.43,and 0.71-2.96 mm for F.mandshurica,and 0.17-0.76,0.23-1.02,0.26-1.10,0.38-1.77,and 0.84-2.80 mm for L

  5. [Effects of tree species diversity on fine-root biomass and morphological characteristics in subtropical Castanopsis carlesii forests].

    Science.gov (United States)

    Wang, Wei-Wei; Huang, Jin-Xue; Chen, Feng; Xiong, De-Cheng; Lu, Zheng-Li; Huang, Chao-Chao; Yang, Zhi-Jie; Chen, Guang-Shui

    2014-02-01

    Fine roots in the Castanopsis carlesii plantation forest (MZ), the secondary forest of C. carlesii through natural regeneration with anthropogenic promotion (AR), and the secondary forest of C. carlesii through natural regeneration (NR) in Sanming City, Fujian Province, were estimated by soil core method to determine the influence of tree species diversity on biomass, vertical distribution and morphological characteristics of fine roots. The results showed that fine root biomass for the 0-80 cm soil layer in the MZ, AR and NR were (182.46 +/- 10.81), (242.73 +/- 17.85) and (353.11 +/- 16.46) g x m(-2), respectively, showing an increased tendency with increasing tree species diversity. In the three forests, fine root biomass was significantly influenced by soil depth, and fine roots at the 0-10 cm soil layer accounted for more than 35% of the total fine root biomass. However, the interaction of stand type and soil depth on fine-root distribution was not significant, indicating no influence of tree species diversity on spatial niche segregation in fine roots. Root surface area density and root length density were the highest in NR and lowest in the MZ. Specific root length was in the order of AR > MZ > NR, while specific root surface area was in the order of NR > MZ > AR. There was no significant interaction of stand type and soil depth on specific root length and specific root surface area. Fine root morphological plasticity at the stand level had no significant response to tree species diversity.

  6. Soil water and salt movement and spatial distribution of fine alfalfa roots under drip irrigation%滴灌苜蓿田间土壤水盐及苜蓿细根的空间分布

    Institute of Scientific and Technical Information of China (English)

    鲁为华; 任爱天; 杨洁晶; 于磊; 马春晖; 张前兵

    2014-01-01

    为了明确滴灌苜蓿土壤水、盐运移,细根分布及细根生物量动态,该文对苜蓿进行滴灌和漫灌试验,结果表明,漫灌水分集中在15 cm浅层土壤内且分布均匀,含水率在19.5%~20.5%之间。滴灌水分高值区集中在水平方向距滴头15 cm,深度为40 cm的土层中,含水率达到18.0%~20.0%。漫灌对0~25 cm深度土层盐分淋洗作用明显,土水比1:5土壤水提液的电导率由灌前的0.4~0.5 mS/cm下降到0.3 mS/cm以下;滴灌可使根区盐分下降至0.2 mS/cm,显著低于灌溉初始的盐分含量(P<0.05)。与漫灌比较,滴灌苜蓿细根集中分布在水平方向距滴头0~30 cm,垂直深度0~50 cm范围内。生长季各时间节点滴灌细根总量高于漫灌,其平均值分别为211.6和198.3 g/m2。滴灌和漫灌各时间节点细根量表现出明显的波动,其范围分别在193.2~243.6和182.7~219.1 g/m2之间。在整个生长期内,滴灌活根量高于漫灌,且生长前期滴灌死根量变化较漫灌平稳。活细根和死细根之间的周转使得两者呈现出此消彼涨的状态,表明细根具有生长-凋亡-再生长的周期性。该研究可为滴灌技术在苜蓿栽培上的应用提供参考。%Drip irrigation is being effectively used for alfalfa production in arid northwest China. The objectives of this paper were:i) to compare the effects of flood and drip irrigation on the spatial distribution of water and salt;ii) to compare effects of biomass, spatial distribution and dynamics of fine roots of alfalfa on the movement of water and salt in the soil profile under flood and drip irrigation. From May to October 2012, the plot experiments were carried out in Xinjiang Province. Flood irrigation (irrigation quantity is 4 600 m3/hm2) and drip irrigation treatments were set up (irrigation quantity is 4 200 m3/hm2), alfalfa planted in wide-narrow row plantation with a distance of 15 cm + 30 cm + 15 cm between rows. The

  7. Fine Root Productivity and Dynamics on a Forested Floodplain in South Carolina

    Science.gov (United States)

    Terrell T. Baker; William Conner; H. B. Graeme Lockaby; John A. Stanturf; Marianne K. Burke

    2001-01-01

    The highly dynamic, fine root component of forested wetland ecosystems fine root dynamics is a challenging endeavor in any system, but the difficulties are particularly evident in forested floodplains where frequent hydrologic fluctuations directly influence fine root dynamics. Fine root (53 mm) biomass, production, and turnover were estimated for three soils...

  8. Fine roots and ectomycorrhizas as indicators of environmental change.

    NARCIS (Netherlands)

    Cudlin, P.; Kieliszewska-Rokicka, B.; Rudawska, M.; Grebenc, T.; Alberton, O.; Lehto, T.; Bakker, M.R.; Borja, I.; Konopka, B.; Leski, T.; Kraigher, H.; Kuyper, T.W.

    2007-01-01

    Human-induced and natural stress factors can affect fine roots and ectomycorrhizas. Therefore they have potential utility as indicators of environmental change. We evaluated, through meta-analysis, the magnitude of the effects of acidic deposition, nitrogen deposition, increased ozone levels,

  9. Applicability of optical scanner method for fine root dynamics

    Science.gov (United States)

    Kume, Tomonori; Ohashi, Mizue; Makita, Naoki; Khoon Kho, Lip; Katayama, Ayumi; Matsumoto, Kazuho; Ikeno, Hidetoshi

    2016-04-01

    Fine root dynamics is one of the important components in forest carbon cycling, as ~60 % of tree photosynthetic production can be allocated to root growth and metabolic activities. Various techniques have been developed for monitoring fine root biomass, production, mortality in order to understand carbon pools and fluxes resulting from fine roots dynamics. The minirhizotron method is now a widely used technique, in which a transparent tube is inserted into the soil and researchers count an increase and decrease of roots along the tube using images taken by a minirhizotron camera or minirhizotron video camera inside the tube. This method allows us to observe root behavior directly without destruction, but has several weaknesses; e.g., the difficulty of scaling up the results to stand level because of the small observation windows. Also, most of the image analysis are performed manually, which may yield insufficient quantitative and objective data. Recently, scanner method has been proposed, which can produce much bigger-size images (A4-size) with lower cost than those of the minirhizotron methods. However, laborious and time-consuming image analysis still limits the applicability of this method. In this study, therefore, we aimed to develop a new protocol for scanner image analysis to extract root behavior in soil. We evaluated applicability of this method in two ways; 1) the impact of different observers including root-study professionals, semi- and non-professionals on the detected results of root dynamics such as abundance, growth, and decomposition, and 2) the impact of window size on the results using a random sampling basis exercise. We applied our new protocol to analyze temporal changes of root behavior from sequential scanner images derived from a Bornean tropical forests. The results detected by the six observers showed considerable concordance in temporal changes in the abundance and the growth of fine roots but less in the decomposition. We also examined

  10. Do ectomycorrhizal and arbuscular mycorrhizal temperate tree species systematically differ in root order based fine root morphology and biomass?

    Directory of Open Access Journals (Sweden)

    Petra eKubisch

    2015-02-01

    Full Text Available While most temperate broad-leaved tree species form ectomycorrhizal (EM symbioses, a few species have arbuscular mycorrhizas (AM. It is not known whether EM and AM tree species differ systematically with respect to fine root morphology, fine root system size and root functioning. In a species-rich temperate mixed forest, we studied the fine root morphology and biomass of three EM and three AM tree species from the genera Acer, Carpinus, Fagus, Fraxinus and Tilia searching for principal differences between EM and AM trees. We further assessed the evidence of convergence or divergence in root traits among the six co-occurring species. Eight fine root morphological and chemical traits were investigated in root segments of the first to fourth root order in three different soil depths and the relative importance of the factors root order, tree species and soil depth for root morphology was determined. Root order was more influential than tree species while soil depth had only a small effect on root morphology All six species showed similar decreases in specific root length and specific root area from the 1st to the 4th root order, while the species patterns differed considerably in root tissue density, root N concentration, and particularly with respect to root tip abundance. Most root morphological traits were not significantly different between EM and AM species (except for specific root area that was larger in AM species, indicating that mycorrhiza type is not a key factor influencing fine root morphology in these species. The order-based root analysis detected species differences more clearly than the simple analysis of bulked fine root mass. Despite convergence in important root traits among AM and EM species, even congeneric species may differ in certain fine root morphological traits. This suggests that, in general, species identity has a larger influence on fine root morphology than mycorrhiza type.

  11. Patterns in soil fertility and root herbivory interact to influence fine-root dynamics.

    Science.gov (United States)

    Stevens, Glen N; Jones, Robert H

    2006-03-01

    Fine-scale soil nutrient enrichment typically stimulates root growth, but it may also increase root herbivory, resulting in trade-offs for plant species and potentially influencing carbon cycling patterns. We used root ingrowth cores to investigate the effects of microsite fertility and root herbivory on root biomass in an aggrading upland forest in the coastal plain of South Carolina, USA. Treatments were randomly assigned to cores from a factorial combination of fertilizer and insecticide. Soil, soil fauna, and roots were removed from the cores at the end of the experiment (8-9 mo), and roots were separated at harvest into three diameter classes. Each diameter class responded differently to fertilizer and insecticide treatments. The finest roots (root biomass, were the only ones to respond significantly to both treatments, increasing when fertilizer and when insecticide were added (each P root-feeding insects have a strong influence on root standing crop with stronger herbivore impacts on finer roots and within more fertile microsites. Thus, increased vulnerability to root herbivory is a potentially significant cost of root foraging in nutrient-rich patches.

  12. Calculation procedures to estimate fine root production rates in forests using two-dimensional fine root data obtained by the net sheet method.

    Science.gov (United States)

    Noguchi, Kyotaro; Tanikawa, Toko; Inagaki, Yoshiyuki; Ishizuka, Shigehiro

    2017-06-01

    Several recent studies have used the net sheet method to estimate fine root production rates in forest ecosystems, wherein net sheets are inserted into the soil and fine roots growing through them are observed. Although this method has advantages in terms of its easy handling and low cost, there are uncertainties in the estimates per unit soil volume or unit stand area, because the net sheet is a two-dimensional material. Therefore, this study aimed to establish calculation procedures for estimating fine root production rates from two-dimensional fine root data on net sheets. This study was conducted in a hinoki cypress (Chamaecyparis obtusa (Sieb. & Zucc.) Endl.) stand in western Japan. We estimated fine root production rates in length and volume from the number (RN) and cross-sectional area (RCSA) densities, respectively, for fine roots crossing the net sheets, which were then converted to dry mass values. For these calculations, we used empirical regression equations or theoretical equations between the RN or RCSA densities on the vertical walls of soil pits and fine root densities in length or volume, respectively, in the soil, wherein the theoretical equations assumed random orientation of the growing fine roots. The estimates of mean fine root (diameter sheets using these calculation procedures, with the empirical regression equations reflecting fine root orientation in the study site. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Redefining fine roots improves understanding of below-ground contributions to terrestrial biosphere processes.

    Science.gov (United States)

    McCormack, M Luke; Dickie, Ian A; Eissenstat, David M; Fahey, Timothy J; Fernandez, Christopher W; Guo, Dali; Helmisaari, Heljä-Sisko; Hobbie, Erik A; Iversen, Colleen M; Jackson, Robert B; Leppälammi-Kujansuu, Jaana; Norby, Richard J; Phillips, Richard P; Pregitzer, Kurt S; Pritchard, Seth G; Rewald, Boris; Zadworny, Marcin

    2015-08-01

    Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain because of the challenges of consistently measuring and interpreting fine-root systems. Traditionally, fine roots have been defined as all roots ≤ 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. Here, we demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, fine roots are either separated into individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine-root pool. Using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally - a c. 30% reduction from previous estimates assuming a single fine-root pool. Future work developing tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi into fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand below-ground processes in the terrestrial biosphere.

  14. Growth dynamics of fine roots in a coniferous fern forest site close to Forsmark in the central part of Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Hans; Stadenberg, Ingela (SLU, Dept. of Ecology and Environmental Research, Uppsala (Sweden))

    2007-12-15

    The seasonal growth dynamics of live and dead roots for trees and the field layer species (g/m2, varying diameter fractions) and live/dead ratios were analysed at a fresh/moist coniferous fern forest site close to the nuclear power plant at Forsmark in the central eastern parts of Sweden. The changes in depth distribution of fine roots were observed at depth intervals of the top humus horizon down to 40 cm in the mineral soil profile. The bulk of living fine roots of trees (< 1 mm in diameter) were found in the mineral soil horizon the total profile down to 40 cm of the mineral soil, where 89, 82, 83 and 89% of the total amount in the whole profile were found. The upper 2.5 cm part of the humus layer contained 83, 81, 100 and 100% of all roots of the humus layer on the four different sampling occasions. High amounts of living fine roots were found in the upper 10 cm of the mineral soil horizon viz. 84, 76, 91 and 69% of the total mineral soil layer. Consequently, both the top soil horizons of the humus and the mineral soil layers were heavily penetrated by living fine roots. The highest proportion of living fine roots was found in the top 2.5 cm of the humus layer. Accordingly, the live/dead ratio of fine roots (< 1 mm in diameter) decreased from the top of the humus layer to the lower part of mineral soil horizon from 8.0-0.3, 0.8-0.2, 4.4-0.4 and 3.3-0.7 (g g-1) for the four sampling occasions, respectively. We concluded that the decrease in the live/ dead ratio was related to decreased vitality with depth of the fine roots in the soil profile. The highest live/dead ratio was found in the upper 2.5 cm of the humus layer for both the tree and field-layer species. This distribution pattern was most evident for tree fine roots < 1 mm in diameter. The mean fine-root biomass (live tissue < 1 mm in diameter) of tree species for the total profile varied on the four sampling occasions between 317, 113, 139 and 248 g m-2. The related fine root necromass (dead tissue

  15. Space-time dynamics of fine root biomass of six forests in the Maoershan forest region,northeast China

    Institute of Scientific and Technical Information of China (English)

    ZHOU Biao; ZHU Shengying; MAO Zijun; WANG Xiuwei; ZHAO Xizhu; SUN Yuanfa

    2007-01-01

    The Maoershan forestry centre is situated in the Zhangguangcai Mountain of the Changbai mountain range.The main forest types in the Maoershan region are plantation (Pinus sylvestris var.mongolica,Pinus koraiensis and Larix gmelinii) and natural secondary forests (Fraxinus mandshurica,Quercus mongolica and Populus davidiana).Fine roots have enormous surface areas,growing and turning over quickly,which plays an important role in terms of substance cycling and energy flow in the forest ecosystem.This study deals with the dynamics of live,dead,and total fine roots (≤ mm) biomass in the 0-30 cm soil layer using the soil core method.Differences between the six stands in the Maoershan region showed the following results:1) the fine root biomass in the various stands showed obvious differences.The total fine root biomass of six stands from high to low were F.mandshurica (1,030.0 g/m2) > Q.mongolica (973.4 g/m2) > Pinus koraiensis (780.9 g/m2) >L.gmelinii (718.2 g/m2) > Populusdavidiana(709.1 g/m2) > Pinus sylvestris var.mongolica (470.4 g/m2);2) except for L.gmelinii,the development of live fine root biomass agreed with the trend of total fine root biomass.The maximum biomass of live fine roots in Pinus koraiensis or L.gmelinii stand appeared in May,others in June;in the F.mandshurica stand,the minimum biomass of live fine roots occurred in September,others in July or August;3) the proportions of dead fine root biomass varied in different stands;4) the vertical distribution of fine roots was affected by temperature,water,and nutrients;the proportion of fine root biomass was concentrated in the 0-10 cm soil layer.The fine root biomass of six stands in the 0-10 cm soil layer was over 40% of the total fine root biomass;this proportion was 60.3% in F.mandshurica. Space-time dynamics of the various stands had different characteristics.When investigating the substance cycling and energy flows of all forest ecosystems,we should consider the characteristics of

  16. Fine root branch orders contribute differentially to uptake, allocation, and return of potentially toxic metals.

    Science.gov (United States)

    Guo, Ying-Ying; Wang, Jun-Jian; Kong, De-Liang; Wang, Wei; Guo, Da-Li; Wang, Yan-Bing; Xie, Qing-Long; Liu, Yang-Sheng; Zeng, Hui

    2013-10-15

    Growing evidence has revealed high heterogeneity of fine root networks in both structure and function, with different root orders corporately maintaining trees' physiological activities. However, little information is available on how fine root heterogeneity of trees responds to environmental stresses. We examined concentrations of seven potentially toxic metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) within fine root networks and their correlations with root morphological and macro-elemental traits in six Chinese subtropical trees. The contributions of different orders of roots to fine-root metal storage and return were also estimated. Results showed no consistent pattern for the correlation among different metal concentration against root traits. Unlike root metal concentration that generally decreased with root order, root metal storage was commonly lowest in middle root orders. Root senescence was at least comparable to leaf senescence contributing to metal removal. Although the first-order roots constituted 7.2-22.3% of total fine root biomass, they disproportionately contributed to most of metal return fluxes via root senescence. The two distinct root functional modules contributed differentially to metal uptake, allocation, and return, with defensive (lower-order) roots effectively stabilizing and removing toxic metals and bulk buffering (higher-order) roots possessing a persistent but diluted metal pool. Our results suggest a strong association of physiological functions of metal detoxification and metal homeostasis with the structural heterogeneity in fine root architecture.

  17. Impact factors on fine root seasonal dynamics in Fraxinus mandshurica plantations

    Institute of Scientific and Technical Information of China (English)

    MEI Li; HAN Youzhi; YU Shuiqiang; SHI Jianwei; WANG Zhengquan

    2007-01-01

    Fine root turnover plays important roles in carbon allocation and nutrient cycling in forest ecosystems.Seasonal dynamics of fine roots is critical for understanding the processes of fine root turnover.From May to October 2002,soil core method was used for estimating the seasonal pattern of fine root (diameter < 1 mm) parameters (biomass,specific root length (SRL) and root length density (RLD)) in a Manchurian ash (Fraxinus mandshurica) plantation located at the Maoershan Experiment Station,Heilongjiang Province,northeast of China.The relationships of fine root biomass,SRL and RLD with available nitrogen in soil,average soil temperature per month in 10 cm depth and soil moisture content were analyzed.Seasonal variation of fine root biomass was significant (P < 0.05).The peak values of fine root biomass were observed both in spring and in autumn,but SRL and RLD were the highest in spring and lowest in autumn.Specific root length and root length density were higher in spring and summer,which means that fine root diameter was thinner.In autumn,both parameters decreased significantly due to secondary incrassation of fine root diameter or the increase of tissue density.Seasonal dynamics of fine roots was associated with available nitrogen in soil,soil temperature in 10 cm depth and moisture content.Fine root biomass has a significant relationship with available NH4+-N in soil.Available NO3--N in soil,soil temperature in 10-cm depth and moisture content have a positive correlation with fine root biomass,SRL and RLD,although these correlations are not significant (P >0.05).But the compound effects of soil available N,soil temperature and soil moisture content are significant to every root parameter.The variations of these three root parameters in different seasons show different physiological and ecological functions in different growing periods.

  18. Fine Root Production and Decomposition in Lowland Rainforest and Oil Palm Plantations in Sumatra, Indonesia

    Directory of Open Access Journals (Sweden)

    Violita

    2016-01-01

    Full Text Available Transformation of tropical rainforest into oil palm plantation not only has impacts on biodiversity but also affects ecosystem functions such as production and decomposition of fine roots as a nutrient source for plant. The objective of the research was to evaluate the production and decomposition rate of fine roots in natural forest (NF at Bukit 12 National Park and oil palm plantation (OP in Jambi, Sumatra. The soil core and litter bag methods were used to obtain fine root production and decomposition data. The results showed that generally, there was the same pattern in fine root production between NF and OP. The annual fine root productivity was found to be higher in NF than that of OP. Rainfall in NF and air temperature in NF and OP were the most significant climate factors affecting fine root production. The remaining fine root biomass decreased as the incubation time increased. The decomposition rate constant (k value was significantly higher in NF than in OP. Our data showed that the nutrient turn-over of NF fine roots was faster than of OP fine roots. Nitrogen, carbon content, and C/N ratio were the main factors that influenced fine root decomposition.

  19. Elevated CO2 or O3 effects on fine-root survivorship in ponderosa pine

    Science.gov (United States)

    Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demograp...

  20. ELEVATED CO2 AND O3 EFFECTS ON FINE-ROOT SURVIVORSHIP IN PONDEROSA PINE MESOCOSMS

    Science.gov (United States)

    Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demograph...

  1. Effects of warming treatment and precipitation manipulation on fine root length of Pinus densiflora seedlings.

    Science.gov (United States)

    Han, S. H.; Yoon, S. J.; Lee, J.; Kim, S.; Li, G.; Park, M.; An, J.; Son, Y.

    2015-12-01

    Fine roots are important for water and nutrient uptake and storage of carbon and nutrients in terrestrial ecosystems. In order to examine effects of climate change on fine root of Pinus densiflora seedlings, an open-field experiment with the warming treatment and precipitation manipulation had been conducted at a nursery in Seoul, South Korea. Two-year-old P. seedlings were planted in April, 2013. The air temperature of the warmed plots (W) was set to increase by 3°C compared to the temperature control plots (C) using infrared lamps. The precipitation manipulation consisted of the precipitation decreased using transparent panel (-30%; P-), the precipitation increased using pump and drip-irrigation (+30%; P+), and the precipitation control (0%; P0). The fine root length of the seedlings near the soil surface (0-15 cm depth) was estimated from January, 2014 to January, 2015 trimonthly using minirhizotrons. The mean fine root length (mm mm-2) were 115.0 (WP0), 163.7 (WP-), 90.5 (WP+), 114.4 (CP0), 130.2 (CP-), and 100.6 (CP+) during the study period, respectively. The mean fine root length was significantly affected by the precipitation manipulation (P0.1). There was no interaction between warming and precipitation effects in fine root length. The fine root length in P- plot was higher than those in P0 plot and P+ plot, regardless of the warming treatment, which indicated that water stress caused by P- might stimulate the fine root growth. Meanwhile, the no consistent patterns of fine root length by warming treatment was found under P+ plot and P0 plot, but a positive effect of warming on fine root length was observed under P+ plot only. Estimations of fine root production and mortality are required to determine the interaction between warming and precipitation effects on fine root dynamics more exactly. This study was supported by Korea Ministry of Environment (2014001310008).

  2. Nutrient Dynamics of Fine Roots in the Mixed Plantation of Poplar and Black Locust

    Institute of Scientific and Technical Information of China (English)

    Zhai Mingpu; Jiang Sannai; Jia Liming

    2006-01-01

    The mixed plantation of poplar (Populus spp.)and black locust (Robinia pseudoacacia) is one of the typical mixed stands with nitrogen-fixing and non-nitrogen-fixing species.Interaction between the two species in the mixed stand is harmonious and productivity is high,making this kind of mixed plantation a very successful pattern on poor sandy sites in north China.In this study,the fine root decomposition of the two species was investigated in the mixed plantation of 27-year-old Canadian poplar (P.canadansis)and 22-year-old black locust on sandy sites along the Chaobai River in Beijing.Mechanism of harmonious interaction between the two species was observed in the view of the nutrient cycle of fine roots.Results showed that:(1) the fine root decomposition of Canadian poplar and black locust trees was different.Concentrations of N,Ca and Mg gradually increased and those of P and K gradually decreased in the fine roots of poplar during the period of decomposition.Concentrations of N,P and K gradually decreased in the fine roots of black locust during decomposition.The speed of nutrient decomposition in mixed fine roots of the two species fell between the speed of the two pure samples.(2) During decomposition,the annual return amount of N,K and Mg in fine roots of black locust was highest,followed by the mixed fine roots of the two species,and then the fine roots of poplar.(3) The increased return amount of N in mixed fine roots could improve the N nutrient condition of poplar trees.The return amount of P in poplar Fine roots was greater than that of black locust,which could improve the P nutrient of black locust trees.The interaction of mutual supplements of N and P nutrient cycle of fine roots between these two species formed.

  3. Fine root dynamics of mature European beech (Fagus sylvatica L.) as influenced by elevated ozone concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Mainiero, Raphael, E-mail: raphael.mainiero@iap.c [Department for Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany); Kazda, Marian, E-mail: marian.kazda@uni-ulm.d [Department for Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany); Haeberle, Karl-Heinz, E-mail: haeberle@wzw.tum.d [Technische Universitaet Muenchen, Ecophysiology of Plants, Department of Ecology, Am Hochanger 13, 85354 Freising (Germany); Nikolova, Petia Simeonova, E-mail: nikolova@wzw.tum.d [Technische Universitaet Muenchen, Ecophysiology of Plants, Department of Ecology, Am Hochanger 13, 85354 Freising (Germany); Matyssek, Rainer, E-mail: matyssek@wzw.tum.d [Technische Universitaet Muenchen, Ecophysiology of Plants, Department of Ecology, Am Hochanger 13, 85354 Freising (Germany)

    2009-10-15

    Fine root dynamics (diameter < 1 mm) in mature Fagus sylvatica, with the canopies exposed to ambient or twice-ambient ozone concentrations, were investigated throughout 2004. The focus was on the seasonal timing and extent of fine root dynamics (growth, mortality) in relation to the soil environment (water content, temperature). Under ambient ozone concentrations, a significant relationship was found between fine root turnover and soil environmental changes indicating accelerated fine root turnover under favourable soil conditions. In contrast, under elevated ozone, this relationship vanished as the result of an altered temporal pattern of fine root growth. Fine root survival and turnover rate did not differ significantly between the different ozone regimes, although a delay in current-year fine root shedding was found under the elevated ozone concentrations. The data indicate that increasing tropospheric ozone levels can alter the timing of fine root turnover in mature F. sylvatica but do not affect the turnover rate. - Doubling of ozone concentrations in mature European beech affected the seasonal timing of fine root turnover rather than the turnover rate.

  4. Mixing Eucalyptus and Acacia trees leads to fine root over-yielding and vertical segregation between species.

    Science.gov (United States)

    Laclau, Jean-Paul; Nouvellon, Yann; Reine, Caroline; Gonçalves, José Leonardo de Moraes; Krushe, Alex Vladimir; Jourdan, Christophe; le Maire, Guerric; Bouillet, Jean-Pierre

    2013-07-01

    The consequences of diversity on belowground processes are still poorly known in tropical forests. The distributions of very fine roots (diameter Acacia mangium (100A) stands and a mixture with the same stocking density and 50% of each species (50A:50E). The total fine root (FR) biomass down to a depth of 2 m was about 27% higher in 50A:50E than in 100A and 100E. Fine root over-yielding in 50A:50E resulted from a 72 % rise in E. grandis fine root biomass per tree relative to 100E, whereas A. mangium FR biomass per tree was 17% lower than in 100A. Mixing A. mangium with E. grandis trees led to a drop in A. mangium FR biomass in the upper 50 cm of soil relative to 100A, partially balanced by a rise in deep soil layers. Our results highlight similarities in the effects of directional resources on leaf and FR distributions in the mixture, with A. mangium leaves below the E. grandis canopy and a low density of A. mangium fine roots in the resource-rich soil layers relative to monospecific stands. The vertical segregation of resource-absorbing organs did not lead to niche complementarity expected to increase the total biomass production.

  5. FINE ROOT QUANTIFICATION IN A Pinus taeda L. STAND AND IN GRASSLAND AREA IN CAMBARÁ DO SUL (RS

    Directory of Open Access Journals (Sweden)

    Vicente Guilherme Lopes

    2010-12-01

    Full Text Available The objectives of this study were to comparatively quantify length and biomass of fine roots (≤ 2.0 mm in the soil profile (0-10, 10-20, 20-30, 30-40 cm  and in the litter of a 15-year-old Pinus taeda L. stand, as well as in an adjacent Grassland area. The samples were obtained through monolith excavation. Roots were separated through washing and collecting and were then distributed over a white sheet of paper, where images were obtained with a digital camera. Using the software Image Tool for Windows version 3.00© the images were processed to quantify root length. Subsequently, roots were dried in a stove and, weighed to determine the biomass. The vegetation in the Grassland area showed 234.28% greater density of fine roots than the adjacent area where the Pinus taeda L.stand is located.

  6. Fine-root responses to fertilization reveal multiple nutrient limitation in a lowland tropical forest.

    Science.gov (United States)

    Wurzburger, Nina; Wright, S Joseph

    2015-08-01

    Questions remain as to which soil nutrients limit primary production in tropical forests. Phosphorus (P) has long been considered the primary limiting element in lowland forests, but recent evidence demonstrates substantial heterogeneity in response to nutrient addition, highlighting a need to understand and diagnose nutrient limitation across diverse forests. Fine-root characteristics including their abundance, functional traits, and mycorrhizal symbionts can be highly responsive to changes in soil nutrients and may help to diagnose nutrient limitation. Here, we document the response of fine roots to long-term nitrogen (N), P, and potassium (K) fertilization in a lowland forest in Panama. Because this experiment has demonstrated that N and K together limit tree growth and P limits fine litter production, we hypothesized that fine roots would also respond to nutrient addition. Specifically we hypothesized that N, P, and K addition would reduce the biomass, diameter, tissue density, and mycorrhizal colonization of fine roots, and increase nutrient concentration in root tissue. Most morphological root traits responded to the single addition of K and the paired addition of N and P, with the greatest response to all three nutrients combined. The addition of N, P, and K together reduced fine-root biomass, length, and tissue density, and increased specific root length, whereas root diameter remained unchanged. Nitrogen addition did not alter root N concentration, but P and K addition increased root P and K concentration, respectively. Mycorrhizal colonization of fine roots declined with N, increased with P, and was unresponsive to K addition. Although plant species composition remains unchanged after 14 years of fertilization, fine-root characteristics responded to N, P, and K addition, providing some of the strongest stand-level responses in this experiment. Multiple soil nutrients regulate fine-root abundance, morphological and chemical traits, and their association

  7. Fine roots refilling process in an artificial gap in a Picea mongolica forest

    Institute of Scientific and Technical Information of China (English)

    Zou Chun-jing; Ma Yong-liang; Zhang Chao; Xu Wen-duo

    2007-01-01

    Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of fine roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m-2, respectively. The fine root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m-2, respectively.In the gap, the fine root length density of trees was 151 m·m-2. The mean fine root densities of shrubs and herbs in the gap were 756 and 2,568 m·m-2. The fine root biomass of trees, shrubs and herbs were 9, 52 and 47 g·m-2, respectively. Two growing seasons after the gap creation, hardly any fine tree roots were found in the middle of the gap. The living tree roots in the gap edge zone were mainly located within a 4.5 m distance from the standing trees. Indices developed to show the influence of trees on fine root length density clearly revealed the effect of the vicinity of living trees on fine root length density. The root densities of shrubs and herbs did not show a clear response to gap creation despite the increase of their foliage. Our results suggest that in P mongolica forests a gap disturbance creates a distinct tree root gap and that the gap edge trees do not extend their root systems rapidly into the formed root gap.

  8. Coupling Fine-Scale Root and Canopy Structure Using Ground-Based Remote Sensing

    Directory of Open Access Journals (Sweden)

    Brady S. Hardiman

    2017-02-01

    Full Text Available Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL and ground penetrating radar (GPR along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation at multiple spatial scales ≤10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.

  9. The effect of limited availability of N or water on C allocation to fine roots and annual fine root turnover in Alnus incana and Salix viminalis.

    Science.gov (United States)

    Rytter, Rose-Marie

    2013-09-01

    The effect of limited nitrogen (N) or water availability on fine root growth and turnover was examined in two deciduous species, Alnus incana L. and Salix viminalis L., grown under three different regimes: (i) supply of N and water in amounts which would not hamper growth, (ii) limited N supply and (iii) limited water supply. Plants were grown outdoors during three seasons in covered and buried lysimeters placed in a stand structure and filled with quartz sand. Computer-controlled irrigation and fertilization were supplied through drip tubes. Production and turnover of fine roots were estimated by combining minirhizotron observations and core sampling, or by sequential core sampling. Annual turnover rates of fine roots organic carbon increased by ca. 20% at N limitation in Salix. However, future studies on fine root decomposition under various environmental conditions are required. Fine root growth responses to N or water limitation were less pronounced in Alnus, thus indicating species differences caused by N-fixing capacity and slower initial growth in Alnus, or higher fine root plasticity in Salix. A similar seasonal growth pattern across species and treatments suggested the influence of outer stimuli, such as temperature and light.

  10. Fine root carbon: sources and turnover by diameter class and root order using 13C tracer at the conclusion of a long-term FACE experiment

    Science.gov (United States)

    Lynch, D. J.; Matamala, R.; Norby, R. J.; Iversen, C.; Gonzalez-Meler, M. A.

    2012-12-01

    Fine roots comprise an important component of terrestrial ecosystems, acting as the main conduit for uptake of water and nutrients and a major source of transfer of carbon to the soil. Ecological properties of fine roots remain difficult to quantify; in particular fine root turnover times have been debated with estimates from isotope-derived studies much longer compared to minirhizotron studies. Here we tracked isotope relaxation in fine root C pools following the cessation of fumigation at the FACE site at Oak Ridge National Laboratory, a Liquidambar styraciflua plantation. Intact soil cores were extracted at regular intervals in 2010 and 2011 and fine roots separated by root diameter class (cessation and sources of C for fine root respiration through root incubations of fine roots. After two full growing seasons following fumigation cessation, about 60% and 40% of C has been turned over in the model, indicating heterogeneity in turnover of fine roots. Fine roots of the lowest orders (1 and 2) are isotopically enriched relative to higher order (3 - 5) roots, indicating a faster turnover time in lower orders. However, after two growing seasons a significant amount of C in roots of the lowest orders persists from the time of fumigation. Lower order roots additionally have more nitrogen, indicating a different physiological role, important for water and nutrient uptake. We also find that new fine root growth in L. styraciflua is derived mostly from new assimilate, while fine root respiration uses a significant amount of storage C of at least several years old.

  11. A SPATIAL ANALYSIS OF FINE-ROOT BIOMASS FROM STAND DATA IN OREGON AND WASHINGTON

    Science.gov (United States)

    Because of the high spatial variability of fine roots in natural forest stands, accurate estimates of stand-level fine root biomass are difficult and expensive to obtain by standard coring methods. This study compares two different approaches that employ aboveground tree metrics...

  12. A SPATIAL ANALYSIS OF THE FINE ROOT BIOMASS FROM STAND DATA IN THE PACIFIC NORTHWEST

    Science.gov (United States)

    High spatial variability of fine roots in natural forest stands makes accurate estimates of stand-level fine root biomass difficult and expensive to obtain by standard coring methods. This study uses aboveground tree metrics and spatial relationships to improve core-based estima...

  13. Soil acidification effects on fine root growth of Douglas-fir on sandy soils.

    NARCIS (Netherlands)

    Olsthoorn, A.F.M.

    1998-01-01

    The ammonium sulphate deposited in forest ecosystems in the Netherlands as a result of air pollution currently exceeds 80 kg N ha -1yr -1locally. To study the influence of this air pollution on fine root density and its dynamics, fine root growth was monitored for three years i

  14. Seasonal dynamics of fine root biomass, root length density, specific root length, and soil resource availability in a Larix gmelinii plantation

    Institute of Scientific and Technical Information of China (English)

    CHENG Yunhuan; HAN Youzhi; WANG Qingcheng; WANG Zhengquan

    2006-01-01

    Fine root tumover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive to many global change factors.Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics and the tremendous research efforts in the past,our understanding of it remains limited.This is because the dynamics processes associated with soil resources availability are still poorly understood.Soil moisture,temperature,and available nitrogen are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch and at the ecosystem level.In temperate forest ecosystems,seasonal changes of soil resource availability will alter the pattern of carbon allocation to belowground.Therefore,fine root biomass,root length density(RLD)and specific root length(SRL)vary during the growing season.Studying seasonal changes of fine root biomass,RLD,and SRL associated with soil resource availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover.The objective of this study was to understand whether seasonal variations of fine root biomass,RLD and SRL were associated with soil resource availability,such as moisture,temperature,and nitrogen,and to understand how these soil components impact fine root dynamics in Larix gmelinii plantation.We used a soil coring method to obtain fine root samples(≤2 mm in diameter)every month from Mav to October in 2002 from a 17-year-old L.gmelinii plantation in Maoershan Experiment Station,Northeast Forestry University,China.Seventy-two soil cores(inside diameter 60 mm;depth intervals:0-10 cm,10-20 cm,20-30 cm)were sampled randomly from three replicates 25 m×30 m plots to estimate fine root biomass(live and dead),and calculate RLD and SRL.Soil moisture,temperature,and nitrogen(ammonia and nitrates)at three depth intervals were also analyzed in these plots.Results showed that the average standing fine

  15. A global analysis of fine root production as affected by soil nitrogen and phosphorus.

    Science.gov (United States)

    Yuan, Z Y; Chen, Han Y H

    2012-09-22

    Fine root production is the largest component of belowground production and plays substantial roles in the biogeochemical cycles of terrestrial ecosystems. The increasing availability of nitrogen (N) and phosphorus (P) due to human activities is expected to increase aboveground net primary production (ANNP), but the response of fine root production to N and P remains unclear. If roots respond to nutrients as ANNP, fine root production is anticipated to increase with increasing soil N and P. Here, by synthesizing data along the nutrient gradient from 410 natural habitats and from 469 N and/or P addition experiments, we showed that fine root production increased in terrestrial ecosystems with an average increase along the natural N gradient of up to 0.5 per cent with increasing soil N. Fine root production also increased with soil P in natural conditions, particularly at P soil types. The global average increases in fine root production are lower than those of ANNP, indicating that above- and belowground counterparts are coupled, but production allocation shifts more to aboveground with higher soil nutrients. Our results suggest that the increasing fertilizer use and combined N deposition at present and in the future will stimulate fine root production, together with ANPP, probably providing a significant influence on atmospheric CO(2) emissions.

  16. Effect of drought on fine roots productivity in poplar-based short rotation coppice

    Science.gov (United States)

    Mani Tripathi, Abhishek; Fischer, Milan; Berhongaray, Gonzalo; Orság, Matěj; Trnka, Miroslav

    2015-04-01

    Short rotation woody crops (SRWC) are alternative source of bioenergy, which apart from their 'carbon neutrality' have potential to store carbon (C) into soil and mitigate the increasing CO2 emission. Studies of below ground biomass of trees are divided into two types according to root diameter - analysis of fine roots (less than 2 mm) and coarse roots (more than 2 mm). Trees roots are spatially highly heterogeneous and it requires large number of samples to obtain a representative estimate of belowground biomass. For this study we used hybrid poplar clone J-105 (Populus nigra x P. maximowiczii) grown under short rotation coppice system in the region of Bohemian-Moravian Highland (49o32'N, 16o15'E and altitude 530 m a.s.l.) since April 2000. The plantation with planting density of 9,216 trees ha-1 was established on the former agricultural land and the length of the rotation cycle was set to 6-8 years. While mean annual rainfall was 609 mm with mean annual temperature 7.2oC during 1981-2013 significant increase of temperature and more frequent droughts are expected. In 2011, we established drought experiment based on throughfall exclusion system, reducing up to 70 % of throughfall precipitation. Thus 2 treatments with normal and lowered soil moisture levels were introduced. In January and February 2014, we cored 18 places including drought and control using root bipartite auger. The main goal of the study is to assess the response of fine roots productivity and fine roots vertical distribution on the reduced soil water availability. Results will be presented at the conference. Acknowledgements: This study was funded by research project IGA Mendel University 2014 "Study of below ground biomass in short rotation poplar coppice (J-105) in the Czech-Moravian Highlands", project PASED (KONTAKT II LH12037 ʺDevelopment of models for the assessment of abiotic stresses in selected energy woody plantsʺ and "Building up a multidisciplinary scientific team focused on drought

  17. [Seasonal dynamics of quantitative and morphological traits of poplar fine roots and their differences between successive rotation plantations].

    Science.gov (United States)

    Wang, Yan-ping; Xu, Tan; Zhu, Wan-rui; Wang, Qi-tong; Liu, Meng-ling; Wang, Hua-tian; Li, Chuan-rong; Dong, Yu-feng

    2016-02-01

    Based on the fine root samples of the first and second generations of poplar (Populus x euramericana ' Neva'), this study examined the response of quantitative and morphological traits of fine roots of different orders and the difference between generations. The results showed that, the quantitative traits of fine roots, such as root length, root surface area and root biomass, presented obvious seasonal variation, and the fine root traits had obvious difference among root orders. The quantitative traits of lower-order fine roots showed significant seasonal difference, and the fine root biomass increased in the growing season and then decreased significantly. The specific root length (SRL) of higher-order roots also showed significant change with season, while the root length density (RLD) and root tissue density (RTD) changed a little. The successive rotation resulted in the significant increase of root length, root biomass, SRL and RLD of 1-2 orders in the growing season. The quantitative traits of first order root significantly positively correlated with soil temperature and moisture, and significantly negatively correlated with the soil organic matter and soil available nitrogen content. However, the quantitative traits of second order root only showed significant correlation with soil nutrient content. The seasonal dynamics of poplar fine roots and the difference between successive rotation plantations implied carbon investment change of poplar to roots. Soil nutrient deficiency induced more carbon investment into roots, and this carbon allocation pattern might affect the aboveground productivity of poplar plantation.

  18. Root approach for estimation of statistical distributions

    Science.gov (United States)

    Bogdanov, Yu. I.; Bogdanova, N. A.

    2014-12-01

    Application of root density estimator to problems of statistical data analysis is demonstrated. Four sets of basis functions based on Chebyshev-Hermite, Laguerre, Kravchuk and Charlier polynomials are considered. The sets may be used for numerical analysis in problems of reconstructing statistical distributions by experimental data. Based on the root approach to reconstruction of statistical distributions and quantum states, we study a family of statistical distributions in which the probability density is the product of a Gaussian distribution and an even-degree polynomial. Examples of numerical modeling are given.

  19. Root approach for estimation of statistical distributions

    CERN Document Server

    Bogdanov, Yu I

    2014-01-01

    Application of root density estimator to problems of statistical data analysis is demonstrated. Four sets of basis functions based on Chebyshev-Hermite, Laguerre, Kravchuk and Charlier polynomials are considered. The sets may be used for numerical analysis in problems of reconstructing statistical distributions by experimental data. Based on the root approach to reconstruction of statistical distributions and quantum states, we study a family of statistical distributions in which the probability density is the product of a Gaussian distribution and an even-degree polynomial. Examples of numerical modeling are given. The results of present paper are of interest for the development of tomography of quantum states and processes.

  20. Phenotypic plasticity of fine root growth increases plant productivity in pine seedlings

    Directory of Open Access Journals (Sweden)

    Grissom James E

    2004-09-01

    Full Text Available Abstract Background The plastic response of fine roots to a changing environment is suggested to affect the growth and form of a plant. Here we show that the plasticity of fine root growth may increase plant productivity based on an experiment using young seedlings (14-week old of loblolly pine. We use two contrasting pine ecotypes, "mesic" and "xeric", to investigate the adaptive significance of such a plastic response. Results The partitioning of biomass to fine roots is observed to reduce with increased nutrient availability. For the "mesic" ecotype, increased stem biomass as a consequence of more nutrients may be primarily due to reduced fine-root biomass partitioning. For the "xeric" ecotype, the favorable influence of the plasticity of fine root growth on stem growth results from increased allocation of biomass to foliage and decreased allocation to fine roots. An evolutionary genetic analysis indicates that the plasticity of fine root growth is inducible, whereas the plasticity of foliage is constitutive. Conclusions Results promise to enhance a fundamental understanding of evolutionary changes of tree architecture under domestication and to design sound silvicultural and breeding measures for improving plant productivity.

  1. Does species richness affect fine root biomass and production in young forest plantations?

    DEFF Research Database (Denmark)

    Domisch, Timo; Finér, Leena; Dawud, Seid Muhie;

    2015-01-01

    species composition from fine root biomass samples with the near-infrared reflectance spectroscopy method. We did not observe higher biomass or production in mixed stands compared to monocultures. Neither did we observe any differences in tree root length or fine root turnover. One reason for this could......Tree species diversity has been reported to increase forest ecosystem above-ground biomass and productivity, but little is known about below-ground biomass and production in diverse mixed forests compared to single-species forests. For testing whether species richness increases below-ground biomass...... and production and thus complementarity between forest tree species in young stands, we determined fine root biomass and production of trees and ground vegetation in two experimental plantations representing gradients in tree species richness. Additionally, we measured tree fine root length and determined...

  2. Effects of water and nutrient availability on fine root growth in eastern Amazonian forest regrowth, Brazil.

    Science.gov (United States)

    Lima, Tâmara Thaiz Santana; Miranda, Izildinha Souza; Vasconcelos, Steel Silva

    2010-08-01

    *Fine root dynamics is widely recognized as an important biogeochemical process, but there are few data on fine root growth and its response to soil resource availability, especially for tropical forests. *We evaluated the response of fine root dynamics to altered availability of soil water and nutrients in a 20-yr-old forest regrowth in eastern Amazonia. In one experiment the dry season reduction in soil moisture was alleviated by irrigation. In the other experiment, nutrient supply was reduced by litter removal. We used the ingrowth core technique to measure fine root mass growth, length growth, mortality and specific root length. *Dry-season irrigation had no significant effect on mass and length of live and dead roots, whereas litter removal reduced mass and length of live roots. For both irrigation and litter removal experiments, root growth was significantly greater in the dry season than in the wet season. *Increased root growth was associated with decreased soil water availability. However, root growth did not increase in response to nutrient reduction in litter removal plots. Overall, our results suggest that belowground allocation may differ according to the type of soil resource limitation.

  3. Quantification of fine root responses to selenium toxicity

    Directory of Open Access Journals (Sweden)

    H. HARTIKAINEN

    2008-12-01

    Full Text Available The morphological changes of lettuce and ryegrass roots in response to Se toxicity were quantified by image analysis. Based on the assumption that soil stresses increase endogenous ethylene production in plants, changes indicating higher construction costs for roots, such as decreased specific root length, were expected. As lettuce roots in soil without Se addition (control became older, their width increased whereas their specific length, specific surface area and specific volume decreased. In younger lettuce, large Se additions induced changes resembling those identified in the control plant upon senescence. In older plants, Se fertilisation reversed these changes or made them smaller. Ryegrass roots were not as sensitive to added Se as lettuce roots; a lower dosage stimulated root growth but a higher one reduced it. ;

  4. [Soil moisture content and fine root biomass of rubber tree (Hevea brasiliensis) plantations at different ages].

    Science.gov (United States)

    Lin, Xi-Hao; Chen, Qiu-Bo; Hua, Yuan-Gang; Yang, Li-Fu; Wang, Zhen-Hui

    2011-02-01

    By using soil core sampling method, this paper studied the soil moisture regime of rubber plantations and the fine root biomass of Hevea brasiliensis in immature period (5 a), early yielding period (9 a), and peak yielding period (16 a). With the increasing age of rubber trees, the soil moisture content of rubber plantations increased but the fine root biomass decreased. The soil moisture content at the depth of 0-60 cm in test rubber plantations increased with soil depth, and presented a double-peak pattern over the period of one year. The fine root biomass of rubber trees at different ages had the maximum value in the top 10 cm soil layers and decreased with soil depth, its seasonal variation also showed a double-peak pattern, but the peak values appeared at different time. Soil moisture content and soil depth were the main factors affecting the fine root biomass of H. brasiliensis.

  5. Fine root dynamics in moso bamboo and Japanese cedar forest by scanner method in central Taiwan

    Science.gov (United States)

    Chen, Zhi-Wei; Lin, Po-Hsuan; Kume, Tomonori

    2017-04-01

    Phyllostachys pubescens is one of the most important economic plant in the world. Phyllostachys pubescens originates from China and it had been introduced to neighbor countries about three hundred ago due to its economic value. But substantial bamboo forests were abandoned due to declines in demand. These unmanaged bamboo forests have been expanding to adjacent original forests in northern Taiwan. This vegetation alternation may not only decrease the local biodiversity but also affect the carbon cycle. Fine roots are responsible for water and nutrients acquisition and forming the most active part of the whole root system. The characteristics of fine roots are non-woody, small diameter and short lifespan. When roots keep producing new roots and replacing old roots, carbon and nutrients was transported into soil. Consequently, fine root production is one of the important component to understand the below-ground carbon cycle. However, there is few studies about fine root production in moso bamboo forests. We still lack effective method to obtain quantitative and objective data in Taiwan. It severely limits us to understand the below-ground carbon dynamics there. Minirhizotrons method has been used to investigate fine root dynamics by inserting transparent tubes into soil and by comparing changes in root length in images taken by micro-camera. But this method has some shortcomings; i.e. Most of image analysis are conducted manually and time-consuming. And it is difficult to estimate the stand level fine root production from small observation view. A new method "scanner method", which collect A4-size image (bigger than minirhizotrons) can overcome some parts of the shortcoming of minirhizotrons. The transparent acrylic box with A4-box view is inserted into soil and the interface between soil and box is scanned by commercial scanner. We can monitor the total projected root area, growth and decomposition separately by series of images. The primary objective of this study

  6. Evidence of old carbon used to grow new fine roots in a tropical forest.

    Science.gov (United States)

    Vargas, Rodrigo; Trumbore, Susan E; Allen, Michael F

    2009-01-01

    In this study, we explore how a hurricane disturbance influenced carbon allocation for the production of new fine roots. Before and after a hurricane, we measured the age of carbon (time since fixation from the atmosphere) in fine root structural tissues using natural abundance radiocarbon (14C) measured by accelerator mass spectrometry. Roots were sampled from five seasonally dry tropical forests ranging in age from 6 yr to a mature forest. Structural carbon in combined live + dead roots picked from soil cores sampled 1 month before the hurricane had mean ages ranging from 4 to 11 yr, whereas live roots alone had ages of 1-2 yr. Structural carbon in new live fine roots produced over a period lasting from 3 wk before the hurricane to 2 months after the event had mean ages of between 2 and 10 yr. Contrary to expectations, our results showed that plants allocate long-lived storage carbon pools to the production of new fine roots after canopy defoliation and root mortality. The age of the carbon allocated for new roots increased with forest age and forest above-ground biomass, suggesting an adaptation of plants to survive and recover from severe disturbances.

  7. Mass, nutrient pool, and mineralization of litter and fine roots in a tropical mountain cloud forest.

    Science.gov (United States)

    Campos C, Adolfo; Cruz H, Lourdes; Rocha O, Sandra

    2017-01-01

    We used fine root and litter mass from a tropical mountain cloud forest to assess their relative contribution to nutrient content and to examine mineralization processes during a laboratory incubation experiment. Our results showed that average fine root mass density ranged from 2.86kgm(-3) to 11.59kgm(-3), while litter mass density ranged from 72.5kgm(-3) to 177.3kgm(-3). On average, fine root mass density represented 4.7% of the mass density of the O horizon. Fine root mass density followed an exponentially declining trend with soil depth. On average, 83% of fine root mass density within the soil profile was concentrated in the O horizon. Mean element pools in litter decreased from 44.08mgcm(-3) to 0.49μgcm(-3) in the following sequence: C>N>Fe>S>Ca>P>K>Mg>Na>Mn>Zn>Cu. For fine roots, a different mean element pool sequence (C>N>Ca>K>Fe>S>Mg>Na>P>Mn>Zn>Cu) in decreasing abundance (from 2.88mgcm(-3) to 0.13μgcm(-3)) was observed with respect to litter. Regarding C, litter mineralized faster than fine roots, with a mean k value of 0.25d(-1) for litter and 0.13d(-1) for fine roots. Principal component analysis (PCA) combined with stepwise regression analysis revealed that the main mass density predictors were N, S, Zn, and Mn for litter (plitter mass and therefore the nutrient availability and C sequestration.

  8. Root distribution of rootstocks for 'Tahiti' lime

    Directory of Open Access Journals (Sweden)

    Neves Carmen Silvia Vieira Janeiro

    2004-01-01

    Full Text Available Field studies on citrus roots are important for genetic selection of cultivars and for management practices such as localized irrigation and fertilization. To characterize root systems of six rootstocks, taking into consideration chemical and physical characteristics of a clayey Typic Hapludox of the Northern State of Paraná, this study was performed having as scion the 'IAC-5 Tahiti' lime [Citrus latifolia (Yu. Tanaka]. The rootstocks 'Rangpur' lime (C. limonia Osbeck, 'Africa Rough' lemon (C. jambhiri Lush., 'Sunki' mandarin [C. sunki (Hayata hort. ex Tan.], Poncirus trifoliata (L. Raf., 'C13' citrange [C. sinensis (L. Osb. x P. trifoliata (L. Raf] and 'Catânia 2' Volkamer lemon (C. volkameriana Ten. & Pasq. were used applying the trench profile method and the SIARCS® 3.0 software to determine root distribution. 'C-13' citrange had the largest root system. 'Volkamer' lemon and 'Africa Rough' lemon presented the smallest amount of roots. The effective depth for 80 % of roots was 31-53 cm in rows and 67-68 cm in inter-rows. The effective distance of 80 % of roots measured from the tree trunk exceeded the tree canopy for P. trifoliata, 'Sunki' mandarin, and 'Volkamer' and 'Africa Rough' lemons.

  9. Fine root productivity varies along nitrogen and phosphorus gradients in high-rainfall mangrove forests of Micronesia

    Science.gov (United States)

    Cormier, Nicole; Twilley, Robert R.; Ewel, Katherine C.; Krauss, Ken W.

    2015-01-01

    Belowground biomass is thought to account for much of the total biomass in mangrove forests and may be related to soil fertility. The Yela River and the Sapwalap River, Federated States of Micronesia, contain a natural soil resource gradient defined by total phosphorus (P) density ranging from 0.05 to 0.42 mg cm−3 in different hydrogeomorphic settings. We used this fertility gradient to test the hypothesis that edaphic conditions constrain mangrove productivity through differential allocation of biomass to belowground roots. We removed sequential cores and implanted root ingrowth bags to measure in situ biomass and productivity, respectively. Belowground root biomass values ranged among sites from 0.448 ± 0.096 to 2.641 ± 0.534 kg m−2. Root productivity (roots ≤20 mm) did not vary significantly along the gradient (P = 0.3355) or with P fertilization after 6 months (P = 0.2968). Fine root productivity (roots ≤2 mm), however, did vary significantly among sites (P = 0.0363) and ranged from 45.88 ± 21.37 to 118.66 ± 38.05 g m−2 year−1. The distribution of total standing root biomass and fine root productivity followed patterns of N:P ratios as hypothesized, with larger root mass generally associated with lower relative P concentrations. Many of the processes of nutrient acquisition reported from nutrient-limited mangrove forests may also occur in forests of greater biomass and productivity when growing along soil nutrient gradients.

  10. Morphological and physiological responses of Scots pine fine roots to water supply in a dry climatic region in Switzerland.

    Science.gov (United States)

    Brunner, Ivano; Pannatier, Elisabeth Graf; Frey, Beat; Rigling, Andreas; Landolt, Werner; Zimmermann, Stephan; Dobbertin, Matthias

    2009-04-01

    In recent decades, Scots pine (Pinus sylvestris L.) forests in inner-Alpine dry valleys of Switzerland have suffered from drought and elevated temperatures, resulting in a higher mortality rate of trees than the mean mortality rate in Switzerland. We investigated the responses of fine roots (standing crop, morphological and physiological features) to water supply in a Scots pine forest in the Rhone valley. Before irrigation started in 2003, low- and high-productivity Scots pine trees were selected based on their crown transparency. The fine root standing crop measured in spring from 2003 to 2005 was unaffected by the irrigation treatment. However, irrigation significantly enhanced the fine root standing crop during the vegetation period when values from spring were compared with values from fall in 2005. Irrigation slightly increased specific root length but decreased root tissue density. Fine root O2-consumption capacity decreased slightly in response to the irrigation treatment. Using ingrowth cores to observe the responses of newly produced fine roots, irrigation had a significantly positive effect on the length of fine roots, but there were no differences between the low- and high-productivity trees. In contrast to the weak response of fine roots to irrigation, the aboveground parts responded positively to irrigation with more dense crowns. The lack of a marked response of the fine root biomass to irrigation in the low- and high-productivity trees suggests that fine roots have a high priority for within-tree carbon allocation.

  11. Mean age of carbon in fine roots from temperate forests and grasslands with different management

    Science.gov (United States)

    Solly, E.; Schöning, I.; Boch, S.; Müller, J.; Socher, S. A.; Trumbore, S. E.; Schrumpf, M.

    2013-07-01

    Fine roots are the most dynamic portion of a plant's root system and a major source of soil organic matter. By altering plant species diversity and composition, soil conditions and nutrient availability, and consequently belowground allocation and dynamics of root carbon (C) inputs, land-use and management changes may influence organic C storage in terrestrial ecosystems. In three German regions, we measured fine root radiocarbon (14C) content to estimate the mean time since C in root tissues was fixed from the atmosphere in 54 grassland and forest plots with different management and soil conditions. Although root biomass was on average greater in grasslands 5.1 ± 0.8 g (mean ± SE, n = 27) than in forests 3.1 ± 0.5 g (n = 27) (p soils in northern Germany and of 1.8 ± 0.3 yr (n = 9) and 2.6 ± 0.3 (n = 9) in central and southern Germany (p soil nutrient contents and soil moisture conditions between study regions, which affected plant species diversity and the presence of perennial species. Our results indicate more long-lived roots or internal redistribution of C in perennial species and suggest linkages between fine root C age and management in grasslands. These findings improve our ability to predict and model belowground C fluxes across broader spatial scales.

  12. Response of root distribution of Haloxylon ammodendron seedlings to irrigation amounts in the hinterlands of the Taklimakan Desert, China

    Institute of Scientific and Technical Information of China (English)

    Lishan SHAN; Ximing ZHANG; Yonghui HUA; Tingting XIE; Hailong YAN; Hua FAN

    2009-01-01

    We excavated soil to study root distribution in Haloxylon ammodendron seedlings grown with different amounts of irrigation (35, 24.5 and 14 kg water for each plant each time) in the hinterland of the Taklimakan Desert.The results indicated that: 1) With decreasing irrigation amounts, the root biomass tended to be distributed in deeper soil layers. Underground biomass had a signifi-cantly negative logarithmic relationship with soil depth under different irrigation amounts. 2) Maximum horizontal spread of roots was twice that of vertical root spread, and horizontal distribution of root biomass was similar under all irrigation amounts. 3) Vertical distribution of fine roots was nearly consistent with vertical changes in soil moisture, and all had a unimodal curve; but peak values of fine root biomass in different soil layers varied with different irrigation amounts. The smaller the amount of irrigation, the deeper were the fine roots concentrated in soil layers. 4) Root length, root surface area and root volume all exhibited a unimodal curve under different irrigation amounts; the less the irrigation amount, the deeper the peak values appeared in soil layers. 5) Root- shoot ratio and ratio of vertical root depth to plant height both increased as irrigation amounts decreased.

  13. Massive turnover rates of fine root detrital carbon in tropical Australian mangroves.

    Science.gov (United States)

    Robertson, Alistar I; Alongi, Daniel M

    2016-03-01

    Dead fine roots are the major component of organic carbon (C) stored in mangrove forests. We measured the mass and decomposition of fine root detritus in three mangrove forests along an intertidal gradient in tropical Australia to provide the first integrated estimates of the rate of turnover of fine root detritus. The grand mean dry masses of dead fine roots in the forests decreased in the order mid-intertidal Rhizophora (mean 28.4 kg m(-2)), low-intertidal Rhizophora (16.3 kg m(-2)) and high-intertidal Ceriops (mean 8.9 kg m(-2)), and were some of the highest on record. The first-order decay coefficients (day(-1)) for dead fine roots in the low Rhizophora, mid Rhizophora and high Ceriops forest sites were 0.0014, 0.0017 and 0.0007, respectively, and were the lowest on record. The estimated mean fluxes of C via decomposition of dead fine roots were very high in all forests, decreasing in the order mid Rhizophora (18.8 g C m(-2) day(-1)), low Rhizophora (8.4 g C m(-2) day(-1)) and high Ceriops (2.5 g C m(-2) day(-1)). There were relatively low levels of uncertainty in these estimates when all sources of error were considered. The fluxes of C for the two Rhizophora sites integrate all losses from saprophytic decay and leaching of dissolved C and were 50-200 % higher than the estimated total annual loss of C derived by summing rates of bacterial metabolism and export via groundwater and surface waters in these forests. The significant difference reflects both the very high dead root masses and the incorporation of the impact of fungi in our estimates.

  14. Mean age of carbon in fine roots from temperate forests and grasslands with different management

    Directory of Open Access Journals (Sweden)

    E. Solly

    2013-03-01

    Full Text Available Fine roots are the most dynamic portion of a plant's root system and a major source of soil organic matter. By altering plant species diversity and composition, soil conditions and nutrient availability, and consequently belowground allocation and dynamics of root carbon (C inputs, land-use and management changes may influence organic C storage in terrestrial ecosystems. In three German regions we measured fine root radiocarbon (14C content to estimate the mean time since C in root tissues was fixed from the atmosphere in 54 grassland and forest plots with different management and soil conditions. Although root biomass was on average greater in grasslands 5.1 ± 0.8 g (mean ± SE, n = 27 than in forests 3.1 ± 0.5 g (n = 27, the mean age of C in fine roots in forests averaged 11.3 ± 1.8 yr and was significantly older and more variable compared to grasslands 1.7 ± 0.4 yr. We further found that management affects the mean age of fine root C in temperate grasslands mediated by changes in plant species diversity and composition. Fine root mean C age is positively correlated to plant diversity (r = 0.65 and to the number of perennial species (r = 0.77. In temperate grasslands the mean age of fine root C is also influenced by the study region mainly driven by differences in soil characteristics and climate which reflect in plant composition variations, with averages of 0.7 ± 0.1 yr (n = 9 on mostly organic sandy soils in northern Germany and of 1.8 ± 0.3 yr (n = 9 and 2.6 ± 0.3 (n = 9 in more silty and clayey soils respectively in central and southern Germany. Our results indicate an internal redistribution of C in perennial species and suggest linkages between fine root C age and management in grasslands. These findings improve our ability to predict and model belowground C fluxes across broader spatial scales.

  15. Does species richness affect fine root biomass and production in young forest plantations?

    Science.gov (United States)

    Domisch, Timo; Finér, Leena; Dawud, Seid Muhie; Vesterdal, Lars; Raulund-Rasmussen, Karsten

    2015-02-01

    Tree species diversity has been reported to increase forest ecosystem above-ground biomass and productivity, but little is known about below-ground biomass and production in diverse mixed forests compared to single-species forests. For testing whether species richness increases below-ground biomass and production and thus complementarity between forest tree species in young stands, we determined fine root biomass and production of trees and ground vegetation in two experimental plantations representing gradients in tree species richness. Additionally, we measured tree fine root length and determined species composition from fine root biomass samples with the near-infrared reflectance spectroscopy method. We did not observe higher biomass or production in mixed stands compared to monocultures. Neither did we observe any differences in tree root length or fine root turnover. One reason for this could be that these stands were still young, and canopy closure had not always taken place, i.e. a situation where above- or below-ground competition did not yet exist. Another reason could be that the rooting traits of the tree species did not differ sufficiently to support niche differentiation. Our results suggested that functional group identity (i.e. conifers vs. broadleaved species) can be more important for below-ground biomass and production than the species richness itself, as conifers seemed to be more competitive in colonising the soil volume, compared to broadleaved species.

  16. Fine root branch orders respond differentially to carbon source-sink manipulations in a longleaf pine forest.

    Science.gov (United States)

    Guo, Dali L; Mitchell, Robert J; Hendricks, Joseph J

    2004-08-01

    Fine roots are a key component of carbon (C) flow and nitrogen (N) cycling in forest ecosystems. However, the complexity and heterogeneity of the fine root branching system have hampered the assessment and prediction of C and N dynamics at ecosystem scales. We examined how root morphology, biomass, and chemistry differed with root branch orders (1-5 with root tips classified as first order roots) and how different root orders responded to increased C sink strength (via N fertilization) and reduced carbon source strength (via canopy scorching) in a longleaf pine (Pinus palustris L.) ecosystem. With increasing root order, the diameter and length of individual roots increased, whereas the specific root length decreased. Total root biomass on an areal basis was similar among the first four orders but increased for the fifth order roots. Consequently, total root length and total root surface area decreased systematically with increasing root order. Fine root N and lignin concentrations decreased, while total non-structural carbohydrate (TNC) and cellulose concentrations increased with increasing root order. N addition and canopy disturbance did not alter root morphology, but they did influence root chemistry. N fertilization increased fine root N concentration and content per unit area in all five orders, while canopy scorching decreased root N concentration. Moreover, TNC concentration and content in fifth order roots were also reduced by canopy scorching. Our results indicate that the small, fragile, and more easily overlooked first and second order roots may be disproportionately important in ecosystem scale C and N fluxes due to their large proportions of fine root biomass, high N concentrations, relatively short lifespans, and potentially high decomposition rates.

  17. Mean age of carbon in fine roots from temperate forests and grasslands with different management

    Directory of Open Access Journals (Sweden)

    E. Solly

    2013-07-01

    Full Text Available Fine roots are the most dynamic portion of a plant's root system and a major source of soil organic matter. By altering plant species diversity and composition, soil conditions and nutrient availability, and consequently belowground allocation and dynamics of root carbon (C inputs, land-use and management changes may influence organic C storage in terrestrial ecosystems. In three German regions, we measured fine root radiocarbon (14C content to estimate the mean time since C in root tissues was fixed from the atmosphere in 54 grassland and forest plots with different management and soil conditions. Although root biomass was on average greater in grasslands 5.1 ± 0.8 g (mean ± SE, n = 27 than in forests 3.1 ± 0.5 g (n = 27 (p p r = 0.65 and with the number of perennial species (r = 0.77. Fine root mean C age in grasslands was also affected by study region with averages of 0.7 ± 0.1 yr (n = 9 on mostly organic soils in northern Germany and of 1.8 ± 0.3 yr (n = 9 and 2.6 ± 0.3 (n = 9 in central and southern Germany (p < 0.05. This was probably due to differences in soil nutrient contents and soil moisture conditions between study regions, which affected plant species diversity and the presence of perennial species. Our results indicate more long-lived roots or internal redistribution of C in perennial species and suggest linkages between fine root C age and management in grasslands. These findings improve our ability to predict and model belowground C fluxes across broader spatial scales.

  18. Changes in very fine root respiration and morphology with time since last fire in a boreal forest

    Science.gov (United States)

    Makita, Naoki; Pumpanen, Jukka; Köster, Kajar; Berninger, Frank

    2016-04-01

    We examined the physiological and morphological responses of individual fine root segments in boreal forests stands with different age since the last fire to determine changes in specific fine root respiration and morphological traits during forest succession. We investigated the respiration of fine roots divided into three diameter classes (geographic area, we suggest that the recovery of boreal forests following wildfire induces a strategy that favors carbon investment in nutrient and water exploitation efficiency with consequences for higher respiration, length, and lower tissue density of very fine roots.

  19. Accumulation of trace metals in grey mangrove Avicennia marina fine nutritive roots: the role of rhizosphere processes.

    Science.gov (United States)

    Chaudhuri, Punarbasu; Nath, Bibhash; Birch, Gavin

    2014-02-15

    Mangrove sediment has long been recognized as being important in restricting the mobility of contaminants in estuarine environments. To investigate the role of rhizosphere processes in the accumulation of trace metals in mangrove fine nutritive roots, the mangrove sediments and associated fine nutritive roots are collected from five major embayments of Sydney estuary (Australia) for geochemical studies. In this estuary Avicennia marina sediments are accumulating large quantities of trace metals due to presence of abundant fine sediment (trace metals in fine nutritive roots responds to total sediment chemistry mainly due to rhizosphere sediment geochemical processes resulting in a strong linear correlation between metal concentrations in fine nutritive roots vs. total and bio-available contents in sediments. Accumulation of trace metals in fine nutritive roots is almost always exceeds rhizosphere total sediment metal concentrations. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. The effect of mycorrhizal inoculation on hybrid poplar fine root dynamics in hydrocarbon contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Gunderson, J.; Knight, J.D.; Van Rees, K.C.J. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Soil Science

    2006-07-01

    The biological remediation of contaminated soils using plants was discussed. Hybrid poplars are good candidates for phytoremediation because they root deeply, cycle large amounts of water and grow quickly. Their fine root system is pivotal in nutrient and water acquisition. Therefore, in order to maximize the phytoremediation potential, it is important to understand the response of the fine root system. In addition to degrading organic chemicals, ectomycorrhizal (ECM) fungi provide the host with greater access to nutrients. This study determined the relationship between residual soil hydrocarbons and soil properties at a field site. The effects of residual contamination on hybrid poplar fine root dynamics was also examined along with the effect of ectomycorrhizal colonization on hybrid poplar fine root dynamics when grown in diesel contaminated soil under controlled conditions. A minirhizotron camera inside a growth chamber captured images of mycorrhizal inoculation on hybrid poplar fine root production. Walker hybrid poplar seedlings were grown for 12 weeks in a control soil and also in a diesel contaminated soil. Seedlings were also grown in control and diesel contaminated, ectomycorrhizal inoculated soils. The inoculum was a mycorrhizal mix containing Pisolithus tinctorius and Rhizopogon spp. The images showed that colonization by ECM fungi increased hybrid poplar fine root production and aboveground biomass in a diesel contaminated soil compared to non-colonized trees in the same soil. Root:shoot ratios were much higher in the diesel contaminated/non-inoculated treatment than in either of the control soil treatments. Results of phytoremediation in diesel contaminated soil were better in the non-colonized treatment than in the colonized treatment. Both treatments removed more contaminants from the soil than the unplanted control. Much higher quantities of hydrocarbons were found sequestered in the roots from the inoculated treatment than from the non

  1. Estimation of fine root production, mortality and turnover with Minirhizotron in Larix gmelinii and Fraxinus mandshurica plantations

    Institute of Scientific and Technical Information of China (English)

    Jianwei SHI; Zhengquan WANG; Shuiqiang YU; Xiankui QUAN; Yue SUN; Shuxia JIA; Li MEI

    2008-01-01

    Fine root turnover is a major pathway for car-bon and nutrient cycling in forest ecosystems. However, to estimate fine root turnover, it is important to first understand the fine root dynamic processes associated with soil resource availability and climate factors. The objectives of this study were: (1) to examine patterns of fine root production and mortality in different seasons and soil depths in the Larix gmelinii and Fraxinus man-dshurica plantations, (2) to analyze the correlation of fine root production and mortality with environmental factors such as air temperature, precipitation, soil temperature and available nitrogen, and (3) to estimate fine root turn-over. We installed 36 Minirhizotron tubes in six mono-specific plots of each species in September 2003 in the Mao'ershan Experimental Forest Station. Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005. We calculated the average fine root length, annual fine root length production and mortality using image data of Minirhizotrons, and estimated fine root turnover using three approaches. Results show that the average growth rate and mortality rate in L. melinii were markedly smaller than in F. mandshurica, and were high-est in the surface soil and lowest at the bottom among all the four soil layers. The annual fine root production and mortality in F. mandshurica were significantly higher than in L. gmelinii. The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F. mandshurica and 24.0% and 51.2% in L. gmelinii. The majority of fine root mortality occurred in spring and summer for F. mandshurica and in summer and autumn for L. gmelinii. The turnover rate was 3.1 a-1 for L. gmelinii and 2.7 a-1 for F. mandshurica. Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the varia-tions of the fine root seasonal growth and 95% of the seasonal mortality. In conclusion, fine

  2. Differences in Fine-Root Biomass of Trees and Understory Vegetation among Stand Types in Subtropical Forests.

    Science.gov (United States)

    Fu, Xiaoli; Wang, Jianlei; Di, Yuebao; Wang, Huimin

    2015-01-01

    Variation of total fine-root biomass among types of tree stands has previously been attributed to the characteristics of the stand layers. The effects of the understory vegetation on total fine-root biomass are less well studied. We examined the variation of total fine-root biomass in subtropical tree stands at two sites of Datian and Huitong in China. The two sites have similar humid monsoon climate but different soil organic carbon. One examination compared two categories of basal areas (high vs. low basal area) in stands of single species. A second examination compared single-species and mixed stands with comparable basal areas. Low basal area did not correlate with low total fine-root biomass in the single-species stands. The increase in seedling density but decrease in stem density for the low basal area stands at Datian and the quite similar stand structures for the basal-area contrast at Huitong helped in the lack of association between basal area and total fine-root biomass at the two sites, respectively. The mixed stands also did not yield higher total fine-root biomasses. In addition to the lack of niche complementarity between tree species, the differences in stem and seedling densities and the belowground competition between the tree and non-tree species also contributed to the similarity of the total fine-root biomasses in the mixed and single-species stands. Across stand types, the more fertile site Datian yielded higher tree, non-tree and total fine-root biomasses than Huitong. However, the contribution of non-tree fine-root biomass to the total fine-root biomass was higher at Huitong (29.4%) than that at Datian (16.7%). This study suggests that the variation of total fine-root biomass across stand types not only was associated with the characteristics of trees, but also may be highly dependent on the understory layer.

  3. Differences in Fine-Root Biomass of Trees and Understory Vegetation among Stand Types in Subtropical Forests.

    Directory of Open Access Journals (Sweden)

    Xiaoli Fu

    Full Text Available Variation of total fine-root biomass among types of tree stands has previously been attributed to the characteristics of the stand layers. The effects of the understory vegetation on total fine-root biomass are less well studied. We examined the variation of total fine-root biomass in subtropical tree stands at two sites of Datian and Huitong in China. The two sites have similar humid monsoon climate but different soil organic carbon. One examination compared two categories of basal areas (high vs. low basal area in stands of single species. A second examination compared single-species and mixed stands with comparable basal areas. Low basal area did not correlate with low total fine-root biomass in the single-species stands. The increase in seedling density but decrease in stem density for the low basal area stands at Datian and the quite similar stand structures for the basal-area contrast at Huitong helped in the lack of association between basal area and total fine-root biomass at the two sites, respectively. The mixed stands also did not yield higher total fine-root biomasses. In addition to the lack of niche complementarity between tree species, the differences in stem and seedling densities and the belowground competition between the tree and non-tree species also contributed to the similarity of the total fine-root biomasses in the mixed and single-species stands. Across stand types, the more fertile site Datian yielded higher tree, non-tree and total fine-root biomasses than Huitong. However, the contribution of non-tree fine-root biomass to the total fine-root biomass was higher at Huitong (29.4% than that at Datian (16.7%. This study suggests that the variation of total fine-root biomass across stand types not only was associated with the characteristics of trees, but also may be highly dependent on the understory layer.

  4. Identification of coniferous fine roots to species using ribosomal PCR products of pooled root samples

    Science.gov (United States)

    Background/Question/Methods To inform an individual-based forest stand model emphasizing belowground competition, we explored the potential of using the relative abundances of ribosomal PCR products from pooled and milled roots, to allocate total root biomass to each of the thre...

  5. EFFECTS OF ELEVATED CO2 AND N-FERTILIZATION ON SURVIVAL OF PONDEROSA PINE FINE ROOTS

    Science.gov (United States)

    We used minihizaotrons to assess the effects of elevated CO2N and season on the life-span of ponderosa pine (Pinus ponderosa Dougl. Ex Laws.) fine roots. CO2 levels were ambient air (A), ambient air + 175 ?mol mol-1 (A+175) and ambient air + 350 ?mol mol-1 (A+350). N treatments ...

  6. Fine Root Dynamics and Forest Production Across a Calcium Gradient in Northern Hardwood and Conifer Ecosystems

    Science.gov (United States)

    Byung Bae Park; Ruth D. Yanai; Timothy J. Fahey; Scott W. Bailey; Thomas G. Siccama; James B. Shanley; Natalie L. Cleavitt

    2008-01-01

    Losses of soil base cations due to acid rain have been implicated in declines of red spruce and sugar maple in the northeastern USA. We studied fine root and aboveground biomass and production in five northern hardwood and three conifer stands differing in soil Ca status at Sleepers River, VT; Hubbard Brook, NH; and Cone Pond, NH. Neither aboveground biomass and...

  7. Fine root dynamics for forests on contrasting soils in the colombian Amazon

    Directory of Open Access Journals (Sweden)

    E. M. Jiménez

    2009-03-01

    Full Text Available It has been hypothesized that in a gradient of increase of soil resources carbon allocated to belowground production (fine roots decreases. To evaluate this hypothesis, we measured the mass and production of fine roots (<2 mm by two methods: 1 ingrowth cores and, 2 sequential soil coring, during 2.2 years in two lowland forests with different soils in the colombian Amazon. Differences of soil resources were determined by the type and physical and chemical properties of soil: a forest on loamy soil (Ultisol at the Amacayacu National Natural Park and, the other on white sands (Spodosol at the Zafire Biological Station, located in the Forest Reservation of the Calderón River. We found that mass and production of fine roots was significantly different between soil depths (0–10 and 10–20 cm and also between forests. White-sand forest allocated more carbon to fine roots than the clayey forest; the production in white-sand forest was twice (2.98 and 3.33 Mg C ha−1 year−1, method 1 and 2, respectively as much as in clayey forest (1.51 and 1.36–1.03 Mg C ha−1 year−1, method 1 and 2, respectively; similarly, the average of fine root mass was higher in the white-sand forest (10.94 Mg C ha−1 than in the forest on clay soils (3.04–3.64 Mg C ha−1. The mass of fine roots also showed a temporal variation related to rainfall, such that production of fine roots decreased substantially in the dry period of the year 2005. Our results suggest that soil resources play an important role in patterns of carbon allocation in these forests; carbon allocated to above-and belowground organs is different between forest types, in such a way that a trade-off above/belowground seems to exist; as a result, it is probable that there are not differences in total net primary productivity between these two forests: does belowground offset lower aboveground production in poorer soils?

  8. Leaf and fine root carbon stocks and turnover are coupled across Arctic ecosystems.

    Science.gov (United States)

    Sloan, Victoria L; Fletcher, Benjamin J; Press, Malcolm C; Williams, Mathew; Phoenix, Gareth K

    2013-12-01

    Estimates of vegetation carbon pools and their turnover rates are central to understanding and modelling ecosystem responses to climate change and their feedbacks to climate. In the Arctic, a region containing globally important stores of soil carbon, and where the most rapid climate change is expected over the coming century, plant communities have on average sixfold more biomass below ground than above ground, but knowledge of the root carbon pool sizes and turnover rates is limited. Here, we show that across eight plant communities, there is a significant positive relationship between leaf and fine root turnover rates (r(2) = 0.68, P dynamics supports the theory of a whole-plant economics spectrum. We also show that the size of the fine root carbon pool initially increases linearly with increasing LAI, and then levels off at LAI = 1 m(2) m(-2), suggesting a functional balance between investment in leaves and fine roots at the whole community scale. These ecological relationships not only demonstrate close links between above and below-ground plant carbon dynamics but also allow plant carbon pool sizes and their turnover rates to be predicted from the single readily quantifiable (and remotely sensed) parameter of LAI, including the possibility of estimating root data from satellites.

  9. Nine years of irrigation cause vegetation and fine root shifts in a water-limited pine forest.

    Directory of Open Access Journals (Sweden)

    Claude Herzog

    Full Text Available Scots pines (Pinus sylvestris L. in the inner-Alpine dry valleys of Switzerland have suffered from increased mortality during the past decades, which has been caused by longer and more frequent dry periods. In addition, a proceeding replacement of Scots pines by pubescent oaks (Quercus pubescens Willd. has been observed. In 2003, an irrigation experiment was performed to track changes by reducing drought pressure on the natural pine forest. After nine years of irrigation, we observed major adaptations in the vegetation and shifts in Scots pine fine root abundance and structure. Irrigation permitted new plant species to assemble and promote canopy closure with a subsequent loss of herb and moss coverage. Fine root dry weight increased under irrigation and fine roots had a tendency to elongate. Structural composition of fine roots remained unaffected by irrigation, expressing preserved proportions of cellulose, lignin and phenolic substances. A shift to a more negative δ13C signal in the fine root C indicates an increased photosynthetic activity in irrigated pine trees. Using radiocarbon (14C measurement, a reduced mean age of the fine roots in irrigated plots was revealed. The reason for this is either an increase in newly produced fine roots, supported by the increase in fine root biomass, or a reduced lifespan of fine roots which corresponds to an enhanced turnover rate. Overall, the responses belowground to irrigation are less conspicuous than the more rapid adaptations aboveground. Lagged and conservative adaptations of tree roots with decadal lifespans are challenging to detect, hence demanding for long-term surveys. Investigations concerning fine root turnover rate and degradation processes under a changing climate are crucial for a complete understanding of C cycling.

  10. Interspecific coordination and intraspecific plasticity of fine root traits in North American temperate tree species

    Directory of Open Access Journals (Sweden)

    Cornelia Marie Tobner

    2013-07-01

    Full Text Available Fine roots play an important role in nutrient and water absorption and hence overall tree performance. However, current understanding of the ecological role of belowground traits lags considerably behind those of aboveground traits. In this study, we used data on specific root length (SRL, fine root diameter (D and branching intensity (BI of two datasets to examine interspecific trait coordination as well as intraspecific trait variation across ontogenetic stage and soil conditions (i.e. plasticity. The first dataset included saplings of twelve North American temperate tree species grown in monocultures in a common garden experiment to examine interspecific trait coordination. The second dataset included adult and juvenile individuals of four species (present in both datasets co-occurring in natural forests on contrasting soils (i.e. humid organic, mesic and xeric podzolic. The three fine root traits investigated were strongly coordinated, with high SRL being related to low D and high BI. Fine root traits and aboveground life-strategies (i.e. relative growth rate were weakly coordinated and never significant. Intraspecific responses to changes in ontogenetic stage or soil conditions were trait dependent. SRL was significantly higher in juveniles compared to adults for A. balsamea and A. rubrum, but did not vary with soil condition. BI did not vary significantly with either ontogeny or soil conditions, while D was generally significantly lower in juveniles and higher in humid organic soils. D also had the least total (natural variation most of which was due to changes in the environment (plasticity. This study brings support for the emerging evidence for interspecific root trait coordination in trees. It also indicates that intraspecific responses to both ontogeny and soil conditions are trait dependent and less concerted. D appears to be a better indicator of environmental change than SRL and BI.

  11. Dynamics of soil exploration by fine roots down to a depth of 10 m throughout the entire rotation in Eucalyptus grandis plantations.

    Science.gov (United States)

    Laclau, Jean-Paul; da Silva, Eder A; Rodrigues Lambais, George; Bernoux, Martial; le Maire, Guerric; Stape, José L; Bouillet, Jean-Pierre; Gonçalves, José L de Moraes; Jourdan, Christophe; Nouvellon, Yann

    2013-01-01

    Although highly weathered soils cover considerable areas in tropical regions, little is known about exploration by roots in deep soil layers. Intensively managed Eucalyptus plantations are simple forest ecosystems that can provide an insight into the belowground growth strategy of fast-growing tropical trees. Fast exploration of deep soil layers by eucalypt fine roots may contribute to achieving a gross primary production that is among the highest in the world for forests. Soil exploration by fine roots down to a depth of 10 m was studied throughout the complete cycle in Eucalyptus grandis plantations managed in short rotation. Intersects of fine roots, less than 1 mm in diameter, and medium-sized roots, 1-3 mm in diameter, were counted on trench walls in a chronosequence of 1-, 2-, 3.5-, and 6-year-old plantations on a sandy soil, as well as in an adjacent 6-year-old stand growing in a clayey soil. Two soil profiles were studied down to a depth of 10 m in each stand (down to 6 m at ages 1 and 2 years) and 4 soil profiles down to 1.5-3.0 m deep. The root intersects were counted on 224 m(2) of trench walls in 15 pits. Monitoring the soil water content showed that, after clear-cutting, almost all the available water stored down to a depth of 7 m was taken up by tree roots within 1.1 year of planting. The soil space was explored intensively by fine roots down to a depth of 3 m from 1 year after planting, with an increase in anisotropy in the upper layers throughout the rotation. About 60% of fine root intersects were found at a depth of more than 1 m, irrespective of stand age. The root distribution was isotropic in deep soil layers and kriged maps showed fine root clumping. A considerable volume of soil was explored by fine roots in eucalypt plantations on deep tropical soils, which might prevent water and nutrient losses by deep drainage after canopy closure and contribute to maximizing resource uses.

  12. Towards understanding tree root profiles: simulating hydrologically optimal strategies for root distribution

    Directory of Open Access Journals (Sweden)

    M. T. van Wijk

    2001-01-01

    Full Text Available In this modelling study differences in vertical root distributions measured in four contrasting forest locations in the Netherlands were investigated. Root distributions are seen as a reflection of the plant’s optimisation strategy, based on hydrological grounds. The 'optimal' root distribution is defined as the one that maximises the water uptake from the root zone over a period of ten years. The optimal root distributions of four forest locations with completely different soil physical characteristics are calculated using the soil hydrological model SWIF. Two different model configurations for root interactions were tested: the standard model configuration in which one single root profile was used (SWIF-NC, and a model configuration in which two root profiles compete for the same available water (SWIF-C. The root profiles were parameterised with genetic algorithms. The fitness of a certain root profile was defined as the amount of water uptake over a simulation period of ten years. The root profiles of SWIF-C were optimised using an evolutionary game. The results showed clear differences in optimal root distributions between the various sites and also between the two model configurations. Optimisation with SWIF-C resulted in root profiles that were easier to interpret in terms of feasible biological strategies. Preferential water uptake in wetter soil regions was an important factor for interpretation of the simulated root distributions. As the optimised root profiles still showed differences with measured profiles, this analysis is presented, not as the final solution for explaining differences in root profiles of vegetation but as a first step using an optimisation theory to increase understanding of the root profiles of trees. Keywords: forest hydrology, optimisation, roots

  13. Fine root dynamics for forests on contrasting soils in the Colombian Amazon

    Directory of Open Access Journals (Sweden)

    E. M. Jiménez

    2009-12-01

    Full Text Available It has been hypothesized that as soil fertility increases, the amount of carbon allocated to below-ground production (fine roots should decrease. To evaluate this hypothesis, we measured the standing crop fine root mass and the production of fine roots (<2 mm by two methods: (1 ingrowth cores and, (2 sequential soil coring, during 2.2 years in two lowland forests growing on different soils types in the Colombian Amazon. Differences of soil resources were defined by the type and physical and chemical properties of soil: a forest on clay loam soil (Endostagnic Plinthosol at the Amacayacu National Natural Park and, the other on white sand (Ortseinc Podzol at the Zafire Biological Station, located in the Forest Reservation of the Calderón River. We found that the standing crop fine root mass and the production was significantly different between soil depths (0–10 and 10–20 cm and also between forests. The loamy sand forest allocated more carbon to fine roots than the clay loam forest with the production in loamy sand forest twice (mean±standard error=2.98±0.36 and 3.33±0.69 Mg C ha−1 yr−1, method 1 and 2, respectively as much as for the more fertile loamy soil forest (1.51±0.14, method 1, and from 1.03±0.31 to 1.36±0.23 Mg C ha−1 yr−1, method 2. Similarly, the average of standing crop fine root mass was higher in the white-sands forest (10.94±0.33 Mg C ha−1 as compared to the forest on the more fertile soil (from 3.04±0.15 to 3.64±0.18 Mg C ha−1. The standing crop fine root mass also showed a temporal pattern related to rainfall, with the production of fine roots decreasing substantially in the dry period of the year 2005. These results suggest that soil resources may play an important role in patterns of carbon allocation to the production of fine roots in these forests as the proportion of carbon allocated to above- and below-ground organs is different

  14. Elevated atmospheric CO2 stimulates soil fungal diversity through increased fine root production in a semiarid shrubland ecosystem.

    Science.gov (United States)

    Lipson, David A; Kuske, Cheryl R; Gallegos-Graves, La Verne; Oechel, Walter C

    2014-08-01

    Soil fungal communities are likely to be central in mediating microbial feedbacks to climate change through their effects on soil carbon (C) storage, nutrient cycling, and plant health. Plants often produce increased fine root biomass in response to elevated atmospheric carbon dioxide (CO2 ), but the responses of soil microbial communities are variable and uncertain, particularly in terms of species diversity. In this study, we describe the responses of the soil fungal community to free air CO2 enrichment (FACE) in a semiarid chaparral shrubland in Southern California (dominated by Adenomstoma fasciculatum) using large subunit rRNA gene sequencing. Community composition varied greatly over the landscape and responses to FACE were subtle, involving a few specific groups. Increased frequency of Sordariomycetes and Leotiomycetes, the latter including the Helotiales, a group that includes many dark septate endophytes known to associate positively with roots, was observed in the FACE plots. Fungal diversity, both in terms of richness and evenness, increased consistently in the FACE treatment, and was relatively high compared to other studies that used similar methods. Increases in diversity were observed across multiple phylogenetic levels, from genus to class, and were distributed broadly across fungal lineages. Diversity was also higher in samples collected close to (5 cm) plants compared to samples in canopy gaps (30 cm away from plants). Fungal biomass correlated well with soil organic matter (SOM) content, but patterns of diversity were correlated with fine root production rather than SOM. We conclude that the fungal community in this ecosystem is tightly linked to plant fine root production, and that future changes in the fungal community in response to elevated CO2 and other climatic changes will be primarily driven by changes in plant belowground allocation. Potential feedbacks mediated by soil fungi, such as soil C sequestration, nutrient cycling, and

  15. Distribution of Primitive λ-Roots of Composite Moduli Ⅱ

    Institute of Scientific and Technical Information of China (English)

    Zhiyong ZHENG; Todd COCHRANE

    2006-01-01

    We improve estimates for the distribution of primitive λ-roots of a composite modulus q yielding an asymptotic formula for the number of primitive λ-roots in any interval Ⅰ of length |I| (>>) q1/2+∈. Similar results are obtained for the distribution of ordered pairs (x, x-1) with x a primitive λ-root, and for the number of primitive λ-roots satisfying inequalities such as |x -x-1| ≤ B.

  16. Fine-tuning by strigolactones of root response to low phosphate

    Institute of Scientific and Technical Information of China (English)

    Yoram Kapulnik; Hinanit Koltai

    2016-01-01

    Strigolactones are plant hormones that regulate the development of different plant parts. In the shoot, they regulate axillary bud outgrowth and in the root, root architecture and root-hair length and density. Strigolactones are also involved with communication in the rhizosphere, including enhancement of hyphal branching of arbuscular mycorrhizal fungi. Here we present the role and activity of strigolactones under conditions of phosphate deprivation. Under these conditions, their levels of biosynthesis and exudation increase, leading to changes in shoot and root development. At least for the latter, these changes are likely to be associated with alterations in auxin transport and sensitivity. On the other hand, strigolactones may positively affect plant–mycorrhiza interactions and thereby promote phosphate acquisition by the plant. Strigolactones may be a way for plants to fine-tune their growth pattern under phosphate deprivation.

  17. Fine Root Biomass Distribution and its Relationship with Soil in Pinus massoniana Natural Forest%天然马尾松林细根生物量分布及其与土壤理化性质相关性研究

    Institute of Scientific and Technical Information of China (English)

    肖欣; 韩天一; 欧阳勋志

    2015-01-01

    基于江西中部天然马尾松林不同生长阶段细根生物量及土壤性质的调查,分0~20 cm、20~40 cm土层探讨细根生物量的分布规律及其与土壤理化性质的相关关系。结果表明,不同龄组土壤细根总生物量大小表现为:过熟林>幼龄林>成熟林>中龄林>近熟林,同一土层不同龄组生物量之间无显著差异( P>0.05),各龄组细根生物量主要集中在0~20 cm土层中。各土层不同龄组间土壤含水率均表现为成熟林显著大于幼龄林( P<0.05),容重与土壤碳氮磷含量差异均不显著(P>0.05),且碳氮磷大部分都储存在0~20 cm土层中。0~20 cm土层中,活细根生物量与土壤含水率、容重、有机碳、全氮含量相关性均达显著水平( P<0.05),而死细根生物量与土壤理化性质之间的相关性均不显著(P>0.05),细根总生物量与土壤含水率、容重相关性显著(P<0.05),与全氮含量相关性达极显著水平(P<0.01);20~40 cm土层中,活细根生物量与土壤理化性质之间相关性均不显著(P>0.05),但全氮含量与细根总生物量相关性显著(P<0.05),与死细根生物量相关性达极显著水平(P<0.01);活细根总生物量、死细根总生物量及细根总生物量与全磷含量相关性在两土层中均不显著(P>0.05)。%Based on a survey of fine root biomass and soil properties between different growth stages of Pinus mas-soniana natural forest in central of Jiangxi province, the soil was divided into 0~20 cm and 20~40 cm layers to investigate the distribution of fine root biomass and its correlation with the physical and chemical properties of soil. The results showed that the total fine root biomass of different age groups in soil were as follows:over-mature forest>young forest >mature forest >middle-age forest >near-mature forest.However, the biomass in different age groups in the

  18. Vegetation and soil environment influence the spatial distribution of root-associated fungi in a mature beech-maple forest.

    Science.gov (United States)

    Burke, David J; López-Gutiérrez, Juan C; Smemo, Kurt A; Chan, Charlotte R

    2009-12-01

    Although the level of diversity of root-associated fungi can be quite high, the effect of plant distribution and soil environment on root-associated fungal communities at fine spatial scales has received little attention. Here, we examine how soil environment and plant distribution affect the occurrence, diversity, and community structure of root-associated fungi at local patch scales within a mature forest. We used terminal restriction fragment length polymorphism and sequence analysis to detect 63 fungal species representing 28 different genera colonizing tree root tips. At least 32 species matched previously identified mycorrhizal fungi, with the remaining fungi including both saprotrophic and parasitic species. Root fungal communities were significantly different between June and September, suggesting a rapid temporal change in root fungal communities. Plant distribution affected root fungal communities, with some root fungi positively correlated with tree diameter and herbaceous-plant coverage. Some aspects of the soil environment were correlated with root fungal community structure, with the abundance of some root fungi positively correlated with soil pH and moisture content in June and with soil phosphorous (P) in September. Fungal distribution and community structure may be governed by plant-soil interactions at fine spatial scales within a mature forest. Soil P may play a role in structuring root fungal communities at certain times of the year.

  19. Fine roots are the dominant source of recalcitrant plant litter in sugar maple-dominated northern hardwood forests.

    Science.gov (United States)

    Xia, Mengxue; Talhelm, Alan F; Pregitzer, Kurt S

    2015-11-01

    Most studies of forest litter dynamics examine the biochemical characteristics and decomposition of leaf litter, but fine roots are also a large source of litter in forests. We quantified the concentrations of eight biochemical fractions and nitrogen (N) in leaf litter and fine roots at four sugar maple (Acer saccharum)-dominated hardwood forests in the north-central United States. We combined these results with litter production data to estimate ecosystem biochemical fluxes to soil. We also compared how leaf litter and fine root biochemistry responded to long-term simulated N deposition. Compared with leaf litter, fine roots contained 2.9-fold higher acid-insoluble fraction (AIF) and 2.3-fold more condensed tannins; both are relatively difficult to decompose. Comparatively, leaf litter had greater quantities of more labile components: nonstructural carbohydrates, cellulose and soluble phenolics. At an ecosystem scale, fine roots contributed over two-thirds of the fluxes of AIF and condensed tannins to soil. Fine root biochemistry was also less responsive than leaf litter to long-term simulated N deposition. Fine roots were the dominant source of difficult-to-decompose plant carbon fractions entering the soil at our four study sites. Based on our synthesis of the literature, this pattern appears to be widespread in boreal and temperate forests.

  20. Winter climate change and fine root biogenic silica in sugar maple trees (Acer saccharum): Implications for silica in the Anthropocene

    Science.gov (United States)

    Maguire, Timothy J.; Templer, Pamela H.; Battles, John J.; Fulweiler, Robinson W.

    2017-03-01

    Winter temperatures are projected to increase over the next century, leading to reductions in winter snowpack and increased frequency of soil freezing in many northern forest ecosystems. Here we examine biogenic silica (BSi) concentrations in sugar maple (Acer saccharum) fine roots collected from a snow manipulation experiment at Hubbard Brook Experimental Forest (New Hampshire, USA). Increased soil freezing significantly lowered the BSi content of sugar maple fine roots potentially decreasing their capacity to take up water and dissolved nutrients. The reduced silica uptake (8 ± 1 kmol silica km-2) by sugar maple fine roots is comparable to silica export from temperate forest watersheds. We estimate that fine roots account for 29% of sugar maple BSi, despite accounting for only 4% of their biomass. These results suggest that increased frequency of soil freezing will reduce silica uptake by temperate tree roots, thereby changing silica availability in downstream receiving waters.

  1. Vertical and horizontal root distribution of mature aspen clones: mechanisms for resource acquisition

    Science.gov (United States)

    Landhäusser, S. M.; Snedden, J.; Silins, U.; Devito, K. J.

    2012-04-01

    Spatial root distribution, root morphology, and intra- and inter-clonal connections of mature boreal trembling aspen clones (Populus tremuloides Michx.) were explored to shed light on the functional relationships between vertical and horizontal distribution of roots and the variation in soil water availability along hill slopes. Root systems of mature aspen were hydraulically excavated in large plots (6 m wide and 12 m long) and to a depth of 30 cm. Most aspen roots were located in the upper 20 cm of the soil and fine and coarse root occupancy was highest in the lower slope positions and lowest towards the upper hill slope position likely because of soil moisture availability. Observation of the root system distribution along the hill slope correlated well with the observation of greater leaf area carried by trees growing at the lower portion of the hill slope. Interestingly, trees growing at the bottom of the slope required also less sapwood area to support the same amount of leaf area of trees growing at the top of a slope. These observations appear to be closely related to soil moisture availability and with that greater productivity at the bottom of the slope. However, trees growing on the upper slope tended to have long lateral roots extending downslope, which suggests long distance water transport through these lateral feeder roots. Genetic analysis indicated that both intra- and inter-clonal root connections occur in aspen, which can play a role in the sharing of resources along moisture gradients. Root systems of boreal aspen growing on upper slope positions exhibited a combination of three attributes (1) asymmetric lateral root systems, that are skewed downslope, (2) deeper taproots, and (3) intra and inter-clonal root connections, which can all be considered adaptive strategies to avoid drought stress in upper slope positions.

  2. Plant uptake, translocation, and return of polycyclic aromatic hydrocarbons via fine root branch orders in a subtropical forest ecosystem.

    Science.gov (United States)

    Chen, Zheng-Xia; Ni, Hong-Gang; Jing, Xin; Chang, Wen-Jing; Sun, Jian-Lin; Zeng, Hui

    2015-07-01

    Fine roots of woody plants are a heterogeneous system differing markedly in structure and function. Nevertheless, knowledge about the plant uptake of organic pollutants via fine roots is scarce to date. In the present study, plant uptake, translocation, and return of polycyclic aromatic hydrocarbons (PAHs) via fine roots in a subtropical forest ecosystem were investigated. Levels of Σ15PAHs in different fine root branch orders of Michelia macclurei, Cryptocarya concinna, Cryptocarya chinensis, and Canthium dicoccums varied from 5072±1419 ng g(-1) to 6080±1656 ng g(-1), 4037±410 ng g(-1) to 6101±972 ng g(-1), 3308±1191 ng g(-1) to 4283±237 ng g(-1), and 3737±800 ng g(-1) to 4895±1216 ng g(-1), respectively. Overall, concentrations of low-molecular-weight PAHs with 2-3 aromatic rings were higher than high-molecular-weight PAHs with 4-6 aromatic rings in all fine root branch orders. There were obvious translocations of PAHs between adjacent branch orders and a net accumulation of PAHs may occur in the fourth- and fifth-order roots. The storage of PAHs in the fine root system showed an obvious increasing trend along the branch orders ascending for all tree species. The return flux of PAHs via fine roots mortality showed an obvious decreasing trend with the branch orders ascending across the four tree species. Lower order roots contributed greatly to the total PAHs return flux. Our results indicated that fine roots turnover is an effective pathway for perennial tree species to remove environmental toxicants absorbed into them.

  3. Effects of long-term temperature and nutrient manipulation on Norway spruce fine roots and mycelia production

    DEFF Research Database (Denmark)

    Leppälammi-Kujansuu, J.; Ostonen, I.; Strömgren, M.;

    2013-01-01

    production were determined from soil cores and mesh bags. Results and conclusions The fine root biomass and necromass were highest in the fertilized plots, following similar trends in the above-ground biomass, whereas the EcM root tip biomass per basal area decreased by 22 % in the fertilized plots compared......Aims and methods The effects of changing climate on ectomycorrhizal (EcM) fine roots were studied in northern Sweden by manipulating soil temperature for 14 years and/or by fertilizing for 22 years. Fine root biomass, necromass, EcM root tip biomass, morphology and number as well as mycelia...... to the control. Warming increased the fine root biomass, live/dead-ratio and the number of EcM root tips in the mineral soil and tended to increase the production of EcM mycelia. Greater fine root biomass meant more EcM root tips, although the tip frequency was not affected by fertilization or warming...

  4. Distribution of the residual roots in principal components analysis.

    Directory of Open Access Journals (Sweden)

    A. M. Kshirsagar

    1964-10-01

    Full Text Available The latent of distribution of latent roots of the covariance martix of normal variables, when a hypothetical linear function of the variables is eliminated, is derived in this paper. The relation between original roots and the residual roots- after elimination of, is also derived by an analytical method. An exact test for the goodness of fit of a single nonisotropic hypothetical principal components, using the residual roots, is then obtained.

  5. Tree Age Effects on Fine Root Biomass and Morphology over Chronosequences of Fagus sylvatica, Quercus robur and Alnus glutinosa Stands.

    Science.gov (United States)

    Jagodzinski, Andrzej M; Ziółkowski, Jędrzej; Warnkowska, Aleksandra; Prais, Hubert

    2016-01-01

    There are few data on fine root biomass and morphology change in relation to stand age. Based on chronosequences for beech (9-140 years old), oak (11-140 years) and alder (4-76 years old) we aimed to examine how stand age affects fine root biomass and morphology. Soil cores from depths of 0-15 cm and 16-30 cm were used for the study. In contrast to previously published studies that suggested that maximum fine root biomass is reached at the canopy closure stage of stand development, we found almost linear increases of fine root biomass over stand age within the chronosequences. We did not observe any fine root biomass peak in the canopy closure stage. However, we found statistically significant increases of mean fine root biomass for the average individual tree in each chronosequence. Mean fine root biomass (0-30 cm) differed significantly among tree species chronosequences studied and was 4.32 Mg ha(-1), 3.71 Mg ha(-1) and 1.53 Mg ha(-1), for beech, oak and alder stands, respectively. The highest fine root length, surface area, volume and number of fine root tips (0-30 cm soil depth), expressed on a stand area basis, occurred in beech stands, with medium values for oak stands and the lowest for alder stands. In the alder chronosequence all these values increased with stand age, in the beech chronosequence they decreased and in the oak chronosequence they increased until ca. 50 year old stands and then reached steady-state. Our study has proved statistically significant negative relationships between stand age and specific root length (SRL) in 0-30 cm soil depth for beech and oak chronosequences. Mean SRLs for each chronosequence were not significantly different among species for either soil depth studied. The results of this study indicate high fine root plasticity. Although only limited datasets are currently available, these data have provided valuable insight into fine root biomass and morphology of beech, oak and alder stands.

  6. Fine root dynamics in lodgepole pine and white spruce stands along productivity gradients in reclaimed oil sands sites.

    Science.gov (United States)

    Jamro, Ghulam Murtaza; Chang, Scott X; Naeth, M Anne; Duan, Min; House, Jason

    2015-10-01

    Open-pit mining activities in the oil sands region of Alberta, Canada, create disturbed lands that, by law, must be reclaimed to a land capability equivalent to that existed before the disturbance. Re-establishment of forest cover will be affected by the production and turnover rate of fine roots. However, the relationship between fine root dynamics and tree growth has not been studied in reclaimed oil sands sites. Fine root properties (root length density, mean surface area, total root biomass, and rates of root production, turnover, and decomposition) were assessed from May to October 2011 and 2012 using sequential coring and ingrowth core methods in lodgepole pine (Pinus contorta Dougl.) and white spruce (Picea glauca (Moench.) Voss) stands. The pine and spruce stands were planted on peat mineral soil mix placed over tailings sand and overburden substrates, respectively, in reclaimed oil sands sites in Alberta. We selected stands that form a productivity gradient (low, medium, and high productivities) of each tree species based on differences in tree height and diameter at breast height (DBH) increments. In lodgepole pine stands, fine root length density and fine root production, and turnover rates were in the order of high > medium > low productivity sites and were positively correlated with tree height and DBH and negatively correlated with soil salinity (P productivity gradient and was negatively correlated with soil compaction. In conclusion, fine root dynamics along the stand productivity gradients were closely linked to stand productivity and were affected by limiting soil properties related to the specific substrate used for reconstructing the reclaimed soil. Understanding the impact of soil properties on fine root dynamics and overall stand productivity will help improve land reclamation outcomes.

  7. Species-specific patterns of fine root demography and hydraulic lift among trees of the fall-line sandhills

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Below ground processes, such as fine root demography and soil water redistribution, can alter carbon, nutrient and water cycles in terrestrial ecosystems. Although...

  8. Compensation in Root Water Uptake Models Combined with Three-Dimensional Root Length Density Distribution

    NARCIS (Netherlands)

    Heinen, M.

    2014-01-01

    A three-dimensional root length density distribution function is introduced that made it possible to compare two empirical uptake models with a more mechanistic uptake model. Adding a compensation component to the more empirical model resulted in predictions of root water uptake distributions

  9. Phenolic profile within the fine-root branching orders of an evergreen species highlights a disconnect in root tissue quality predicted by elemental- and molecular-level carbon composition.

    Science.gov (United States)

    Wang, Jun-Jian; Tharayil, Nishanth; Chow, Alex T; Suseela, Vidya; Zeng, Hui

    2015-06-01

    Fine roots constitute a significant source of plant productivity and litter turnover across terrestrial ecosystems, but less is known about the quantitative and qualitative profile of phenolic compounds within the fine-root architecture, which could regulate the potential contribution of plant roots to the soil organic matter pool. To understand the linkage between traditional macro-elemental and morphological traits of roots and their molecular-level carbon chemistry, we analyzed seasonal variations in monomeric yields of the free, bound, and lignin phenols in fine roots (distal five orders) and leaves of Ardisia quinquegona. Fine roots contained two-fold higher concentrations of bound phenols and three-fold higher concentrations of lignin phenols than leaves. Within fine roots, the concentrations of free and bound phenols decreased with increasing root order, and seasonal variation in the phenolic profile was more evident in lower order than in higher order roots. The morphological and macro-elemental root traits were decoupled from the quantity, composition and tissue association of phenolic compounds, revealing the potential inability of these traditional parameters to capture the molecular identity of phenolic carbon within the fine-root architecture and between fine roots and leaves. Our results highlight the molecular-level heterogeneity in phenolic carbon composition within the fine-root architecture, and imply that traits that capture the molecular identity of the root construct might better predict the decomposition dynamics within fine-root orders.

  10. [Response of fine root decomposition to simulated nitrogen deposition in Pleioblastus amarus plantation, rainy area of West China].

    Science.gov (United States)

    Tu, Li-Hua; Chen, Gang; Peng, Yong; Hu, Hong-Ling; Hu, Ting-Xing; Zhang, Jian

    2014-08-01

    As an important contributor to carbon (C) flux in the global C cycle, fine root litter decomposition in forests has the potential to be affected by the elevated nitrogen (N) deposition observed globally. From November 2007 to January 2013, a field experiment involving monthly simulated deposition of N in a Pleioblastus amarus plantation was conducted in the Rainy Area of West China. Four levels of nitrogen deposition were included as control (0 g N x m(-2) x a(-1)), low nitrogen (5 g N x m(-2) x a(-1)), medium nitrogen (15 g N x m(-2) x a(-1)) and high nitrogen (30 g N x m(-2) x a(-1)). After 3 years of simulated N deposition experiment (January 2011) , a two-year fine root decomposition experiment was conducted in the simulated N deposition plots using litterbag method, under monthly experimental N deposition. The decomposition rates of fine roots were fast first and then slow. Mass loss of fine roots in the first year of decomposition was up to 60%, and the change of the remaining mass was very slow in the second year. The time of 50% and 95% mass loss of fine roots was 1.20 and 5.17 years, respectively, under the conditions of no addition N input. In general, decomposition rates were underestimated using negative exponential model. Simulated N deposition significantly inhibited the decomposition of fine roots. The remaining mass in the high nitrogen treatment was 51.0% higher than that in the control, after two years of decomposition. Simulated N deposition increased C, P and K contents in the remaining mass of litter. Compared with the control, soil pH decreased significantly in the medium and high nitrogen treatments, soil organic C, total N, ammonium and nitrate contents and fine root biomass of P. amarus increased significantly in the high nitrogen treatment after simulated N deposition for 4. 5 years. Key words: nitrogen deposition; fine root decomposition; Pleioblastus amarus.

  11. N, P and K limitation of fine root growth along an elevation transect in tropical mountain forests

    Science.gov (United States)

    Graefe, Sophie; Hertel, Dietrich; Leuschner, Christoph

    2010-11-01

    It is generally assumed that tree growth in tropical low-elevation forests is primarily limited by phosphorus while nitrogen limitation is more prominent in tropical montane forests where temperature is lower and the soils are poorly developed. We tested this hypothesis in mountain rainforests of South Ecuador by investigating the growth response of tree fine roots to N, P and K fertilization in ingrowth cores exposed at 1050 m (pre-montane) and 3060 m (upper montane) elevation. Root growth into unfertilized ingrowth cores (control treatment) was about 10 times slower at 3060 m than at 1050 m. At 1050 m, root growth was stimulated not only by P, but also by N and K. In contrast, N was the only element to promote root growth at 3060 m. The N concentration in fine root biomass dropped to nearly a third between 1050 and 3060 m, those of P, K, Ca and Mg decreased as well, but to a lesser degree. According to a 15NO 315NH 4 tracer study along the slope, tree fine roots accumulated nitrate and ammonium in root biomass at similar rates between 1050 and 3060 m, despite lower temperatures higher upslope. We conclude that the nature of nutrient limitation of tree fine root growth changes with elevation from an apparent co-limitation by P together with N and K at 1050 m to predominant N limitation at 3060 m, which is also reflected by low foliar N concentrations. Increasing N limitation may have caused the high fine root biomass and root/shoot ratio in the high elevation forest, while the capability of the roots to acquire mineral N apparently was not affected by lower temperatures at high elevations.

  12. Estimation of tree root distribution using electrical resistivity tomography

    Science.gov (United States)

    Schmaltz, Elmar; Uhlemann, Sebastian

    2016-04-01

    Trees influence soil-mantled slopes mechanically by anchoring in the soil with coarse roots. Forest-stands play an important role in mechanical reinforcement to reduce the susceptibility to slope failures. However, the effect of stabilisation of roots is connected with the distribution of roots in the ground. The architecture and distribution of tree roots is diverse and strongly dependent on species, plant age, stand density, relief, nutrient supply as well as climatic and pedologic conditions. Particularly trees growing on inclined slopes show shape-shifting root systems. Geophysical techniques are commonly used to non-invasively study hydrological and geomorphological subsurface properties, by imaging contrasting physical properties of the ground. This also poses the challenge for geophysical imaging of root systems, as properties, such as electrical resistivity, of dry and wet roots fall within the range of soils. The objective of this study is whether electrical resistivity tomography (ERT) allows a reliable reproduction of root systems of alone-standing trees on diverse inclined slopes. In this regard, we set the focus on the branching of secondary roots of two common walnut trees (Juglans regia L.) that were not disturbed in the adjacencies and thus expected to develop their root systems unhindered. Walnuts show a taproot-cordate root system with a strong tap-root in juvenile age and a rising cordate rooting with increasing age. Hence, mature walnuts can exhibit a root system that appears to be deformed or shifted respectively when growing at hillslope locations. We employed 3D ERT centred on the tree stem, comprising dipole-dipole measurements on a 12-by-41 electrode grid with 0.5 m and 1.0m electrode spacing in x- and y-direction respectively. Data were inverted using a 3D smoothness constrained non-linear least-squares algorithm. First results show that the general root distribution can be estimated from the resistivity models and that shape

  13. Correlation between specific fine root length and mycorrhizal colonization of maize in different soil types

    Institute of Scientific and Technical Information of China (English)

    Wenke LIU

    2009-01-01

    A pot experiment was conducted in a glass-house to investigate the correlation between specific fine root length (SFRL) and root colonization (RC) of maize inoculated with six arbuscular mycorrhizal fungi (AMF) in three soil types. The results showed that six AMF associated with maize presented different abilities in RC and effects on SFRL. In addition, there was a significant correlation between SFRL and RC of arbuscular mycor-rhizal maize in Beijing soil (Cinnamon soil), but no significant correlation in Hubei soil (Brunisolic soil) and Guangdong soil (Red soil). It is concluded that mycor-rhizal colonization decreased the SFRL of maize, and the correlation between SFRL and RC of mycorrhizal maize depended on soil type.

  14. Studies on the spatial and time development of soil- and root-chemical stress parameters and on the effects of said parameters on fine root development in acid soil forest ecosystems of the Hils. Untersuchungen zur raumzeitlichen Entwicklung boden- und wurzelchemischer Stressparameter und deren Einfluss auf die Feinwurzelentwicklung in bodensauren Waldgesellschaften des Hils

    Energy Technology Data Exchange (ETDEWEB)

    Raben, G.H.

    1988-01-01

    The soil chemistry parameters of different forest ecosystems were investigated. Increased aluminium concentrations were found in acid soils. The depth distribution of the living and dead fine root mass was investigated, and root-damaging Ca/Al ratios were marked out.

  15. Study of root distribution of Macaranga tanarius (L. Müll. Arg. (Parasol leaf tree on East-West highway slope, Malaysia

    Directory of Open Access Journals (Sweden)

    Nazi Avani

    2013-01-01

    Full Text Available Vegetation influences the stability of slope by both hydrological events and mechanical reinforcement of the soil. The magnitude of such effects is subject to the root system growth, which in turn is a purpose of the genetic properties of the species and site appearances. In this study, we investigated the root distribution of Macaranga tanarius (L. Müll. Arg. as a native species in Malaysia, with an aim to rise our knowledge on root area ratio distribution inside the soil. Concerning the estimation of root distribution within the soil, we assessed the root area ratio (the proportion between the area occupied by the roots in a slice area of soil according to its depth for four samples in the rainforest. Results show that the root area ratio (RAR declined with depth, and the higher RAR values were calculated in the higher layers. RAR values were between 0.950% and 18.477%. There is a plentiful diversity of root density in depth classes. Also, the result showed that about 50% of the roots are located in the first 10 cm layer, and about 87% of roots were in the fine root diameter (>2 mm. There is not a significant difference between RAR and soil depth. Spearman correlation showed no significant and negative correlation between RAR and depth. The maximum RAR percentage was in the first layer 0-10 cm (44.59%. Also, the results showed that the amount of RAR decreased with depth in fine roots (d<2mm, but RAR in thin roots (2fine root number was much higher than the number of thin roots, but the RAR value in thin roots was much higher than of the fine roots.

  16. Amyloplast Distribution Directs a Root Gravitropic Reaction

    Science.gov (United States)

    Kordyum, Elizabeth

    Immobile higher plants are oriented in the gravitational field due to gravitropim that is a physiological growth reaction and consists of three phases: reception of a gravitational signal by statocytes, its transduction to the elongation zone, and finally the organ bending. As it is known, roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector, stems - with negative gravitropism, i. e. they grow in the direction opposite to a gravitational vector. According to the Nemec’s and Haberlandt’s starch-statolith hypothesis, amyloplasts in diameter of 1.5 - 3 μ in average, which appear to act as gravity sensors and fulfill a statolythic function in the specialized graviperceptive cells - statocytes, sediment in the direction of a gravitational vector in the distal part of a cell, while a nucleus is in the proximal one. There are reasonable data that confirm the amyloplasts-statoliths participation in gravity perception: 1) correlation between the statoliths localization and the site of gravity sensing, 2) significant redistribution (sedimentation) of amyloplasts in statocytes under gravistimulation in comparison with other cell organelles, 3) root decreased ability to react on gravity under starch removal from amyloplasts, 4) starchless Arabidopsis thaliana mutants are agravitropic, 5) amyloplasts-statoliths do not sediment in the absence of the gravitational vector and are in different parts or more concentrated in the center of statocytes. Plant tropisms have been intensively studied for many decades and continue to be investigated. Nevertheless, the mechanisms by which plants do so is still not clearly explained and many questions on gravisensing and graviresponse remain unanswered. Even accepted hypotheses are now being questioned and recent data are critically evaluated. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence

  17. An Invariant Allometric Scaling of Nitrogen and Phosphorus in Leaves, Stems and Fine roots Along an Altitudinal Gradient

    Science.gov (United States)

    Zhao, Ning; He, Nianpeng; Wang, Qiufeng; Wang, Ruili; Xu, Zhiwei; YU, Guirui

    2014-05-01

    Plant nutrient allocation explicitly links the plant resource capture strategy to the material and energy cycles of ecosystems. The nitrogen (N) to phosphorus (P) relationship in plant organs is of particular interest, as N and P are the major limiting elements for plant growth. Here we analyze the relations of N and P in leaves, stems and fine roots of 269 species along an altitudinal transect on the northern slope of Changbai Mountain, China, to explore the partitioning of nutrients in major plant organs and its response to environmental gradient. We find that N, P contents as well as N: P ratio are significantly higher in leaves than in stems and fine roots. Nutrient contents of major plant organs show consistent response to the altitudinal gradient. N and P contents of leaves, stems and fine roots increased while N:P ratios decreased with elevation. Moreover, general allometric scaling relations of N and P is found in leaves, stems and fine roots with slopes of 0.78, 0.72 and 0.87, respectively, and differences exist among different plant growth forms. In general, the exponent values of the allometric scaling of N and P in leaves, stems and fine roots keep as an invariant constant along the altitudinal gradient, which implies the existence of conserved nutrient allocation strategies in plant.

  18. A quantitative analysis of fine scale distribution of intertidal meiofauna in response to food resources

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Gauns, M.

    Fine scale vertical and spatial distribution of meiofauna in relation to food abundance was studied in the intertidal sediment at Dias Beach. The major abiotic factors showed significant changes and progressive fine scale decrease in vertical...

  19. The roots of diversity: below ground species richness and rooting distributions in a tropical forest revealed by DNA barcodes and inverse modeling.

    Directory of Open Access Journals (Sweden)

    F Andrew Jones

    Full Text Available BACKGROUND: Plants interact with each other, nutrients, and microbial communities in soils through extensive root networks. Understanding these below ground interactions has been difficult in natural systems, particularly those with high plant species diversity where morphological identification of fine roots is difficult. We combine DNA-based root identification with a DNA barcode database and above ground stem locations in a floristically diverse lowland tropical wet forest on Barro Colorado Island, Panama, where all trees and lianas >1 cm diameter have been mapped to investigate richness patterns below ground and model rooting distributions. METHODOLOGY/PRINCIPAL FINDINGS: DNA barcode loci, particularly the cpDNA locus trnH-psba, can be used to identify fine and small coarse roots to species. We recovered 33 species of roots from 117 fragments sequenced from 12 soil cores. Despite limited sampling, we recovered a high proportion of the known species in the focal hectare, representing approximately 14% of the measured woody plant richness. This high value is emphasized by the fact that we would need to sample on average 13 m(2 at the seedling layer and 45 m(2 for woody plants >1 cm diameter to obtain the same number of species above ground. Results from inverse models parameterized with the locations and sizes of adults and the species identifications of roots and sampling locations indicates a high potential for distal underground interactions among plants. CONCLUSIONS: DNA barcoding techniques coupled with modeling approaches should be broadly applicable to studying root distributions in any mapped vegetation plot. We discuss the implications of our results and outline how second-generation sequencing technology and environmental sampling can be combined to increase our understanding of how root distributions influence the potential for plant interactions in natural ecosystems.

  20. Impact of tapping and soil water status on fine root dynamics in a rubber tree plantation in Thailand

    Directory of Open Access Journals (Sweden)

    Naruenat eChairungsee

    2013-12-01

    Full Text Available Fine roots (FR play a major role in the water and nutrient uptake of plants and contribute significantly to the carbon and nutrient cycles of ecosystems through their annual production and turnover. FR growth dynamics were studied to understand the endogenous and exogenous factors driving these processes in a 14 year-old plantation of rubber trees located in eastern Thailand. FR dynamics were observed using field rhizotrons from Oct. 2007 to Oct. 2009. This period covered two complete dry seasons (Nov.-Mar. and two complete rainy seasons (Apr.-Oct., allowing us to study the effect of rainfall seasonality on FR dynamics. Rainfall and its distribution during the two successive years showed strong differences with 1500 mm and 950 mm in 2008 and 2009, respectively. Fine root production (FRP completely stopped during the dry seasons and resumed quickly after the first rains. During the rainy seasons, FRP and the daily root elongation rate (RER were highly variable and exhibited strong annual variations with a total FRP of 139.8 and 40.4 m m-² and an average RER of 0.16 and 0.12 cm d-1 in 2008 and 2009, respectively. The significant positive correlations found between FRP, RER, the appearance of new roots and rainfall at monthly intervals revealed the impact of rainfall seasonality on FR dynamics. However, the rainfall patterns failed to explain the weekly variations of FR dynamics observed particularly during the rainy seasons. At this time step, FRP, RER and the appearance of new FR were negatively correlated to the average soil matric potential measured at a depth of between 30 and 60 cm. In addition, our study revealed a significant negative correlation between FR dynamics and the monthly production of dry rubber. Consequently, latex harvesting might disturb carbon dynamics in the whole tree, far beyond the trunk where the tapping was performed. These results exhibit the impact of climatic conditions and tapping system in the carbon budget of

  1. Integrating water by plant roots over spatially distributed soil salinity

    Science.gov (United States)

    Homaee, Mehdi; Schmidhalter, Urs

    2010-05-01

    In numerical simulation models dealing with water movement and solute transport in vadose zone, the water budget largely depends on uptake patterns by plant roots. In real field conditions, the uptake pattern largely changes in time and space. When dealing with soil and water salinity, most saline soils demonstrate spatially distributed osmotic head over the root zone. In order to quantify such processes, the major difficulty stems from lacking a sink term function that adequately accounts for the extraction term especially under variable soil water osmotic heads. The question of how plants integrate such space variable over its rooting depth remains as interesting issue for investigators. To move one step forward towards countering this concern, a well equipped experiment was conducted under heterogeneously distributed salinity over the root zone with alfalfa. The extraction rates of soil increments were calculated with the one dimensional form of Richards equation. The results indicated that the plant uptake rate under different mean soil salinities preliminary reacts to soil salinity, whereas at given water content and salinity the "evaporative demand" and "root activity" become more important to control the uptake patterns. Further analysis revealed that root activity is inconstant when imposed to variable soil salinity. It can be concluded that under heterogeneously distributed salinity, most water is taken from the less saline increment while the extraction from other root zone increments with higher salinities never stops.

  2. Evaluating ecohydrological theories of woody root distribution in the Kalahari.

    Directory of Open Access Journals (Sweden)

    Abinash Bhattachan

    Full Text Available The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1 the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis, and (2 the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis. Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity.

  3. Differences in U root-to-shoot translocation between plant species explained by U distribution in roots

    Energy Technology Data Exchange (ETDEWEB)

    Straczek, Anne; Duquene, Lise [Belgium Nuclear Research Centre (SCK.CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol (Belgium); Wegrzynek, Dariusz [IAEA, Seibersdorf Laboratories, A-2444 Seibersdorf (Austria); Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Chinea-Cano, Ernesto [IAEA, Seibersdorf Laboratories, A-2444 Seibersdorf (Austria); Wannijn, Jean [Belgium Nuclear Research Centre (SCK.CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol (Belgium); Navez, Jacques [Royal Museum of Africa, Department of Geology, Leuvensesteenweg 13, 3080 Tervuren (Belgium); Vandenhove, Hildegarde, E-mail: hvandenh@sckcen.b [Belgium Nuclear Research Centre (SCK.CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol (Belgium)

    2010-03-15

    Accumulation and distribution of uranium in roots and shoots of four plants species differing in their cation exchange capacity of roots (CECR) was investigated. After exposure in hydroponics for seven days to 100 mumol U L{sup -1}, distribution of uranium in roots was investigated through chemical extraction of roots. Higher U concentrations were measured in roots of dicots which showed a higher CECR than monocot species. Chemical extractions indicated that uranium is mostly located in the apoplasm of roots of monocots but that it is predominantly located in the symplasm of roots of dicots. Translocation of U to shoot was not significantly affected by the CECR or distribution of U between symplasm and apoplasm. Distribution of uranium in roots was investigated through chemical extraction of roots for all species. Additionally, longitudinal and radial distribution of U in roots of maize and Indian mustard, respectively showing the lowest and the highest translocation, was studied following X-ray fluorescence (XRF) analysis of specific root sections. Chemical analysis and XRF analysis of roots of maize and Indian mustard clearly indicated a higher longitudinal and radial transport of uranium in roots of Indian mustard than in roots of maize, where uranium mostly accumulated in root tips. These results showed that even if CECR could partly explain U accumulation in roots, other mechanisms like radial and longitudinal transport are implied in the translocation of U to the shoot.

  4. Root system distribution and yield of 'Conilon' coffee propagated by seeds or cuttings

    Directory of Open Access Journals (Sweden)

    Fábio Luiz Partelli

    2014-05-01

    Full Text Available The objective of this work was to evaluate the root system distribution and the yield of 'Conilon' coffee (Coffea canephora propagated by seeds or cuttings. The experiment was carried out with 2x1 m spacing, in an Oxisol with sandy clay loam texture. A randomized complete block design was used, following a 2x9x6 factorial arrangement, with two propagation methods (seeds and cuttings, nine sampling spacings (0.15, 0.30, 0.45, 0.60, 0.75, and 0.90 m between rows, and 0.15, 0.30, and 0.45 between plants within rows, six soil depths (0.10-0.20, 0.20-0.30, 0.30-0.40, 0.40-0.50, and 0.50-0.60 m, and six replicates. Soil cores (27 cm3 with roots were taken from 12 experimental units, 146 months after planting. The surface area of the root system and root diameter, length, and volume were assessed for 13 years and, then, correlated with grain yield. The highest fine root concentration occurred at the superficial soil layers. The variables used to characterize the root system did not differ between propagation methods. Moreover, no differences were observed for net photosynthetic CO2 assimilation rate, stomatal conductance, internal CO2 concentrations, and instantaneous water-use efficiency in the leaves. Cutting-propagated plants were more productive than seed-propagated ones.

  5. 拉萨-林芝植被样带不同群落类型的细根生物量%Biomass of Fine Root in Different Community Type on the Tibetan Vegetation Transect

    Institute of Scientific and Technical Information of China (English)

    何永涛; 石培礼; 徐玲玲

    2009-01-01

    Fine root biomass was measured by soil core sampler in four community type on Tibetan Plateau, of which include two coppice of Betida platyphylla and Quercus aquifolioides , one shrub of Salix oritrepha, and one coniferous woodland of Pinus densata. The fine root density were Betida platyphylla of (785.9±290.4) g·m~(-2), Quercus aquifolioides of (801.0±279.5) g·m~(-2) , Salix oritrepha of (376.0±146.0) g·m~(-2) and Pinus densata of (431.2 ±171.1) g·m~(-2) . Result showed that the fine root density of two coppices was significantly higher than that of shrub and coniferous woodland. Dead fine root was 16.2% of the total fine root in Betula platyphylla, and the percentage were about 25% in other three type of forest. Distribution of fine root had the same pattern that high density of fine root appeared at 0~10 cm soil depth.%@@ 细根通常是指植被地下根系中直径小于2 nun的根,其生产和周转直接影响着整个生态系统的碳平衡和养分循环.在森林生态系统中约3%~84%(大部分为10%-60%)的净初级生产力被用于细根的生产(张小全等,2001);而细根的周转则是森林土壤C累积的最大输入量,如果忽略细根的生产、死亡和分解,土壤有机物质和养分元素的周转将被低估20%-80%(Vogt et al.,1986;1996).

  6. CO2 AND N-FERTILIZATION EFFECTS ON FINE ROOT LENGTH, PRODUCTION, AND MORTALITY: A 4-YEAR PONDEROSA PINE STUDY

    Science.gov (United States)

    We conducted a 4-year study of Pinus ponderosa fine root (<2 mm) responses to atmospheric CO2 and N-fertilization. Seedlings were grown in open-top chambers at 3 CO2 levels (ambient, ambient+175 mol/mol, ambient+350 mol/mol) and 3 N-fertilization levels (0, 10, 20 g?m-2?yr-1). ...

  7. Viewing forests from below: fine root mass declines relative to leaf area in aging lodgepole pine stands.

    Science.gov (United States)

    Schoonmaker, A S; Lieffers, V J; Landhäusser, S M

    2016-07-01

    In the continued quest to explain the decline in productivity and vigor with aging forest stands, the most poorly studied area relates to root system change in time. This paper measures the wood production, root and leaf area (and mass) in a chronosequence of fire-origin lodgepole pine (Pinus contorta Loudon) stands consisting of four age classes (12, 21, 53, and ≥100 years), each replicated ~ five times. Wood productivity was greatest in the 53-year-old stands and then declined in the ≥100-year-old stands. Growth efficiency, the quantity of wood produced per unit leaf mass, steadily declined with age. Leaf mass and fine root mass plateaued between the 53- and ≥100-year-old stands, but leaf area index actually increased in the older stands. An increase in the leaf area index:fine root area ratio supports the idea that older stand are potentially limited by soil resources. Other factors contributing to slower growth in older stands might be lower soil temperatures and increased self-shading due to the clumped nature of crowns. Collectively, the proportionally greater reduction in fine roots in older stands might be the variable that predisposes these forests to be at a potentially greater risk of stress-induced mortality.

  8. Fine-root carbon and nitrogen concentration of European beech (Fagus sylvatica L. in Italy Prealps: possible implications of coppice conversion to high forest

    Directory of Open Access Journals (Sweden)

    Mattia eTerzaghi

    2013-06-01

    Full Text Available Fine-root systems represent a very sensitive plant compartment to environmental changes. Gaining further knowledge about their dynamics would improve soil carbon input understanding. This paper investigates C and N concentrations in fine roots in relation to different stand characteristics resulting from conversion of coppiced forests to high forests. In order to evaluate possible interferences due to different vegetative stages of vegetation, fine-root sampling was repeated 6 times in each stand during the same 2008 growing season. Fine-root sampling was conducted within three different soil depths (0-10; 10-20; and 20-30 cm. Fine-root traits were measured by means of WinRHIZO software which enable us to separate them into three different diameter classes (0-0.5, 0.5-1.0 and 1.0-2.0 mm. The data collected indicate that N concentration was higher in converted stands than in the coppiced stand whereas C concentration was higher in the coppiced stand than in converted stands. Consequently the fine-root C:N ratio was significantly higher in coppiced than in converted stands and showed an inverse relationship with fine-root turnover rate, confirming a significant change of fine-root status after the conversion of a coppice to high forest.

  9. Fine-root carbon and nitrogen concentration of European beech (Fagus sylvatica L.) in Italy Prealps: possible implications of coppice conversion to high forest.

    Science.gov (United States)

    Terzaghi, Mattia; Montagnoli, Antonio; Di Iorio, Antonino; Scippa, Gabriella S; Chiatante, Donato

    2013-01-01

    Fine-root systems represent a very sensitive plant compartment to environmental changes. Gaining further knowledge about their dynamics would improve soil carbon input understanding. This paper investigates C and N concentrations in fine roots in relation to different stand characteristics resulting from conversion of coppiced forests to high forests. In order to evaluate possible interferences due to different vegetative stages of vegetation, fine-root sampling was repeated six times in each stand during the same 2008 growing season. Fine-root sampling was conducted within three different soil depths (0-10; 10-20; and 20-30 cm). Fine-root traits were measured by means of WinRHIZO software which enable us to separate them into three different diameter classes (0-0.5, 0.5-1.0 and 1.0-2.0 mm). The data collected indicate that N concentration was higher in converted stands than in the coppiced stand whereas C concentration was higher in the coppiced stand than in converted stands. Consequently the fine-root C:N ratio was significantly higher in coppiced than in converted stands and showed an inverse relationship with fine-root turnover rate, confirming a significant change of fine-root status after the conversion of a coppice to high forest.

  10. Root Ecological Niche Index and Root Distribution Characteristics of Artificial Phytocommunities in Rehabilitated Fields

    Institute of Scientific and Technical Information of China (English)

    Hu Jianzhong; Zhen Jiali; Shen Jingyu

    2006-01-01

    In the implementation phase of the Conversion of Cropland to Forest and Grassland (CCFG) project in China,it is important,from a scientific point of view,to recognize phytocommunities' characteristics,species compatibility,and ecological function.The ecological niche that roots occupy,their abundance and distribution,and the factors that affect them must be acknowledged.Following the methodology of community ecology,the total root mass of a phytocommunity is measured as cubic volume.Root biomass,length,and the number of roots in every diameter class,for each soil layer and for each plant species,are regarded as observation variables.In the first instance therefore,a new method to calculate the root ecological niche index (REND is proposed,embracing the entire phytocommunity of plantations.Using the new method,the roots of pbytocommunities in Datong County,Qinghai Province (one of the counties selected for the national CCFG experiment),are dealt with in this paper.The results show that most of the vertical distributions of plant roots belong to the type wherein the roots are concentrated in the topsoil layer (0-20 cm),far more than those in the lower soil layers.The RENI of pbytocommunities is higher than that of pure stands or monocultures.The distribution of RENI by root diameter can be divided into four types:J-type,inverse J-type,recumbent S-type,and U-type.RENI is positively correlated with the wet biomass of aboveground level stems,branches,and plant leaves,and with the species richness of phytocommunities.Although the RENIs of plantations in rehabilitated fields are a little lower than those of natural forests,they are higher than those of cultivated crops.The RENIs of three community types (Picea crassifolia+Hippophae rhamnoides ssp.sinensis,H.rhamnoides ssp.sinensis,and P.crassifolia) in rehabilitated fields benefit greatly from the restoration project.The implementation of the CCFG project is important for the increase in RENI and the multiple functions of

  11. Root cold hardiness and native distribution of subalpine conifers

    Science.gov (United States)

    Mark D. Coleman; Thomas M. Hinckley; Geoffrey McNaughton; Barbara A. Smit

    1992-01-01

    Root and needle cold hardiness were compared in seedlings of subalpine conifers to determine if differences existed among species originating from either cold continental climates or mild maritime climates. Abies amabilis (Dougl.) Carr. and Tsuga mertensiana (Bong.) Carr. are exclusively distributed in maritime environments,...

  12. Effect of Leucaena Leucocephala Fine Root on Soil Fixation in Debris Flow Area of Jiangjia Gully%蒋家沟泥石流区新银合欢细根固土效应

    Institute of Scientific and Technical Information of China (English)

    郭灵辉; 王道杰; 陈东; 陈晓艳

    2011-01-01

    以蒋家沟泥石流区不同龄级新银合欢根系为研究对象,在分析其垂直分布与构成特征的基础上,运用加筋原理研究其固土效应。结果显示,不同龄级新银合欢根系表聚现象明显,随土层深度的增加呈减少趋势,约80%集中在0—120cm土层范围内;细根(D≤1mm)在整个细根根系中所占比例较大,决定着整个细根的分布趋势;10年生新银合欢D≤1mm细根较5年生增幅明显,15年生1mm%Variously aged Leucaena leucocephala in debris flow area of Jiangjia gully were chosen and the fine root systems were dug out from the surface to the bottom layers at different distances from the stem in three directions.Basing on the analysis of fine root vertical distributions and composition,the effect of fine roots on the soil shear strength were estimated according to reinforcement theory.The result show that fine roots exhibited an obvious accumulation trait in the topsoil layer,which reduced with depth.Approximately 80% of the fine root materials were found in the layer between 0—120 cm depths.Fine roots were mainly composed of smaller ones(D≤1 mm)and determined the development of root distribution.The 10-year stands had more fine roots(D≤1 mm) than 5-year ones,and the 15-year stands had obviously more intermediate roots(1 mm≤D≤2 mm) comparing to the 10-year stands.Root tensile strength decreased significantly with increasing diameter,following a power law function.The soil shear strength enhanced by fine roots was highly variable among depths and ages,largely depended on the smaller roots(D≤1 mm).

  13. Numerical distribution functions of fractional unit root and cointegration tests

    DEFF Research Database (Denmark)

    MacKinnon, James G.; Nielsen, Morten Ørregaard

    We calculate numerically the asymptotic distribution functions of likelihood ratio tests for fractional unit roots and cointegration rank. Because these distributions depend on a real-valued parameter, b, which must be estimated, simple tabulation is not feasible. Partly due to the presence...... of this parameter, the choice of model specification for the response surface regressions used to obtain the numerical distribution functions is more involved than is usually the case. We deal with model uncertainty by model averaging rather than by model selection. We make available a computer program which, given...

  14. Deconvolution of the particle size distribution of ProRoot MTA and MTA Angelus.

    Science.gov (United States)

    Ha, William Nguyen; Shakibaie, Fardad; Kahler, Bill; Walsh, Laurence James

    2016-01-01

    Objective Mineral trioxide aggregate (MTA) cements contain two types of particles, namely Portland cement (PC) (nominally 80% w/w) and bismuth oxide (BO) (20%). This study aims to determine the particle size distribution (PSD) of PC and BO found in MTA. Materials and methods The PSDs of ProRoot MTA (MTA-P) and MTA Angelus (MTA-A) powder were determined using laser diffraction, and compared to samples of PC (at three different particle sizes) and BO. The non-linear least squares method was used to deconvolute the PSDs into the constituents. MTA-P and MTA-A powders were also assessed with scanning electron microscopy. Results BO showed a near Gaussian distribution for particle size, with a mode distribution peak at 10.48 μm. PC samples milled to differing degrees of fineness had mode distribution peaks from 19.31 down to 4.88 μm. MTA-P had a complex PSD composed of both fine and large PC particles, with BO at an intermediate size, whereas MTA-A had only small BO particles and large PC particles. Conclusions The PSD of MTA cement products is bimodal or more complex, which has implications for understanding how particle size influences the overall properties of the material. Smaller particles may be reactive PC or unreactive radiopaque agent. Manufacturers should disclose particle size information for PC and radiopaque agents to prevent simplistic conclusions being drawn from statements of average particle size for MTA materials.

  15. Spatial tissue distribution of polyacetylenes in carrot root.

    Science.gov (United States)

    Baranska, Malgorzata; Schulz, Hartwig

    2005-06-01

    The presented results show the usefulness of Raman spectroscopy in the investigation of polyacetylenes in carrot root. The components are measured directly in the plant tissue without any preliminary sample preparation. Compared with the strong polyacetylene signals the spectral impact of the surrounding biological matrix is weak, except for carotenoids, and therefore it does not contribute significantly to the obtained results. Three different Raman mapping techniques applied here have revealed essential information about the investigated compounds. Using point acquisition several spectra have been measured to demonstrate the complex composition of the polyacetylene fraction in carrot root. The molecular structures of falcarinol, falcarindiol and falcarindiol 3-acetate are similar but their Raman spectra exhibit differences demonstrated by the shift of their -C triple bond C- mode. Line mapping performed along the diameter of transversely cut carrot roots has been used to investigate the relative concentration of polyacetylenes and carotenoids. An area map provides detailed information regarding the distribution of both components. It has been found that high accumulation of polyacetylenes is located in the outer section of the root, namely the pericyclic parenchyma, and in the phloem part close to the secondary cambium. The highest concentration of carotenes is seen in the immediate vicinity to polyacetylene conglomerates.

  16. Fine-scale spatial distribution of plants and resources on a sandy soil in the Sahel

    NARCIS (Netherlands)

    Rietkerk, M; Ouedraogo, T; Kumar, L; Sanou, S; van Langevelde, F; Kiema, A; van de Koppel, J; van Andel, J; Hearne, J; Skidmore, AK; de Ridder, N; Stroosnijder, L; Prins, HHT

    We studied fine-scale spatial plant distribution in relation to the spatial distribution of erodible soil particles, organic matter, nutrients and soil water on a sandy to sandy loam soil in the Sahel. We hypothesized that the distribution of annual plants would be highly spatially autocorrelated

  17. Fine-scale spatial distribution of plants and resources on a sandy soil in the Sahel

    NARCIS (Netherlands)

    Rietkerk, M.G.; Ouedraogo, T.; Kumar, L.; Sanou, S.; Langevelde, F. van; Kiema, A.; Koppel, J. van de; Andel, J. van; Hearne, J.; Skidmore, A.K.; Ridder, N. de; Stroosnijder, L.; Prins, H.H.T.

    2002-01-01

    We studied fine-scale spatial plant distribution in relation to the spatial distribution of erodible soil particles, organic matter, nutrients and soil water on a sandy to sandy loam soil in the Sahel. We hypothesized that the distribution of annual plants would be highly spatially autocorrelated

  18. Discrepancy in fine root turnover estimates between diameter-based and branch-order-based approaches: a case study in two temperate tree species

    Institute of Scientific and Technical Information of China (English)

    SUN Jing-jue; GU Jia-cun; WANG Zheng-quan

    2012-01-01

    Fine root turnover plays a key role in carbon (C) budgets and nutrients cycles in forest ecosystems.However,the difference between branch-order-based and diameter-based approaches in estimating fine root turnover is still unclear.We studied root biomass turnover based on multiplying root standing biomass by turnover rate (inverse of median root longevity) in two Chinese temperate tree species,Fraxinus mandshurica Rupr.and Larix gmelinii Rupr.The minirhizotron (MR) technique was used to estimate longevities for first and second order roots,and total roots (Rtotal) apparent on the MR tube surface.The corresponding biomass for each root group was estimated by soil monolith.The difference in biomass turnover between Rtotal and the sum of the first and second order roots was used to represent the discrepancy between diameter-and order-based approaches.First order roots had shorter life spans and higher biomass turnover rates than the second order roots in both species.Biomass turnover estimated by the order-based method for F.mandshurica and L.gmelinii were 155.4 g·m-2·a-1 and 158.9 g·m-2·a-1,respectively,in comparison with 99.5 g·m-2·a-1 and 117.7 g·m-2·a-1 estimated by the diameter-based method,indicating that the diameter-based approach underestimated biomass turnover.The most probable reason was that the order-based method enhanced separation of the heterogeneous root population into relatively homogenous root groups with varying turnover rates.We conclude that separating fine root pool into different branch orders can improve the accuracy of estimates for fine root turnover,as well as the understanding of the belowground C allocation and nutrient cycling at ecosystem level.

  19. Consequences of insect herbivory on grape fine root systems with different growth rates.

    Science.gov (United States)

    Bauerle, T L; Eissenstat, D M; Granett, J; Gardner, D M; Smart, D R

    2007-07-01

    Herbivory tolerance has been linked to plant growth rate where plants with fast growth rates are hypothesized to be more tolerant of herbivory than slower-growing plants. Evidence supporting this theory has been taken primarily from observations of aboveground organs but rarely from roots. Grapevines differing in overall rates of new root production, were studied in Napa Valley, California over two growing seasons in an established vineyard infested with the sucking insect, grape phylloxera (Daktulosphaira vitifoliae Fitch). The experimental vineyard allowed for the comparison of two root systems that differed in rates of new root tip production (a 'fast grower', Vitis berlandieri x Vitis rupestris cv. 1103P, and a slower-growing stock, Vitis riparia x Vitis rupestris cv. 101-14 Mgt). Each root system was grafted with a genetically identical shoot system (Vitis vinifera cv. Merlot). Using minirhizotrons, we did not observe any evidence of spatial or temporal avoidance of insect populations by root growth. Insect infestations were abundant throughout the soil profile, and seasonal peaks in phylloxera populations generally closely followed peaks in new root production. Our data supported the hypothesis that insect infestation was proportional to the number of growing tips, as indicated by similar per cent infestation in spite of a threefold difference in root tip production. In addition, infested roots of the fast-growing rootstock exhibited somewhat shorter median lifespans (60 d) than the slower-growing rootstock (85 d). Lifespans of uninfested roots were similar for the two rootstocks (200 d). As a consequence of greater root mortality of younger roots, infested root populations in the fast-growing rootstock had an older age structure. While there does not seem to be a trade-off between potential growth rate and relative rate of root infestation in these cultivars, our study indicates that a fast-growing root system may more readily shed infested roots that are

  20. Replicated throughfall exclusion experiment in an Indonesian perhumid rainforest: wood production, litter fall and fine root growth under simulated drought.

    Science.gov (United States)

    Moser, Gerald; Schuldt, Bernhard; Hertel, Dietrich; Horna, Viviana; Coners, Heinz; Barus, Henry; Leuschner, Christoph

    2014-05-01

    Climate change scenarios predict increases in the frequency and duration of ENSO-related droughts for parts of South-East Asia until the end of this century exposing the remaining rainforests to increasing drought risk. A pan-tropical review of recorded drought-related tree mortalities in more than 100 monitoring plots before, during and after drought events suggested a higher drought-vulnerability of trees in South-East Asian than in Amazonian forests. Here, we present the results of a replicated (n = 3 plots) throughfall exclusion experiment in a perhumid tropical rainforest in Sulawesi, Indonesia. In this first large-scale roof experiment outside semihumid eastern Amazonia, 60% of the throughfall was displaced during the first 8 months and 80% during the subsequent 17 months, exposing the forest to severe soil desiccation for about 17 months. In the experiment's second year, wood production decreased on average by 40% with largely different responses of the tree families (ranging from -100 to +100% change). Most sensitive were trees with high radial growth rates under moist conditions. In contrast, tree height was only a secondary factor and wood specific gravity had no influence on growth sensitivity. Fine root biomass was reduced by 35% after 25 months of soil desiccation while fine root necromass increased by 250% indicating elevated fine root mortality. Cumulative aboveground litter production was not significantly reduced in this period. The trees from this Indonesian perhumid rainforest revealed similar responses of wood and litter production and root dynamics as those in two semihumid Amazonian forests subjected to experimental drought. We conclude that trees from paleo- or neotropical forests growing in semihumid or perhumid climates may not differ systematically in their growth sensitivity and vitality under sublethal drought stress. Drought vulnerability may depend more on stem cambial activity in moist periods than on tree height or wood

  1. Intraspecific variation in fine root respiration and morphology in response to in situ soil nitrogen fertility in a 100-year-old Chamaecyparis obtusa forest.

    Science.gov (United States)

    Makita, Naoki; Hirano, Yasuhiro; Sugimoto, Takanobu; Tanikawa, Toko; Ishii, Hiroaki

    2015-12-01

    Soil N fertility has an effect on belowground C allocation, but the physiological and morphological responses of individual fine root segments to variations in N availability under field conditions are still unclear. In this study, the direction and magnitude of the physiological and morphological function of fine roots in response to variable in situ soil N fertility in a forest site were determined. We measured the specific root respiration (Rr) rate, N concentration and morphology of fine root segments with 1-3 branching orders in a 100-year-old coniferous forest of Chamaecyparis obtusa. Higher soil N fertility induced higher Rr rates, root N concentration, and specific root length (SRL), and lower root tissue density (RTD). In all fertility levels, the Rr rates were significantly correlated positively with root N and SRL and negatively with RTD. The regression slopes of respiration with root N and RTD were significantly higher along the soil N fertility gradient. Although no differences in the slopes of Rr and SRL relationship were found across the levels, there were significant shifts in the intercept along the common slope. These results suggest that a contrasting pattern in intraspecific relationships between specific Rr and N, RTD, and SRL exists among soils with different N fertility. Consequently, substantial increases in soil N fertility would exert positive effects on organ-scale root performance by covarying the Rr, root N, and morphology for their potential nutrient and water uptake.

  2. Mechanical failure of fine root cortical cells initiates plant hydraulic decline during drought

    Science.gov (United States)

    Root systems perform the crucial task of absorbing water from the soil to meet the demands of a transpiring canopy. Roots are thought to operate like electrical fuses, which break when carrying an excessive load under conditions of drought stress. Yet the exact site and sequence of this dysfunction ...

  3. Distribution spatiale intra-urbaine des particules fines : monitoring ...

    African Journals Online (AJOL)

    SARAH

    30 sept. 2014 ... Intra-urban spatial distribution of particulate matter: monitoring by leaf Saturation Isothermal Remanent ... les changements microclimatiques au sein des villes ... déterminer l'impact des saisons sur la teneur des ... Ce District jouit d'un climat de type ... Sélection et description des espèces : Un inventaire.

  4. Treatment of young spruce shoots with SO2 and H2S : Effects on fine root chromosomes in relation to changes in the thiol content and redox state

    NARCIS (Netherlands)

    Wonisch, A; Tausz, M; Muller, M; Weidner, W; De Kok, LJ; Grill, D

    1999-01-01

    Three year old spruce trees (Picea omorika) were exposed to 100 and 225 nl l(-1) SO2 and H2S for three weeks. The number of chromosomal aberrations and the mitotic index in the root tip meristems, and glutathione and cysteine contents in fine roots were determined twice weekly. An increase in

  5. Relocation of carbon from decomposition of {sup 14}C-labelled needle and fine root litter in peat soil

    Energy Technology Data Exchange (ETDEWEB)

    Domish, T.; Laine, J.; Laiho, R. [Helsinki Univ. (Finland). Dept. of Forest Ecology; Finer, L. [Finnish Forest Research Inst. (Finland). Joensuu Research Station; Karsisto, M. [Finnish Forest Research Inst. (Finland). Dept. of Forest Ecology

    1996-12-31

    Drainage of peatlands promotes a shift of biomass and production from the ground vegetation to the trees. Thus, the above-ground (e.g. needles) and below-ground (roots) litter production of trees increases. Fine roots in particular are an important factor in the carbon and nutrient cycle in forest ecosystems. A major part of the annual net primary production of trees may be allocated below ground, the relative proportion being smaller on fertile sites than on less fertile ones. For modelling the carbon balance of drained peatlands, it is important to know the fate of carbon from newly introduced and decomposing litter. Newly added and fertilised tree litter material may be decomposed at a rate different than litter from the ground vegetation. The objectives of this study are to study the pathways of decomposing litter carbon in peat soil and to evaluate the use of the litterbag method in a controlled environment. (9 refs.)

  6. Fine structure of mass size distributions in an urban environment

    Science.gov (United States)

    Salma, Imre; Ocskay, Rita; Raes, Nico; Maenhaut, Willy

    As part of an urban aerosol research project, aerosol samples were collected by a small deposit area low-pressure impactor and a micro-orifice uniform deposit impactor in downtown Budapest in spring 2002. A total number of 23 samples were obtained with each device for separate daytime periods and nights. The samples were analysed by particle-induced X-ray emission spectrometry for 29 elements, or by gravimetry for particulate mass. The raw size distribution data were processed by the inversion program MICRON utilising the calibrated collection efficiency curve for each impactor stage in order to study the mass size distributions in the size range of about 50 nm to 10 μm in detail. Concentration, geometric mean aerodynamic diameter, and geometric standard deviation for each contributing mode were determined and further evaluated. For the crustal elements, two modes were identified in the mass size distributions: a major coarse mode and a (so-called) intermediate mode, which contained about 4% of the elemental mass. The coarse mode was associated with suspension, resuspension, and abrasion processes, whereby the major contribution likely came from road dust, while the particles of the intermediate mode may have originated from the same but also from the other sources. The typical anthropogenic elements exhibited usually trimodal size distributions including a coarse mode and two submicrometer modes instead of a single accumulation mode. The mode diameter of the upper submicrometer mode was somewhat lower for the particulate mass (PM) and S than for the anthropogenic metals, suggesting different sources and/or source processes. The different relative intensities of the two submicrometer modes for the anthropogenic elements and the PM indicate that the elements and PM have multiple sources. An Aitken mode was unambiguously observed for S, Zn, and K, but in a few cases only. The relatively large coarse mode of Cu and Zn, and the small night-to-daytime period

  7. Effects of liming and wood ash application on root biomass, root distribution and soil chemistry in a Norway spruce stand in southwest Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Viebke, C.G.

    2001-07-01

    Effects of liming (CaPK) and wood ash application (A) on soil chemistry, root (< 2 mm and 2-5 mm in diameter) biomass and distribution, root length density (RLD, cm/cm{sup 3} ) and specific root length (SRL, m/g) were investigated in a 60 year old Norway spruce stand in SW Sweden. Soil cores were taken from the litter fermented humus (LFH) and mineral soil layers to a depth of 30 cm, eight years after treatments. The pH values of the LM layer increased significantly (p< 0.05) in the lime and ash treatments compared to the control, while in the top 5 cm of the mineral soil, pH was increased only in the A treatment compared to CaPK. The P, K, Ca and Mg concentrations increased in the CaPK treatment in the LM layer, while K and Ca decreased significantly at 5-10 cm depth in CaPK treated plots compared to the control and A. The highest amounts of ammonium and nitrate were found in A treatment in all soil layers. The A treatment increased fine root (< 2 mm in diameter) biomass in the LFH layer compared to the control but decreased it in the top 10 cm of the mineral soil compared to CaPK. A shallower fine root system was found in the A treated plots compared to the control and CaPK. The coarser root (2-5 mm in diameter) biomass was higher in the mineral soil in the A treatment compared to the control and CaPK but the differences were not significant. RLD increased in both CaPK and A in the upper soil layers. SRL increased in almost all layers in the CaPK and A treatments compared to the control. The number of root tips were also higher in the treated plots compared to the control, except in the 10-20 cm layer. It was concluded that CaPK and A treatments resulted in improved root vitality with a higher capacity for nutrient uptake.

  8. Fine tuning consensus optimization for distributed radio interferometric calibration

    CERN Document Server

    Yatawatta, Sarod

    2016-01-01

    We recently proposed the use of consensus optimization as a viable and effective way to improve the quality of calibration of radio interferometric data. We showed that it is possible to obtain far more accurate calibration solutions and also to distribute the compute load across a network of computers by using this technique. A crucial aspect in any consensus optimization problem is the selection of the penalty parameter used in the alternating direction method of multipliers (ADMM) iterations. This affects the convergence speed as well as the accuracy. In this paper, we use the Hessian of the cost function used in calibration to appropriately select this penalty. We extend our results to a multi-directional calibration setting, where we propose to use a penalty scaled by the squared intensity of each direction.

  9. Nutrient limitation in three lowland tropical forests in southern China receiving high nitrogen deposition: insights from fine root responses to nutrient additions.

    Science.gov (United States)

    Zhu, Feifei; Yoh, Muneoki; Gilliam, Frank S; Lu, Xiankai; Mo, Jiangming

    2013-01-01

    Elevated nitrogen (N) deposition to tropical forests may accelerate ecosystem phosphorus (P) limitation. This study examined responses of fine root biomass, nutrient concentrations, and acid phosphatase activity (APA) of bulk soil to five years of N and P additions in one old-growth and two younger lowland tropical forests in southern China. The old-growth forest had higher N capital than the two younger forests from long-term N accumulation. From February 2007 to July 2012, four experimental treatments were established at the following levels: Control, N-addition (150 kg N ha(-1) yr(-1)), P-addition (150 kg P ha(-1) yr(-1)) and N+P-addition (150 kg N ha(-1) yr(-1) plus 150 kg P ha(-1) yr(-1)). We hypothesized that fine root growth in the N-rich old-growth forest would be limited by P availability, and in the two younger forests would primarily respond to N additions due to large plant N demand. Results showed that five years of N addition significantly decreased live fine root biomass only in the old-growth forest (by 31%), but significantly elevated dead fine root biomass in all the three forests (by 64% to 101%), causing decreased live fine root proportion in the old-growth and the pine forests. P addition significantly increased live fine root biomass in all three forests (by 20% to 76%). The combined N and P treatment significantly increased live fine root biomass in the two younger forests but not in the old-growth forest. These results suggest that fine root growth in all three study forests appeared to be P-limited. This was further confirmed by current status of fine root N:P ratios, APA in bulk soil, and their responses to N and P treatments. Moreover, N addition significantly increased APA only in the old-growth forest, consistent with the conclusion that the old-growth forest was more P-limited than the younger forests.

  10. Nutrient limitation in three lowland tropical forests in southern China receiving high nitrogen deposition: insights from fine root responses to nutrient additions.

    Directory of Open Access Journals (Sweden)

    Feifei Zhu

    Full Text Available Elevated nitrogen (N deposition to tropical forests may accelerate ecosystem phosphorus (P limitation. This study examined responses of fine root biomass, nutrient concentrations, and acid phosphatase activity (APA of bulk soil to five years of N and P additions in one old-growth and two younger lowland tropical forests in southern China. The old-growth forest had higher N capital than the two younger forests from long-term N accumulation. From February 2007 to July 2012, four experimental treatments were established at the following levels: Control, N-addition (150 kg N ha(-1 yr(-1, P-addition (150 kg P ha(-1 yr(-1 and N+P-addition (150 kg N ha(-1 yr(-1 plus 150 kg P ha(-1 yr(-1. We hypothesized that fine root growth in the N-rich old-growth forest would be limited by P availability, and in the two younger forests would primarily respond to N additions due to large plant N demand. Results showed that five years of N addition significantly decreased live fine root biomass only in the old-growth forest (by 31%, but significantly elevated dead fine root biomass in all the three forests (by 64% to 101%, causing decreased live fine root proportion in the old-growth and the pine forests. P addition significantly increased live fine root biomass in all three forests (by 20% to 76%. The combined N and P treatment significantly increased live fine root biomass in the two younger forests but not in the old-growth forest. These results suggest that fine root growth in all three study forests appeared to be P-limited. This was further confirmed by current status of fine root N:P ratios, APA in bulk soil, and their responses to N and P treatments. Moreover, N addition significantly increased APA only in the old-growth forest, consistent with the conclusion that the old-growth forest was more P-limited than the younger forests.

  11. DO ELEVATED CO2 AND N FERTILIZATION ALTER FINE ROOT-MYCORRHIZAE RELATIONSHIPS IN PINUS PONDEROSA?

    Science.gov (United States)

    Despite extensive studies on the response of plants to elevated CO2, climate change and N deposition, little is known about the response of roots and mycorrhizae in spite of their key role in plant water and nutrient acquisition. The effects of elevated CO2 and N fertilization on...

  12. Community- Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance

    OpenAIRE

    Ilja Sonnemann; Hans Pfestorf; Florian Jeltsch; Susanne Wurst

    2015-01-01

    Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calc...

  13. Sediment studies at Bikini Atoll part 1. distribution of fine and coarse components in surface sediments

    Energy Technology Data Exchange (ETDEWEB)

    Noshkin, V. E.; Eagle, R.J.; Robison, W.L.

    1997-01-01

    In 1979, 21 years after the moratorium on nuclear testing in the Marshall Islands, surface sediment samples (to depths of 2 and 4 cm) were collected from 87 locations over the floor of Bikini lagoon. The main purpose for the collections was to map the distribution of long- lived man-made radionuclides associated with the bottom material. In addition the samples were processed to estimate the fraction of fine and coarse components to show what modifications occurred since the sediment composition was first described in samples collected before testing in 1946. In this report a comparison is made of the amount and distribution of fine material associated with the lagoon surface sediment before and after the testing of nuclear devices. Nuclear testing produced more finely divided material in-the surface sediment layer over large areas of the lagoon and especially in regions of the lagoon and reef adjacent to test sites. Five cratering events at Bikini Atoll generated sufficient material to account for the inventory of new fine material found over the bottom surface of the lagoon. Although the fraction of fine material in the bottom sediments was altered by the nuclear events, the combined processes of formation, transport and deposition were not sufficiently dynamic to alter the geographical features of the major sedimentary components over most of the lagoon floor.

  14. Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China.

    Directory of Open Access Journals (Sweden)

    Cunguo Wang

    Full Text Available Knowledge of the responses of soil nitrogen (N availability, fine root mass, production and turnover rates to atmospheric N deposition is crucial for understanding fine root dynamics and functioning in forest ecosystems. Fine root biomass and necromass, production and turnover rates, and soil nitrate-N and ammonium-N in relation to N fertilization (50 kg N ha(-1 year(-1 were investigated in a temperate forest over the growing season of 2010, using sequential soil cores and ingrowth cores methods. N fertilization increased soil nitrate-N by 16% (P<0.001 and ammonium-N by 6% (P<0.01 compared to control plots. Fine root biomass and necromass in 0-20 cm soil were 13% (4.61 vs. 5.23 Mg ha(-1, P<0.001 and 34% (1.39 vs. 1.86 Mg ha(-1, P<0.001 less in N fertilization plots than those in control plots. The fine root mass was significantly negatively correlated with soil N availability and nitrate-N contents, especially in 0-10 cm soil layer. Both fine root production and turnover rates increased with N fertilization, indicating a rapid underground carbon cycling in environment with high nitrogen levels. Although high N supply has been widely recognized to promote aboveground growth rates, the present study suggests that high levels of nitrogen supply may reduce the pool size of the underground carbon. Hence, we conclude that high levels of atmospheric N deposition will stimulate the belowground carbon cycling, leading to changes in the carbon balance between aboveground and underground storage. The implications of the present study suggest that carbon model and prediction need to take the effects of nitrogen deposition on underground system into account.

  15. Stoichiometry in aboveground and fine roots of Seriphidium korovinii in desert grassland in response to artificial nitrogen addition.

    Science.gov (United States)

    Li, Lei; Gao, Xiaopeng; Gui, Dongwei; Liu, Bo; Zhang, Bo; Li, Xiangyi

    2017-07-01

    Nitrogen (N) input by atmospheric deposition and human activity enhances the availability of N in various ecosystems, which may further affect N and phosphorus (P) cycling and use by plants. However, the internal use of N, P, and N:P stoichiometry by plants in response to N supply, particularly for grass species in a desert steppe ecosystem, remains unclear. In this work, a field experiment was conducted at an infertile area in a desert steppe to investigate the effects of N fertilizer addition rates on the stoichiometry of N and P in a dominant grass species, Seriphidium korovinii. Results showed that for both aboveground and fine roots of S. korovinii, N inputs exponentially increased the N concentration and N:P ratios while P concentrations decreased. Meanwhile, the relationships between N and P concentrations for both aboveground and fine roots were significantly negative. Furthermore, while the N concentrations in the plants were relatively low, P concentrations were higher than the global means, resulting in a relatively low N:P ratio. These results suggest that the stoichiometric characteristics of N were different from that of P for this desert plant species. Results also show that the intraspecific variations in the main element traits (N, P, and N:P ratios) were consistent at the whole-plant level. Our results also suggest that N should be part of any short-term fertilization plan that is part of a management strategy designed to restore degraded desert grassland. These findings highlight that nutrient addition by atmospheric N deposition and human activity can have significant effects on the internal use of N and P by plants. Therefore, establishing a nutrient-conservation strategy for desert grasslands is important.

  16. Dynamics of soil exploration by fine roots down to a depth of 10 m throughout the entire rotation in #Eucalyptus grandis# plantations

    OpenAIRE

    Jean-Paul eLaclau; Eder Araújo da Silva; George eRodrigues Lambais; Martial eBernoux; Guerric ele Maire; José Luiz eStape; Jean-Pierre eBouillet; José leonardo Moraes Gonçalves; Christophe eJourdan; Yann eNouvellon

    2013-01-01

    Although highly weathered soils cover considerable areas in tropical regions, little is known about exploration by roots in deep soil layers. Intensively managed Eucalyptus plantations are simple forest ecosystems that can provide an insight into the belowground growth strategy of fast-growing tropical trees. Fast exploration of deep soil layers by eucalypt fine roots may contribute to achieving a gross primary production that is among the highest in the world for forests. Soil exploration by...

  17. A Modelling Approach on Fine Particle Spatial Distribution for Street Canyons in Asian Residential Community

    Science.gov (United States)

    Ling, Hong; Lung, Shih-Chun Candice; Uhrner, Ulrich

    2016-04-01

    Rapidly increasing urban pollution poses severe health risks.Especially fine particles pollution is considered to be closely related to respiratory and cardiovascular disease. In this work, ambient fine particles are studied in street canyons of a typical Asian residential community using a computational fluid dynamics (CFD) dispersion modelling approach. The community is characterised by an artery road with a busy traffic flow of about 4000 light vehicles (mainly cars and motorcycles) per hour at rush hours, three streets with hundreds light vehicles per hour at rush hours and several small lanes with less traffic. The objective is to study the spatial distribution of the ambient fine particle concentrations within micro-environments, in order to assess fine particle exposure of the people living in the community. The GRAL modelling system is used to simulate and assess the emission and dispersion of the traffic-related fine particles within the community. Traffic emission factors and traffic situation is assigned using both field observation and local emissions inventory data. High resolution digital elevation data (DEM) and building height data are used to resolve the topographical features. Air quality monitoring and mobile monitoring within the community is used to validate the simulation results. By using this modelling approach, the dispersion of fine particles in street canyons is simulated; the impact of wind condition and street orientation are investigated; the contributions of car and motorcycle emissions are quantified respectively; the residents' exposure level of fine particles is assessed. The study is funded by "Taiwan Megacity Environmental Research (II)-chemistry and environmental impacts of boundary layer aerosols (Year 2-3) (103-2111-M-001-001-); Spatial variability and organic markers of aerosols (Year 3)(104-2111-M-001 -005 -)"

  18. Characterizing root distribution with adaptive neuro-fuzzy analysis

    Science.gov (United States)

    Root-soil relationships are pivotal to understanding crop growth and function in a changing environment. Plant root systems are difficult to measure and remain understudied relative to above ground responses. High variation among field samples often leads to non-significance when standard statistics...

  19. NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Li Zhang; Jun Zhou; Yasunobu Iwasaka

    2003-01-01

    Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45°N, 117°E) using a stratospheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored.The vertical distributions of the number concentration, number-size (that is, particle number versus particle size)distribution, and the fraction of fine particles (0.5 μm>r>0.15 μm/r>0.15 μm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 μm, ~0.88 μm and ~7.0 μm) and a bi-modal (r=~0.13 μm and 2.0 μm). The number-size distribution almost fits the Junge distribution for particles with r<0.5 μm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r>0.5 μm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the troposphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the troposphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.

  20. Root Growth and Water distribution in living walls

    DEFF Research Database (Denmark)

    Jørgensen, Lars

    walls; the vertical orientation of the growing medium, plants are growing vertically above or below each other in a limited rooting volume; there is an increased exposure to weather and the plants can react differently to water conditions and competition from other plants. Plant growth is the core......Living walls is a way of bringing plants and green areas into cities, and offer both positive environmental and aesthetical effects. A prerequisite for optimal performance of a living wall is that the plant cover is properly established why the individual plant should have optimal conditions...... for root growth. This thesis investigates the correlations between the growing media and root and shoots growth, and studies root growth patterns of different plant species and effects of planting position and root interactions of plants growing in living walls. There are a number of challenges with living...

  1. Changes in fine root production and longevity in response to water and nutrient availability in a Norway spruce stand in northern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Majdi, Hooshang [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Ecology and Environmental Research

    2003-03-01

    Effects of nutritional availability and soil warming on carbon turnover via fine roots (<2 mm in diameter) were studied at a Norway spruce stand in north Sweden in the following treatments: liquid fertilization (IL), soil warming of treated plots (HIL) and control (C). Minirhizotrons were installed in October 1994 and recorded once a month during the growing season, in 1997. Fine root production increased significantly in I and IL treatments compared with C plots at 0-10 and 10-20 cm depths. Soil warming enhanced effects of IL. Root mortality was not increased significantly in IL. Soil warming showed almost the similar effect on root mortality at depth 10-20 cm as it was for depth 0-10 cm. The root longevity in IL plots was significantly lower compared with C plots at depth 0-20 cm. The effects of soil warming were more pronounced at depth 10-25 cm. Soil warming increased root biomass three times in HIL plots and this increase. It is concluded that an eventual increase in temperature followed by increased CO{sub 2} and other greenhouse gases, results in an increase in root production and mortality and consequently higher carbon allocation to the soil.

  2. Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China.

    Science.gov (United States)

    Wang, Cunguo; Han, Shijie; Zhou, Yumei; Yan, Caifeng; Cheng, Xubing; Zheng, Xingbo; Li, Mai-He

    2012-01-01

    Knowledge of the responses of soil nitrogen (N) availability, fine root mass, production and turnover rates to atmospheric N deposition is crucial for understanding fine root dynamics and functioning in forest ecosystems. Fine root biomass and necromass, production and turnover rates, and soil nitrate-N and ammonium-N in relation to N fertilization (50 kg N ha(-1) year(-1)) were investigated in a temperate forest over the growing season of 2010, using sequential soil cores and ingrowth cores methods. N fertilization increased soil nitrate-N by 16% (Psoil were 13% (4.61 vs. 5.23 Mg ha(-1), Psoil N availability and nitrate-N contents, especially in 0-10 cm soil layer. Both fine root production and turnover rates increased with N fertilization, indicating a rapid underground carbon cycling in environment with high nitrogen levels. Although high N supply has been widely recognized to promote aboveground growth rates, the present study suggests that high levels of nitrogen supply may reduce the pool size of the underground carbon. Hence, we conclude that high levels of atmospheric N deposition will stimulate the belowground carbon cycling, leading to changes in the carbon balance between aboveground and underground storage. The implications of the present study suggest that carbon model and prediction need to take the effects of nitrogen deposition on underground system into account.

  3. FINE-GRAINED DISTRIBUTED MULTIMEDIA SYNCHRONIZA- TION MODEL--ENHANCED FUZZY-TIMING PETRI NET

    Institute of Scientific and Technical Information of China (English)

    韩莹洁; 孙永强; 吴哲辉

    2001-01-01

    A fine-grained distributed multimedia synchronization model--Enhanced Fuzzy timing Petri Net was proposed which is good at modeling indeterminacy and fuzzy. To satisfy the need of maximum tolerable jitter, the sufficient conditions are given in intra-object synchronization. Method to find a proper granularity in inter-object synchronization is also given to satisfy skew. Exceptions are detected and corrected as early as possible using restricted blocking method.

  4. Electrical impedance imaging of water distribution in the root zone

    Science.gov (United States)

    Newill, P.; Karadaglić, D.; Podd, F.; Grieve, B. D.; York, T. A.

    2014-05-01

    The paper describes a technique that is proposed for imaging water transport in and around the root zone of plants using distributed measurements of electrical impedance. The technique has the potential to analyse sub-surface phenotypes, for instance drought tolerance traits in crop breeding programmes. The technical aim is to implement an automated, low cost, instrument for high-throughput screening. Ultimately the technique is targeted at in-field, on-line, measurements. For demonstration purposes the present work considers measurements on laboratory scale rhizotrons housing growing maize plants. Each rhizotron is fitted with 60 electrodes in a rectangular array. To reduce electrochemical effects the capacitively coupled contactless conductivity (C4D) electrodes have an insulating layer on the surface and the resistance of the bulk material is deduced from spectroscopic considerations. Electrical impedance is measured between pairs of electrodes to build up a two-dimensional map. A modified electrical model of such electrodes is proposed which includes the resistive and reactive components of both the insulating layer and the bulk material. Measurements taken on a parallel-plate test cell containing water confirm that the C4D technique is able to measure electrical impedance. The test cell has been used to explore the effects of water content, compaction and temperature on measurements in soil. Results confirm that electrical impedance measurements are very sensitive to moisture content. Impedance fraction changes up to 20% are observed due to compaction up to a pressure of 0.21 kg cm-2 and a temperature fraction sensitivity of about 2%/°C. The effects of compaction and temperature are most significant under dry conditions. Measurements on growing maize reveal the changes in impedance across the rhizotron over a period of several weeks. Results are compared to a control vessel housing only soil.

  5. Effect of soil frost on growing season nitrogen uptake by fine roots of mature trees in northern hardwood forests of the United States

    Science.gov (United States)

    Socci, A. M.; Templer, P. H.

    2010-12-01

    Forests of the northeastern United States are predicted to experience a decrease in the depth and duration of the winter snowpack over the next 100 years. Even when coupled with warmer winter air temperatures, the absence of snow as insulation can increase soil frost during the winter months. Past research has determined that there are species-level effects of soil frost on dominant forest trees. For example, in stands dominated by sugar maple (Acer saccharum), induced soil frost led to increased fine root mortality and soil nitrate leaching. Soil frost also increased fine root mortality in stands dominated by yellow birch (Betula allegheniensis), but there was no significant change in leaching of soil nitrate. We hypothesized that greater nitrogen (N) losses from stands dominated by sugar maple may be due to reduced N uptake by fine roots of this tree species. To determine the impact of increased soil freezing on fine root uptake of N, we established a snow manipulation experiment in mixed sugar maple/American beech (Fagus grandifolia) forests at the Hubbard Brook Experimental Forest in New Hampshire (n=4 paired snow-removal and reference plots; each 13m X 13m). Snow removal occurred during the first six weeks of winter over two years. During each growing season following snow removal, we used the N depletion technique to measure in situ rates of uptake of ammonium and nitrate by fine roots of sugar maple during the early, peak and late growing season. Among all sampling dates and plots, we observed significantly lower uptake of N as nitrate compared to ammonium. During the first growing season, at moderate ammonium availability (35 μM N) we observed significantly less uptake of ammonium by fine roots of sugar maple in the snow removal plots relative to the reference plots during the early growing season (April-May), with no significant differences in uptake of ammonium during the peak (July) and late (September) growing season. We observed no differences in

  6. Investigation of fine-root systems and mycorrhiza of spruces damaged by air pollutants; Untersuchungen der Feinwurzelsysteme und Mykorrhiza der durch Luftverunreinigungen geschaedigten Fichten

    Energy Technology Data Exchange (ETDEWEB)

    Korotaev, A.A. [Forsttechnische Akademie St. Petersburg, Lehrstuhl fuer Forstkulturen (Russian Federation)

    1993-04-01

    The investigation was conducted in a damaged 80-years-old sprucestand in the industrial region of St. Petersburg. The investigation had to determine if there is a connection between crown and fine-root damages of spruce. The tests have shown that the proportion of dead fine roots of healthy trees varys much more than that of damaged trees. Healthy trees outside the industrial area have a stable small proportion of dead fine roots. This indicates that root damages appear earlier than crown damages. There were pronounced differences in seasonal root growth between damaged and healthy trees. (orig.) [Deutsch] Untersuchungen wurden im geschaedigten 80jaehrigen Fichtenbestand im Lehrwald ``Ochta`` im Belastungsgebiet von St. Petersburg durchgefuehrt. Die Untersuchung sollte festgestellt haben, ob oberirdische Kronenschaedigungen der Fichte mit Feinwurzelschaeden verbunden sind. Probenahmen haben gezeigt, dass der Anteil abgestorbener Feinwurzeln bei aeusserlich gesunden Baeumen im Belastungsgebiet viel staerker variiert als bei geschaedigten. Gesunde Fichtenbaeume ausserhalb des Belastungsgebiets haben stabil einen kleinen Anteil abgestorbener Feinwurzeln. Das zeigt eindeutig darauf, dass Wurzelschaeden frueher als Kronenschaeden erscheinen. Bedeutende Unterschiede des Wurzelwachstums waehrend der Vegetationsperiode der geschaedigten und gesunden Fichtenbaeume wurden festgestellt. (orig.)

  7. Competition for light and water increases tree carbon allocation to fine roots and leaves in a next-generation dynamic vegetation model

    Science.gov (United States)

    Lichstein, J. W.; Zhang, T.; Weng, E.; Farrior, C.; Dybzinski, R.; Birdsey, R.; Pacala, S. W.

    2015-12-01

    The response of the terrestrial carbon (C) cycle to climate change is a key uncertainty in land models. An important component of this uncertainty concerns plant functional diversity, which is typically represented in land models by ~10 functional types (PFTs) with fixed traits. However, few land models include the individual-level competitive mechanisms that largely determine how plant functional traits are distributed in time and space in real ecosystems. We have developed a new land model that represents height-structured competition for light with a simple canopy space-filling algorithm, the perfect plasticity approximation (PPA). The new land model, LM3-PPA, allows for an arbitrary number of PFTs (or 'species') whose spatial-temporal distributions are determined by the outcome of competition for light and water. We performed experiments with a modified version of LM3-PPA in 10 eastern U.S. grid cells and across simulated precipitation gradients to determine how competition for light and water affects tree C allocation to leaves, fine roots, and wood across climate gradients and in response to episodic drought. We studied the performance of 16 allocational types ('species') in monoculture and in competition with each other to determine the competitively-optimal, NPP-maximizing, and biomass-maximizing C allocation strategy under different environmental conditions. Under chronically moist conditions, competitively-optimal, NPP-maximizing, and biomass-maximizing trees all had similar C allocation. However, under chronically dry conditions, competitively-optimal trees allocated more C to both fine roots and leaves, and less C to wood, compared to NPP- or biomass-maximizing strategies. When subject to episodic drought, the most drought-tolerant allocational strategies had relatively low allocation to leaves (and thus low leaf area and low water demand). Thus, the "over-investment" in leaves that results from resource competition increases the vulnerability of

  8. Effects of different irrigation methods on micro-environments and root distribution in winter wheat ifelds

    Institute of Scientific and Technical Information of China (English)

    L Guo-hua; SONG Ji-qing; BAI Wen-bo; WU Yong-feng; LIU Yuan; KANG Yao-hu

    2015-01-01

    The irrigation method used in winter wheat ifelds affects micro-environment factors, such as relative humidity (RH) within canopy, soil temperature, topsoil bulk density, soil matric potential, and soil nutrients, and these changes may affect plant root growth. An experiment was carried out to explore the effects of irrigation method on micro-environments and root distribution in a winter wheat ifeld in the 2007–2008 and 2008–2009 growing seasons. The results showed that border irrigation (BI), sprinkler irrigation (SI), and surface drip irrigation (SDI) had no signiifcant effects on soil temperature. Topsoil bulk density, RH within the canopy, soil available N distribution, and soil matric potential were signiifcantly affected by the three treatments. The change in soil matric potential was the key reason for the altered root proifle distribution patterns. Additional y, more ifne roots were produced in the BI treatment when soil water content was low and topsoil bulk density was high. Root growth was most stimulated in the top soil layers and inhibited in the deep layers in the SDI treatment, fol owed by SI and BI, which was due to the different water application frequencies. As a result, the root proifle distribution differed, depending on the irrigation method used. The root distribution pattern changes could be described by the power level variation in the exponential function. A good knowledge of root distribution patterns is important when attempting to model water and nutrient movements and when studying soil-plant interactions.

  9. Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

    Directory of Open Access Journals (Sweden)

    Ilja Sonnemann

    Full Text Available Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae larvae (43% in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height, and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio. Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of

  10. Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

    Science.gov (United States)

    Sonnemann, Ilja; Pfestorf, Hans; Jeltsch, Florian; Wurst, Susanne

    2015-01-01

    Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root

  11. Contenido de nutrientes en las raices finas y el mantillo de rodales de Eucalyptus grandis de diferente edad en la Mesopotomia Argentina [Fine roots and litter nutrient content of Eucalyptus grandis stands presenting different ages in Mesopotomia Argentina

    Science.gov (United States)

    C. Perez; J. Frangi; J.F. Goya; A. Luy; M. Arturi; NO-VALUE

    2013-01-01

    Entre Ríos province is an important center of Eucalyptus spp. plantations in Argentina. It was hypothesized that fine root biomass and litter mass increased with age increasing in plantations. Five, seven and seventeen year old stands of Eucalyptus grandis were sampled. All of them were first rotation stands. We estimated the mass of litter and fine roots (

  12. Impacts of leaves, roots, and earthworms on soil organic matter composition and distribution in sycamore maple stands

    Science.gov (United States)

    Rivera, N.; Mueller, K. E.; Mueller, C. W.; Oleksyn, J.; Hale, C.; Freeman, K. H.; Eissenstat, D.

    2009-12-01

    The relative contributions of leaf and root material to soil organic matter (SOM) are poorly understood despite the importance of constraining SOM sources to conceptual and numeric models of SOM dynamics. Selective ingestion and bioturbation of litter and soil by earthworms can alter the fate and spatial distribution of OM in soils, including stabilization pathways of leaf and root litter. However, studies on the contributions of leaves, roots, and earthworms to SOM dynamics are rare. In 3 stands of sycamore maple (Acer pseudoplatanus) with minimal O horizon development and high earthworm activity, we sampled surface litter (> 2 mm) from the Oi horizon, fine roots (cutin was low relative to plant litter, confirming the often-observed selective preservation of aliphatic over aromatic biomolecules. The ratio of lignin to cutin/suberin acids in earthworm casts was also low; based on the minimal extent of decomposition in casts evident by lignin acid to aldehyde ratios, we attribute this to selective ingestion by L. terrestris of leaf litter rich in aliphatic biomolecules at the expense of woody debris and petioles rich in lignin, rather than selective preservation.

  13. Nonparametric Fine Tuning of Mixtures: Application to Non-Life Insurance Claims Distribution Estimation

    Science.gov (United States)

    Sardet, Laure; Patilea, Valentin

    When pricing a specific insurance premium, actuary needs to evaluate the claims cost distribution for the warranty. Traditional actuarial methods use parametric specifications to model claims distribution, like lognormal, Weibull and Pareto laws. Mixtures of such distributions allow to improve the flexibility of the parametric approach and seem to be quite well-adapted to capture the skewness, the long tails as well as the unobserved heterogeneity among the claims. In this paper, instead of looking for a finely tuned mixture with many components, we choose a parsimonious mixture modeling, typically a two or three-component mixture. Next, we use the mixture cumulative distribution function (CDF) to transform data into the unit interval where we apply a beta-kernel smoothing procedure. A bandwidth rule adapted to our methodology is proposed. Finally, the beta-kernel density estimate is back-transformed to recover an estimate of the original claims density. The beta-kernel smoothing provides an automatic fine-tuning of the parsimonious mixture and thus avoids inference in more complex mixture models with many parameters. We investigate the empirical performance of the new method in the estimation of the quantiles with simulated nonnegative data and the quantiles of the individual claims distribution in a non-life insurance application.

  14. 凋落物分解与细根生长的相互作用%Interaction of Litter Decomposition and Fine-Root Growth

    Institute of Scientific and Technical Information of China (English)

    王微; 胡凯; 党成强; 陶建平

    2016-01-01

    本文综述了细根在凋落物层的觅食行为与策略,细根生长与凋落物数量、质量及分解过程的关系,细根生长与凋落物分解的相互作用机制及影响因素等以期为理解森林生态系统中细根对凋落物分解的作用机制以及凋落物分解对细根生长的影响提供依据。一方面,凋落物的数量和质量影响细根生长,地上凋落物的数量影响细根的觅食行为,并驱动细根在凋落物层的生长动态,凋落物质量的差异也对细根的生长产生影响,不同性质的地上凋落物对细根的生长是促进还是阻碍主要取决于分解过程中所产生的养分以及多酚含量的正平衡或负平衡;另一方面,生长进入凋落物层的细根通过根际激发效应、养分吸收以及共生真菌等作用综合影响凋落物的分解过程,生活的细根对凋落物分解的激发效应主要表现在根系分泌物控制微生物群落的活力及组成,进而加速或抑制凋落物分解; N的有效性是影响凋落物分解的重要因素,处于分解后期的凋落物层中生长的细根,通过吸收凋落物表面矿化形成的大量无机 N,避免过量的 N对微生物群落及其生境的不利影响;根系的共生伙伴———菌根真菌也对凋落物的分解产生重要影响,这与真菌类型及其分泌的酶和有机酸有关。未来该领域应注重全球变化背景下细根生长对凋落物分解作用机制以及细根的分支结构与其获取凋落物层养分功能的联系等方面的研究。%In different forest ecosystems,fine roots commonly proliferate into litter layers,especially into those with favorable conditions for root growth. Our aim is to provide a basis for better understanding the role and mechanism of action in litter decomposition by fine roots and the influence of litter decomposition on fine root growth. We reviewed the advances of recent studies,including how roots forage into

  15. Phosphate DIstribution and Movement in Soil—Root Interface Zone:Ⅲ.Dynamics

    Institute of Scientific and Technical Information of China (English)

    XUMING-GANG; ZHANGYI-PING; 等

    1995-01-01

    The depletion rate of phosphate in the soil-root interface zone increased along with growth and phosphate uptske of wheat or maize,which indicated that the phosphate distribution in soil near the root surface agreed well with the phosphate movement in rhizosphere and phosphate uptake by plant,The relative accumulation zone of phosphate within 0.5mm apart from the root surface developed at the 15th day or so after cultivating wheat or maize since the root phosphate secretion increased gradually in this stage.The phosphate distribution in the soil-root interface zone against the growing time(t)and the distance from the root plane(x) could be described by the non-linear regression equation with the third powers of x and t.

  16. The distribution of prime numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2008-01-01

    Prime Numbers clearly accumulate on defined spiral graphs,which run through the Square Root Spiral. These spiral graphs can be assigned to different spiral-systems, in which all spiral-graphs have the same direction of rotation and the same -second difference- between the numbers, which lie on these spiral-graphs. A mathematical analysis shows, that these spiral graphs are caused exclusively by quadratic polynomials. For example the well known Euler Polynomial x2+x+41 appears on the Square Root Spiral in the form of three spiral-graphs, which are defined by three different quadratic polynomials. All natural numbers,divisible by a certain prime factor, also lie on defined spiral graphs on the Square Root Spiral (or Spiral of Theodorus, or Wurzelspirale). And the Square Numbers 4, 9, 16, 25, 36 even form a highly three-symmetrical system of three spiral graphs, which divides the square root spiral into three equal areas. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Wit...

  17. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Burnet

    2015-09-01

    Full Text Available Background: The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Methods: Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Results: Parasites displayed heterogeneous distribution patterns, as reflected by significant (oocyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. Conclusion: This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

  18. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir.

    Science.gov (United States)

    Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

    2015-09-23

    The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

  19. Evolution of root plasticity responses to variation in soil nutrient distribution and concentration.

    Science.gov (United States)

    Grossman, Judah D; Rice, Kevin J

    2012-12-01

    Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected for increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity for plasticity in crop plants like barley (Hordeum vulgare). However, the effects of domestication on the evolution of root plasticity are essentially unknown. Using a split container approach, we examined the differences in root plasticity among three domestication levels of barley germplasm (wild, landrace, and cultivar) grown under different concentrations and distribution patterns of soil nutrients. Domestication level, nutrient concentration, and nutrient distribution interactively affected average root diameter; differential root allocation (within-plant plasticity) was greatest in wild barley (Hordeum spontaneum), especially under low nutrient levels. Correlations of within-plant root plasticity and plant size were most pronounced in modern cultivars under low-nutrient conditions. Barley plants invested more resources to root systems when grown in low-nutrient soils and allocated more roots to higher-nutrient locations. Root plasticity in barley is scale dependent and varies with domestication level. Although wild barley harbors a greater capacity for within-plant root plasticity than domesticated barley, cultivars exhibited the greatest capacity to translate within-plant plasticity into increased plant size.

  20. Root distribution of three co-occurring desert shrubs and their physiological response to precipitation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.

  1. [Effects of simulated nitrogen deposition on the fine root characteristics and soil respiration in a Pleioblastus amarus plantation in rainy area of West China].

    Science.gov (United States)

    Tu, Li-hua; Hu, Ting-xing; Zhang, Jian; He, Yuan-yang; Tian, Xiang-yu; Xiao, Yin-long

    2010-10-01

    Fine root is critical in the belowground carbon (C) cycling in forest ecosystem. Aimed to understand the effects of nitrogen (N) deposition on the fine root characteristics and soil respiration in Pleioblastus amarus plantation, a two-year field experiment was conducted in the Rainy Area of West China. Four treatments with different levels of N deposition were installed, i. e., CK (0 g N x m(-2) x a(-1)), low N (5 g N x m(-2) x a(-1)), medium N (15 g N x m(-2) x a(-1)), and high N (30 g N x m(-2) x a(-1)). There were great differences in the biomass and element contents of Nitrogen deposition increased the biomass of deposition. The annual soil respiration rate in treatments CK, low N, medium N, and high N was (5.85 +/- 0.43), (6.48 +/- 0.71), (6.84 +/- 0.57), and (7.62 +/- 0.55) t C x hm(-2) x a(-1), respectively, indicating that N deposition had obvious promotion effects on soil respiration. There were significant linear relationships between the annual soil respiration rate and the biomass and N content of deposition increased the fine root biomass and promoted the root metabolism, and stimulated the rhizospheric soil respiration rate via promoting microbial activities.

  2. Root Growth and Water distribution in living walls

    DEFF Research Database (Denmark)

    Jørgensen, Lars

    walls; the vertical orientation of the growing medium, plants are growing vertically above or below each other in a limited rooting volume; there is an increased exposure to weather and the plants can react differently to water conditions and competition from other plants. Plant growth is the core...

  3. Uptake and Distribution of Aluminum in Root Apices of Two Rice Varieties under Aluminum Stress

    Directory of Open Access Journals (Sweden)

    MIFTAHUDIN

    2007-09-01

    Full Text Available Aluminum (Al toxicity is the major limiting factor of plant growth and production in acid soils. The target of Al toxicity is the root tip, which affects mainly on root growth inhibition. The aim of this research was to study the uptake and distribution of Al in root apices of two rice varieties IR64 (Al-sensitive and Krowal (Al-tolerant, which were grown on nutrient solution containing 0, 15, 30, 45, and 60 ppm of Al. The root growth was significantly inhibited in both rice varieties at as low as 15 ppm Al concentration. The adventive roots of both varieties showed stunted growth in respons to Al stress. There was no difference in root growth inhibition between both rice varieties as well as among Al concentrations. Al uptake on root apices was qualitatively and quantitatively analyzed. Histochemical staining of roots using hematoxylin showed dark purple color on 1 mm region of Al-treated root apices. Rice var. IR 64 tended to take up more Al in root tip than Krowal did. However, there was no statistically significant difference (p = 0.176 in root Al content of both varieties in response to different concentration and period of Al treatments. Al distribution in root apices was found in the epidermal and subepidermal region in both rice varieties. Based on those results, rice var. Krowal that was previously grouped as Al-tolerant variety has similar root growth and physiological response to Al stress as compared to Al-sensitive variety IR64.

  4. Detecting Densely Distributed Graph Patterns for Fine-Grained Image Categorization.

    Science.gov (United States)

    Zhang, Luming; Yang, Yang; Wang, Meng; Hong, Richang; Nie, Liqiang; Li, Xuelong

    2016-02-01

    Fine-grained image categorization is a challenging task aiming at distinguishing objects belonging to the same basic-level category, e.g., leaf or mushroom. It is a useful technique that can be applied for species recognition, face verification, and so on. Most of the existing methods either have difficulties to detect discriminative object components automatically, or suffer from the limited amount of training data in each sub-category. To solve these problems, this paper proposes a new fine-grained image categorization model. The key is a dense graph mining algorithm that hierarchically localizes discriminative object parts in each image. More specifically, to mimic the human hierarchical perception mechanism, a superpixel pyramid is generated for each image. Thereby, graphlets from each layer are constructed to seamlessly capture object components. Intuitively, graphlets representative to each super-/sub-category is densely distributed in their feature space. Thus, a dense graph mining algorithm is developed to discover graphlets representative to each super-/sub-category. Finally, the discovered graphlets from pairwise images are integrated into an image kernel for fine-grained recognition. Theoretically, the learned kernel can generalize several state-of-the-art image kernels. Experiments on nine image sets demonstrate the advantage of our method. Moreover, the discovered graphlets from each sub-category accurately capture those tiny discriminative object components, e.g., bird claws, heads, and bodies.

  5. Particle size distribution and property of bacteria attached to carbon fines in drinking water treatment

    Institute of Scientific and Technical Information of China (English)

    Wang Leilei; Chen Wei; Lin Tao

    2008-01-01

    The quantitative change and size distribution of particles in the effluents from a sand filter and a granular activated carbon (GAC) filter in a drinking water treatment plant were investigated. The average total concentration of particles in the sand filter effluent during a filter cycle was 148 particles/mL, 27 of which were larger than 2 μm in size. The concentration in the GAC effluent (561 particles/mL) was significantly greater than that in the sand filter effluent. The concentration of particles larger than 2 μm in the GAC filter effluent reached 201 particles/mL, with the amount of particles with sizes between 2 μm and 15 μm increasing. The most probable number (MPN) of carbon fines reached 43 unit/L after six hours and fines between 0.45 μm and 8.0 μm accounted for more than 50%. The total concentration of outflowing bacteria in the GAC filter effluent, 350 CFU (colony-forming units) /mL, was greater than that in the sand filter effluent, 210 CFU/mL. The desorbed bacteria concentration reached an average of 310 CFU/mg fines. The disinfection efficiency of desorbed bacteria was lower than 40% with 1.5 mg/L of chlorine. The disinfection effect showed that the inactivation rate with 2.0 mg/L of chloramine (90%) was higher than that with chlorine (70%). Experimental results indicated that the high particle concentration in raw water and sedimentation effluent led to high levels of outflowing particles in the sand filter effluent. The activated carbon fines in the effluent accounted for a small proportion of the total particle amount, but the existing bacteria attached to carbon fines may influence the drinking water safety. The disinfection efficiency of desorbed bacteria was lower than that of free bacteria with chlorine, and the disinfection effect on bacteria attached to carbon fines with chloramine was better than that with only chlorine.

  6. Distributed Lag Analyses of Daily Hospital Admissions and Source-Apportioned Fine Particle Air Pollution

    OpenAIRE

    2010-01-01

    Background Past time-series studies of the health effects of fine particulate matter [aerodynamic diameter ≤ 2.5 μm (PM2.5)] have used chemically nonspecific PM2.5 mass. However, PM2.5 is known to vary in chemical composition with source, and health impacts may vary accordingly. Objective We tested the association between source-specific daily PM2.5 mass and hospital admissions in a time-series investigation that considered both single-lag and distributed-lag models. Methods Daily PM2.5 speci...

  7. Development of an invasive species distribution model with fine-resolution remote sensing

    Science.gov (United States)

    Diao, Chunyuan; Wang, Le

    2014-08-01

    Saltcedar (Tamarix spp.) is recognized as one of the most aggressively invasive species throughout the Western United States. Mapping its suitable habitat is of paramount importance to effective management, and thus, becomes a high priority for conservation practitioners. In previous studies, species distribution models (SDMs) have been applied to predicting the suitable habitats of saltcedar at national scale, but at coarser spatial resolution (1 km). Although such studies achieved some success, they are lacking of capability to accommodate fine-scale resolution environmental variables, and therefore, fail to uncover detailed spatial pattern of habitats. The objective of this study was to develop a remote sensing driven SDM so as to characterize suitable habitats of saltcedar at very fine spatial scale (30 m). We exploited several fine-scale environmental predictors through remote sensing images, and utilized the logistic regression model to analyze the species-habitat relationship by identifying influential factors with subset selection criteria. We also incorporated the spatial autocorrelation with regression kriging method. Our results indicated that the model incorporating spatial autocorrelation achieved a higher accuracy than that of regression only model. Among 10 environmental variables, the distance to the river and the phenological attributes summarized by the harmonic analysis were regarded as the most significant in predicting the invasive potential of saltcedar. We conclude that remote sensing driven SDM has potential to identify the suitable habitat of saltcedar at a fine scale and locate appropriate areas at high risk of saltcedar infestation, which could benefit the early control and proactive management strategies to a large extent.

  8. Shallow landsliding, root reinforcement, and the spatial distribution of trees in the Oregon Coast Range

    Science.gov (United States)

    Roering, J.J.; Schmidt, K.M.; Stock, J.D.; Dietrich, W.E.; Montgomery, D.R.

    2003-01-01

    The influence of root reinforcement on shallow landsliding has been well established through mechanistic and empirical studies, yet few studies have examined how local vegetative patterns influence slope stability. Because root networks spread outward from trees, the species, size, and spacing of trees should influence the spatial distribution of root strength. We documented the distribution and characteristics of trees adjacent to 32 shallow landslides that occurred during 1996 in the Oregon Coast Range. Although broadly classified as a conifer-dominated forest, we observed sparse coniferous and abundant hardwood trees near landslide scars in an industrial forest (Mapleton) that experienced widespread burning in the 19th century. In industrial forests that were burned, selectively harvested, and not replanted (Elliott State Forest), swordfern was ubiquitous near landslides, and we observed similar numbers of live conifer and hardwood trees proximal to landslide scarps. We demonstrate that root strength quantified in landslide scarps and soil pits correlates with a geometry-based index of root network contribution derived from mapping the size, species, condition, and spacing of local trees, indicating that root strength can be predicted by mapping the distribution and characteristics of trees on potentially unstable slopes. In our study sites, landslides tend to occur in areas of reduced root strength, suggesting that to make site-specific predictions of landslide occurrence slope stability analyses must account for the diversity and distribution of vegetation in potentially unstable terrain.

  9. Effect of soil water content on spatial distribution of root exudates and mucilage in the rhizosphere

    Science.gov (United States)

    Holz, Maire; Zarebanadkouki, Mohsen; Kuzyakov, Yakov; Carminati, Andrea

    2016-04-01

    Water and nutrients are expected to become the major factors limiting food production. Plant roots employ various mechanisms to increase the access to these limited soil resources. Low molecular root exudates released into the rhizosphere increase nutrient availability, while mucilage improves water availability under low moisture conditions. However, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was therefore to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging at different levels of water stress. Maize plants were grown in rhizotrons filled with a silty soil and were exposed to varying soil conditions, from optimal to dry. Mucilage distribution around the roots was estimated from the profiles of water content in the rhizosphere - note that mucilage increases the soil water content. The profiles of water content around different root types and root ages were measured with neutron radiography. Rhizosphere extension was approx. 0.7 mm and did not differ between wet and dry treatments. However, water content (i.e. mucilage concentration) in the rhizosphere of plants grown in dry soils was higher than for plants grown under optimal conditions. This effect was particularly pronounced near the tips of lateral roots. The higher water contents near the root are explained as the water retained by mucilage. 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) was used to estimate the distribution of all rhizodeposits. Two days after labelling, 14C distribution was measured using phosphor-imaging. To quantify 14C in the rhizosphere a calibration was carried out by adding given amounts of 14C-glucose to soil. Plants grown in wet soil transported a higher percentage of 14C to the roots (14Croot/14Cshoot), compared to plants grown under dry conditions (46 vs. 36 %). However, the percentage of 14C allocated from roots to

  10. Root distributions in a laboratory box evaluated using two different techniques (gravimetric and image processing and their impact on root water uptake simulated with HYDRUS

    Directory of Open Access Journals (Sweden)

    Klement Aleš

    2016-06-01

    Full Text Available Knowledge of the distribution of plant roots in a soil profile (i.e. root density is needed when simulating root water uptake from soil. Therefore, this study focused on evaluating barley and wheat root densities in a sand-vermiculite substrate. Barley and wheat were planted in a flat laboratory box under greenhouse conditions. The box was always divided into two parts, where a single plant row and rows cross section (respectively was simulated. Roots were excavated at the end of the experiment and root densities were assessed using root zone image processing and by weighing. For this purpose, the entire area (width of 40 and height of 50 cm of each scenario was divided into 80 segments (area of 5×5 cm. Root density in each segment was expressed as a root percentage of the entire root cluster. Vertical root distributions (i.e. root density with respect to depth were also calculated as a sum of root densities in each 5 cm layer. Resulting vertical root densities, measured evaporation from the water table (used as the potential root water uptake, and the Feddes stress response function model were used for simulating substrate water regime and actual root water uptake for all scenarios using HYDRUS-1D. All scenarios were also simulated using HYDRUS-2D. One scenario (areal root density of barley sown in a single row, obtained using image analysis is presented in this paper (because most scenarios showed root water uptakes similar to results of 1D scenarios.

  11. On the noncentral distribution of the ratio of the extreme roots of wishart matrix

    Directory of Open Access Journals (Sweden)

    V. B. Waikar

    1981-01-01

    Full Text Available The distribution of the ratio of the extreme latent roots of the Wishart matrix is useful in testing the sphericity hypothesis for a multivariate normal population. Let X be a p×n matrix whose columns are distributed independently as multivariate normal with zero mean vector and covariance matrix ∑. Further, let S=XX′ and let 11>…>1p>0 be the characteristic roots of S. Thus S has a noncentral Wishart distribution. In this paper, the exact distribution of fp=1−1p/11 is derived. The density of fp is given in terms of zonal polynomials. These results have applications in nuclear physics also.

  12. Modeling plant species distributions under future climates: how fine scale do climate projections need to be?

    Science.gov (United States)

    Franklin, Janet; Davis, Frank W; Ikegami, Makihiko; Syphard, Alexandra D; Flint, Lorraine E; Flint, Alan L; Hannah, Lee

    2013-02-01

    Recent studies suggest that species distribution models (SDMs) based on fine-scale climate data may provide markedly different estimates of climate-change impacts than coarse-scale models. However, these studies disagree in their conclusions of how scale influences projected species distributions. In rugged terrain, coarse-scale climate grids may not capture topographically controlled climate variation at the scale that constitutes microhabitat or refugia for some species. Although finer scale data are therefore considered to better reflect climatic conditions experienced by species, there have been few formal analyses of how modeled distributions differ with scale. We modeled distributions for 52 plant species endemic to the California Floristic Province of different life forms and range sizes under recent and future climate across a 2000-fold range of spatial scales (0.008-16 km(2) ). We produced unique current and future climate datasets by separately downscaling 4 km climate models to three finer resolutions based on 800, 270, and 90 m digital elevation models and deriving bioclimatic predictors from them. As climate-data resolution became coarser, SDMs predicted larger habitat area with diminishing spatial congruence between fine- and coarse-scale predictions. These trends were most pronounced at the coarsest resolutions and depended on climate scenario and species' range size. On average, SDMs projected onto 4 km climate data predicted 42% more stable habitat (the amount of spatial overlap between predicted current and future climatically suitable habitat) compared with 800 m data. We found only modest agreement between areas predicted to be stable by 90 m models generalized to 4 km grids compared with areas classified as stable based on 4 km models, suggesting that some climate refugia captured at finer scales may be missed using coarser scale data. These differences in projected locations of habitat change may have more serious implications than net

  13. Effect of Water Stress on Root Distribution and Extension of Different Triticale Genotypes

    Directory of Open Access Journals (Sweden)

    H.R. Khazaei

    2014-12-01

    Full Text Available Root depth and distribution have an important role in drought resistance and optimization of moisture content of soil. This research was carried out in order to consider of root response of triticale genotypes to water stress and recognition of root trait that can effective in resistance of water stress. This experiment was in a factorial experiment based on completely random design on the year 2009. The genotypes of triticale was included (i ET-82-15 (ii ET-82-8 (iii ET-82-17 and commercial triticale genotype Juanillo-92. Two irrigation regimes included 100 and 50 % of field capacity, respectively. The result showed that water stress result in increased 9% of root depth in each plant. Differences between minimum root depth was observed in ET-82-15 rather than maximum root depth in Juanillo-92 was approximately 8.2 centimeters. Late irrigation caused to diminish 25% of root length. Differences between maximum root length in ET-82-15 and minimum root length in ET-82-17 was not significant (p

  14. Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution

    Science.gov (United States)

    Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A.

    2000-01-01

    This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

  15. The causes and consequences of deeper rooting distributions under elevated [CO2]: Improved understanding of root-soil interactions from a Free-Air CO2 Enrichment experiment in a sweetgum plantation (Invited)

    Science.gov (United States)

    Iversen, C. M.; Childs, J.; Norby, R. J.

    2013-12-01

    Belowground processes are increasingly recognized as an important foundation for ecosystem responses to rising atmospheric [CO2]. Elevated [CO2] has been shown to increase the proportion of biomass in fine roots, and experimental evidence from a diverse set of forested ecosystems indicates that CO2-enrichment may lead to deeper rooting distributions. Deeper rooting distributions in CO2-enriched forests are likely a result of three interacting factors: (1) increased resource demand, (2) greater carbon (C) available for belowground allocation, and (3) increased competition for scarce resources in shallower soil. Increased production of fine roots at depth in the soil could drive changes in C cycling because fine roots turn over quickly in forests. However, the consequences of increased fine-root proliferation and turnover at depth are still poorly understood; this is in part because belowground research is often truncated at relatively shallow soil depths. We examined soil C dynamics after 12 years of CO2-enrichment and at soil depths to 90 cm in soil pits harvested at the conclusion of the Oak Ridge National Laboratory (ORNL) Free-Air CO2 Enrichment (FACE) located in a sweetgum plantation in eastern Tennessee, USA. We hypothesized that: (1) soil C content would increase in response to elevated [CO2], especially at deeper soil depths where large increases in root production and mortality were observed, and (2) greater C inputs under elevated [CO2] would lead to increased potential C mineralization in long-term laboratory incubations. As we hypothesized, total soil C content under elevated [CO2] was 20% greater throughout the soil profile to 90 cm depth. The CO2 effect was driven by an increase in the C content of the relatively labile particulate organic matter (POM) pool, which is likely derived primarily from fine roots. Contrary to what we hypothesized, we did not observe a significant increase in potential soil C mineralization under elevated [CO2]. While C

  16. Spatial root distribution of plants growing in vertical media for use in living walls

    DEFF Research Database (Denmark)

    Jørgensen, Lars; Dresbøll, Dorte Bodin; Thorup-Kristensen, Kristian

    2014-01-01

    Background and Aims: For plants growing in living walls, the growth potential is correlated to the roots ability to utilize resources in all parts of the growing medium and thereby to the spatial root distribution. The aim of the study was to test how spatial root distribution was affected...... by growing medium, planting position and competition from other plants. Methods: Five species (Campanula poscharskyana cv. 'Stella', Fragaria vesca cv. 'Småland', Geranium sanguineum cv. 'Max Frei', Sesleria heufleriana and Veronica officinalis cv. 'Allgrün') were grown in three growing media (coir and two...... of growing medium, plant species and planting position is important for a living wall as it affects the spatial root growth of the plants. © 2014 Springer International Publishing Switzerland....

  17. Root and soil carbon distribution at shoulderslope and footslope positions of temperate toposequences cropped to winter wheat

    DEFF Research Database (Denmark)

    Chirinda, Ngoni; Roncossek, Svenja Doreen; Heckrath, Goswin Johann;

    2014-01-01

    Crop root residues are an important source of soil organic carbon (SOC) in arable systems. However, the spatial distribution of root biomass in arable systems remains largely unknown. In this study, we determined the spatial distribution of macro-root and shoot biomass of winter wheat at shoulder......Crop root residues are an important source of soil organic carbon (SOC) in arable systems. However, the spatial distribution of root biomass in arable systems remains largely unknown. In this study, we determined the spatial distribution of macro-root and shoot biomass of winter wheat...... to simulate or predict C dynamics and crop productivity should consider topography-controlled variations in root C input and SOC redistribution as well as their effects on soil properties, root growth and crop productivity....

  18. Sowing Density: A Neglected Factor Fundamentally Affecting Root Distribution and Biomass Allocation of Field Grown Spring Barley (Hordeum Vulgare L.).

    Science.gov (United States)

    Hecht, Vera L; Temperton, Vicky M; Nagel, Kerstin A; Rascher, Uwe; Postma, Johannes A

    2016-01-01

    Studies on the function of root traits and the genetic variation in these traits are often conducted under controlled conditions using individual potted plants. Little is known about root growth under field conditions and how root traits are affected by agronomic practices in particular sowing density. We hypothesized that with increasing sowing density, root length density (root length per soil volume, cm cm(-3)) increases in the topsoil as well as specific root length (root length per root dry weight, cm g(-1)) due to greater investment in fine roots. Therefore, we studied two spring barley cultivars at ten different sowing densities (24-340 seeds m(-2)) in 2 consecutive years in a clay loam field in Germany and established sowing density dose-response curves for several root and shoot traits. We took soil cores for measuring roots up to a depth of 60 cm in and between plant rows (inter-row distance 21 cm). Root length density increased with increasing sowing density and was greatest in the plant row in the topsoil (0-10 cm). Greater sowing density increased specific root length partly through greater production of fine roots in the topsoil. Rooting depth (D50) of the major root axes (root diameter class 0.4-1.0 mm) was not affected. Root mass fraction decreased, while stem mass fraction increased with sowing density and over time. Leaf mass fraction was constant over sowing density but greater leaf area was realized through increased specific leaf area. Considering fertilization, we assume that light competition caused plants to grow more shoot mass at the cost of investment into roots, which is partly compensated by increased specific root length and shallow rooting. Increased biomass per area with greater densities suggest that density increases the efficiency of the cropping system, however, declines in harvest index at densities over 230 plants m(-2) suggest that this efficiency did not translate into greater yield. We conclude that plant density is a

  19. Distribution of polycyclic aromatic hydrocarbons in subcellular root tissues of ryegrass (Lolium multiflorum Lam.

    Directory of Open Access Journals (Sweden)

    Zhang Yi

    2010-09-01

    Full Text Available Abstract Background Because of the increasing quantity and high toxicity to humans of polycyclic aromatic hydrocarbons (PAHs in the environment, several bioremediation mechanisms and protocols have been investigated to restore PAH-contaminated sites. The transport of organic contaminants among plant cells via tissues and their partition in roots, stalks, and leaves resulting from transpiration and lipid content have been extensively investigated. However, information about PAH distributions in intracellular tissues is lacking, thus limiting the further development of a mechanism-based phytoremediation strategy to improve treatment efficiency. Results Pyrene exhibited higher uptake and was more recalcitrant to metabolism in ryegrass roots than was phenanthrene. The kinetic processes of uptake from ryegrass culture medium revealed that these two PAHs were first adsorbed onto root cell walls, and they then penetrated cell membranes and were distributed in intracellular organelle fractions. At the beginning of uptake ( Conclusions Transpiration and the lipid content of root cell fractions are the main drivers of the subcellular partition of PAHs in roots. Initially, PAHs adsorb to plant cell walls, and they then gradually diffuse into subcellular fractions of tissues. The lipid content of intracellular components determines the accumulation of lipophilic compounds, and the diffusion rate is related to the concentration gradient established between cell walls and cell organelles. Our results offer insights into the transport mechanisms of PAHs in ryegrass roots and their diffusion in root cells.

  20. The tardigrade cuticle. I. Fine structure and the distribution of lipids.

    Science.gov (United States)

    Wright, J C

    1988-01-01

    Fine structure and lipid distribution are studied in cuticles of five tardigrade species using TEM and SEM. Double osmication using partitioning methods reveals a substantial lipid component in the intracuticle and in irregular granular regions within the procuticle. These results are substantiated by the loss of osmiophily following lipid extraction with chloroform and methanol. Other lipid components are revealed by osmication following unmasking of lipo-protein complexes with thymol. These occur in the outer epicuticle and in the trilaminar layer lying between the epi- and intracuticles. Anhydrous fixation of dehydrated tardigrades (tuns) reveals dense, superficial masses of osmiophilic material, apparently concentrated lumps of the surface mucopolysaccharide ('flocculent coat'). However, cryo-SEMs of tuns reveal similar dense aggregations which apparently exude from pores (not visible) and are removed by chloroform. These results suggest extruded lipids since the flocculent coat is unaffected by chloroform; likely functions of such lipids are discussed.

  1. Spatial distribution of enzyme activities along the root and in the rhizosphere of different plants

    Science.gov (United States)

    Razavi, Bahar S.; Zarebanadkouki, Mohsen; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2015-04-01

    Extracellular enzymes are important for decomposition of many biological macromolecules abundant in soil such as cellulose, hemicelluloses and proteins. Activities of enzymes produced by both plant roots and microbes are the primary biological drivers of organic matter decomposition and nutrient cycling. So far acquisition of in situ data about local activity of different enzymes in soil has been challenged. That is why there is an urgent need in spatially explicit methods such as 2-D zymography to determine the variation of enzymes along the roots in different plants. Here, we developed further the zymography technique in order to quantitatively visualize the enzyme activities (Spohn and Kuzyakov, 2013), with a better spatial resolution We grew Maize (Zea mays L.) and Lentil (Lens culinaris) in rhizoboxes under optimum conditions for 21 days to study spatial distribution of enzyme activity in soil and along roots. We visualized the 2D distribution of the activity of three enzymes:β-glucosidase, leucine amino peptidase and phosphatase, using fluorogenically labelled substrates. Spatial resolution of fluorescent images was improved by direct application of a substrate saturated membrane to the soil-root system. The newly-developed direct zymography shows different pattern of spatial distribution of enzyme activity along roots and soil of different plants. We observed a uniform distribution of enzyme activities along the root system of Lentil. However, root system of Maize demonstrated inhomogeneity of enzyme activities. The apical part of an individual root (root tip) in maize showed the highest activity. The activity of all enzymes was the highest at vicinity of the roots and it decreased towards the bulk soil. Spatial patterns of enzyme activities as a function of distance from the root surface were enzyme specific, with highest extension for phosphatase. We conclude that improved zymography is promising in situ technique to analyze, visualize and quantify

  2. Molecular diversity and distribution of indigenous arbuscular mycorrhizal communities colonizing roots of two different winter cover crops in response to their root proliferation.

    Science.gov (United States)

    Higo, Masao; Isobe, Katsunori; Miyazawa, Yusuke; Matsuda, Yukiya; Drijber, Rhae A; Torigoe, Yoichi

    2016-02-01

    A clear understanding of how crop root proliferation affects the distribution of the spore abundance of arbuscular mycorrhizal fungi (AMF) and the composition of AMF communities in agricultural fields is imperative to identify the potential roles of AMF in winter cover crop rotational systems. Toward this goal, we conducted a field trial using wheat (Triticum aestivum L.) or red clover (Trifolium pratense L.) grown during the winter season. We conducted a molecular analysis to compare the diversity and distribution of AMF communities in roots and spore abundance in soil cropped with wheat and red clover. The AMF spore abundance, AMF root colonization, and abundance of root length were investigated at three different distances from winter crops (0 cm, 7.5 cm, and 15 cm), and differences in these variables were found between the two crops. The distribution of specific AMF communities and variables responded to the two winter cover crops. The majority of Glomerales phylotypes were common to the roots of both winter cover crops, but Gigaspora phylotypes in Gigasporales were found only in red clover roots. These results also demonstrated that the diversity of the AMF colonizing the roots did not significantly change with the three distances from the crop within each rotation but was strongly influenced by the host crop identity. The distribution of specific AMF phylotypes responded to the presence of wheat and red clover roots, indicating that the host crop identity was much more important than the proliferation of crop roots in determining the diversity of the AMF communities.

  3. Distribution of root exudates and mucilage in the rhizosphere: combining 14C imaging with neutron radiography

    Science.gov (United States)

    Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov

    2015-04-01

    Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and 14C imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later 14C distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, 14C activity on the image was related to the absolute 14C activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (14C imaging), we were able to differentiate between mucilage and root

  4. Seasonal Patterns of Fine Root Production and Turnover in a Mature Rubber Tree (Hevea brasiliensis Müll. Arg.) Stand- Differentiation with Soil Depth and Implications for Soil Carbon Stocks.

    Science.gov (United States)

    Maeght, Jean-Luc; Gonkhamdee, Santimaitree; Clément, Corentin; Isarangkool Na Ayutthaya, Supat; Stokes, Alexia; Pierret, Alain

    2015-01-01

    Fine root dynamics is a main driver of soil carbon stocks, particularly in tropical forests, yet major uncertainties still surround estimates of fine root production and turnover. This lack of knowledge is largely due to the fact that studying root dynamics in situ, particularly deep in the soil, remains highly challenging. We explored the interactions between fine root dynamics, soil depth, and rainfall in mature rubber trees (Hevea brasiliensis Müll. Arg.) exposed to sub-optimal edaphic and climatic conditions. A root observation access well was installed in northern Thailand to monitor root dynamics along a 4.5 m deep soil profile. Image-based measurements of root elongation and lifespan of individual roots were carried out at monthly intervals over 3 years. Soil depth was found to have a significant effect on root turnover. Surprisingly, root turnover increased with soil depth and root half-life was 16, 6-8, and only 4 months at 0.5, 1.0, 2.5, and 3.0 m deep, respectively (with the exception of roots at 4.5 m which had a half-life similar to that found between depths of 1.0 and 2.5 m). Within the first two meters of the soil profile, the highest rates of root emergence occurred about 3 months after the onset of the rainy season, while deeper in the soil, root emergence was not linked to the rainfall pattern. Root emergence was limited during leaf flushing (between March and May), particularly within the first two meters of the profile. Between soil depths of 0.5 and 2.0 m, root mortality appeared independent of variations in root emergence, but below 2.0 m, peaks in root emergence and death were synchronized. Shallow parts of the root system were more responsive to rainfall than their deeper counterparts. Increased root emergence in deep soil toward the onset of the dry season could correspond to a drought acclimation mechanism, with the relative importance of deep water capture increasing once rainfall ceased. The considerable soil depth regularly explored by

  5. Seasonal patterns of fine root production and turnover in a mature rubber tree (Hevea brasiliensis Müll. Arg. stand - differentiation with soil depth and implications for soil carbon stocks.

    Directory of Open Access Journals (Sweden)

    Jean-Luc eMaeght

    2015-11-01

    Full Text Available Fine root dynamics is a main driver of soil carbon stocks, particularly in tropical forests, yet major uncertainties still surround estimates of fine root production and turnover. This lack of knowledge is largely due to the fact that studying root dynamics in situ, particularly deep in the soil, remains highly challenging.We explored the interactions between fine root dynamics, soil depth and rainfall in mature rubber trees (Hevea brasiliensis Müll. Arg. exposed to sub-optimal edaphic and climatic conditions. A root observation access well was installed in northern Thailand to monitor root dynamics along a 4.5 m deep soil profile. Image-based measurements of root elongation and lifespan of individual roots were carried out at monthly intervals over 3 years. Soil depth was found to have a significant effect on root turnover. Surprisingly, root turnover increased with soil depth and root half-life was 16, 6 - 8 and only 4 months at 0.5, 1.0, 2.5 and 3.0 m deep, respectively (with the exception of roots at 4.5 m which had a half-life similar to that found between depths of 1.0 and 2.5 m. Within the first two meters of the soil profile, the highest rates of root emergence occurred about three months after the onset of the rainy season, while deeper in the soil, root emergence was not linked to the rainfall pattern. Root emergence was limited during leaf flushing (between March and May, particularly within the first two meters of the profile. Between soil depths of 0.5 and 2.0 m, root mortality appeared independent of variations in root emergence, but below 2.0 m, peaks in root emergence and death were synchronized.Shallow parts of the root were more responsive to rainfall than their deeper counterparts. Increased root emergence in deep soil towards the onset of the dry season could correspond to a drought acclimation mechanism, with the relative importance of deep water capture increasing once rainfall ceased. The considerable soil depth regularly

  6. Root anatomy and element distribution vary between two Salix caprea isolates with different Cd accumulation capacities.

    Science.gov (United States)

    Vaculík, Marek; Konlechner, Cornelia; Langer, Ingrid; Adlassnig, Wolfram; Puschenreiter, Markus; Lux, Alexander; Hauser, Marie-Theres

    2012-04-01

    The understanding of the influence of toxic elements on root anatomy and element distribution is still limited. This study describes anatomical responses, metal accumulation and element distribution of rooted cuttings of Salix caprea after exposure to Cd and/or Zn. Differences in the development of apoplastic barriers and tissue organization in roots between two distinct S. caprea isolates with divergent Cd uptake and accumulation capacities in leaves might reflect an adaptive predisposition based on different natural origins. Energy-dispersive X-ray spectroscopy (EDX) revealed that Cd and Zn interfered with the distribution of elements in a tissue- and isolate-specific manner. Zinc, Ca, Mg, Na and Si were enriched in the peripheral bark, K and S in the phloem and Cd in both vascular tissues. Si levels were lower in the superior Cd translocator. Since the cuttings originated from stocks isolated from polluted and unpolluted sites we probably uncovered different strategies against toxic elements.

  7. Visualization of physico-chemical properties and microbial distribution in soil and root microenvironments

    Science.gov (United States)

    Eickhorst, Thilo; Schmidt, Hannes

    2016-04-01

    Plant root development is influenced by soil properties and environmental factors. In turn plant roots can also change the physico-chemical conditions in soil resulting in gradients between roots and the root-free bulk soil. By releasing a variety of substances roots facilitate microbial activities in their direct vicinity, the rhizosphere. The related microorganisms are relevant for various ecosystem functions in the root-soil interface such as nutrient cycling. It is therefore important to study the impact and dynamics of microorganisms associated to different compartments in root-soil interfaces on a biologically meaningful micro-scale. The analysis of microorganisms in their habitats requires microscopic observations of the respective microenvironment. This can be obtained by preserving the complex soil structure including the root system by resin impregnation resulting in high quality thin sections. The observation of such sections via fluorescence microscopy, SEM-EDS, and Nano-SIMS will be highlighted in this presentation. In addition, we will discuss the combination of this methodological approach with other imaging techniques such as planar optodes or non-invasive 3D X-ray CT to reveal the entire spatial structure and arrangement of soil particles and roots. When combining the preservation of soil structure via resin impregnation with 16S rRNA targeted fluorescence in situ hybridization (FISH) single microbial cells can be visualized, localized, and quantified in the undisturbed soil matrix including the root-soil interfaces. The simultaneous use of multiple oligonucleotide probes thereby provides information on the spatial distribution of microorganisms belonging to different phylogenetic groups. Results will be shown for paddy soils, where management induced physico-chemical dynamics (flooding and drying) as well as resulting microbial dynamics were visualized via correlative microscopy in resin impregnated samples.

  8. Influence of Olea europea L. and Ficus Carrica L. fine root activity on the K biodisponibility and clay mineralogy of the rhizosphere

    Directory of Open Access Journals (Sweden)

    Sophia Mouas-Bourbia

    2015-10-01

    Full Text Available The objective of this study was to compare the effect of fine root activity of Olea europea L. and Ficus carrica L. of soil in its immediate vicinity (in the so-called rhizosphere zone. The study was conducted on two stations in Northern Algeria: Guendoul and Bouira. Olea europea L. and Ficus carrica L. roots significantly modified some chemical properties of rhizosphere soil. Increases of soil carbon, KNH4+ and KHNO3- were observed in the Olea europea L. and Ficus carrica L rhizosphere soil at both stations. Bulk and rhizosphere soil clay mineralogy was similar. Interstratified illite-smectite, smectite-illite and illite were predominant in the clay fraction. Chlorite and kaolinite were less represented. The decomposition of XRD diffractograms of two soil clay fractions using the Decomp program revealed that Olea europea L. roots promote nK+ storage in interlayer position. Indeed, the lower abscissa position of the gravity center (cg of the X-ray patterns, the peak displacement of clays populations PCI, I/S, S/I toward illite peak position indicates an increase of “illite-like” layer content in the vicinity of Olea europea L. roots. Olea europea L. roots appeared to have more influence on the rhizosphere soil than Ficus carrica L. roots probably because of its higher root biomass and the greater activity of the tree in winter (contrary to Ficus Carrica L., Olea europea L. keep their leaves in winter. The two species underground activity seems to be well reflected in their respective rhizosphere.

  9. Effects of Soil Moisture on Dynamic Distribution of Dry Matter Between Winter Wheat Root and Shoot

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-yuan; LIU Xiao-ying; LUO Yuan-pei

    2003-01-01

    The dynamic relationship of dry matter accumulation and distribution between winter wheatroot and shoot was studied under different soil water conditions. The dry matter accumulation in root wasgreatly influenced by water stress, so as to the final root weight of the treatment with 40 % field moisturecapacity (FMC) was less than 1/4 of that of the treatment with 80 % FMC on average. Water stress duringthe 3-leaf stage to the tillering stage had the greatest influence on root, and the influence of water stressduring the jointing stage to the booting stage on shoot was greater than root. However, water stress duringthe tillering stage to the booting stage had a balanced effect on root and shoot, and the proportion of drymatter that distributed to root and shoot was almost the same after rewatering. Water recovery during thejointing stage to booting stage could promote R/S, but the increasing degree was related to the duration ofwater limitation. Soil water condition had the lowest effect on R/S during the flowering stage to the fillingstage and the maximal effect on R/S during the jointing stage to the heading stage, R/S of 40% FMCtreatment was 20.93 and 126.09 % higher than that of 60 % FMC and 80 % FMC treatments respectivelyat this period.

  10. Iron- and ferritin-dependent reactive oxygen species distribution: impact on Arabidopsis root system architecture.

    Science.gov (United States)

    Reyt, Guilhem; Boudouf, Soukaina; Boucherez, Jossia; Gaymard, Frédéric; Briat, Jean-Francois

    2015-03-01

    Iron (Fe) homeostasis is integrated with the production of reactive oxygen species (ROS), and distribution at the root tip participates in the control of root growth. Excess Fe increases ferritin abundance, enabling the storage of Fe, which contributes to protection of plants against Fe-induced oxidative stress. AtFer1 and AtFer3 are the two ferritin genes expressed in the meristematic zone, pericycle and endodermis of the Arabidopsis thaliana root, and it is in these regions that we observe Fe stained dots. This staining disappears in the triple fer1-3-4 ferritin mutant. Fe excess decreases primary root length in the same way in wild-type and in fer1-3-4 mutant. In contrast, the Fe-mediated decrease of lateral root (LR) length and density is enhanced in fer1-3-4 plants due to a defect in LR emergence. We observe that this interaction between excess Fe, ferritin, and root system architecture (RSA) is in part mediated by the H2O2/O2·- balance between the root cell proliferation and differentiation zones regulated by the UPB1 transcription factor. Meristem size is also decreased in response to Fe excess in ferritin mutant plants, implicating cell cycle arrest mediated by the ROS-activated SMR5/SMR7 cyclin-dependent kinase inhibitors pathway in the interaction between Fe and RSA.

  11. Fine fragmentation distribution from structural reactive material casings under explosive loading

    Science.gov (United States)

    Wilson, William; Zhang, Fan; Kim, Kibong

    2015-06-01

    Structural reactive material (SRM) can be used for explosive casings to provide additional blast energy. SRM fragments can react either promptly or after impact with nearby structure. Better understanding of fine fragment distributions from SRM casings is important for optimization of initiation and reaction of the SRM fragments. Key to this is knowledge of the initial fragmentation character before it has been altered by early reaction or by subsequent impact with surrounding structure. The study must be conducted beyond critical charge diameter to minimize effects of the expansion wave on fragment sizes. The collection and analysis of fragment distribution down to 40 micron size from thick SRM casings are therefore investigated in a 1.18 m diameter, 2.1 m3 closed cylindrical chamber filled with artificially-made pure snow packed to density 0.35 g/cm3. The snow quenches early reaction of SRM fragments and soft-catches the fragments before impact with the chamber walls. A 100 g cylindrical C-4 explosive charge is used, packed in a 3.3 cm inner diameter SRM casing, with length-to-diameter ratio of L/d = 2, and casing-to-explosive mass ratio of M/C = 1.75. Three types of SRM are investigated, including a baseline of Aluminum 6061 for comparison. The cased charge is suspended in an argon filled cavity, 20 cm in diameter and 40 cm long, within the snow filed chamber.

  12. Fine structure of Tibetan kefir grains and their yeast distribution, diversity, and shift.

    Directory of Open Access Journals (Sweden)

    Man Lu

    Full Text Available Tibetan kefir grains (TKGs, a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii the diversity of yeasts is relatively low on genus level with three dominant species--Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic

  13. Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

    Science.gov (United States)

    Lu, Man; Wang, Xingxing; Sun, Guowei; Qin, Bing; Xiao, Jinzhou; Yan, Shuling; Pan, Yingjie; Wang, Yongjie

    2014-01-01

    Tibetan kefir grains (TKGs), a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i) yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii) the diversity of yeasts is relatively low on genus level with three dominant species – Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii) S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic associations between S

  14. Distribution of polycyclic aromatic hydrocarbons in subcellular root tissues of ryegrass (Lolium multiflorum Lam.)

    Science.gov (United States)

    2010-01-01

    Background Because of the increasing quantity and high toxicity to humans of polycyclic aromatic hydrocarbons (PAHs) in the environment, several bioremediation mechanisms and protocols have been investigated to restore PAH-contaminated sites. The transport of organic contaminants among plant cells via tissues and their partition in roots, stalks, and leaves resulting from transpiration and lipid content have been extensively investigated. However, information about PAH distributions in intracellular tissues is lacking, thus limiting the further development of a mechanism-based phytoremediation strategy to improve treatment efficiency. Results Pyrene exhibited higher uptake and was more recalcitrant to metabolism in ryegrass roots than was phenanthrene. The kinetic processes of uptake from ryegrass culture medium revealed that these two PAHs were first adsorbed onto root cell walls, and they then penetrated cell membranes and were distributed in intracellular organelle fractions. At the beginning of uptake (lipid contents of each component. Phenanthrene and pyrene primarily accumulated in plant root cell walls and organelles, with about 45% of PAHs in each of these two fractions, and the remainder was retained in the dissolved fraction of the cells. Because of its higher lipophilicity, pyrene displayed greater accumulation factors in subcellular walls and organelle fractions than did phenanthrene. Conclusions Transpiration and the lipid content of root cell fractions are the main drivers of the subcellular partition of PAHs in roots. Initially, PAHs adsorb to plant cell walls, and they then gradually diffuse into subcellular fractions of tissues. The lipid content of intracellular components determines the accumulation of lipophilic compounds, and the diffusion rate is related to the concentration gradient established between cell walls and cell organelles. Our results offer insights into the transport mechanisms of PAHs in ryegrass roots and their diffusion in root

  15. Dissipation and distribution of chlorpyrifos in selected vegetables through foliage and root uptake.

    Science.gov (United States)

    Ge, Jing; Lu, Mengxiao; Wang, Donglan; Zhang, Zhiyong; Liu, Xianjin; Yu, Xiangyang

    2016-02-01

    Dissipation, distribution and uptake pathways of chlorpyrifos were investigated in pakchoi (Brassica chinensis L.) and lettuce (Lactuca sativa) with foliage treatments under a greenhouse trial and root treatments under a hydroponic experiment. The dissipation trends were similar for chlorpyrifos in pakchoi and lettuce with different treatments. More than 94% of chlorpyrifos was degraded in the samples for both of the vegetables 21 days after the foliage treatments. For the root treatment, the dissipation rate of chlorpyrifos in pakchoi and lettuce at the low concentration was greater than 93%, however, for the high concentrations, the dissipation rates were all under 90%. Both shoots and roots of the vegetables were able to absorb chlorpyrifos from the environment and distribute it inside the plants. Root concentration factor (RCF) values at different concentrations with the hydroponic experiment ranged from 5 to 39 for pakchoi, and from 14 to 35 for lettuce. The translocation factor (TF) representing the capability of the vegetables to translocate contaminants was significantly different for pakchoi and lettuce with foliage and root treatments. The values of TF with foliage treatments ranged from 0.003 to 0.22 for pakchoi, and from 0.032 to 1.63 for lettuce. The values of TF with root treatments ranged from 0.01 to 0.17 for pakchoi, and from 0.003 to 0.23 for lettuce. Significant difference of TF was found between pakchoi and lettuce with foliage treatments, and at high concentrations (10 and 50 mg L(-1)) with root treatments as well. However, there was no significant difference of TF between pakchoi and lettuce at 1 mg L(-1) with root treatment.

  16. Effects of Soil Water Content on Cotton Root Growth and Distribution Under Mulched Drip Irrigation

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-tang; CHEN Hu; WANG Jing; MENG Xiao-bin; CHEN Fu-hong

    2009-01-01

    The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation.Based on the field experiments,three treatments of soil water content were conducted with 90%θf,75%θf,and 60%θf (θf is field water capacity).Cotton roots and root-shoot ratio were studied with digging method,and the soil moisture was observed with TDR (time domain reflector),and cotton yield was measured.The results indicated that the growth of cotton root accorded with Logistic growth curve in the three treatments,the cotton root grew quickly and its weight was very high under 75%θf because of the suitable soil water condition,while grew slowly and its weight was lower under 90%θf due to water moisture beyond the suitable condition,and the root weight was in between under 60%θf.For the three water treatments,the cotton root weight decreased with soil depth,and decreased more significantly in deeper soil layer with the soil moisture increasing.And the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under 75%θf.The cotton root system was distributed mainly in the soil of narrow row and wide row mulched with plastic film,and little in the soil outside plastic film.The weight of cotton root was the highest in the soil of narrow row or wide row mulched with plastic film under 75%θf.Root-shoot ratio decreased with the soil moisture increasing.The soil water content affected cotton yields,and cotton yield was the highest under 75%θf.The higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.

  17. Effect of restoration technique on stress distribution in roots with flared canals: an FEA study.

    Science.gov (United States)

    Belli, Sema; Eraslan, Öznur; Eraslan, Oğuz; Eskitaşcıoğlu, Gürcan

    2014-04-01

    The aim of this finite element analysis (FEA) study was to test the effect of different restorative techniques on stress distribution in roots with flared canals. Five three-dimensional (3D) FEA models that simulated a maxillary incisor with excessive structure loss and flared root canals were created and restored with the following techniques/materials: 1) a prefabricated post: 2) one main and two accessory posts; 3) i-TFC post-core (Sun Medical); 4) the thickness of the root was increased by using composite resin and the root was then restored using a prefabricated post; 5) an anatomic post was created by using composite resin and a prefabricated glass-fiber post. Composite cores and ceramic crowns were created. A 300-N static load was applied at the center of the palatal surface of the tooth to calculate stress distributions. SolidWorks/Cosmosworks structural analysis programs were used for FEA analysis. The analysis of the von Mises and tensile stress values revealed that prefabricated post, accessory post, and i-TFC post systems showed similar stress distributions. They all showed high stress areas at the buccal side of the root (3.67 MPa) and in the cervical region of the root (> 3.67 MPa) as well as low stress accumulation within the post space (0 to 1 MPa). The anatomic post kept the stress within its body and directed less stress towards the remaining tooth structure. The creation of an anatomic post may save the remaining tooth structure in roots with flared canals by reducing the stress levels.

  18. Nanoscale measurement of trace element distributions in Spartina alterniflora root tissue during dormancy

    Science.gov (United States)

    Feng, Huan; Qian, Yu; Cochran, J. Kirk; Zhu, Qingzhi; Hu, Wen; Yan, Hanfei; Li, Li; Huang, Xiaojing; Chu, Yong S.; Liu, Houjun; Yoo, Shinjae; Liu, Chang-Jun

    2017-01-01

    This paper reports a nanometer-scale investigation of trace element (As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn) distributions in the root system Spartina alterniflora during dormancy. The sample was collected on a salt marsh island in Jamaica Bay, New York, in April 2015 and the root was cross-sectioned with 10 μm resolution. Synchrotron X-ray nanofluorescence was applied to map the trace element distributions in selected areas of the root epidermis and endodermis. The sampling resolution was 60 nm to increase the measurement accuracy and reduce the uncertainty. The results indicate that the elemental concentrations in the epidermis, outer endodermis and inner endodermis are significantly (p Pearson correlation analysis on the average concentrations of each element in the selected areas shows that most of the elements are significantly (p correlated, which suggests that these elements may share the same transport pathways.

  19. Predicting fine-scale distributions of peripheral aquatic species in headwater streams

    Science.gov (United States)

    DeRolph, Christopher R.; Nelson, S.; Kwak, Thomas J.; Hain, Ernie F.

    2015-01-01

    Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. We predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.

  20. Modeling the Interdependence of Hydropedology and Root Distributions of Larrea Tridentata in the Mojave Desert

    Science.gov (United States)

    Caldwell, T. G.; McDonald, E. V.; Young, M. H.; Stevenson, B. A.

    2005-12-01

    The root distribution of perennial desert plants is ultimately tied to the search for water. Soil development and resulting morphology are functions of time. Morphological features are known to affect the soil water storage and infiltration in arid soils, but they have not been linked with the root distributions of perennial plant. For this study, the depth and lateral spread of Creosote ( Larrea tridentata) roots, a common evergreen shrub of the Mojave Desert, were hypothesized to be coupled with the depth of water penetration and associated hydropedology (i.e. soil age and structure). Soil morphology, soil hydrologic properties, L. tridentata root distributions, and canopy size were measured from the plant canopy to the interspace at three Mojave Desert sites. Each site consisted of a paired geomorphic chronosequence containing a young (Holocene) weakly developed soil and an older (Pleistocene) strongly developed soil on the same geomorphic unit. Particle-size distribution, coarse fragments, bulk density and horizon thickness were used to parameterize the HYDRUS and the Simultaneous Heat and Water (SHAW) models. A 50-year climatic records were developed for each site using the long-term meteorological records and the CLIGEN stochastic weather simulator. Numerical simulations were conducted to evaluate soil water distributions in relation to measure rooting patterns for each chronosequence. Numerical simulations indicated greater depth of water penetration at young sites, coinciding with the measured root distributions. Water penetration was limited to approximately 1.5 m on the young surface and 0.75 on the old interspace surfaces throughout the 50-year simulations. Deeper penetration occurred under all plant mounds, but no drainage below 2 m occurred at any site. Results from infiltrometers showed that younger coarser textured surfaces had saturated conductivities (Ksat) nearly twice that of older surfaces. Plant mound microsites were more sand-rich than

  1. Cobalt Distribution and Speciation: Effect of Aging, Intermittent Submergence, In situ Rice Roots

    Science.gov (United States)

    The speciation and distribution of cobalt (Co) in soils is poorly understood. This study was conducted using X-ray absorption spectroscopy (XAS) techniques to examine the influence of soluble Co(II) aging, submergence-dried cycling, and the presence of in vivo rice roots on the...

  2. Cobalt Distribution and Speciation: Effect of Aging, Intermittent Submergence, In situ Rice Roots

    Science.gov (United States)

    The speciation and distribution of cobalt (Co) in soils is poorly understood. This study was conducted using X-ray absorption spectroscopy (XAS) techniques to examine the influence of soluble Co(II) aging, submergence-dried cycling, and the presence of in vivo rice roots on the...

  3. Three potential pathways influencin/contrastin/decomposition rates of fine roots%细根异速分解的3个可能影响途径

    Institute of Scientific and Technical Information of China (English)

    王存国; 陈正侠; 马承恩; 林贵刚; 韩士杰

    2016-01-01

    Plant root decomposition is one of the critical processes of carbon and nutrient cycling in terrestrial ecosystems. Plant roots less than 2 mm in diameter constitute a heterogeneous branching system. Within the system, lower order roots (e. g. 1st -3rd order) or fine roots in smaller diameter (e. g. less than 0. 5 mm in diameter) which mainly serve for water and nutrient uptake have fast turnover rates (0. 5 -2. 5 times per year) , and contribute greatly to soil carbon and nutrients pools. Recently, increasing number of studies have shown that lower order roots decompose more slowly than higher order roots ( e. g. more than 3rd order) or fine roots in larger diameter (e. g. more than 0. 5 mm in diameter) which mainly serve for water﹣nutrient transport and carbon storage. Here, we review three main factors explaining the contrasting decomposition rates across different root orders or diameter classes: mycorrhizal, carbon quality and nitrogen content. Overall, we intend to provide insights into the important roles of functional traits ( e. g. diameter ) of fine roots that play in ecosystem carbon and nutrient cycling in a changing world.%植物根系分解是驱动陆地生态系统碳和养分循环的关键过程之一。直径小于2 mm的根是一个复杂的异质性细根系统。位于细根系统末端的低级根(如1~3级根)或直径较小的细根(如直径小于0.5 mm的细根),执行水分和养分吸收功能,其周转迅速(0.5~2.5次/a),是植物根系向土壤输入碳和养分的主要途径。近年来对细根分解的研究表明,在细根系统中,低级根的分解速率显著慢于高级根(如3级以上的根)或直径较大的细根(如直径大于0.5 mm的细根),执行输导和储藏功能。本文综述了影响细根异速分解的3个可能途径:菌根、碳质量和氮含量,旨在增强研究者对全球变化下细根功能属性(如细根直径)如何影响生态系统碳和养分循环的理解。

  4. [Effects of different drip irrigation modes on root distribution of wine grape 'Cabernet Sauvignon' in desert area of Northwest China].

    Science.gov (United States)

    Mao, Juan; Chen, Bai-Hong; Cao, Jian-Dong; Wang, Li-Jun; Wang, Hai; Wang, Yan-Xiu

    2013-11-01

    To study the effects of different drip irrigation modes on the wine grape root distribution is the basis of formulating fertilization, irrigation, and over-wintering management practices for wine grape. Taking the wine grape "Cabernet Sauvignon" as test material, this paper studied the effects of different water-saving irrigation modes (drip irrigation under straw mulching, drip irrigation under plastic mulching, double-tube drip irrigation, and single-tube drip irrigation) on the root distribution of wine grape in the desert area of Northwest China, with the conventional furrow irrigation as the control. The root system of the "Cabernet Sauvignon" was distributed from 0 to 70 cm vertically, and from 0 to 120 cm horizontally. With double-tube drip irrigation, the root amount was the largest (138.3 roots per unit profile), but the root vertical distribution scope was narrowed by 20 cm, as compared to the control. Drip irrigation with straw mulching increased the root amount significantly, and increased the root horizontal distribution scope by 9.1%, as compared to the control. No significant difference was observed in the root number and root horizontal distribution scope between the drip irrigation under plastic mulching and the control, but the root vertical distribution scope with the drip irrigation under plastic mulching decreased by 20 cm. Single-tube drip irrigation increased the root number significantly, but had lesser effects on the root vertical or horizontal distribution, as compared to the conventional irrigation. It was suggested that the drip irrigation under straw mulching could be the best water-saving practice for the wine grape "Cabernet Sauvignon" in the study area.

  5. Use of spatially distributed time-integrated sediment sampling networks and distributed fine sediment modelling to inform catchment management.

    Science.gov (United States)

    Perks, M T; Warburton, J; Bracken, L J; Reaney, S M; Emery, S B; Hirst, S

    2017-11-01

    Under the EU Water Framework Directive, suspended sediment is omitted from environmental quality standards and compliance targets. This omission is partly explained by difficulties in assessing the complex dose-response of ecological communities. But equally, it is hindered by a lack of spatially distributed estimates of suspended sediment variability across catchments. In this paper, we demonstrate the inability of traditional, discrete sampling campaigns for assessing exposure to fine sediment. Sampling frequencies based on Environmental Quality Standard protocols, whilst reflecting typical manual sampling constraints, are unable to determine the magnitude of sediment exposure with an acceptable level of precision. Deviations from actual concentrations range between -35 and +20% based on the interquartile range of simulations. As an alternative, we assess the value of low-cost, suspended sediment sampling networks for quantifying suspended sediment transfer (SST). In this study of the 362 km(2) upland Esk catchment we observe that spatial patterns of sediment flux are consistent over the two year monitoring period across a network of 17 monitoring sites. This enables the key contributing sub-catchments of Butter Beck (SST: 1141 t km(2) yr(-1)) and Glaisdale Beck (SST: 841 t km(2) yr(-1)) to be identified. The time-integrated samplers offer a feasible alternative to traditional infrequent and discrete sampling approaches for assessing spatio-temporal changes in contamination. In conjunction with a spatially distributed diffuse pollution model (SCIMAP), time-integrated sediment sampling is an effective means of identifying critical sediment source areas in the catchment, which can better inform sediment management strategies for pollution prevention and control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Properties of the prominence magnetic field and plasma distributions as obtained from 3D whole-prominence fine structure modeling

    Science.gov (United States)

    Gunár, S.; Mackay, D. H.

    2016-07-01

    Aims: We analyze distributions of the magnetic field strength and prominence plasma (temperature, pressure, plasma β, and mass) using the 3D whole-prominence fine structure model. Methods: The model combines a 3D magnetic field configuration of an entire prominence, obtained from non-linear force-free field simulations, with a detailed semi-empirically derived description of the prominence plasma. The plasma is located in magnetic dips in hydrostatic equilibrium and is distributed along multiple fine structures within the 3D magnetic model. Results: We show that in the modeled prominence, the variations of the magnetic field strength and its orientation are insignificant on scales comparable to the smallest dimensions of the observed prominence fine structures. We also show the ability of the 3D whole-prominence fine structure model to reveal the distribution of the prominence plasma with respect to its temperature within the prominence volume. This provides new insights into the composition of the prominence-corona transition region. We further demonstrate that the values of the plasma β are small throughout the majority of the modeled prominences when realistic photospheric magnetic flux distributions and prominence plasma parameters are assumed. While this is generally true, we also find that in the region with the deepest magnetic dips, the plasma β may increase towards unity. Finally, we show that the mass of the modeled prominence plasma is in good agreement with the mass of observed non-eruptive prominences.

  7. Fruit yield and root system distribution of 'Tommy Atkins' mango under different irrigation regimes

    Directory of Open Access Journals (Sweden)

    Marcelo R. dos Santos

    2014-04-01

    Full Text Available This study aimed to evaluate the fruit yield and the distribution of 'Tommy Atkins' mango root system under different irrigation regimes in the semiarid region of Bahia. The experimental design was completely randomized with five treatments and three replicates: 1 - Irrigation supplying 100% of ETc in phases I, II and III; 2 - Regulated deficit irrigation (RDI supplying 50% of ETc in phase I (beginning of flowering to early fruit growth; 3 - RDI supplying 50% ETc in phase II (start of expansion until the beginning of physiological maturity; 4 - RDI supplying 50% ETc in phase III (physiological mature fruits; 5 - No irrigation during all three phases. The regulated deficit irrigation supplying 50% of the ETc during phase I and II provided larger root length density of 'Tommy Atkins' mango. Regardless of management strategy, the roots were developed in all evaluated soil volume and the highest density is concentrated from 0.50 to 1.50 m distance from the trunk and in 0.20 to 0.90 m depth in the soil, that suggests this region to be the best place for fertilizer application as well for soil water sensor placement. The application of RDI during fruit set does not influence either root distribution or production. Root system and crop production is significantly reduced under no irrigation conditions.

  8. Habitat Preferences, Distribution Pattern, and Root Weight Estimation of Pasak Bumi (Eurycoma longifolia Jack.

    Directory of Open Access Journals (Sweden)

    Siti Masitoh Kartikawati

    2014-04-01

    Full Text Available Pasak bumi (Eurycoma longifolia Jack is one of non timber forest products with “indeterminate” conservation status and commercially traded in West Kalimantan. The research objective was to determine the potential of pasak bumi root per hectare and its ecological condition under natural habitat. Root weight of E. longifolia Jack was estimated using simple linear regression and exponential equation with stem diameter and height as independent variables. The results showed that the individual number of the population was 114 with the majority in seedling stage with 71 individuals (62.28%. The distribution was found in clumped pattern. Conditions of the habitat could be described as follows: daily average temperature of 25.6oC, daily average relative humidity of 73.6%, light intensity of 0.9 klx, and red-yellow podsolic soil with texture ranged from clay to sandy clay. The selected estimator model for E. longifolia Jack root weight used exponential equation with stem height as independent variable using the equation of Y= 21.99T0,010 and determination coefficient of 0.97. After height variable was added, the potential of E. longifolia Jack minimum root weight that could be harvested per hectare was 0.33 kg.Keywords: Eurycoma longifolia, habitat preference, distribution pattern, root weight

  9. Evaluation of Species Distribution Model Algorithms For Fine-Scale Container Breeding Mosquito Risk Prediction

    Science.gov (United States)

    Khatchikian, C.; Sangermano, F.; Kendell, D.; Livdahl, T.

    2010-01-01

    The present work evaluates the use of species distribution model (SDM) algorithms to classify high density of small container Aedes mosquitoes at a fine scale, in the Bermuda islands. Weekly ovitrap data collected by the Health Department of Bermuda (UK) for the years 2006 and 2007 were used for the models. The models evaluated included the following algorithms: Bioclim, Domain, GARP, logistic regression, and MaxEnt. Models were evaluated according to performance and robustness. The area Receiver Operating Characteristic (ROC) curve was used to evaluate each model’s performance, and robustness was assessed considering the spatial correlation between classification risks for the two datasets. Relative to the other algorithms, logistic regression was the best model for classifying high risk areas, and the maximum entropy approach (MaxEnt) presented the second best performance. We report the importance of covariables for these two models, and discuss the utility of SDMs for vector control efforts and the potential for the development of scripts that automate the task of creating risk assessment maps. PMID:21198711

  10. Changes in the Fine Structure of Stochastic Distributions as a Consequence of Space-Time Fluctuations

    Directory of Open Access Journals (Sweden)

    Shnoll S. E.

    2006-04-01

    Full Text Available This is a survey of the fine structure stochastic distributions in measurements obtained by me over 50 years. It is shown: (1 The forms of the histograms obtained at each geographic point (at each given moment of time are similar with high probability, even if we register phenomena of completely different nature — from biochemical reactions to the noise in a gravitational antenna, or α-decay. (2 The forms of the histograms change with time. The iterations of the same form have the periods of the stellar day (1.436 min, the solar day (1.440 min, the calendar year (365 solar days, and the sidereal year (365 solar days plus 6 hours and 9 min. (3 At the same instants of the local time, at different geographic points, the forms of the histograms are the same, with high probability. (4 The forms of the histograms depend on the locations of the Moon and the Sun with respect to the horizon. (5 All the facts are proof of the dependance of the form of the histograms on the location of the measured objects with respect to stars, the Sun, and the Moon. (6 At the instants of New Moon and the maxima of solar eclipses there are specific forms of the histograms. (7 It is probable that the observed correlations are not connected to flow power changes (the changes of the gravity force — we did not find the appropriate periods in changes in histogram form. (8 A sharp anisotropy of space was discovered, registered by α-decay detectors armed with collimators. Observations at 54◦ North (the collimator was pointed at the Pole Star showed no day-long periods, as was also the case for observations at 82◦ North, near the Pole. Histograms obtained by observations with an Easterly-directed collimator were determined every 718 minutes (half stellar day and with observations using a Westerly-directed collimator. (9 Collimators rotating counter-clockwise, in parallel with the celestial equator, gave the probability of changes in histograms as the number of the

  11. Changes in the Fine Structure of Stochastic Distributions as a Consequence of Space-Time Fluctuations

    Directory of Open Access Journals (Sweden)

    Shnoll S. E.

    2006-04-01

    Full Text Available This is a survey of the fine structure stochastic distributions in measurements obtained by me over 50 years. It is shown: (1 The forms of the histograms obtained at each geographic point (at each given moment of time are similar with high probability, even if we register phenomena of completely different nature --- from biochemical reactions to the noise in a gravitational antenna, or alpha-decay. (2 The forms of the histograms change with time. The iterations of the same form have the periods of the stellar day (1.436 min, the solar day (1.440 min, the calendar year (365 solar days, and the sidereal year (365 solar days plus 6 hours and 9 min. (3 At the same instants of the local time, at different geographic points, the forms of the histograms are the same, with high probability. (4 The forms of the histograms depend on the locations of the Moon and the Sun with respect to the horizon. (5 All the facts are proof of the dependance of the form of the histograms on the location of the measured objects with respect to stars, the Sun, and the Moon. (6 At the instants of New Moon and the maxima of solar eclipses there are specific forms of the histograms. (7 It is probable that the observed correlations are not connected to flow power changes (the changes of the gravity force --- we did not find the appropriate periods in changes in histogram form. (8 A sharp anisotropy of space was discovered, registered by alpha-decay detectors armed with collimators. Observations at 54 North (the collimator was pointed at the Pole Star showed no day-long periods, as was also the case for observations at 82 North, near the Pole. Histograms obtained by observations with an Easterly-directed collimator were determined every 718 minutes (half stellar day and with observations using a Westerly-directed collimator. (9 Collimators rotating counter-clockwise, in parallel with the celestial equator, gave the probability of changes in histograms as the number of the

  12. Distribution and Speciation of Cu in the Root Border Cells of Rice by STXM Combined with NEXAFS.

    Science.gov (United States)

    Peng, Cheng; Wang, Yi; Sun, Lijuan; Xu, Chen; Zhang, Lijuan; Shi, Jiyan

    2016-03-01

    Root border cells (RBCs) serve plants in their initial line of defense against stress from the presence of heavy metals in the soil. In this research, light microscopy and synchrotron-based scanning transmission X-ray microscopy (STXM) combined with near edge X-ray absorption fine structure spectroscopy (NEXAFS) with a nanoscale spatial resolution were used to investigate the effects of copper (Cu) upon the RBCs, as well as its distribution and speciation within the RBCs of rice (Oryza sativa L.) under aeroponic culture. The results indicated that with increasing exposure time and concentration, the attached RBCs were surrounded by a thick mucilage layer which changed in form from an ellipse into a strip in response to Cu ion stress. Copper was present as Cu(II), which accumulated not only in the cell wall but also in the cytoplasm. To our knowledge, this is the first time that STXM has been used in combination with NEXAFS to provide new insight into the distribution and speciation of metal elements in isolated plant cells.

  13. Species and Distribution of Rice Root Nematode in Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    HUXian-qi; YUMin; LINLi-fei; WANGYang; YUSheng-fu

    2004-01-01

    Rice root nematodes, Hirschmanniella spp. parasitize in the roots of rice and water plant spread widely. Ten species of the genus Hirschmanniella Luc et Goody, 1964 (Nemata:Pratylenchidae) collected from the root of rice in Yunnan Province are reported. They are H. belli, H. caudacrena, H. diversa, H. gracilis, H. imamuri, H. mexicana, H. microtyla,H. mucronata, H. oryzae and H. spinicaudata, including seven species of important pathogenic nematodes of rice and two dominant species H. oryzae and H. imamari. Generally,the trend of species composition pattern is H. oryzae and H. imamari, which is a common composition pattern in the world, but the species composition mode varies with the difference of altitude and latitude. Their distribution relates to altitude and latitude closely, and also to the type of rice, such as indica or japonica rice.

  14. Species and Distribution of Rice Root Nematode in Yunnan Province,China

    Institute of Scientific and Technical Information of China (English)

    HU Xian-qi; YU Min; LIN Li-fei; WANG Yang; YU Sheng-fu

    2004-01-01

    Rice root nematodes, Hirschmanniella spp. parasitize in the roots of rice and water plant spread widely. Ten species of the genus Hirschmanniella Luc et Goody, 1964 (Nemata:Pratylenchidae) collected from the root of rice in Yunnan Province are reported. They are H. belli, H. caudacrena, H. diversa, H. gracilis, H. imamuri, H. mexicana, H. microtyla,H. mucronata, H. oryzae and H. spinicaudata, including seven species of important pathogenic nematodes of rice and two dominant species H. oryzae and H. imamari. Generally,the trend of species composition pattern is H. oryzae and H. imamari, which is a common composition pattern in the world, but the species composition mode varies with the difference of altitude and latitude. Their distribution relates to altitude and latitude closely, and also to the type of rice, such as indica or japonica rice.

  15. TEMPORAL DISTRIBUTION OF TOTAL NITROGEN CONCENTRATION IN ROOT ZONE OF MAIZE ( Zea mays L.

    Directory of Open Access Journals (Sweden)

    Mthandi J

    2013-09-01

    Full Text Available Nitrogen (N plays an important role in the production of maize. In the absence of N in soils plants shows stunted growth and yellowish leaves and result into reduced crop yield. The study was conducted during two irrigation seasons of 2012 at Nkango Irrigation Scheme, Malawi in a Randomised Complete Block Design (RCBD. The factors were water and nitrogen and both were at four levels . The study inferred that movement, direction and distribution patterns of nitrogen concentration is influenced by evaporation of water from the soil surfaces, pulling effects by plant roots, deep percolation through gravitational force, and ability of plant roots to create environment that is conducive to diffusion of nitrogen. To minimize losses of nitrogen through leachi ng and ensure that nitrogen is deposited within active root zone, plant should not receive water after physiological maturity.

  16. Spatial distribution of nematodes in three banana ( Musa AAA) root parts considering two root thickness in three farm management systems

    Science.gov (United States)

    Araya, M.; De Waele, D.

    2004-10-01

    The spatial location of the banana ( Musa AAA) root parasitic nematodes within three root parts considering two root thickness was determined in three commercial farm management systems, which differ in weed and nematode management. Roots in each farm management system were classified in thick (>5 mm-d) and thin (1 ≤ 5 mm-d) roots. From each root type, the epidermis, the cortical parenchyma (CP) and the vascular cylinder (VC) were separated by fingernail, and nematodes were extracted by maceration of each root part. Independent of the farm management system, and for either root thickness, highest numbers of Radopholus similis per gram of root was found in the CP, followed by the epidermis and VC. The highest number of Helicotylencus spp., Pratylenchus spp. and the total nematode population per gram of root was found in the epidermis. Considering the number of nematodes per root part, the highest number of R. similis and total nematodes was located in the CP, while Helicotylenchus spp. and Pratylenchus spp. were concentrated in the epidermis. These patterns were approximately reproduced in the two root thickness and in the three farm management systems. This behavior suggests that injection of systemic nematicides into the plant pseudostem to replace the granular applications on surface soil might be promissory.

  17. Amounts of carbon mineralised and leached as DOC during decomposition of Norway spruce needles and fine roots

    NARCIS (Netherlands)

    Hansson, K.; Berggren Kleja, D.; Kalbitz, K.; Larsson, H.

    2010-01-01

    Changes in climate or forest management practices leading to increased litter production will most likely cause increased leaching rates of dissolved organic carbon (DOC) from the O horizon. The rhizosphere is often assumed to have a large carbon flux associated with root turnover and exudation. How

  18. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    Directory of Open Access Journals (Sweden)

    R. Schulin

    2012-07-01

    Full Text Available Large areas of land are restored with un-weathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils as they only depend on atmospheric nitrogen (N fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites the experimental Chicken Creek Catchment (CCC in eastern Germany and a nearby experimental site (ES with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5×10 cm with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P

  19. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    Directory of Open Access Journals (Sweden)

    B. Felderer

    2013-03-01

    Full Text Available Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils, as they only depend on atmospheric nitrogen (N fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites, the experimental Chicken Creek Catchment (CCC in eastern Germany and a nearby experimental site (ES with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition, we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5 × 10 cm with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P

  20. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    Science.gov (United States)

    Felderer, B.; Boldt-Burisch, K. M.; Schneider, B. U.; Hüttl, R. F. J.; Schulin, R.

    2013-03-01

    Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P) is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils, as they only depend on atmospheric nitrogen (N) fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites, the experimental Chicken Creek Catchment (CCC) in eastern Germany and a nearby experimental site (ES) with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition, we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5 × 10 cm) with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P concentrations. In

  1. Temperature drives global patterns in forest biomass distribution in leaves, stems, and roots.

    Science.gov (United States)

    Reich, Peter B; Luo, Yunjian; Bradford, John B; Poorter, Hendrik; Perry, Charles H; Oleksyn, Jacek

    2014-09-23

    Whether the fraction of total forest biomass distributed in roots, stems, or leaves varies systematically across geographic gradients remains unknown despite its importance for understanding forest ecology and modeling global carbon cycles. It has been hypothesized that plants should maintain proportionally more biomass in the organ that acquires the most limiting resource. Accordingly, we hypothesize greater biomass distribution in roots and less in stems and foliage in increasingly arid climates and in colder environments at high latitudes. Such a strategy would increase uptake of soil water in dry conditions and of soil nutrients in cold soils, where they are at low supply and are less mobile. We use a large global biomass dataset (>6,200 forests from 61 countries, across a 40 °C gradient in mean annual temperature) to address these questions. Climate metrics involving temperature were better predictors of biomass partitioning than those involving moisture availability, because, surprisingly, fractional distribution of biomass to roots or foliage was unrelated to aridity. In contrast, in increasingly cold climates, the proportion of total forest biomass in roots was greater and in foliage was smaller for both angiosperm and gymnosperm forests. These findings support hypotheses about adaptive strategies of forest trees to temperature and provide biogeographically explicit relationships to improve ecosystem and earth system models. They also will allow, for the first time to our knowledge, representations of root carbon pools that consider biogeographic differences, which are useful for quantifying whole-ecosystem carbon stocks and cycles and for assessing the impact of climate change on forest carbon dynamics.

  2. Temperature drives global patterns in forest biomass distribution in leaves, stems, and roots

    Science.gov (United States)

    Reich, Peter B.; Lou, Yunjian; Bradford, John B.; Poorter, Hendrik; Perry, Charles H.; Oleksyn, Jacek

    2014-01-01

    Whether the fraction of total forest biomass distributed in roots, stems, or leaves varies systematically across geographic gradients remains unknown despite its importance for understanding forest ecology and modeling global carbon cycles. It has been hypothesized that plants should maintain proportionally more biomass in the organ that acquires the most limiting resource. Accordingly, we hypothesize greater biomass distribution in roots and less in stems and foliage in increasingly arid climates and in colder environments at high latitudes. Such a strategy would increase uptake of soil water in dry conditions and of soil nutrients in cold soils, where they are at low supply and are less mobile. We use a large global biomass dataset (>6,200 forests from 61 countries, across a 40 °C gradient in mean annual temperature) to address these questions. Climate metrics involving temperature were better predictors of biomass partitioning than those involving moisture availability, because, surprisingly, fractional distribution of biomass to roots or foliage was unrelated to aridity. In contrast, in increasingly cold climates, the proportion of total forest biomass in roots was greater and in foliage was smaller for both angiosperm and gymnosperm forests. These findings support hypotheses about adaptive strategies of forest trees to temperature and provide biogeographically explicit relationships to improve ecosystem and earth system models. They also will allow, for the first time to our knowledge, representations of root carbon pools that consider biogeographic differences, which are useful for quantifying whole-ecosystem carbon stocks and cycles and for assessing the impact of climate change on forest carbon dynamics.

  3. Application of Normal Distribution Model to Estimate Root Water Uptake Profile by an Isotopic Approach

    Science.gov (United States)

    Yamanaka, T.; Matsuo, D.; Hirota, M.

    2008-12-01

    To confirm usefulness of a diagnostic model for estimating root water uptake profile by an isotopic approach, isotopic measurements of plant xylem water, soil water and groundwater were conducted at seven Japanese red pine forest sites and then the model was applied to the measured results. The model assumes that depth profile of relative uptake rate can be approximated by the normal distribution function, and xylem water isotopic composition is computed from interpolated depth profile of isotopic composition of subsurface waters. The peak depth and distribution range of water uptake zone for a given species at a given site are inversely determined by direct search method (assuming depth interval of 5 cm up to 2 m) so as to minimize root mean square error throughout observation period. Estimated water uptake profiles showed that in six sites the uptake zone of Japanese red pine (Pinus densiflora) ranged from 5 to 60 cm depth, while it was changed to deeper depths in the other site where Quercus myrsinaefolia and Pleioblastus chino coexist. On the other hand, Populus sieboldi and Malus sieboldii take up water from depths deeper than those for Pinus densiflora within a community, although the two species are usually considered as shallow rooted plants. These results indicate water source partitioning under inter-species competition, and we conclude that the present model is capable of making clear the plant water use strategy. Estimated water uptake zone also provides useful information for improving/calibrating prognostic, physical models of root water uptake.

  4. Effect of Soil on the Growth and Life of Fine Root of Trees%土壤对树木细根生长及寿命的影响

    Institute of Scientific and Technical Information of China (English)

    王刚

    2016-01-01

    细根是树木与土壤之间进行水分、养分交换的主要器官,而土壤是树木细根赖以生存的主要环节。土壤的温度、水分、养分等对树木细根的生长和寿命均有较大影响。%Fine root is the main organ to exchange water and nutrients between the trees and the soil. And soil can supply an environment for fine root of trees. This paper briefly introduces the influence of soil temperature,moisture,nutrients on tree growth and longevity of fine root.

  5. Carbon transfer from photosynthesis to below ground fine root/hyphae respiration in Quercus serrata using stable carbon isotope pulse labeling

    Science.gov (United States)

    Dannoura, M.; Kominami, Y.; Takanashi, S.; Takahashi, K.

    2013-12-01

    Studying carbon allocation in trees is a key to better understand belowground carbon cycle and its response to climate change. Tracing 13C in tree and soil compartments after pulse labeling is one of powerful tool to study the fate of carbon in forest ecosystems. This experiment was conducted in Yamashiro experimental forest, Kyoto, Japan. Annual mean temperature and precipitation from 1994 to 2009 are 15.5 ° C and 1,388 mm respectively. The branch pulse labeling were done 7 times in 2011 using same branch of Quercus serrata (H:11.7 m, DBH; 33.7 cm) to see seasonal variations of carbon velocity. Whole crown labeling of Quercus serrata (H:9 m, DBH; 13.7 cm) was done in 2012 to study carbon allocation and to especially focus on belowground carbon flux until to the hyphae respiration. Pure 13CO2 (99.9%) was injected to the labeling chamber which was set to branch or crown. Then, after one hour of branch labeling and 3.5 hour for crown labeling, the chamber was opened. Trunk respiration chambers, fine root chambers and hyphae chambers were set to the target tree to trace labeled carbon in the CO2 efflux. 41 μm mesh was used to exclude ingrowth of roots into hyphae chambers. The results show that the velocity of carbon through the tree varied seasonally, with higher velocity in summer than autumn, averaging 0.47 m h-1. Half-lives of labeled carbon in autotrophic respiration were similar above and below ground during the growing season, but they were twice longer in trunk than in root in autumn. From the whole crown labeling done end of growing season, the 13CO2 signal was observed 25 hours after labeling in trunk chamber and 34-37.7 hours after labeling in fine root and hyphae respiration almost simultaneously. Half-lives of 13 was longer in trunk than below ground. Trunk respiration was still using labelled carbon during winter suggesting that winter trunk respiration is partly fueled by carbon stored in the trunk at the end of the growing season.

  6. Modal Analysis of the EMU Car-Body in the Preparation Condition Based on Mass Fineness Distribution

    Science.gov (United States)

    Li, Ya-Na; Rao, Ben-Teng; Xie, Su-Ming; Ma, Si-Qun

    Analyzing the car-body modal of EMU is the key of assessing EMU dynamic quality at high speed. The car-body modal can be influenced to same degree by the mass fineness distribution and the rationality of coupling stiffness of suspension device. Considering all equipments layout including internal decoration, FEM of the EMU car-body under preparation based on mass fineness distribution was created and the free modal was carried out with FEA software. The vertical bend frequency 10.03Hz, that is closer to the experimental data, satisfies the relative requirement. And on this basis, different vibration frequencies were studied under different elastic hanging stiffness of suspension device. Vibration frequency change is same on three direction with vertical direction stiffness, which indicate vertical stiffness is more important than the other direction stiffness. Thus these results provide some rational references for EMU car-body structural design.

  7. Subcellular distribution of uranium in the roots of Spirodela punctata and surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Xiaoqin, E-mail: xiaoqin_nie@163.com [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China); Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Dong, Faqin, E-mail: fqdong2004@163.com [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China); Liu, Ning [Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Liu, Mingxue [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China); Zhang, Dong; Kang, Wu [Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics, Mianyang 621900 (China); Sun, Shiyong; Zhang, Wei; Yang, Jie [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang 621010 (China)

    2015-08-30

    Graphical abstract: - Highlights: • The proportion of uranium concentration approximate as 8:2:1 in the cell wall organelle and cytosol fractions of roots of S. punctata. • The particles including 35% Fe (wt%) released from the cells after 100 mg/L U treatment 48 h. • Most of the uranium bound onto the root surface and contacted with phosphorus ligands and formed as nano-scales U-P lamellar crystal. • FTIR and XPS analyses result indicates the uranium changed the band position and shapes of phosphate group, and the region of characteristic peak belongs to U(VI) and U(IV) were also observed. - Abstract: The subcellular distribution of uranium in roots of Spirodela punctata (duckweed) and the process of surface interaction were studied upon exposure to U (0, 5–200 mg/L) at pH 5. The concentration of uranium in each subcelluar fraction increased significantly with increasing solution U level, after 200 mg/L uranium solution treatment 120 h, the proportion of uranium concentration approximate as 8:2:1 in the cell wall organelle and cytosol fractions of roots of S. punctata. OM SEM and EDS showed after 5–200 mg/L U treatment 4–24 h, some intracellular fluid released from the root cells, after 100 mg/L U treatment 48 h, the particles including 35% Fe (wt%) and other organic matters such as EPS released from the cells, most of the uranium bound onto the root surface and contacted with phosphorus ligands and formed as nano-scales U-P lamellar crystal, similar crystal has been found in the cell wall and organelle fractions after 50 mg/L U treatment 120 h. FTIR and XPS analyses result indicates the uranium changed the band position and shapes of phosphate group, and the region of characteristic peak belongs to U(VI) and U(IV) were also observed.

  8. Investigations of fine root and mycorrhizal development of Norway spruce (Picea abies (L.) Karst.) in the upper soil layers of the open-top chambers at Edelmannshof

    Energy Technology Data Exchange (ETDEWEB)

    Kottke, I.; Qian, M. [Tuebingen Univ. (Germany). Botanisches Inst.

    1997-12-01

    Fine root density and mycorrhizal development of Norway spruce (Picea abies (L.) Karts.) were investigated after one sampling date in the OTC-experimental plots Edelmannshof. No disturbance of development by stress from soil or fumigation treatments could be found. Surprisingly, the mycorrhizas of two trees fumigated by ambient air revealed higher FDA-hydrolysing activity than the mycorrhizas of the four trees fumigated by filtered air. This finding correlates to the higher leaching rate in the unfiltered air and may have compensated the loss by higher uptake rate of cations. This may explain why no deficiency of nutrients was found in the ambient air chambers. The probing date in early spring, however, may also have influenced the actual activity of the mycorrhizas of the different trees. (orig.)

  9. Long-term effects of deep soil loosening on root distribution and soil physical parameters in compacted lignite mine soils

    Science.gov (United States)

    Badorreck, Annika; Krümmelbein, Julia; Raab, Thomas

    2015-04-01

    Soil compaction is a major problem of soils on dumped mining substrates in Lusatia, Germany. Deep ripping and cultivation of deep rooting plant species are considered to be effective ways of agricultural recultivation. Six years after experiment start, we studied the effect of initial deep soil loosening (i.e. down to 65 cm) on root systems of rye (Secale cereale) and alfalfa (Medicago sativa) and on soil physical parameters. We conducted a soil monolith sampling for each treatment (deep loosened and unloosened) and for each plant species (in three replicates, respectively) to determine root diameter, length density and dry mass as well as soil bulk density. Further soil physical analysis comprised water retention, hydraulic conductivity and texture in three depths. The results showed different reactions of the root systems of rye and alfalfa six years after deep ripping. In the loosened soil the root biomass of the rye was lower in depths of 20-40 cm and the root biomass of alfalfa was also decreased in depths of 20-50 cm together with a lower root diameter for both plant species. Moreover, total and fine root length density was higher for alfalfa and vice versa for rye. The soil physical parameters such as bulk density showed fewer differences, despite a higher bulk density in 30-40cm for the deep loosened rye plot which indicates a more pronounced plough pan.

  10. Distribution of inert gases in fines from the Cayley-Descartes region

    Science.gov (United States)

    Walton, J. R.; Lakatos, S.; Heymann, D.

    1973-01-01

    The inert gases in 14 different fines and in one sample of 2 to 4 mm fines from Apollo 16 were measured by mass spectroscopy with respect to trapped solar wind gases, cosmogenic gases, and 'parentless' Ar-40. Such studies are helpful for the understanding of regolith evolution, of transport of regolith fines, and of the lunar atmosphere. The Apollo 16 soils are unique because they represent, after Luna 20, the second and much more extensive record from the lunar highlands. The landing site presents the problem of materials from the Cayley Formation vs those from the Descartes Formation. There are two large, relatively fresh craters in the area, North Ray and South Ray, whose ejecta patterns may be recognized in the inert-gas record.

  11. Distribution of inert gases in fines from the Cayley-Descartes region

    Science.gov (United States)

    Walton, J. R.; Lakatos, S.; Heymann, D.

    1973-01-01

    The inert gases in 14 different fines and in one sample of 2 to 4 mm fines from Apollo 16 were measured by mass spectroscopy with respect to trapped solar wind gases, cosmogenic gases, and 'parentless' Ar-40. Such studies are helpful for the understanding of regolith evolution, of transport of regolith fines, and of the lunar atmosphere. The Apollo 16 soils are unique because they represent, after Luna 20, the second and much more extensive record from the lunar highlands. The landing site presents the problem of materials from the Cayley Formation vs those from the Descartes Formation. There are two large, relatively fresh craters in the area, North Ray and South Ray, whose ejecta patterns may be recognized in the inert-gas record.

  12. Distribution of the root system of peach palm under drip irrigation

    Directory of Open Access Journals (Sweden)

    Adriano da Silva Lopes

    2014-07-01

    Full Text Available The incorporation of technologies has resulted in increased productivity and the more rational management of peach palm, with irrigation being an important tool for certain regions. Thus, studies leading to proper crop management are extremely important, such as the estimate of the effective depth of the root system, which is indispensable for proper irrigation management. The objective of this study was to evaluate the effects of different irrigation depths, as applied by drip irrigation, on the distribution of the root system of peach palm. This experiment was conducted in Ilha Solteira, São Paulo State, Brazil, with drip irrigation, with the two systems (flow of 0.0023 m3 h-1 consisting of four irrigation treatments corresponding to 0, 50, 100 and 150% of Class ‘A’ pan evaporation. After five years, an analysis of the Bactris gasipaes root system was performed at a distance of 0.0, 0.5 and 1.0 meters from the trunk, collecting sampling at two depths (0.0 to 0.3 m and 0.3 to 0.6 m via the auger method (volumetric analysis. We concluded that the effective depth of the root system used for irrigation management should be a maximum of 0.3 meters.

  13. Habitat Preferences, Distribution Pattern, and Root Weight Estimation of Pasak Bumi (Eurycoma longifolia Jack.

    Directory of Open Access Journals (Sweden)

    Siti Masitoh Kartikawati

    2014-04-01

    Full Text Available Pasak bumi (Eurycoma longifolia Jack is one of non timber forest products with “indeterminate” conservation status and commercially traded in West Kalimantan. The research objective was to determine the potential of pasak bumi root per hectare and its ecological condition under natural habitat. Root weight of E. longifolia Jack was estimated using simple linear regression and exponential equation with stem diameter and height as independent variables. The results showed that the individual number of the population was 114 with the majority in seedling stage with 71 individuals (62.28%. The distribution was found in clumped pattern. Conditions of the habitat could be described as follows: daily average temperature of 25.6oC, daily average relative humidity of 73.6%, light intensity of 0.9 klx, and red-yellow podsolic soil with texture ranged from clay to sandy clay. The selected estimator model for E. longifolia Jack root weight used exponential equation with stem height as independent variable using the equation of Y= 21.99T0,010 and determination coefficient of 0.97. After height variable was added, the potential of E. longifolia Jack minimum root weight that could be harvested per hectare was 0.33 kg.

  14. Uptake and distribution of root-applied or foliar-applied 65Zn after flowering in aerobic rice

    NARCIS (Netherlands)

    Jiang, W.; Struik, P.C.; Lingna, J.; Keulen, van H.; Ming, Z.; Stomph, T.J.

    2007-01-01

    We investigated the uptake and distribution of zinc (Zn) either applied to the roots or to the leaves in rice during grain development. Plants of two aerobic rice cultivars were grown in a nutrient solution with either sufficient Zn or surplus Zn. Root treatment with 1 week`s supply of both 65Zn and

  15. 季节性冻融期亚高山/高山森林细根分解动态%Fine Root Decomposition Dynamics during Freeze-Thaw Season in the Subalpine/Alpine Forests

    Institute of Scientific and Technical Information of China (English)

    魏圆云; 武志超; 杨万勤; 吴福忠

    2013-01-01

    The ongoing winter warming inevitably alters the process of fine root decomposition in high-altitude area by changing the pattern of seasonal soil freezing and thawing.As yet,the dynamics of fine root decomposition at different stages in the freeze-thaw season remain uncertainty.In order to characterize the dynamics of fine root decomposition at different stages of a freeze-thaw season in cold biomes under climate change scenarios,litterbags with 10 g fine roots of Picea asperata,Betula albo-sinensis and Abies faxoniana were buried in the forest soil at the 3 582,3 298 and 3 023 m altitudes in western Sichuan,China.These litterbags were recovered at onset of freezing (OF),deep frozen stage (DF),early thawing stage (ETS),middle thawing stage (MTS),and later thawing stage (LTS) from December 10,2009 to April 28,2010.The residual rate of fine roots was 88%-92% after a freeze-thaw season,and varied significantly with altitudes and tree species.The fine root decomposition occurred at all stages of the freeze-thaw season,among which OF had the highest rate of fine root decomposition.However,the rate of the fine root decomposition declined as decomposing,especially in the lower altitude.The decay rate constant of fine roots varied from 0.177 6 to 0.242 4,and the relative mass loss was correlated closely with soil temperature at the different stages,but the rate of the fine root decomposition was not significantly correlated with the indices of the measured initial qualities of fine roots.The regression model based on average soil temperature,fluctuated soil temperature,calcium concentration of fine roots and the ratio of lignin to nitrogen in fine roots during the freeze-thaw season,interpreted 95% of the reason of differences in the fine root decay rate.It is concluded that the soil freeze-thaw process caused by temperature fluctuations was an important factor in influencing the rate of the fine root decomposition during the freeze-thaw season in the high

  16. Distribution of implanted ions in seeds and roots of mung bean

    Institute of Scientific and Technical Information of China (English)

    LiuDong-Hua; HouWen-Qiang

    1998-01-01

    Doses of 1×1016,and 2×1016cmand 1×1016,2×1016,3×1016and 3.6×1016cm-2 for iron and cpper ioons are implanted in dry seeds of mung bean,respectively.The results show that the accumulated-copper and -iron ion amounts in the seeds and rrots vary with different doses of ion beam,and the fresh and dry weights of the roots decresase progressively with increasing iron and copper doses,except the treatment of 1×1016 Cu+ ions/cm2,and the accumulated-copper and -iron ion amounts in the seeds of the different test groups can be correlated with the ion distribution in the roots.

  17. Systemic distribution of sup 14 C-labeled formaldehyde applied in the root canal following pulpectomy

    Energy Technology Data Exchange (ETDEWEB)

    Hata, G.I.; Nishikawa, I.; Kawazoe, S.; Toda, T.

    1989-11-01

    The systemic distribution of {sup 14}C-labeled formaldehyde which had been placed in the root canals of the canines of cats following pulpectomies was studied using liquid scintillation counting and whole-body autoradiographic technique. Radioactive {sup 14}C which had been placed in the canals was found in the plasma 30 min after the root canal procedure. The recovery of systemic {sup 14}C radioactivity increased with time. In addition, it seemed that approximately 3% of the dose placed in the teeth was excreted in the urine within 36 h. Whole-body autoradiograms indicated extensive concentration of {sup 14}C radioactivity in tissues other than those analyzed with the liquid scintillation technique.

  18. Catalog of fine-structured electron velocity distribution functions - Part 1: Antiparallel magnetic-field reconnection (Geospace Environmental Modeling case)

    Science.gov (United States)

    Bourdin, Philippe-A.

    2017-09-01

    To understand the essential physics needed to reproduce magnetic reconnection events in 2.5-D particle-in-cell (PIC) simulations, we revisit the Geospace Environmental Modeling (GEM) setup. We set up a 2-D Harris current sheet (that also specifies the initial conditions) to evolve the reconnection of antiparallel magnetic fields. In contrast to the GEM setup, we use a much smaller initial perturbation to trigger the reconnection and evolve it more self-consistently. From PIC simulation data with high-quality particle statistics, we study a symmetric reconnection site, including separatrix layers, as well as the inflow and the outflow regions. The velocity distribution functions (VDFs) of electrons have a fine structure and vary strongly depending on their location within the reconnection setup. The goal is to start cataloging multidimensional fine-structured electron velocity distributions showing different reconnection processes in the Earth's magnetotail under various conditions. This will enable a direct comparison with observations from, e.g., the NASA Magnetospheric MultiScale (MMS) mission, to identify reconnection-related events. We find regions with strong non-gyrotropy also near the separatrix layer and provide a refined criterion to identify an electron diffusion region in the magnetotail. The good statistical significance of this work for relatively small analysis areas reveals the gradual changes within the fine structure of electron VDFs depending on their sampling site.

  19. Mycorrhizal colonization and lead distribution in root tissues of Norway spruce seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Jentschke, G. [Goettingen Univ. (Germany). Inst. fuer Forstbotanik]|[Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (Germany). Inst. fuer Bodenbiologie; Fritz, E.; Marschner, P.; Godbold, D.L. [Goettingen Univ. (Germany). Inst. fuer Forstbotanik; Rapp, C. [Goettingen Univ. (Germany). Inst. fuer Waldbau; Wolters, V. [Giessen Univ. (Germany). Inst. fuer Allgemeine und Spezielle Zoologie

    1997-12-01

    Non-inoculated spruce seedlings (Picea abies Karst.) and spruce seedlings colonized with Lactarius rufus Fr., Pisolithus tinctorius Coker and Couch or Paxillus involutus Fr. were grown for 35 to 37 weeks in a microscosm system on two types of natural forest humus differing in Pb content. Using X-ray microanalysis, the distribution and content of Pb in the tissues of mycorrhizal and non-mycorrhizal root tips were compared. No significant difference in the Pb contents of root cortex cell walls of non-mycorrhizal and seedlings colonized by Lactarius rufus, Pisolithus tinctorius, or indigenous mycorrhizal fungi (mainly Tylospora sp.) was found. However, in root tips of seedlings colonized by Paxillus involutus, due to a higher binding capacity for cations, the Pb content in cell walls of the root cortex were higher than in non-mycorrhizal roots. Pb contents in cell walls of the cortex of mycorrhizal and non-mycorrhizal roots were 3 times higher in plants growing in humus with a high Pb content than in plants growing in humus with a low Pb content. It is concluded that increasing contents of Pb in the organic matter may lead to an increased loading of the apoplast with Pb. The mycobionts tested in this investigation did not exclude Pb from root tissues. (orig.) [Deutsch] Nichtmykorrhizierte und mit Lactarius rufus Fr., Pisolithus tinctorius Coker und Couch oder Paxillus involutus Fr. beimpfte Fichtenkeimlinge (Picea abies Karst.) wurden in Kuturgefaesse gepflanzt, die mit Humusmaterial aus zwei unterschiedlich mit Blei belasteten Waldoekosystemen gefuellt waren. Nach 35 bzw. 37 Wochen wurde mittels Roentgenmikroanalyse der Bleigehalt in den Geweben mykorrhizierter und nichtmykorrhizierter Wurzelspitzen gemessen. Die Bleitgehalte in den Cortexzellwaenden der Mykorrhizen von L. rufus, P. tinctorius oder Tylospora sp. (gebildet durch spontane Infektion) unterschieden sich nicht signifikant von denen nichtmykorrhizierter Wurzelspitzen. Aufgrund einer hoeheren

  20. The distribution of natural numbers divisible by 2,3,5,11,13 and 17 on the Square Root Spiral

    CERN Document Server

    Hahn, Harry K

    2008-01-01

    The natural numbers divisible by the Prime Factors 2, 3, 5, 11, 13 and 17 lie on defined spiral graphs, which run through the Square Root Spiral. A mathematical analysis shows, that these spiral graphs are defined by specific quadratic polynomials. Basically all natural number which are divisible by the same prime factor lie on such spiral graphs. And these spiral graphs can be assigned to a certain number of Spiral Graph Systems, which have a defined spatial orientation to each other. This document represents a supplementation to my detailed introduction study to the Square Root Spiral, and it contains the missing diagrams and analyses, showing the distribution of the natural numbers divisible by 2, 3, 5, 11, 13 and 17 on the Square Root Spiral. My introduction study to the Square Root Spiral can be found in the arxiv-archive. The title of this study : The ordered distribution of the natural numbers on the Square Root Spiral.

  1. Phosphate Distribution and Movement in Soil—Root Interface Zone:I.The Influence of Transpiration Rate

    Institute of Scientific and Technical Information of China (English)

    XUMING-GANG; ZHANGYI-PING; 等

    1995-01-01

    The experiments were conducted in the artificial climate laboratory using 32P labelled soil and soil-root plane system to investigate phosphate distribution and its movement in the soil-root interface zone and their relations with phosphate uptake by plant as well as transpiration rate (atmosphere humidity).It was found that although the phosphate in the soil-root interface zone was of depletive distribution as a function C/Co=axb(C/Co is the relative content of fertilizer phosphate in a distance from the root surface x,a and b are the regression constants),and a relative accumulation zone of phosphate within 0.5 mm near the root surface was often boserved especially in the heavier texture soils because of root phosphate secretion.The depletion intensity of phosphate in the soil-root interface zone was in agreement with the phophate uptake by plants under two humidities very well.However,the effects of air humidity on characteristics of the phosphate distribution near wheat or maize root surface were different.Wheat grew better under lower atmosphere humidity while maize,under higher humidity,which caused a more intensive uptake and thus a stronger depletion of phosphate in the rhizosphere,Moreover,the depletion intensity was greater by the bottom or the middle part of wheat roots and by the top or the middle part of maize roots.The depletive distribution of phosphate in the rhizosphere soil and the relative contribution of phosphate diffusion to plant,which was more than 98% in the cultural experiments,indicated that diffusion was a major process for phosphorus supply to plants.

  2. [Investigation on the characteristics and space-time distribution of fine particles in the atmosphere of residential area in Shanghai City].

    Science.gov (United States)

    Zhao, Jinzhuo; Li, Li; Qian, Chunyan; Jiang, Rongfang; Song, Weimin

    2012-01-01

    To observe the ambient fine particle pollution and the trend of its space-time distribution in residential areas in Shanghai, and to explore the effects of vehicle exhaust emission on the ambient fine particle pollution. Two residential areas A and B were selected for monitoring the pollution of fine particles. Area A is a normal residential area and area B is closed to a main road with heavy traffic. Four monitoring sites were set in the distance of 0 m, 50 m, 100 m and 200 m to the roadside and on a place 1.5 - 1.8 m above the ground. The concentration of fine particles in the air were measured in April, July, October 2010 and Jan 2011 for 1l0 days in each month in both areas using SIDEPAK AM510 (TSI, USA) fine particle monitors. The pollution of fine particle was varied in different seasons (spring > winter > autumn > summer) and at different time (with two peaks at 8:00 AM and 19:00 PM, corresponding to the rush hours). The pollution of fine particles is higher in residential area B than that in area A. The concentration of fine particles was reduced with the increase of the distance to the roadside. The level of fine particles in residential areas is comparatively high in Shanghai, and the vehicle exhaust emissions have significant effects on the concentration of fine particles in the atmosphere of residential area.

  3. Mercury speciation and fine particle size distribution on combustion of Chinese coals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Wang, Shuxiao; Hao, Jiming [Tsinghua Univ., Beijing (China). Dept. of Environmental Science and Engineering and State Key Joint Lab. of Environment Simulation and Pollution Control; Daukoru, Michael; Torkamani, Sarah; Biswas, Pratim [Washington Univ., St. Louis, MO (United States). Aerosol and Air Quality Research Lab.

    2013-07-01

    Coal combustion is the dominant anthropogenic mercury emission source of the world. Electrostatic precipitator (ESP) can remove almost all the particulate mercury (Hg{sub p}), and wet flue gas desulfurization (WFGD) can retain a large part of the gaseous oxidized mercury (Hg{sup 2+}). Only a small percentage of gaseous elemental mercury (Hg{sup 0}) can be abated by the air pollution control devices (APCDs). Therefore, the mercury behavior across APCDs largely depends on the mercury speciation in the flue gas exhausting from the coal combustor. To better understand the formation process of three mercury species, i.e. Hg{sup 0}, Hg{sup 2+} and Hg{sub p}, in gaseous phase and fine particles, bench-scale measurements for the flue gas exhausting from combustion of different types of coal in a drop-tube furnace set-up, were carried out. It was observed that with the limitation of reaction kinetics, higher mercury concentration in flue gas will lead to lower Hg{sup 2+} proportion. The concentration of chlorine has the opposite effect, not as significantly as that of mercury though. With the chlorine concentration increasing, the proportion of Hg{sup 2+} increases. Combusting the finer coal powder results in the formation of more Hg{sup 2+}. Mineral composition of coal and coal particle size has a great impact on fine particle formation. Al in coal is in favor of finer particle formation, while Fe in coal can benefit the formation of larger particles. The coexistence of Al and Si can strengthen the particle coagulation process. This process can also be improved by the feeding of more or finer coal powder. The oxy-coal condition can make for both the mercury oxidation process and the metal oxidation in the fine particle formation process.

  4. Climate-based analysis of spatial and temporal distribution of fine sediment sources in an Alpine environment

    Science.gov (United States)

    Costa, Anna; Molnar, Peter; Stutenbecker, Laura; Schlunegger, Fritz; Bakker, Maarten; Lane, Stuart N.

    2016-04-01

    Four main sediment sources can be identified in an Alpine environment: glacier erosion, hillslope erosion, channel erosion and mass wasting events (e.g. rockfalls and landslides). The spatial distibution of fine sediment sources varies throughout the hydrological year according to climatic conditions. While during spring, temperature-driven snow melting largely contributes to discharge and transport capacity of the catchment, autumn intense rainfalls can trigger debris flow events and landslides with a large pulse of sediment mobilized and released to the channel network. At the end of the summer, when the catchment is snow free up to high elevations, glacier melting discloses a large amount of fine sediments to be mobilized. In this work, precipitation and temperature are considered as control factors for activating different sediment sources and different sediment transport processes. The aim of this work is to analyse and understand basin-scale sediment dynamics of the Upper Rhône basin, a 5200 km2 cathcment located in the south-western part of Switzerland. The correlation between fine sediment loads and climatic variables is used to infer information on the spatial and temporal variability of active sediment sources. Turbidity data measured continuously at the outlet of the Upper Rhône River are considered as a proxy for suspended sediment concentration. Gridded climatic datasets are used to compute total daily precipitation and mean daily air temperature over the entire basin and over different tributary catchments. The relation between fine sediment loads and climatic conditions is analysed by estimating the Spearman's rank correlation coefficient between turbidity, precipitation and temperature time series, assuming different time lags. The indirect effects of temperature are better evaluated by analysing the temporal evolution of snow covered areas simulated by a simple temperature index model. The correlation of fine sediment loads is much greater with

  5. Vertical distribution of the root system of linseed (Linum usitatissimum L. and legumes in pure and mixed sowing

    Directory of Open Access Journals (Sweden)

    Agnieszka Klimek-Kopyra

    2015-03-01

    Full Text Available Root competition for below-ground resources between edible plants may provide for long-term sustainability of agriculture systems. Intercropping can be more productive than a pure crop due to taking advantage of the morphological differences between species. In pure cropping, all biophysical interactions between plants occur through soil conditions. In intercropping, competition for water and nutrients is of major importance, but if the roots of one species occupy the zone just underneath the roots of the other crop, they can better use the resources of the root zone of the crop. The root system demonstrates a high degree of plasticity in its development in response to local heterogeneity of the soil profile and plant density. This study aimed at determining: (i the morphological characteristics of the root systems of linseed, pea and vetch depending on the method of sowing; (ii the root distribution in various soil types and at different soil profile depths (0–15 cm, 15–30 cm. Two three-year field experiments were conducted on two soil types in south Poland: soil A – Luvic Phaeozem (s1 and soil B – Eutric Cambisol (s2. These results show that linseed was more aggressive toward both legumes in mixture, but it produced lower yield compared to pure cropping. The environmental stress of plants in mixtures increased the relative weight of roots, which resulted in decreasing the root-shoot ratio (RSR.

  6. Analysis of Fine and Coarse mode Aerosol Distributions from AERONET's mini-DRAGON Set-up at Singapore 2012

    Science.gov (United States)

    Salinas Cortijo, S. V.; Chew, B. N.; Muller, A.; Liew, S.

    2013-12-01

    Aerosol optical depth combined with the Angstrom exponent and its derivative, are often used as a qualitative indicator of aerosol type and particle size regime. In Singapore, the sources of aerosols are mostly from fossil fuel burning (energy stations, incinerators, urban transport etc.) and from industrial and urban areas. However, depending on the time of the year (July-October), there can be a strong bio-mass component originated from uncontrolled forest/plantation fires from the neighboring land masses of Sumatra and Borneo. Unlike urban/fossil fuel aerosols, smoke or bio-mass related aerosol particles are typically characterized by showing a large optical depth and small, sub-micron particle size distributions. Trans-boundary smoke episodes has become an annual phenomenon in this region. Severe episodes were recorded in 1997 and 2006 and other minor episodes happened during 2002, 2004, 2010 and more recently on 2013. On August-September 2012, as part of CRISP participation on the August-September ground campaign of the Southeast Asia Composition, Cloud Climate Coupling Regional Study (SEAC4RS), a Distributed Regional Aerosol Gridded Observation Networks (DRAGON) set of six CIMEL CE-318A automatic Sun-tracking photometers have been deployed at sites located at North (Yishun ITE), East (Temasek Poly), West (NUS and Pandan Reservoir), Central (NEA) and South (St. John's island) of Singapore. In order to fully discriminate bio-mass burning events over other local sources, we perform a spectral discrimination of fine/coarse mode particle regime to all DRAGON sites; subsequently, the fine mode parameters such as optical depth, optical ratio and fine mode Angstrom exponent are used to identify possible bio-mass related events within the data set. Spatio-temporal relationship between sites are also investigated.

  7. Fine Distributed Moderating Material with Improved Thermal Stability Applied to Enhance the Feedback Effects in SFR Cores

    Directory of Open Access Journals (Sweden)

    Bruno Merk

    2013-01-01

    Full Text Available The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effect in sodium-cooled fast reactor cores is described. The influence of the moderating material on the fuel assembly geometry, the neutron spectrum, the feedback effects, the power and burnup distribution, and the transmutation performance is given. An overview on possible materials is provided and the relationship between hydrogen content and thermal stability is described. A solution for the problem of the limited thermal stability of primarily proposed hydrogen-bearing moderating material ZrH1.6 is developed by the use of yttrium-mono-hydride. The similarity in the effects reached by ZrH and YH is demonstrated by comparison calculations. The topic is closed by an overview on material properties, manufacturing issues, experience in fast reactors, and a comparison of raw material costs.

  8. Soil Tillage Management Affects Maize Grain Yield by Regulating Spatial Distribution Coordination of Roots, Soil Moisture and Nitrogen Status.

    Science.gov (United States)

    Wang, Xinbing; Zhou, Baoyuan; Sun, Xuefang; Yue, Yang; Ma, Wei; Zhao, Ming

    2015-01-01

    The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0-20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20-30 cm layer. Soil moisture in the 20-50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20-50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants' ability to access nutrients and water. An optimal

  9. Modeling and analysis of the vertical roots distribution in levees - a case study of the third Rhone correction

    Science.gov (United States)

    Gianetta, Ivan; Schwarz, Massimiliano; Glenz, Christian; Lammeranner, Walter

    2013-04-01

    In recent years the effects of roots on river banks and levees have been the subject of major discussions. The main issue about the presence of woody vegetation on levees is related to the possibility that roots increase internal erosion processes and the superimposed load of large trees compromise the integrity of these structures. However, ecologists and landscape managers argue that eliminating the natural vegetation from the riverbanks also means eliminating biotopes, strengthening anthropisation of the landscape, as well as limiting recreations areas. In the context of the third correction of the Rhone in Switzerland, the discussion on new levee geometries and the implementation of woody vegetation on them, lead to a detailed analysis of this issue for this specific case. The objective of this study was to describe quantitatively the processes and factors that influence the root distribution on levees and test modeling approaches for the simulation of vertical root distribution with laboratory and field data. An extension of an eco-hydrological analytic model that considers climatic and pedological condition for the quantification of vertical root distribution was validated with data provided by the University of Vienna (BOKU) of willows' roots (Salix purpurea) grown under controlled conditions. Furthermore, root distribution data of four transversal sections of a levee near Visp (canton Wallis, Switzerland) was used to validate the model. The positions of the levee's sections were chosen based on the species and dimensions of the woody vegetation. The dominant species present in the sections were birch (Betula pendula) and poplar (Populus nigra). For each section a grid of 50x50 cm was created to count and measure the roots. The results show that vertical distribution of root density under controlled growing conditions has an exponential form, decreasing with increasing soil depth, and can be well described by the eco-hydrological model. Vice versa, field

  10. Demonstrating the Uneven Importance of Fine-Scale Forest Structure on Snow Distributions using High Resolution Modeling

    Science.gov (United States)

    Broxton, P. D.; Harpold, A. A.; van Leeuwen, W.; Biederman, J. A.

    2016-12-01

    Quantifying the amount of snow in forested mountainous environments, as well as how it may change due to warming and forest disturbance, is critical given its importance for water supply and ecosystem health. Forest canopies affect snow accumulation and ablation in ways that are difficult to observe and model. Furthermore, fine-scale forest structure can accentuate or diminish the effects of forest-snow interactions. Despite decades of research demonstrating the importance of fine-scale forest structure (e.g. canopy edges and gaps) on snow, we still lack a comprehensive understanding of where and when forest structure has the largest impact on snowpack mass and energy budgets. Here, we use a hyper-resolution (1 meter spatial resolution) mass and energy balance snow model called the Snow Physics and Laser Mapping (SnowPALM) model along with LIDAR-derived forest structure to determine where spatial variability of fine-scale forest structure has the largest influence on large scale mass and energy budgets. SnowPALM was set up and calibrated at sites representing diverse climates in New Mexico, Arizona, and California. Then, we compared simulations at different model resolutions (i.e. 1, 10, and 100 m) to elucidate the effects of including versus not including information about fine scale canopy structure. These experiments were repeated for different prescribed topographies (i.e. flat, 30% slope north, and south-facing) at each site. Higher resolution simulations had more snow at lower canopy cover, with the opposite being true at high canopy cover. Furthermore, there is considerable scatter, indicating that different canopy arrangements can lead to different amounts of snow, even when the overall canopy coverage is the same. This modeling is contributing to the development of a high resolution machine learning algorithm called the Snow Water Artificial Network (SWANN) model to generate predictions of snow distributions over much larger domains, which has implications

  11. Investigation of fine-structure dips in fission-fragment mass distribution: An asymmetric two centre shell model approach

    Science.gov (United States)

    Malik, Sham S.

    2017-04-01

    The fission fragment mass distribution followed by neutron emission is studied for the 208Pb (18O , f) reaction using the asymmetric two centre shell model. The measured mass distribution spectrum reveals new kind of systematics on shell structure and leads to an improved understanding of structure effects in nuclear fission. A detailed investigation of shell effects both in potential and cranking mass parameter has been carried out for explaining the observed fine structure dips (i.e., less probable distributions) corresponding to shell closure (Z = 50 and/or N = 82) of fission fragments and their complementary partners. The available energy states for the decay process are obtained by solving the Schrödinger equation and found that first-five eigenstates are sufficient in reproducing the observed mass distribution spectrum. An outcome of the asymmetric two centre shell model also completely favours the observed claim that ;the total number of emitted neutrons between correlated pairs of fission fragments should not exceed 6;. A complete observed spectrum is obtained by adding the mass distribution yields of all 6-neutron emission channels. This suggests a possible importance of extending these calculations to get new insight into an understanding of the dynamical behaviour of fragment formation in the fission process.

  12. Roots distribution of Jatropha curcas trees in Brazilian savana; Distribuicao das raizes de plantas adultas de pinhao manso no cerrado

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Fausto J.M.; Costa, Hugo T.; Alves Junior, Jose; Evangelista, Adao W.P.; Oliveira, Pedro H. L. de [Universidade Federal de Goias (EA/UFG), Goiania, GO (Brazil). Escola de Agronomia e Eng. de Alimentos], E-mail: jose.junior@pq.cnpq.br

    2010-07-01

    The Jatropha curcas L. presents a great potential for fuel, but there are few studies to assess roots distribution of this species. The root system is responsible for water uptake and should be considered in irrigation water requirement calculations. Studies show that Jatropha curcas trees irrigated can be double productivity. The objective of the work was to evaluate root distribution of Jatropha curcas L. trees spacing 3 x 2 m in a Clay soil of Brazilian Savana (Porangatu, north of Goias state). The evaluation was carried in three trees non-irrigated with three years old, five deeps 0.0-0.30 m, 0.30-0.60 m, 0.60-0.90 m, 0.90-1.2, 1.2-1.5 m and five distances from the trunk 0.0-0.25; 0.25-0.50; 0.50-0.75, 0.75-1.0 and 1.0-1.25 m. Trenches were dug from the plant trunk longitudinally and orthogonally in respect to row plants. Afterwards, root samples were collected according to the monolith method and separated from the soil. Root length and root density were determined by using grid 1 cm{sup 2}. The results showed more than 80% of roots concentrated at 0.0-1.0 m of deep, 1.0 m horizontal distance from the trunk. (author)

  13. Measurement of dijet angular distributions at square root(s) = 1.96 TeV and searches for quark compositeness and extra spatial dimensions.

    Science.gov (United States)

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Ancu, L S; Andeen, T; Anzelc, M S; Aoki, M; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Atramentov, O; Avila, C; BackusMayes, J; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Blazey, G; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Bu, X B; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burnett, T H; Buszello, C P; Calfayan, P; Calpas, B; Calvet, S; Cammin, J; Carrasco-Lizarraga, M A; Carrera, E; Carvalho, W; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Cheu, E; Cho, D K; Choi, S; Choudhary, B; Christoudias, T; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; Das, A; Davies, G; De, K; de Jong, S J; De la Cruz-Burelo, E; DeVaughan, K; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dorland, T; Dubey, A; Dudko, L V; Duflot, L; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Escalier, M; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Geng, W; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gómez, B; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinson, A P; Heintz, U; Hensel, C; Heredia-De la Cruz, I; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Huske, N; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jamin, D; Jesik, R; Johns, K; Johnson, C; Johnson, M; Johnston, D; Jonckheere, A; Jonsson, P; Juste, A; Kajfasz, E; Karmanov, D; Kasper, P A; Katsanos, I; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y N; Khatidze, D; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kozelov, A V; Kraus, J; Kuhl, T; Kumar, A; Kupco, A; Kurca, T; Kuzmin, V A; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lebrun, P; Lee, W M; Leflat, A; Lellouch, J; Li, J; Li, L; Li, Q Z; Lietti, S M; Lim, J K; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna-Garcia, R; Lyon, A L; Maciel, A K A; Mackin, D; Mättig, P; Magaña-Villalba, R; Magerkurth, A; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Maravin, Y; Martin, B; McCarthy, R; McGivern, C L; Meijer, M M; Melnitchouk, A; Mendoza, L; Menezes, D; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Mitrevski, J; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nogima, H; Novaes, S F; Nunnemann, T; Obrant, G; Ochando, C; Onoprienko, D; Orduna, J; Oshima, N; Osman, N; Osta, J; Otec, R; Otero y Garzón, G J; Owen, M; Padilla, M; Padley, P; Pangilinan, M; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perfilov, M; Peters, K; Peters, Y; Pétroff, P; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Polozov, P; Popov, A V; Prado da Silva, W L; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Ranjan, K; Ratoff, P N; Renkel, P; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rominsky, M; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Sanghi, B; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schlobohm, S; Schwanenberger, C; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Stolin, V; Stoyanova, D A; Strandberg, J; Strang, M A; Strauss, E; Strauss, M; Ströhmer, R; Strom, D; Stutte, L; Sumowidagdo, S; Svoisky, P; Takahashi, M; Tanasijczuk, A; Taylor, W; Tiller, B; Titov, M; Tokmenin, V V; Torchiani, I; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; van den Berg, P J; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Verdier, P; Vertogradov, L S; Verzocchi, M; Vilanova, D; Vint, P; Vokac, P; Voutilainen, M; Wagner, R; Wahl, H D; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Welty-Rieger, L; Wenger, A; Wetstein, M; White, A; Wicke, D; Williams, M R J; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Xu, C; Yacoob, S; Yamada, R; Yang, W-C; Yasuda, T; Yatsunenko, Y A; Ye, Z; Yin, H; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zeitnitz, C; Zelitch, S; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zivkovic, L; Zutshi, V; Zverev, E G

    2009-11-06

    We present the first measurement of dijet angular distributions in pp collisions at square root(s) = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0.7 fb(-1) collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV(-1) scale extra dimensions. For all models considered, we set the most stringent direct limits to date.

  14. Distribution, host plants and natural enemies of sugar beet root aphid (Pemphigus fuscicornis In Slovakia

    Directory of Open Access Journals (Sweden)

    Tóth Peter

    2006-01-01

    Full Text Available During 2003-2004, field surveys were realized to observe the distribution of sugar beet aphid, Pemphigus fuscicornis (K o c h (Sternorrhyncha Pemphigidae in southwestern Slovakia. The research was carried out at 60 different localities with altitudes 112-220 m a. s. l. Sugar beet root aphid was recorded at 30 localities. The aphid was recorded in Slovakia for the first time, but its occurrence was predicted and symptoms and harmfulness overlooked by now. The presence of P. fuscicornis was investigated on roots of various plants from Chenopodiaceae. The most important host plants were various species of lambsquarters (above all Chenopodium album. Furthermore sugar beet (Beta vulgaris provar. altissima, red beet (B. vulgaris provar. conditiva and oraches (Atriplex spp act as host plants. Infestation of sugar beet by P. fuscicornis never exceeded 5% at single locality in Slovakia. Dry and warm weather create presumptions for strong harmfulness. In Slovakia, Chenopodium album is a very important indicator of sugar beet aphid presence allowing evaluation of control requirements. During the study, the larvae of Thaumatomyia glabra (Diptera: Chloropidae were detected as important natural enemies of sugar beet aphid. The species occurred at each location evaluated.

  15. Response of Watermelon to Gravel-Mulch and Supplementary Irrigation:Yield,Water Use Efficiency and Root Distribution

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-shan; LI Xin-rong; ZHANG Pei-dong; ZHANG Jing-guang; WANG Xin-ping; LIU Li-chao

    2004-01-01

    A field experiment was conducted to investigate the effect of supplementary irrigation on watermelon (Citullus lanatus) yield, water-use efficiency (WUE) and root distribution in gravel-mulched field in northwest Loess Plateau, China, during 2001 and 2002 growing seasons. The results showed that gravel mulch significantly improved seedling emergence,increased yield and WUE, and alleviated the influence of drought on plant growth. Regardless of gravel mulch application, supplementary irrigation increased watermelon yields, average fruit weight and number of fruit, especially yield increased as the amount of irrigation increased (P<0.05). Generally, WUE of irrigated treatments were higher than that of non-irrigation treatment in gravel-mulched field. The effect of water supply on root distribution was different in two years. In 2001, average root length density (RLD) and root weight density (RWD) whole the soil profile increased. In 2002, however, RLD and RWD decreased as water supply increased. The average RLD and RWD in 2001 were significantly higher than those in 2002. Maybe we can interpret the phenomenon with the theory that there is a need to optimize root distribution (in termsof water relations) and aboveground biomass for a given water supply. The yield may not depend as much on root growth as on the amount of water required at critical stages. A significant effect of soil depth on RLD and RWD were observed in both years, but did not rapidly decrease with depth.

  16. Seasonal Dynamics of Fine Root Growth and Death in Urban Forests and Lawns of Fuzhou%福州市片林和草坪细根生长与死亡的季节动态

    Institute of Scientific and Technical Information of China (English)

    邵棉丽; 曾文静; 黄惠; 张江勇; 刘静; 李熙波

    2014-01-01

    The net growth and turnover of fine roots have crucial impacts on underground carbon process in urban green space .This study used soil core method and minirhizotron technique to investi-gate seasonal dynamic of fine root growth , fine root death as well as the net production of urban green space in Fuzhou.The results indicates: 1) There were obviously and similar seasonal dynamics in fine root growth and death in urban forests and lawns .2 ) Climatic factors ( air temperature and precip-itation) had different effect on the changes of growth and death of fine root in urban green space , be-sides, there were other factors related to death of fine root .3) Seasonal dynamics of the fine root net production in urban forests and urban lawn were different .The fine root net production in the urban forests was higher than that of urban lawns .4) The net productions of foot root in urban green space were lower than that in natural forests and grasslands , which may be due to the influences of human management and the deviation of different methods .%细根的净生长与周转在城市绿地地下碳过程中具有至关重要的影响。本研究采用微根管法与土钻法相结合,对福建省福州市市区内城市绿地细根生长死亡及其净生产量的季节动态进行研究。结果表明:1)城市片林与城市草坪的细根生长死亡的季节动态明显,且季节动态模式相似。2)气温和降水因子对于城市片林和草坪的细根生长量及死亡量的影响不同。细根的死亡除了与气温、降水等因子有关之外,还与其他因子密切联系。3)城市片林与城市草坪的细根净生产量的季节动态有所不同,且片林的细根年净生产量大于草坪。4)城市片林和草坪的细根年净生产量小于天然森林和天然草原,这可能与人为管理措施的影响以及不同研究方法的偏差有关。

  17. Fine-scale spatial genetic structure and clonal distribution of the cold-water coral Lophelia pertusa

    Science.gov (United States)

    Dahl, M. P.; Pereyra, R. T.; Lundälv, T.; André, C.

    2012-12-01

    Determining the spatial genetic structure within and among cold-water coral populations is crucial to understanding population dynamics, assessing the resilience of cold-water coral communities and estimating genetic effects of habitat fragmentation for conservation. The spatial distribution of genetic diversity in natural populations depends on the species' mode of reproduction, and coral species often have a mixed strategy of sexual and asexual reproduction. We describe the clonal architecture of a cold-water coral reef and the fine-scale population genetic structure (Asexual reproduction was found to be a highly important mode of reproduction for L. pertusa: 35 genetic individuals were found on the largest reef, with the largest clone covering an area of nearly 300 m2.

  18. Mass size distributions and size resolved chemical composition of fine particulate matter at the Pittsburgh supersite

    Science.gov (United States)

    Cabada, Juan C.; Rees, Sarah; Takahama, Satoshi; Khlystov, Andrey; Pandis, Spyros N.; Davidson, Cliff I.; Robinson, Allen L.

    Size-resolved aerosol mass and chemical composition were measured during the Pittsburgh Air Quality Study. Daily samples were collected for 12 months from July 2001 to June 2002. Micro-orifice uniform deposit impactors (MOUDIs) were used to collect aerosol samples of fine particulate matter smaller than 10 μm. Measurements of PM 0.056, PM 0.10, PM 0.18, PM 0.32, PM 0.56, PM 1.0, PM 1.8 and PM 2.5 with the MOUDI are available for the full study period. Seasonal variations in the concentrations are observed for all size cuts. Higher concentrations are observed during the summer and lower during the winter. Comparison between the PM 2.5 measurements by the MOUDI and other integrated PM samplers reveals good agreement. Good correlation is observed for PM 10 between the MOUDI and an integrated sampler but the MOUDI underestimates PM 10 by 20%. Bouncing of particles from higher stages of the MOUDI (>PM 2.5) is not a major problem because of the low concentrations of coarse particles in the area. The main cause of coarse particle losses appears to be losses to the wall of the MOUDI. Samples were collected on aluminum foils for analysis of carbonaceous material and on Teflon filters for analysis of particle mass and inorganic anions and cations. Daily samples were analyzed during the summer (July 2001) and the winter intensives (January 2002). During the summer around 50% of the organic material is lost from the aluminum foils as compared to a filter-based sampler. These losses are due to volatilization and bounce-off from the MOUDI stages. High nitrate losses from the MOUDI are also observed during the summer (above 70%). Good agreement between the gravimetrically determined mass and the sum of the masses of the individual compounds is obtained, if the lost mass from organics and the aerosol water content are included for the summer. For the winter no significant losses of material are detected and there exists reasonable agreement between the gravimetrical mass and the

  19. Use of X-ray microanalysis for study of cation distribution in potassium deficient pumpkin roots

    Directory of Open Access Journals (Sweden)

    Natalia Burmistrova

    2014-01-01

    Full Text Available Ice slices of root tissues were investigated by X-ray microanalysis. It is shown that the cytoplasm of the meristematic and differentiated cells of potassium dificiest roots maintains a high potassium level. The vacuoles of various root cells loose more K and accumulate more Na and Mg than does the cytoplasm.

  20. Temporal and spatial distributions of summer-time ground-level fine particulate matters in Baltimore-DC region

    Science.gov (United States)

    Liu, Y.; Greenwald, R.; Sarnat, J.; Hu, X.; Kewada, P.; Morales, Y.; Goldman, G.; Redman, J.; Russell, A. G.

    2011-12-01

    Environmental epidemiological studies have established a robust association between chronic exposure to ambient level fine particulate matters (PM2.5) and adverse health effects such as COPD, cardiorespiratory diseases, and premature death. Population exposure to PM2.5 has historically been estimated using ground measurements which are often sparse and unevenly distributed. There has been much interest as well as suspicion in both the air quality management and research communities regarding the value of satellite retrieved AOD as particle air pollution indicators. A critical step towards the future use of satellite aerosol products in air quality monitoring and management is to better understand the AOD-PM2.5 association. The existing EPA and IMPROVE networks are insufficient to validate AOD-estimated PM2.5 surface especially when higher resolution satellite products become available in the near future. As part of DISCOVER-AQ mission, we deployed 15 portable filter-based samplers alongside of ground-based sun photometers of the Distributed Regional Aerosol Gridded Observation Network (DRAGON) in July 2011. Gravimetric analyses were conducted to estimate 24h PM2.5 mass concentrations, using Teflon filters and Personal Environmental Monitors (PEMs) operated at a flow rate of 4 LPM. Pre- and post-sampling filters were weighed at our weigh room laboratory facilities at the Georgia Institute of Technology. Our objectives are (1) to examine if AOD measured by ground-based sun-photometers with the support from ground-based lidars can provide the fine scale spatial heterogeneity observed by ground PM monitors, and (2) whether PM2.5 levels estimated by satellite AOD agree with this true PM2.5 surface. Study design, instrumentation, and preliminary results of measured PM2.5 spatial patterns in July 2011 will be presented as well as discussion of further data analysis and model development.

  1. Synchrotron X-ray microfluorescence measurement of metal distributions in Phragmites australis root system in the Yangtze River intertidal zone.

    Science.gov (United States)

    Feng, Huan; Zhang, Weiguo; Qian, Yu; Liu, Wenliang; Yu, Lizhong; Yoo, Shinjae; Wang, Jun; Wang, Jia Jun; Eng, Christopher; Liu, Chang Jun; Tappero, Ryan

    2016-07-01

    This study investigates the distributions of Br, Ca, Cl, Cr, Cu, K, Fe, Mn, Pb, Ti, V and Zn in Phragmites australis root system and the function of Fe nanoparticles in scavenging metals in the root epidermis using synchrotron X-ray microfluorescence, synchrotron transmission X-ray microscope measurement and synchrotron X-ray absorption near-edge structure techniques. The purpose of this study is to understand the mobility of metals in wetland plant root systems after their uptake from rhizosphere soils. Phragmites australis samples were collected in the Yangtze River intertidal zone in July 2013. The results indicate that Fe nanoparticles are present in the root epidermis and that other metals correlate significantly with Fe, suggesting that Fe nanoparticles play an important role in metal scavenging in the epidermis.

  2. Resource selection models are useful in predicting fine-scale distributions of black-footed ferrets in prairie dog colonies

    Science.gov (United States)

    Eads, David A.; Jachowski, David S.; Biggins, Dean E.; Livieri, Travis M.; Matchett, Marc R.; Millspaugh, Joshua J.

    2012-01-01

    Wildlife-habitat relationships are often conceptualized as resource selection functions (RSFs)—models increasingly used to estimate species distributions and prioritize habitat conservation. We evaluated the predictive capabilities of 2 black-footed ferret (Mustela nigripes) RSFs developed on a 452-ha colony of black-tailed prairie dogs (Cynomys ludovicianus) in the Conata Basin, South Dakota. We used the RSFs to project the relative probability of occurrence of ferrets throughout an adjacent 227-ha colony. We evaluated performance of the RSFs using ferret space use data collected via postbreeding spotlight surveys June–October 2005–2006. In home ranges and core areas, ferrets selected the predicted "very high" and "high" occurrence categories of both RSFs. Count metrics also suggested selection of these categories; for each model in each year, approximately 81% of ferret locations occurred in areas of very high or high predicted occurrence. These results suggest usefulness of the RSFs in estimating the distribution of ferrets throughout a black-tailed prairie dog colony. The RSFs provide a fine-scale habitat assessment for ferrets that can be used to prioritize releases of ferrets and habitat restoration for prairie dogs and ferrets. A method to quickly inventory the distribution of prairie dog burrow openings would greatly facilitate application of the RSFs.

  3. Prediction of product distribution in fine biomass pyrolysis in fluidized beds based on proximate analysis.

    Science.gov (United States)

    Kim, Sung Won

    2015-01-01

    A predictive model was satisfactorily developed to describe the general trends of product distribution in fluidized beds of lignocellulosic biomass pyrolysis. The model was made of mass balance based on proximate analysis and an empirical relationship with operating parameters including fluidization hydrodynamics. The empirical relationships between product yields and fluidization conditions in fluidized bed pyrolyzers were derived from the data of this study and literature. The gas and char yields showed strong functions of temperature and vapor residence time in the pyrolyzer. The yields showed a good correlation with fluidization variables related with hydrodynamics and bed mixing. The predicted product yields based on the model well accorded well with the experimental data.

  4. Soil sheaths, photosynthate distribution to roots, and rhizosphere water relations for Opuntia ficus-indica

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B.; North, G.B.; Nobel, P.S. (Univ. of California, Los Angeles, CA (United States))

    1993-09-01

    Soil sheaths incorporating aggregated soil particles surround young roots of many species, but the effects of such sheaths on water movement between roots and the soil are largely unknown. The quantity and location of root exudates associated with soil sheath along the entire length of its young roots, except within 1.4 cm of the tip. The soil sheaths, which average 0.7 mm in thickness, were composed of soil particles and root hairs, both of which were covered with exuded mucilaginous material. As determined with a [sup 14]C pulse-labeling technique, 2% of newly fixed [sup 14]C-photosynthate was translocated into the roots at 3d, 6% at 9 d, and 8% at 15 d after labeling. The fraction of insoluble [sup 14]C in the roots increased twofold from 3 d to 15 d. Over the same time period, 6%-9% of the [sup 14]C translocated to the roots was exuded into the soil. The soluble [sup 14]C compounds exuded into the soil were greater in the 3-cm segment at the root tip than elsewhere along the root, whereas mucilage was exuded relatively uniformly along roots 15 cm in length. The volumetric efflux of water increase for both sheathed and unsheathed roots as the soil water potential decreased form -0.1 MPa to -1.0 MPa. The efflux rate was greater for unsheathed roots than for sheathed roots, which were more turgid and had a higher water potential, especially at lower soil water potentials. During drying, soil particles in the sheaths aggregate more tightly, making the sheaths less permeable to water and possibly creating air gaps. The soil sheaths of O. ficus-indica thus reduce water loss from the roots to a drying soil. 34 refs., 6 figs., 1 tab.

  5. Spatial and temporal patterns of root distribution in developing stands of four woody crop species grown with drip irrigation and fertilization

    Science.gov (United States)

    Mark Coleman

    2007-01-01

    In forest trees, roots mediate such significant carbon fluxes as primary production and soil C02 efflux. Despite the central role of roots in these critical processes, information on root distribution during stand establishment is limited, yet must be described to accurately predict how various forest types, which are growing with a range of...

  6. Low magnification EBSD mapping of texture distribution in a fine-grained matrix

    Science.gov (United States)

    Gardner, Joseph; Mariani, Elisabetta; Wheeler, John

    2016-04-01

    The study of texture (CPO) in rocks is often restricted to individual phases within a given sample or specific area of said sample. Large scale EBSD mapping of the matrix of a greenschist facies albite mylonite has shown that an overall significant CPO within albite grains is strongly domainal, and each domain has a unique CPO that is independent of both common slip systems in plagioclase and the specimen geometry (i.e. foliation and lineation). Observational evidence suggests the metamorphic breakdown of plagioclase to albite (Ab) plus a Ca-bearing phase (clinozoisite, Cz) has produced a two phase mixture in which each phase has a contrasting solubility. New grains of albite are thought to nucleate epitaxially from original plagioclase as a reaction front passes through parent grains. A pseudomorphic region of Ab plus Cz after an original plagioclase crystal, protected from intense deformation by enclosure in a cm-scale augite clast, gives insight into pre-deformation daughter grain distributions. The albite in the region inherits a strong CPO and 180° misorientation peak from a relict twin pattern due to epitaxial growth while clinozoisite is randomly distributed and oriented (despite some grains nucleating from the plagioclase parent twin boundary). In the deformed matrix, daughter Ab is seen to be the more mobile phase, having undergone obvious dissolution, transport and reprecipitation into fractures and pressure shadows, whereas Cz grains are relatively insoluble and rotate into parallelism with the foliation, forming bands that anastamose around Cpx porphyroclasts. Despite this modification, albite in the matrix retains significant CPOs that comprise distinct domains with sharp boundaries. A 180° misorientation peak thought to be a signature of twinning inherited from parent plagioclase is also observed in each domain. Why a CPO should be preserved under these conditions (contrary to our traditional understanding that CPOs are a signature of dislocation

  7. Applying GIS and fine-resolution digital terrain models to assess three-dimensional population distribution under traffic impacts.

    Science.gov (United States)

    Wu, Chih-Da; Lung, Shih-Chun Candice

    2012-01-01

    Pollution exhibits significant variations horizontally and vertically within cities; therefore, the size and three-dimensional (3D) spatial distribution of population are significant determinants of urban health. This paper presents a novel methodology, 3D digital geography (3DIG) methodology, for investigating 3D spatial distributions of population in close proximity to traffic, thus the potential highly exposed population under traffic impacts. 3DIG applies geographic information system and fine-resolution (5 m) digital terrain models to obtain the number of building floors in residential zones of the Taipei metropolis; the vertical distribution of population at different floors was estimated based on demographic data in each census tract. In addition, population within 5, 10, 20, 50, and 100 m from the roadways was estimated. Field validation indicated that model results were reliable and accurate; the final population estimation differs only by 0.88% from the demographic database. The results showed that among the total 6.5 million Taipei residents, 0.8 (12.3%), 1.5 (22.9%), 2.3 (34.9), and 2.7 (41.1%) million residents live on the first or second floor within 5, 10, 20, and 50 m, respectively, of municipal roads. There are 22 census tracts with more than half of their residents living on the first or second floor within 5 m of municipal roads. In addition, half of the towns in Taipei city and county with >13.9% and 12.1% of residents live on the first and second floors within 5 m of municipal roads, respectively. These findings highlight the huge number of Taipei residents in close proximity to traffic and have significant implications for exposure assessment and environmental epidemiological studies. This study demonstrates that 3DIG is a versatile methodology for various research and policy planning in which 3D spatial population distribution is the central focus.

  8. Development of bulk density, total C distribution and OC saturation in fine mineral fractions during paddy soil evolution

    Science.gov (United States)

    Wissing, Livia; Kölbl, Angelika; Cao, Zhi-Hong; Kögel-Knabner, Ingrid

    2010-05-01

    Paddy soils are described as important accumulator for OM (Zhang and He, 2004). In southeast China, paddy soils have the second highest OM stocks (Zhao et al, 1997) and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. The paddy soil management is believed to be favorable for accumulation of organic matter, as its content in paddy soils is statistically higher than that of non-paddy soils (Cai, 1996). However, the mechanism of OM storage and the development of OM distribution during paddy soil evolution is largely unknown. The aim of the project is to identify the role of organo-mineral complexes for the stabilization of organic carbon during management-induced paddy soil formation in a chronosequence ranging from 50 to 2000 years of paddy soil use. The soil samples were analysed for bulk density, total organic carbon (TOC) and total inorganic carbon (TIC) concentrations of bulk soils and the concentration of organic carbon as well as the organic carbon stocks of physical soil fractions. First results indicate distinctly different depth distributions between paddy and non-paddy (control) sites. The paddy soils are characterized by relatively low bulk densities in the puddled layer (between 0.9 and 1.3 g cm-3) and high values in the plough pan (1.4 to 1.6 g cm-3) and the non-paddy soils by relatively homogeneous values throughout the profiles (1.3 to 1.4 g cm-3). In contrast to the carbonate-rich non-paddy sites, we found a significant loss of carbonates during paddy soil formation, resulting in decalcification of the upper 20 cm after 100 yr of paddy soil use, and decalcification of the total soil profile in 700, 1000 and 2000 yr old paddy soils. The calculation of the organic carbon stocks of each horizon indicate that paddy sites always have higher values in topsoils compared to non-paddy sites, and show increasing values with increasing soil age. The capacity of fine mineral fractions to preserve OC was calculated according to

  9. Effect of NaCl stress on ion distribution in roots and growth of Cyclocarya paliurus seedlings

    Institute of Scientific and Technical Information of China (English)

    Ruiling YAO; Shengzuo FANG

    2009-01-01

    We studied ion distribution in roots and the growth of Cyclocarya paliurus seedlings of three provenances, Huangshan in Anhui, Jiujiang in Jiangxi and Kunming in Yunnan, under conditions of 0, 1,3 and 5 g/L NaCI stress using X-ray microanalysis. Results show that under NaCI stress of 3 and 5 g/L, the relative contents of Na+ and Cl in root tissues increased, while the relative contents of K+, Ca2+ and Mg2+ decreased. With an increase in salinity, the relative content of Na+ in the epidermis and cortex of the root increased, while the relative content of Cl in the stele and cortex of the root increased markedly. Thus, ions in the root tissues were unbalanced and the ratios K7Na+ and Ca27Na+ decreased, while Na7(K++ Na++Ca2++Mg2+) increased. The decrease of the K+/Na+ ratio and the substantial increase of Cl" in root tissues contributed to a decline in seedlings survival and reduced the increments for seedling leaf area, height, basal diameter as well biomass. Our preliminary conclusion is that the level of salt tolerance for the tested provenance seedlings was in the order of Huangshan > Kunming > Jiujiang, and the threshold of salt tolerance for C. paliurus seedlings was about 1 g/L.

  10. Artificial Plant Root System Growth for Distributed Optimization: Models and Emergent Behaviors

    Directory of Open Access Journals (Sweden)

    Su Weixing

    2016-01-01

    Full Text Available Plant root foraging exhibits complex behaviors analogous to those of animals, including the adaptability to continuous changes in soil environments. In this work, we adapt the optimality principles in the study of plant root foraging behavior to create one possible bio-inspired optimization framework for solving complex engineering problems. This provides us with novel models of plant root foraging behavior and with new methods for global optimization. This framework is instantiated as a new search paradigm, which combines the root tip growth, branching, random walk, and death. We perform a comprehensive simulation to demonstrate that the proposed model accurately reflects the characteristics of natural plant root systems. In order to be able to climb the noise-filled gradients of nutrients in soil, the foraging behaviors of root systems are social and cooperative, and analogous to animal foraging behaviors.

  11. Incorporation of a dynamic root distribution into CLM4.5: Evaluation of carbon and water fluxes over the Amazon

    Science.gov (United States)

    Wang, Yuanyuan; Xie, Zhenghui; Jia, Binghao

    2016-09-01

    Roots are responsible for the uptake of water and nutrients by plants and have the plasticity to dynamically respond to different environmental conditions. However, most land surface models currently prescribe rooting profiles as a function only of vegetation type, with no consideration of the surroundings. In this study, a dynamic rooting scheme, which describes root growth as a compromise between water and nitrogen availability, was incorporated into CLM4.5 with carbon-nitrogen (CN) interactions (CLM4.5-CN) to investigate the effects of a dynamic root distribution on eco-hydrological modeling. Two paired numerical simulations were conducted for the Tapajos National Forest km83 (BRSa3) site and the Amazon, one using CLM4.5-CN without the dynamic rooting scheme and the other including the proposed scheme. Simulations for the BRSa3 site showed that inclusion of the dynamic rooting scheme increased the amplitudes and peak values of diurnal gross primary production (GPP) and latent heat flux (LE) for the dry season, and improved the carbon (C) and water cycle modeling by reducing the RMSE of GPP by 0.4 g C m-2 d-1, net ecosystem exchange by 1.96 g C m-2 d-1, LE by 5.0 W m-2, and soil moisture by 0.03 m3 m-3, at the seasonal scale, compared with eddy flux measurements, while having little impact during the wet season. For the Amazon, regional analysis also revealed that vegetation responses (including GPP and LE) to seasonal drought and the severe drought of 2005 were better captured with the dynamic rooting scheme incorporated.

  12. Type and distribution of sensilla in the antennae of the red clover root borer, Hylastinus obscurus.

    Science.gov (United States)

    Palma, Rubén; Mutis, Ana; Isaacs, Rufus; Quiroz, Andrés

    2013-01-01

    In order to determine the type, distribution, and structures of sensilla, the antennae of the red clover root borer, Hylastinus obscurus Marsham (Coleoptera: Curculionidae: Scolytinae), were examined by light and electron microscopy (both scanning and transmission). Four different types of sensilla were identified in the club, and one type of chaetica was found in the scape and funicle of both male and female individuals. Chaetica and basiconica were the most abundant sensilla types in the club. They were present in the three sensory bands described, totaling approximately 80% of sensilla in the antennal club of H. obscurus. Chaetica were predominantly mechanoreceptors, although gustatory function could not be excluded. Basiconica forms showed characteristics typical of olfactory sensilla. Trichoidea were not found in the proximal sensory band, and they exhibited abundant pores, suggesting olfactory function. Styloconica were the least abundant sensillum type, and their shape was similar to that reported as having hygro- and thermoreceptor functions. There was no difference in the relative abundance of antennal sensilla between males and females. Finally, the sensillar configuration and abundance of receptors in the H. obscurus antennae suggest that these sensilla have chemoreceptive and other functions.

  13. Root iron uptake efficiency of Ulmus laevis and U. minor and their distribution in soils of the Iberian Peninsula.

    Science.gov (United States)

    Venturas, Martin; Fernández, Victoria; Nadal, Paloma; Guzmán, Paula; Lucena, Juan J; Gil, Luis

    2014-01-01

    The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe)-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (Ulmus minor) and siliceous (U. laevis) soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during 6 weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H(+)) extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. U. minor had a higher root ferric reductase activity and H(+)-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different Fe acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula.

  14. Root iron uptake efficiency of Ulmus laevis and U. minor and their distribution in soils of the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    Martin eVenturas

    2014-03-01

    Full Text Available The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (U. minor and siliceous (U. laevis soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during six weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H+ extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. Ulmus minor had a higher root ferric reductase activity and H+-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different iron acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula.

  15. Use of an adaptive neuro-fuzzy system to characterize root distribution patterns

    Science.gov (United States)

    Root-soil relationships are pivotal to understanding crop growth and function in a changing environmental. Plant root systems are difficult to measure and remain understudied relative to above ground responses. High variation among field samples often leads to non-significance when standard statist...

  16. Macroscopic root water uptake distribution using a matric flux potential approach

    NARCIS (Netherlands)

    Jong van Lier, de Q.; Dam, van J.C.; Metselaar, K.; Jong, de R.; Duijnisveld, W.H.M.

    2008-01-01

    Hydrological models featuring root water uptake usually do not include compensation mechanisms such that reductions in uptake from dry layers are compensated by an increase in uptake from wetter layers. We developed a physically based root water uptake model with an implicit compensation mechanism.<

  17. Macroscopic root water uptake distribution using a matric flux potential approach

    NARCIS (Netherlands)

    Jong van Lier, de Q.; Dam, van J.C.; Metselaar, K.; Jong, de R.; Duijnisveld, W.H.M.

    2008-01-01

    Hydrological models featuring root water uptake usually do not include compensation mechanisms such that reductions in uptake from dry layers are compensated by an increase in uptake from wetter layers. We developed a physically based root water uptake model with an implicit compensation mechanism.<

  18. Estimating root biomass and distribution after fire in a Great Basin woodland using cores and pits

    Science.gov (United States)

    Benjamin M. Rau; Dale W. Johnson; Jeanne C. Chambers; Robert R. Blank; Annmarie Lucchesi

    2009-01-01

    Quantifying root biomass is critical to an estimation and understanding of ecosystem net primary production, biomass partitioning, and belowground competition. We compared 2 methods for determining root biomass: a new soil-coring technique and traditional excavation of quantitative pits. We conducted the study in an existing Joint Fire Sciences demonstration area in...

  19. Mesquite root distribution and water use efficiency in response to long-term soil moisture manipulations

    Science.gov (United States)

    R. J. Ansley; T. W. Boutton; P. W. Jacoby

    2007-01-01

    This study quantified honey mesquite (Prosopis glandulosa) root growth and water use efficiency following chronic soil drought or wetness on a clay loam site in north Texas. Root systems of mature trees were containerized with barriers inserted into the soil. Soil moisture within containers was manipulated with irrigation (Irrigated) or rain...

  20. The ordered distribution of natural numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2007-01-01

    Natural numbers divisible by the same prime factor lie on defined spiral graphs which are running through the Square Root Spiral (also named as the Spiral of Theodorus or Wurzel Spirale or Einstein Spiral). Prime Numbers also clearly accumulate on such spiral graphs. And the square numbers 4, 9, 16, 25, 36,... form a highly three-symmetrical system of three spiral graphs, which divides the square-root-spiral into three equal areas. A mathematical analysis shows that these spiral graphs are defined by quadratic polynomials. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Fibonacci Numbers divide the Square Root Spiral into areas and angle sectors with constant proportions. These proportions are linked to the golden mean (or golden section), which behaves as a self-avoiding-walk-constant in the lattice-like structure of the square root spiral.

  1. Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere.

    Science.gov (United States)

    Lü, Senlin; Zhang, Rui; Yao, Zhenkun; Yi, Fei; Ren, Jingjing; Wu, Minghong; Feng, Man; Wang, Qingyue

    2012-01-01

    Ambient coarse particles (diameter 1.8-10 microm), fine particles (diameter 0.1-1.8 microm), and ultrafine particles (diameter chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 +/- 2.18, 8.82 +/- 3.52, and 2.02 +/- 0.41 microg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.

  2. Impact of soil matric potential on the fine-scale spatial distribution and activity of specific microbial degrader communities.

    Science.gov (United States)

    Monard, Cécile; Mchergui, Chokri; Nunan, Naoise; Martin-Laurent, Fabrice; Vieublé-Gonod, Laure

    2012-09-01

    The impact of the soil matric potential on the relationship between the relative abundance of degraders and their activity and on the spatial distribution of both at fine scales was determined to understand the role of environmental conditions in the degradation of organic substrates. The mineralization of (13) C-glucose and (13) C-2,4-dichlorophenoxyacetic acid (2,4-D) was measured at different matric potentials (-0.001, -0.01 and -0.316 MPa) in 6 × 6 × 6 mm(3) cubes excised from soil cores. At the end of the incubation, total bacterial and 2,4-D degrader abundances were determined by quantifying the 16S rRNA and the tfdA genes, respectively. The mineralization of 2,4-D was more sensitive to changes in matric potential than was that of glucose. The amount and spatial structure of 2,4-D mineralization decreased with matric potential, whilst the spatial variability increased. On the other hand, the spatial variation of glucose mineralization was less affected by changes in matric potential. The relationship between the relative abundance of 2,4-D degraders and 2,4-D mineralization was significantly affected by matric potential: the relative abundance of tfdA needed to be higher to reach a given level of 2,4-D mineralization in dryer than in moister conditions. The data show how microbial interactions with their microhabitat can have an impact on soil processes at larger scales.

  3. The distribution and growth of roots for four sugarcane cultivars irrigated by a subsurface drip irrigation system

    Science.gov (United States)

    Yukitaka Pessinatti Ohashi, Augusto; Barros de Oliveira Silva, André Luiz; Célia de Matos Pires, Regina; Vasconcelos Ribeiro, Rafael

    2013-04-01

    The use of subsurface drip irrigation (SDI) in sugarcane cultivation is an interesting cultural practice to improve production and allow cultivation in marginal lands due to water deficit conditions or to reach high yield and to increase longevity of plants. The SDI allows improving the water use efficiency, due to the application of water and nutrients in the root zone plants. It is necessary knowledge of soil and plant parameters, such as root system to improve irrigation system use efficiency. However, despite of the agronomic importance, few studies of sugarcane roots have been performed. The use of root scanner is an alternative to the evaluation of the root system. The mentioned equipment enables the continuous study of the roots throughout the cycle and for many years, but data about the use of this method for sugarcane are scarce. The aim of this study was to determine the distribution and growth of roots for four sugarcane cultivars root system. The field experiment was carried out in Campinas SP Brazil, with IACSP95-5000, IACSP94-2094, IACSP94-2101 and SP79-1011 cultivars. The irrigation was performed by subsurface drip system and the soil moisture was monitored by capacitance probes. Three access tubes with 1.05 m-length were used for each cultivar. The images were caught with Root Scanner CI-600™ in two dates, 38 and 58 days after harvest (DAH) of cane-plant, in the second cycle (1st cane ratoon) in five depths and were analyzed by the software RootSnap! ™. The results show that, except for cultivar IACSP94-2094, more than 80% of root length was found in the first 0.40 m of soil profile. Until 38 DAH the root growth of cultivar IACSP94-2101 were approximately fourfold higher than other three ones in the 0 to 0.20 m layer, sevenfold higher to 0.20 to 0.40 m layer and threefold to 0.40 to 0.60 m soil profile layer. However, between 38 and 58 DAH the cultivar SP79-1011 presented higher growth taxes, being almost twofold higher than IACSP94-2101 at 0 to

  4. Salinity altered root distribution and increased diversity of bacterial communities in the rhizosphere soil of Jerusalem artichoke

    Science.gov (United States)

    Yang, Hui; Hu, Jinxiang; Long, Xiaohua; Liu, Zhaopu; Rengel, Zed

    2016-02-01

    The interaction between roots and bacterial communities in halophytic species is poorly understood. Here, we used Jerusalem artichoke cultivar Nanyu 1 (NY-1) to characterise root distribution patterns and determine diversity and abundance of bacteria in the rhizosphere soil under variable salinity. Root growth was not inhibited within the salinity range 1.2 to 1.9 g salt/kg, but roots were mainly confined to 0–20 cm soil layer vertically and 0–30 cm horizontally from the plant centre. Root concentrations of K+, Na+, Mg2+ and particularly Ca2+ were relatively high under salinity stress. High salinity stress decreased soil invertase and catalase activity. Using a next-generation, Illumina-based sequencing approach, we determined higher diversity of bacteria in the rhizosphere soil at high than low salinity. More than 15,500 valid reads were obtained, and Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria predominated in all samples, accounting for >80% of the reads. On a genus level, 636 genera were common to the low and high salinity treatments at 0–5 cm and 5–10 cm depth. The abundance of Steroidobacter and Sphingomonas was significantly decreased by increasing salinity. Higher Shannon and Chao 1 indices with increasing severity of salt stress indicated that high salt stress increased diversity in the bacterial communities.

  5. NMR imaging of root water distribution in intact Vicia faba L plants in elevated atmospheric CO[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Bottomley, P.A.; Rogers, H.H.; Prior, S.A. (GE Research and Development Center, Schenectady, NY (USA))

    1993-04-01

    The effect of elevated atmospheric CO[sub 2] on water distribution in the intact roots of Vicia faba L. bean seedlings grown in natural soil was studied noninvasively with proton ([sup 1]H) nuclear magnetic resonance (NMR) imaging. Exposure of 24-d-old plants to atmospheric CO[sub 2] enriched air at 650 cm[sup 3] m[sup -3] produced significant increases in water imaged in upper roots, hypogeal cotyledons and lower stems in response to a short-term drying-stress cycle. Above ground, drying produced negligible stem shrinkage and stomatal resistance was unchanged. In contrast, the same drying cycle caused significant depletion of water imaged in the same upper root structures in control plants subject to ambient CO[sub 2] (350 cm[sup 3] m[sup -3]), and stem shrinkage and increased stomatal resistance. The results suggest that inhibition of transpiration caused by elevated CO[sub 2] does not necessarily result in attenuation of water transport from lower root structures. Inhibition of water loss from upper roots and lower stem in elevated CO[sub 2] environments may be a mitigating factor in assessing deleterious effects of greenhouse changes on crops during periods of dry climate.

  6. Examination of the distribution of arsenic in hydrated and fresh cowpea roots using two- and three-dimensional techniques.

    Science.gov (United States)

    Kopittke, Peter M; de Jonge, Martin D; Menzies, Neal W; Wang, Peng; Donner, Erica; McKenna, Brigid A; Paterson, David; Howard, Daryl L; Lombi, Enzo

    2012-07-01

    Arsenic (As) is considered to be the environmental contaminant of greatest concern due to its potential accumulation in the food chain and in humans. Using novel synchrotron-based x-ray fluorescence techniques (including sequential computed tomography), short-term solution culture studies were used to examine the spatial distribution of As in hydrated and fresh roots of cowpea (Vigna unguiculata 'Red Caloona') seedlings exposed to 4 or 20 µm arsenate [As(V)] or 4 or 20 µm arsenite. For plants exposed to As(V), the highest concentrations were observed internally at the root apex (meristem), with As also accumulating in the root border cells and at the endodermis. When exposed to arsenite, the endodermis was again a site of accumulation, although no As was observed in border cells. For As(V), subsequent transfer of seedlings to an As-free solution resulted in a decrease in tissue As concentrations, but growth did not improve. These data suggest that, under our experimental conditions, the accumulation of As causes permanent damage to the meristem. In addition, we suggest that root border cells possibly contribute to the plant's ability to tolerate excess As(V) by accumulating high levels of As and limiting its movement into the root.

  7. Novel temporal, fine-scale and growth variation phenotypes in roots of adult-stage maize (Zea mays L.) in response to low nitrogen stress.

    Science.gov (United States)

    Gaudin, Amelie C M; McClymont, Sarah A; Holmes, Bridget M; Lyons, Eric; Raizada, Manish N

    2011-12-01

    There is interest in discovering root traits associated with acclimation to nutrient stress. Large root systems, such as in adult maize, have proven difficult to be phenotyped comprehensively and over time, causing target traits to be missed. These challenges were overcome here using aeroponics, a system where roots grow in the air misted with a nutrient solution. Applying an agriculturally relevant degree of low nitrogen (LN) stress, 30-day-old plants responded by increasing lengths of individual crown roots (CRs) by 63%, compensated by a 40% decline in CR number. LN increased the CR elongation rate rather than lengthening the duration of CR growth. Only younger CR were significantly responsive to LN stress, a novel finding. LN shifted the root system architectural balance, increasing the lateral root (LR)-to-CR ratio, adding ∼70 m to LR length. LN caused a dramatic increase in second-order LR density, not previously reported in adult maize. Despite the near-uniform aeroponics environment, LN induced increased variation in the relative lengths of opposing LR pairs. Large-scale analysis of root hairs (RHs) showed that LN decreased RH length and density. Time-course experiments suggested the RH responses may be indirect consequences of decreased biomass/demand under LN. These results identify novel root traits for genetic dissection.

  8. A study about geographical distribution of root lesion nematode (Pratylenchus loosi, Loof 1960) in tea gardens at Guilan Province, Iran.

    Science.gov (United States)

    Hajieghrari, B; Mohammadi, M; Kheiri, A; Maafi, Z T

    2005-01-01

    Root lesion nematode of tea (Pratylenchus loosi) is one of the most dangerous and distractive pests in all over areas in the world where tea grows. In Iran, this species was one of the quarantine pests that for first time it were separated from the Japan imported tea slips and reported by Maafi (1993). Nowadays it has been distributed in some tea growth areas of Guilan and Mazandaran provinces (North of Iran). In this study, geographical distribution of this pest is reported on some tea growth areas of Guilan province. In order to, 147 samples from root and soil around them were investigated. These samples were gathered from various gardens of Guilan province. They were transferred to nematology lab with suitable temperature and moisture conditions and were stored at 5-10 degrees C until extraction time. Centrifugal methods for nematode extraction from soil (Jenkins, 1964) and from root (Coolen & D'Herde, 1972) were used. The nematode was identified by Handoo & Golden (1989) and Frederick & Tarjan (1989) diagnostic keys. According to this study different infested areas and geographical distribution were detected in Guilan province. Results indicated that many important tea growth areas in Guilan were infested by this nematode. In addition, it seems that it has been distributed during short time.

  9. Effect of subsoil tillage depth on nutrient accumulation, root distribution, and grain yield in spring maize

    Directory of Open Access Journals (Sweden)

    Hongguang Cai

    2014-10-01

    Full Text Available A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen (N, phosphorus (P, and potassium (K uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development, increased nutrient accumulation, and increased yield. Compared with conventional soil management (CK, root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm (T1 and subsoil tillage to 50 cm (T2 were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the 12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.

  10. Effect of subsoil tillage depth on nutrient accumulation, root distribution, and grain yield in spring maize

    Institute of Scientific and Technical Information of China (English)

    Hongguang; Cai; Wei; Ma; Xiuzhi; Zhang; Jieqing; Ping; Xiaogong; Yan; Jianzhao; Liu; Jingchao; Yuan; Lichun; Wang; Jun; Ren

    2014-01-01

    A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.

  11. Effects of narrow plant spacing on root distribution and physiological nitrogen use efficiency in summer maize

    Directory of Open Access Journals (Sweden)

    Wenshun Jiang

    2013-10-01

    Full Text Available The objective of this study was to understand the effects of plant spacing on grain yield and root competition in summer maize (Zea mays L.. Maize cultivar Denghai 661 was planted in rectangular tanks (0.54 m × 0.27 m × 1.00 m under 27 cm (normal and 6 cm (narrow plant spacing and treated with zero and 7.5 g nitrogen (N per plant. Compared to normal plant spacing, narrow plant spacing generated less root biomass in the 0–20 cm zone under both N rates, slight reductions of dry root weight in the 20–40 cm and 40–70 cm zones at the mid-grain filling stage, and slight variation of dry root weights in the 70–100 cm zone during the whole growth period. Narrow plant spacing decreased root reductive activity in all root zones, especially at the grain-filling stage. Grain yield and above-ground biomass were 5.0% and 8.4% lower in the narrow plant spacing than with normal plant spacing, although narrow plant spacing significantly increased N harvest index and N use efficiency in both grain yield and biomass, and higher N translocation rates from vegetative organs. These results indicate that the reductive activity of maize roots in all soil layers and dry weights of shallow roots were significantly decreased under narrow plant spacing conditions, resulting in lower root biomass and yield reduction at maturity. Therefore, a moderately dense sowing is a basis for high yield in summer maize.

  12. Effects of narrow plant spacing on root distribution and physiological nitrogen use efficiency in summer maize

    Institute of Scientific and Technical Information of China (English)

    Wenshun; Jiang; Kongjun; Wang; Qiuping; Wu; Shuting; Dong; Peng; Liu; Jiwang; Zhang

    2013-01-01

    The objective of this study was to understand the effects of plant spacing on grain yield and root competition in summer maize(Zea mays L.). Maize cultivar Denghai 661 was planted in rectangular tanks(0.54 m × 0.27 m × 1.00 m) under 27 cm(normal) and 6 cm(narrow) plant spacing and treated with zero and 7.5 g nitrogen(N) per plant. Compared to normal plant spacing, narrow plant spacing generated less root biomass in the 0–20 cm zone under both N rates, slight reductions of dry root weight in the 20–40 cm and 40–70 cm zones at the mid-grain filling stage, and slight variation of dry root weights in the 70–100 cm zone during the whole growth period. Narrow plant spacing decreased root reductive activity in all root zones, especially at the grain-filling stage. Grain yield and above-ground biomass were 5.0% and 8.4% lower in the narrow plant spacing than with normal plant spacing, although narrow plant spacing significantly increased N harvest index and N use efficiency in both grain yield and biomass, and higher N translocation rates from vegetative organs. These results indicate that the reductive activity of maize roots in all soil layers and dry weights of shallow roots were significantly decreased under narrow plant spacing conditions, resulting in lower root biomass and yield reduction at maturity. Therefore, a moderately dense sowing is a basis for high yield in summer maize.

  13. Tissue distribution and deposition pattern of a cellulosic parenchyma-specific protein from cassava roots

    Directory of Open Access Journals (Sweden)

    Petrônio A.S. Souza

    1998-06-01

    Full Text Available A protein with a molecular mass of 22kDa was purified from the cellulosic parenchyma of cassava roots. The amino acid composition of the protein was determined and antibodies generated against the purified protein were used to show that the concentration of the protein remains unchanged during root "tuber" formation. By using a tissue printing technique, as well as western blot, it was shown that the cellulosic parenchyma was the only root tissue in which the protein was deposited.

  14. Effect of Crop cultivation after Mediterranean maquis on soil carbon stock, δ13C spatial distribution and root turnover

    Science.gov (United States)

    Novara, Agata; Gristina, Luciano; Santoro, Antonino; La Mantia, Tommaso

    2013-04-01

    The aim of this work was investigate the effect of land use change on soil organic carbon (SOC) stock and distribution in a Mediterranean succession. A succession composed by natural vegetation, cactus pear crop and olive grove, was selected in Sicily. The land use change from mediterranena maquis (C3 plant) to cactus pear (C4 plant) lead to a SOC decrease of 65% after 28 years of cultivation, and a further decrease of 14% after 7 years since the land use from cactus pear to olive grove (C3 plant). Considering this exchange and decrease as well as the periods after the land use changes we calculated the mean residence time (MRT) of soil C of different age. The MRT of C under Mediterranean maquis was about 142 years, but was 10 years under cactus pear. Total SOC and δ13 C were measured along the soil profile (0-75cm) and in the intra-rows in order to evaluate the distribution of new and old carbon derived and the growth of roots. After measuring of weight of cactus pear root, an approach was developed to estimate the turnover of root biomass. Knowledge of root turnover and carbon input are important to evaluate the correlation between carbon input accumulation and SOC stock in order to study the ability of C sink of soils with different use and managements.

  15. Evolution of root plasticity responses to variation in soil nutrient distribution and concentration

    OpenAIRE

    2012-01-01

    Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected for increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity for plasticity in crop plants like barley (Hordeum vulgare). However, the effects of domestication on the evolution of root plasticity are essentially unknown. Using a split container approach, we examined th...

  16. Ethylene regulates root growth through effects on auxin biosynthesis and transport-dependent auxin distribution

    OpenAIRE

    2007-01-01

    In plants, each developmental process integrates a network of signaling events that are regulated by different phytohormones, and interactions among hormonal pathways are essential to modulate their effect. Continuous growth of roots results from the postembryonic activity of cells within the root meristem that is controlled by the coordinated action of several phytohormones, including auxin and ethylene. Although their interaction has been studied intensively, the molecular and cellular mech...

  17. Mathematical modeling and experimental validation of the spatial distribution of boron in the root of Arabidopsis thaliana identify high boron accumulation in the tip and predict a distinct root tip uptake function.

    Science.gov (United States)

    Shimotohno, Akie; Sotta, Naoyuki; Sato, Takafumi; De Ruvo, Micol; Marée, Athanasius F M; Grieneisen, Verônica A; Fujiwara, Toru

    2015-04-01

    Boron, an essential micronutrient, is transported in roots of Arabidopsis thaliana mainly by two different types of transporters, BORs and NIPs (nodulin26-like intrinsic proteins). Both are plasma membrane localized, but have distinct transport properties and patterns of cell type-specific accumulation with different polar localizations, which are likely to affect boron distribution. Here, we used mathematical modeling and an experimental determination to address boron distributions in the root. A computational model of the root is created at the cellular level, describing the boron transporters as observed experimentally. Boron is allowed to diffuse into roots, in cells and cell walls, and to be transported over plasma membranes, reflecting the properties of the different transporters. The model predicts that a region around the quiescent center has a higher concentration of soluble boron than other portions. To evaluate this prediction experimentally, we determined the boron distribution in roots using laser ablation-inductivity coupled plasma-mass spectrometry. The analysis indicated that the boron concentration is highest near the tip and is lower in the more proximal region of the meristem zone, similar to the pattern of soluble boron distribution predicted by the model. Our model also predicts that upward boron flux does not continuously increase from the root tip toward the mature region, indicating that boron taken up in the root tip is not efficiently transported to shoots. This suggests that root tip-absorbed boron is probably used for local root growth, and that instead it is the more mature root regions which have a greater role in transporting boron toward the shoots.

  18. A deeper look at the relationship between root carbon pools and the vertical distribution of the soil carbon pool

    Directory of Open Access Journals (Sweden)

    R. Dietzel

    2017-08-01

    Full Text Available Plant root material makes a substantial contribution to the soil organic carbon (C pool, but this contribution is disproportionate below 20 cm where 30 % of root mass and 50 % of soil organic C is found. Root carbon inputs changed drastically when native perennial plant systems were shifted to cultivated annual plant systems. We used the reconstruction of a native prairie and a continuous maize field to examine both the relationship between root carbon and soil carbon and the fundamental rooting system differences between the vegetation under which the soils developed versus the vegetation under which the soils continue to change. In all treatments we found that root C  :  N ratios increased with depth, and this plays a role in why an unexpectedly large proportion of soil organic C is found below 20 cm. Measured root C  :  N ratios and turnover times along with modeled root turnover dynamics showed that in the historical shift from prairie to maize, a large, structural-tissue-dominated root C pool with slow turnover concentrated at shallow depths was replaced by a small, nonstructural-tissue-dominated root C pool with fast turnover evenly distributed in the soil profile. These differences in rooting systems suggest that while prairie roots contribute more C to the soil than maize at shallow depths, maize may contribute more C to soil C stocks than prairies at deeper depths.

  19. Contrasting patterns of clonality and fine-scale genetic structure in two rare sedges with differing geographic distributions.

    Science.gov (United States)

    Binks, R M; Millar, M A; Byrne, M

    2015-09-01

    For plants with mixed reproductive capabilities, asexual reproduction is more frequent in rare species and is considered a strategy for persistence when sexual recruitment is limited. We investigate whether asexual reproduction contributes to the persistence of two co-occurring, rare sedges that both experience irregular seed set and if their differing geographic distributions have a role in the relative contribution of clonality. Genotypic richness was high (R=0.889±0.02) across the clustered populations of Lepidosperma sp. Mt Caudan and, where detected, clonal patches were small, both in ramet numbers (⩽3 ramets/genet) and physical size (1.3±0.1 m). In contrast, genotypic richness was lower in the isolated L. sp. Parker Range populations, albeit more variable (R=0.437±0.13), with genets as large as 17 ramets and up to 5.8 m in size. Aggregated clonal growth generated significant fine-scale genetic structure in both species but to a greater spatial extent and with additional genet-level structure in L. sp. Parker Range that is likely due to restricted seed dispersal. Despite both species being rare, asexual reproduction clearly has a more important role in the persistence of L. sp. Parker Range than L. sp. Mt Caudan. This is consistent with our prediction that limitations to sexual reproduction, via geographic isolation to effective gene exchange, can lead to greater contributions of asexual reproduction. These results demonstrate the role of population isolation in affecting the balance of alternate reproductive modes and the contextual nature of asexual reproduction in rare species.

  20. Strain Distribution in Root Surface Dentin of Maxillary Central Incisors during Lateral Compaction.

    Directory of Open Access Journals (Sweden)

    Raphael Pilo

    Full Text Available To precisely quantify the circumferential strains created along the radicular dentin of maxillary incisors during a simulated clinical procedure of lateral compaction.Six miniature strain gauges were bonded on the roots of fourteen recently extracted maxillary central incisors that were subjected to root canal instrumentation. The strain gauges were bonded at three levels (apical, middle, and coronal and four aspects (buccal, lingual, mesial, and distal of the roots. Each tooth was embedded in a PVC cylinder containing polyvinyl-siloxane impression material. Root filling was then performed by simulating the clinical procedure of lateral compaction using nickel-titanium finger spreaders. The force applied to the spreader and the strains developing in the surface root dentin were continuously recorded at a frequency of 10 Hz.The highest strains that developed during lateral compaction were in the mesial and distal aspects at the apical level of the root. The magnitudes of the maximal mesial/distal strains at the apical as well as the mid-root levels were approximately 2.5-3 times higher than those at the buccal/lingual aspects (p = 0.041. The strains decreased significantly (p<0.04 from the apical through the mid-root levels to the coronal level, yielding gradients of 2.5- and 6-fold, respectively. The mesial and distal strains were consistently tensile and did not differ significantly; however, the buccal strains were generally 35-65% higher than the lingual strains (p = 0.078. Lateral compaction resulted in the gradual build-up of residual strains, resulting in generation of a 'stair-step' curve. These strains declined gradually and almost completely disappeared after 1000 sec.With proper mounting of several miniature strain gauges at various levels and aspects of the root, significant circumferential strains can be monitored under clinically relevant compaction forces. The residual strains at the end of lateral compaction are not stored in the

  1. X-ray computed tomography uncovers root-root interactions: quantifying spatial relationships between interacting root systems in three dimensions

    Directory of Open Access Journals (Sweden)

    Alexander Martin Paya

    2015-04-01

    Full Text Available Research in the field of plant biology has recently demonstrated that inter- and intra-specific interactions belowground can dramatically alter root growth. Our aim was to answer questions related to the effect of inter- vs. intra-specific interactions on the growth and utilization of undisturbed space by fine roots within three dimensions (3D using micro X-ray computed tomography. To achieve this, Populus tremuloides (quaking aspen and Picea mariana (black spruce seedlings were planted into containers as either solitary individuals, or inter-/intra-specific pairs, allowed to grow for two months, and 3D metrics developed in order to quantify their use of belowground space. In both aspen and spruce, inter-specific root interactions produced a shift in the vertical distribution of the root system volume, and deepened the average position of root tips when compared to intra-specifically growing seedlings. Inter-specific interactions also increased the minimum distance between root tips belonging to the same root system. There was no effect of belowground interactions on the radial distribution of roots, or the directionality of lateral root growth for either species. In conclusion, we found that significant differences were observed more often when comparing controls (solitary individuals and paired seedlings (inter- or intra-specific, than when comparing inter- and intra-specifically growing seedlings. This would indicate that competition between neighboring seedlings was more responsible for shifting fine root growth in both species than was neighbor identity. However, significant inter- vs. intra-specific differences were observed, which further emphasizes the importance of biological interactions in competition studies.

  2. Porosity distribution in root canals filled with gutta percha and calcium silicate cement

    NARCIS (Netherlands)

    Moinzadeh, A.T.; Zerbst, W.; Boutsioukis, C.; Shemesh, H.; Zaslansky, P.

    2015-01-01

    Objective Gutta percha is commonly used in conjunction with a sealer to produce a fluid-tight seal within the root canal fillings. One of the most commonly used filling methods is lateral compaction of gutta percha coupled with a sealer such as calcium silicate cement. However, this technique may re

  3. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution F Table F-6 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-6 Table F-6 to Subpart F of Part 53—Estimated Mass...

  4. Maize varieties released in different eras have similar root length density distributions in the soil, which are negatively correlated with local concentrations of soil mineral nitrogen.

    Directory of Open Access Journals (Sweden)

    Peng Ning

    Full Text Available Larger, and deeper, root systems of new maize varieties, compared to older varieties, are thought to have enabled improved acquisition of soil resources and, consequently, greater grain yields. To compare the spatial distributions of the root systems of new and old maize varieties and their relationships with spatial variations in soil concentrations of available nitrogen (N, phosphorus (P and potassium (K, two years of field experiments were performed using six Chinese maize varieties released in different eras. Vertical distributions of roots, and available N, P and K in the 0-60 cm soil profile were determined in excavated soil monoliths at silking and maturity. The results demonstrated that new maize varieties had larger root dry weight, higher grain yield and greater nutrient accumulation than older varieties. All varieties had similar total root length and vertical root distribution at silking, but newer varieties maintained greater total root length and had more roots in the 30-60 cm soil layers at maturity. The spatial variation of soil mineral N (Nmin in each soil horizon was larger than that of Olsen-P and ammonium-acetate-extractable K, and was inversely correlated with root length density (RLD, especially in the 0-20 cm soil layer. It was concluded that greater acquisition of mineral nutrients and higher yields of newer varieties were associated with greater total root length at maturity. The negative relationship between RLD and soil Nmin at harvest for all varieties suggests the importance of the spatial distribution of the root system for N uptake by maize.

  5. Maize varieties released in different eras have similar root length density distributions in the soil, which are negatively correlated with local concentrations of soil mineral nitrogen.

    Science.gov (United States)

    Ning, Peng; Li, Sa; White, Philip J; Li, Chunjian

    2015-01-01

    Larger, and deeper, root systems of new maize varieties, compared to older varieties, are thought to have enabled improved acquisition of soil resources and, consequently, greater grain yields. To compare the spatial distributions of the root systems of new and old maize varieties and their relationships with spatial variations in soil concentrations of available nitrogen (N), phosphorus (P) and potassium (K), two years of field experiments were performed using six Chinese maize varieties released in different eras. Vertical distributions of roots, and available N, P and K in the 0-60 cm soil profile were determined in excavated soil monoliths at silking and maturity. The results demonstrated that new maize varieties had larger root dry weight, higher grain yield and greater nutrient accumulation than older varieties. All varieties had similar total root length and vertical root distribution at silking, but newer varieties maintained greater total root length and had more roots in the 30-60 cm soil layers at maturity. The spatial variation of soil mineral N (Nmin) in each soil horizon was larger than that of Olsen-P and ammonium-acetate-extractable K, and was inversely correlated with root length density (RLD), especially in the 0-20 cm soil layer. It was concluded that greater acquisition of mineral nutrients and higher yields of newer varieties were associated with greater total root length at maturity. The negative relationship between RLD and soil Nmin at harvest for all varieties suggests the importance of the spatial distribution of the root system for N uptake by maize.

  6. Arum-type of arbuscular mycorrhizae, dark septate endophytes and Olpidium spp. in fine roots of container-grown seedlings of Sorbus torminalis (Rosaceae

    Directory of Open Access Journals (Sweden)

    Roman M. Bzdyk

    2016-06-01

    Full Text Available The aim of this study was to determine the mycorrhizal status of nursery seedlings of the wild service tree (Sorbus torminalis, which belongs to the Rosaceae family. Its mycorrhizal associations are still fragmentarily known, and data from the few existing studies indicate that it forms ectomycorrhizal symbiosis (ECM. We analyzed the degree of mycorrhizal colonization of thirty 2-year-old container-grown S. torminalis nursery seedlings, which belonged to three single-tree progenies. The roots were dominated by arbuscular mycorrhizae (AM, with the morphology of the Arum-type containing arbuscules, vesicles and hyphae; however, no ECM structures were found. The degree of root colonization of the analyzed seedlings by AM fungi was 83.6% and did not differ significantly between the three single-tree progenies. In addition to AM, structures of dark septate endophytes (0.7% and sporangia of Olpidium spp. (1.1% were found in wild service tree roots. In agreement with previous studies, we confirmed arbuscular mycorrhizae for S. torminalis. Moreover, this is the first report that roots of this Sorbus species show the Arum-type morphology of AM and are associated with Olpidium species.

  7. Effect of Piriformospora indica inoculation on root development and distribution of maize (Zea mays L.) in the presence of petroleum contaminated soil

    Science.gov (United States)

    Zamani, Javad; Hajabbasi, Mohammad Ali; Alaie, Ebrahim

    2014-05-01

    The root systems of most terrestrial plants are confronted to various abiotic and biotic stresses. One of these abiotic stresses is contamination of soil with petroleum hydrocarbon, which the efficiency of phytoremediation of petroleum hydrocarbons in soils is dependent on the ability of plant roots to development into the contaminated soils. Piriformospora indica represents a recently discovered fungus that transfers considerable beneficial impact to its host plants. A rhizotron experiment was conducted to study the effects of P. Indica inoculation on root distribution and root and shoot development of maize (Zea mays L.) in the presence of three patterns of petroleum contamination in the soil (subsurface contamination, continuous contamination and without contamination (control)). Root distribution and root and shoot development were monitored over time. The final root and shoot biomass and the final TPH concentration in the rhizosphere were determined. Analysis of digitized images which were prepared of the tracing of the appeared roots along the front rhizotrons showed the depth and total length of root network in the contamination treatments were significantly decreased. Although the degradation of TPH in the rhizosphere of maize was significant, but there were no significant differences between degradation of TPH in the rhizosphere of +P. indica plants in comparison to -P. indica plants.

  8. Arsenic distribution and speciation near rice roots influenced by iron plaques and redox conditions of the soil matrix.

    Science.gov (United States)

    Yamaguchi, Noriko; Ohkura, Toshiaki; Takahashi, Yoshio; Maejima, Yuji; Arao, Tomohito

    2014-01-01

    Elevated arsenic (As) concentrations in rice and the soil solution result from changes in soil redox conditions, influenced by the water management practices during rice cultivation. Microscale changes in redox conditions from rhizosphere to soil matrix affect the As speciation and Fe plaque deposition. In order to focus on the rhizosphere environment, we observed microscale distribution and speciation of As around the rhizosphere of paddy rice with X-ray fluorescence mapping and X-ray absorption spectroscopy. When the soil matrix was anaerobic during rice growth, Fe-plaque did not cover the entire root, and As(III) was the dominant arsenic species in the soil matrix and rhizosphere. Draining before harvest led the conditions to shift to aerobic. Oxidation of As(III) to As(V) occurred faster in the Fe-plaque than the soil matrix. Arsenic was scavenged by iron mottles originating from Fe-plaque around the roots. The ratio of As(V) to As(III) decreased toward the outer-rim of the subsurface Fe mottles where the soil matrix was not completely aerated. These results provide direct evidence that speciation of As near rice roots depends on spatial and temporal redox variations in the soil matrix.

  9. Modelling deep water habitats to develop a spatially explicit, fine scale understanding of the distribution of the western rock lobster, Panulirus cygnus.

    Directory of Open Access Journals (Sweden)

    Renae K Hovey

    Full Text Available BACKGROUND: The western rock lobster, Panulirus cygnus, is endemic to Western Australia and supports substantial commercial and recreational fisheries. Due to and its wide distribution and the commercial and recreational importance of the species a key component of managing western rock lobster is understanding the ecological processes and interactions that may influence lobster abundance and distribution. Using terrain analyses and distribution models of substrate and benthic biota, we assess the physical drivers that influence the distribution of lobsters at a key fishery site. METHODS AND FINDINGS: Using data collected from hydroacoustic and towed video surveys, 20 variables (including geophysical, substrate and biota variables were developed to predict the distributions of substrate type (three classes of reef, rhodoliths and sand and dominant biota (kelp, sessile invertebrates and macroalgae within a 40 km(2 area about 30 km off the west Australian coast. Lobster presence/absence data were collected within this area using georeferenced pots. These datasets were used to develop a classification tree model for predicting the distribution of the western rock lobster. Interestingly, kelp and reef were not selected as predictors. Instead, the model selected geophysical and geomorphic scalar variables, which emphasise a mix of terrain within limited distances. The model of lobster presence had an adjusted D(2 of 64 and an 80% correct classification. CONCLUSIONS: Species distribution models indicate that juxtaposition in fine scale terrain is most important to the western rock lobster. While key features like kelp and reef may be important to lobster distribution at a broad scale, it is the fine scale features in terrain that are likely to define its ecological niche. Determining the most appropriate landscape configuration and scale will be essential to refining niche habitats and will aid in selecting appropriate sites for protecting critical

  10. Distribution of linear growth rates in different directions in root apical meristems

    Directory of Open Access Journals (Sweden)

    Jerzy Nakielski

    2014-01-01

    Full Text Available Growth of apical meristems in plants may be well described by the growth tensor method. Hejnowicz (Envir. Exp. Bot. 1989, 29 determined growth tensors for roots: one with a minimum and the other with a maximum of the relative elemental growth rate in volume and used them for the description of two types of apices: one with an apical cell and merophytes (I, and the other with files of cells converging towards a quiescent centre, CQ (II. In the present paper the same cases are considered from the point of view of a spatial and directional variation of the relative elemental rate of growth in length, RERG1. Maps of the RERG1 in two planes: axial and tangential, the latter determined by periclinal-longitudinal (PL and periclinal-tangential (PT principal growth directions, are shown. In an apical part of apex i where there is maximum volumetric growth, there also occurs a maximum of RERG1 for all directions. In regions other than this RERG1 decreases although RERG1 in the PL direction predominates everywhere. In apex II RERG1 for all directions has a minimum in CQ and becomes increasingly larger with increasing distance from it - the maximum is in the PL direction in the cylindrical part of the apex. In peripheral parts of both apices, in the place of the root/cap junction, RERG, in the anticlinal direction is significantly small.

  11. The holonomic gradient method for the distribution function of the largest root of a Wishart matrix

    National Research Council Canada - National Science Library

    Hiroki Hashiguchi; Yasuhide Numata; Nobuki Takayama; Akimichi Takemura

    2013-01-01

    ... of a Wishart matrix, which involves a hypergeometric function 1F1 of a matrix argument. Numerical evaluation of the hypergeometric function has been one of the longstanding problems in multivariate distribution theory...

  12. Accumulation and distribution of dry matter in relation to root yield of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-05

    Oct 5, 2009 ... as required but no fertilizer was applied. The first and second ... system (SAS) for microsoft windows, Release 6.12. Mixed model procedure ...... distribution in relation to yield of cassava grown in controlled environments. Can.

  13. [Effects of water storage in deeper soil layers on the root growth, root distribution and economic yield of cotton in arid area with drip irrigation under mulch].

    Science.gov (United States)

    Luo, Hong-Hai; Zhang, Hong-Zhi; Zhang, Ya-Li; Zhang, Wang-Feng

    2012-02-01

    Taking cotton cultivar Xinluzao 13 as test material, a soil column culture expenment was conducted to study the effects of water storage in deeper (> 60 cm) soil layer on the root growth and its relations with the aboveground growth of the cultivar in arid area with drip irrigation under mulch. Two levels of water storage in 60-120 cm soil layer were installed, i. e., well-watered and no watering, and for each, the moisture content in 0-40 cm soil layer during growth period was controlled at two levels, i.e., 70% and 55% of field capacity. It was observed that the total root mass density of the cultivar and its root length density and root activity in 40-120 cm soil layer had significant positive correlations with the aboveground dry mass. When the moisture content in 0-40 cm soil layer during growth season was controlled at 70% of field capacity, the total root mass density under well-watered and no watering had less difference, but the root length density and root activity in 40-120 cm soil layer under well-watered condition increased, which enhanced the water consumption in deeper soil layer, increased the aboveground dry mass, and finally, led to an increased economic yield and higher water use efficiency. When the moisture content in 0-40 cm soil layer during growth season was controlled at 55% of field capacity and the deeper soil layer was well-watered, the root/shoot ratio and root length density in 40-120 cm soil layer and the root activity in 80-120 cm soil layer were higher, the water consumption in deeper soil layer increased, but it was still failed to adequately compensate for the negative effects of water deficit during growth season on the impaired growth of roots and aboveground parts, leading to a significant decrease in the economic yield, as compared with that at 70% of field capacity. Overall, sufficient water storage in deeper soil layer and a sustained soil moisture level of 65% -75% of field capacity during growth period could promote the

  14. Determination of Multimodal Isotopic Distributions: The Case of a (15)N Labeled Protein Produced into Hairy Roots.

    Science.gov (United States)

    Trouillard, Romain; Hubert-Roux, Marie; Tognetti, Vincent; Guilhaudis, Laure; Plasson, Carole; Menu-Bouaouiche, Laurence; Coquet, Laurent; Guerineau, François; Hardouin, Julie; Ele Ekouna, Jean-Pierre; Cosette, Pascal; Lerouge, Patrice; Boitel-Conti, Michèle; Afonso, Carlos; Ségalas-Milazzo, Isabelle

    2015-06-16

    Isotopic labeling is widely used in various fields like proteomics, metabolomics, fluxomics, as well as in NMR structural studies, but it requires an efficient determination of the isotopic enrichment. Mass spectrometry is the method of choice for such analysis. However, when complex expression systems like hairy roots are used for production, multiple populations of labeled proteins may be obtained. If the isotopic incorporation determination is actually well-known for unimodal distributions, the multimodal distributions have scarcely been investigated. Actually, only a few approaches allow the determination of the different labeled population proportions from multimodal distributions. Furthermore, they cannot be used when the number of the populations and their respective isotope ratios are unknown. The present study implements a new strategy to measure the (15)N labeled populations inside a multimodal distribution knowing only the peptide sequence and peak intensities from mass spectrometry analyses. Noteworthy, it could be applied to other elements, like carbon and hydrogen, and extended to a larger range of biomolecules.

  15. Evaluation of the degree of mixing of combinations of dry syrup, powder, and fine granule products in consideration of particle size distribution using near infrared spectrometry.

    Science.gov (United States)

    Yamamoto, Yoshihisa; Suzuki, Toyofumi; Matsumoto, Mika; Ohtani, Michiteru; Hayano, Shuichi; Fukami, Toshiro; Tomono, Kazuo

    2012-01-01

    We used near infrared (NIR) spectroscopy to evaluate the degree of mixing of blended dry syrup (DS) products whose particle sizes are not specified in the Revised 16th Edition of the Japanese Pharmacopoeia, and also evaluated the degree of mixing when powder products or fine granule products were added to DS products. The data obtained were used to investigate the relationship between the particle size distributions of the products studied and the degree of mixing. We found that the particle size distribution characteristics of the 15 DS products studied can be broadly classified into 5 types. Combinations of frequently prescribed products were selected to represent 4 of the 5 particle size distribution types and were blended with a mortar and pestle. The coefficient of variation (CV) decreased as the percent mass of Asverin® Dry Syrup 2% (Asverin-DS) increased in blends of Periactin® Powder 1% (Periactin) and Asverin-DS, indicating an improved degree of mixing (uniformity). In contrast, in blends of Periactin and Mucodyne® DS 33.3%, mixing a combination at a 1:1 mass ratio 40 times resulted in a CV of 20%. Other mixing frequencies and mass ratios resulted in a CV by 50% to 70%, indicating a very poor degree of mixing (poor uniformity). These results suggest that when combining different DSs, or a DS with a powder or fine granule product, the blending obtained with a mortar and pestle improves as the particle size distributions of the components approach each other and as the ranges of the distributions narrow.

  16. In Situ Distribution And Speciation Of Toxic Copper, Nickel, And Zinc In Hydrated Roots Of Cowpea

    Science.gov (United States)

    The phytotoxicity of trace metals is of global concern due to contamination of the landscape by human activities. Using synchrotron-based X-ray fluorescence microscopy and X-ray absorption spectroscopy, the distribution and speciation of Cu, Ni, and Zn was examined in situ

  17. Fine-Scale Mapping by Spatial Risk Distribution Modeling for Regional Malaria Endemicity and Its Implications under the Low-to-Moderate Transmission Setting in Western Cambodia.

    Directory of Open Access Journals (Sweden)

    Suguru Okami

    Full Text Available The disease burden of malaria has decreased as malaria elimination efforts progress. The mapping approach that uses spatial risk distribution modeling needs some adjustment and reinvestigation in accordance with situational changes. Here we applied a mathematical modeling approach for standardized morbidity ratio (SMR calculated by annual parasite incidence using routinely aggregated surveillance reports, environmental data such as remote sensing data, and non-environmental anthropogenic data to create fine-scale spatial risk distribution maps of western Cambodia. Furthermore, we incorporated a combination of containment status indicators into the model to demonstrate spatial heterogeneities of the relationship between containment status and risks. The explanatory model was fitted to estimate the SMR of each area (adjusted Pearson correlation coefficient R2 = 0.774; Akaike information criterion AIC = 149.423. A Bayesian modeling framework was applied to estimate the uncertainty of the model and cross-scale predictions. Fine-scale maps were created by the spatial interpolation of estimated SMRs at each village. Compared with geocoded case data, corresponding predicted values showed conformity [Spearman's rank correlation r = 0.662 in the inverse distance weighed interpolation and 0.645 in ordinal kriging (95% confidence intervals of 0.414-0.827 and 0.368-0.813, respectively, Welch's t-test; Not significant]. The proposed approach successfully explained regional malaria risks and fine-scale risk maps were created under low-to-moderate malaria transmission settings where reinvestigations of existing risk modeling approaches were needed. Moreover, different representations of simulated outcomes of containment status indicators for respective areas provided useful insights for tailored interventional planning, considering regional malaria endemicity.

  18. Distribution and ecological relevance of fine sediments in organic-enriched lagoons: The case study of the Cabras lagoon (Sardinia, Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Magni, P. [CNR-IAMC, National Research Council - Institute for Coastal Marine Environment Localita Sa Mardini, Torregrande, 09072 Oristano (Italy); International Marine Centre, Localita Sa Mardini, Torregrande, 09072 Oristano (Italy)], E-mail: paolo.magni@iamc.cnr.it; De Falco, G. [CNR-IAMC, National Research Council - Institute for Coastal Marine Environment Localita Sa Mardini, Torregrande, 09072 Oristano (Italy); International Marine Centre, Localita Sa Mardini, Torregrande, 09072 Oristano (Italy); Como, S. [International Marine Centre, Localita Sa Mardini, Torregrande, 09072 Oristano (Italy); Casu, D. [Dip. di Botanica ed Ecologia vegetale, Universita di Sassari, 07100 Sassari (Italy); Floris, A. [Dip. di Zoologia e Genetica evoluzionistica, Universita di Sassari, 07100 Sassari (Italy); Petrov, A.N. [Institute of Biology of the Southern Seas NASU, 99011 Sevastopol (Ukraine); Castelli, A. [Dip. di Biologia, Universita di Pisa, 56126 Pisa (Italy); Perilli, A. [CNR-IAMC, National Research Council - Institute for Coastal Marine Environment Localita Sa Mardini, Torregrande, 09072 Oristano (Italy); International Marine Centre, Localita Sa Mardini, Torregrande, 09072 Oristano (Italy)

    2008-03-15

    In organic-enriched sedimentary systems, like many Mediterranean coastal lagoons, a detailed analysis of sediment grain size composition and partitioning within the muds is crucial to investigate sedimentological trends related to both hydrodynamic energy and basin morphology. In these systems, sediment dynamics are particularly important because the partitioning and transport of fine sediments can strongly influence the redistribution and accumulation of large amounts of organic matter, and consequently the distribution of benthic assemblages and the trophic status and functioning of a lagoon. Nevertheless, studies on benthic-sediment relationships have been based mainly on a rather coarse analysis of sediment grain size features. In muddy systems, however, this approach may impede a proper evaluation of the relationships and effects of the distribution of fine sediment and organic matter on the biotic benthic components. Here we show that the distribution of sedimentary organic matter (OM) and total organic carbon (TOC) in the Cabras lagoon (Sardinia, Italy) can be explained (i.e., predicted) as a function of a nonlinear increase in the amount of the cohesive fraction of sediments ({<=}8 {mu}m grain size particles) and that this fraction strongly influences the structure, composition and distribution of macrobenthic assemblages. Even in such a homogeneously muddy system, characterized by 'naturally' occurring impoverished communities, impaired benthic assemblages were found at {<=}8 {mu}m, OM, TOC contents of about 77%, 11% and 3.5%, respectively. A review of studies conducted in Mediterranean coastal lagoons highlighted a lack of direct integrated analysis of sediment features and the biotic components. We suggest that, especially in organic-enriched coastal lagoons, monitoring programs should primarily investigate and consider the cohesive fraction of sediments in order to allow a better assessment of benthic-sediment relationships and ecological

  19. Distribution and ecological relevance of fine sediments in organic-enriched lagoons: the case study of the Cabras lagoon (Sardinia, Italy).

    Science.gov (United States)

    Magni, P; De Falco, G; Como, S; Casu, D; Floris, A; Petrov, A N; Castelli, A; Perilli, A

    2008-03-01

    In organic-enriched sedimentary systems, like many Mediterranean coastal lagoons, a detailed analysis of sediment grain size composition and partitioning within the muds is crucial to investigate sedimentological trends related to both hydrodynamic energy and basin morphology. In these systems, sediment dynamics are particularly important because the partitioning and transport of fine sediments can strongly influence the redistribution and accumulation of large amounts of organic matter, and consequently the distribution of benthic assemblages and the trophic status and functioning of a lagoon. Nevertheless, studies on benthic-sediment relationships have been based mainly on a rather coarse analysis of sediment grain size features. In muddy systems, however, this approach may impede a proper evaluation of the relationships and effects of the distribution of fine sediment and organic matter on the biotic benthic components. Here we show that the distribution of sedimentary organic matter (OM) and total organic carbon (TOC) in the Cabras lagoon (Sardinia, Italy) can be explained (i.e., predicted) as a function of a nonlinear increase in the amount of the cohesive fraction of sediments (< or = 8 microm grain size particles) and that this fraction strongly influences the structure, composition and distribution of macrobenthic assemblages. Even in such a homogeneously muddy system, characterized by "naturally" occurring impoverished communities, impaired benthic assemblages were found at < or = 8 microm, OM, TOC contents of about 77%, 11% and 3.5%, respectively. A review of studies conducted in Mediterranean coastal lagoons highlighted a lack of direct integrated analysis of sediment features and the biotic components. We suggest that, especially in organic-enriched coastal lagoons, monitoring programs should primarily investigate and consider the cohesive fraction of sediments in order to allow a better assessment of benthic-sediment relationships and ecological

  20. Comparison of MRI techniques and modelling with R-SWMS for determining solute distribution patterns and root water uptake of a white lupine plant (Lupinus Albus L.).

    Science.gov (United States)

    Koch, Axelle; Schröder, Natalie; Pohlmeier, Andreas; Garré, Sarah; Vanderborght, Jan; Javaux, Mathieu

    2017-04-01

    Measuring water extraction by plant would allow us to better understand root water uptake processes and how soil and plant properties affect them. Yet, direct measurement of root water uptake is still challenging and determining its distribution requires coupling experimentation and modelling. In this study, we investigated how the 3D monitoring of a tracer movement in a sand container with a lupine plant could inform us about root water uptake process. A sand column (10 cm height, 5 cm inner diameter) planted with an 18-day-old white lupine was subject to a tracer experiment with a chemically inert tracer (1 mmol/L Gd-DTPA2-) applied for 6 days. Then the tracer and water fluxes were stopped. The plume was monitored in 3-D for 7 days by Magnetic Resonance Imaging (Haber-Pohlmeier et al, unp). In addition the breakthrough curve at the outlet was also measured. We used a biophysical 3-D soil-plant model: R-SWMS (Javaux et al, 2008) to extract information from this experiment. First, we ran a virtual experiment to check the assumption that Gd concentration increase around roots is proportional to the extracted soil water during the same period. We also investigated whether this type of experiment helps discriminate different root hydraulic properties with a sensitivity analysis. Then, we compared the experimental and simulated Gd concentration patterns. A preliminary (qualitative) assessment showed that measured Gd distribution patterns were better represented by the model at day 7, where the main driver of the concentration distribution was root and not soil heterogeneity (which is not taken into account in the model). The main spatial and temporal features of the transport where adequately reproduced by the model in particular during the last day. The distribution of the tracer was shown to be sensitive to the root hydraulic properties. To conclude, information about root water uptake distributions and so about root hydraulic properties could be deduced from Gd

  1. Characterization of cadmium ((108)Cd) distribution and accumulation in Tagetes erecta L. seedlings: effect of split-root and of remove-xylem/phloem.

    Science.gov (United States)

    Qin, Qin; Li, Xuemei; Wu, Haiyan; Zhang, Yinqiu; Feng, Qian; Tai, Peidong

    2013-11-01

    Tagetes erecta has a high potential for cadmium (Cd) phytoremediation. Through several hydroponic experiments, characteristics of (108)Cd distribution and accumulation were investigated in T. erecta with split -roots or removed xylem/phloem. The results showed that (108)Cd transport from roots to aboveground tissues showed the homolateral transport phenomenon in split-root seedlings. (108)Cd content of leaves on the +(108)Cd side and the -(108)Cd side was not significantly different, which implied that there was horizontal transport of (108)Cd from the +(108)Cd side to the -(108)Cd side in cut-root seedlings. Like (108)Cd transport, the transport of (70)Zn was homolateral. Reduction of water consumption in the removed xylem treatment significantly decreased (108)Cd accumulation; whereas, the removed phloem treatment had no significant effect on water consumption, but did decrease (108)Cd accumulation in leaves of the seedlings. The removal of phloem significantly reduced distal leaf (108)Cd content, which was significantly lower than that in the basal leaves in both the split-root and unsplit-root seedlings. Overall, the results presented in this study revealed that the root to aboveground cadmium translocation via phloem is as an important and common physiological process as xylem determination of the cadmium accumulation in stems and leaves of marigold seedlings. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Synchrotron X-ray microfluorescence measurement of metal distributions in Phragmites australis root system in the Yangtze River intertidal zone

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huan; Zhang, Weiguo; Qian, Yu; Liu, Wenliang; Yu, Lizhong; Yoo, Shinjae; Wang, Jun; Wang, Jia-Jun; Eng, Christopher; Liu, Chang-Jun; Tappero, Ryan

    2016-06-15

    This study investigates the distributions of Br, Ca, Cl, Cr, Cu, K, Fe, Mn, Pb, Ti, V and Zn inPhragmites australisroot system and the function of Fe nanoparticles in scavenging metals in the root epidermis using synchrotron X-ray microfluorescence, synchrotron transmission X-ray microscope measurement and synchrotron X-ray absorption near-edge structure techniques. The purpose of this study is to understand the mobility of metals in wetland plant root systems after their uptake from rhizosphere soils.Phragmites australissamples were collected in the Yangtze River intertidal zone in July 2013. The results indicate that Fe nanoparticles are present in the root epidermis and that other metals correlate significantly with Fe, suggesting that Fe nanoparticles play an important role in metal scavenging in the epidermis.

  3. Fine-scale spatial distribution of the common lugworm Arenicola marina, and effects of intertidal clam fishing

    Science.gov (United States)

    Boldina, Inna; Beninger, Peter G.

    2014-04-01

    Despite its ubiquity and its role as an ecosystem engineer on temperate intertidal mudflats, little is known of the spatial ecology of the lugworm Arenicola marina. We estimated lugworm densities and analyzed the spatial distribution of A. marina on a French Atlantic mudflat subjected to long-term clam digging activities, and compared these to a nearby pristine reference mudflat, using a combination of geostatistical techniques: point-pattern analysis, autocorrelation, and wavelet analysis. Lugworm densities were an order of magnitude greater at the reference site. Although A. marina showed an aggregative spatial distribution at both sites, the characteristics and intensity of aggregation differed markedly between sites. The reference site showed an inhibition process (regular distribution) at distances marina was clearly aggregated at both sites; however, the autocorrelation strength was much weaker at the impacted site. In addition, the non-impacted site presented multi-scale spatial distribution, which was not evident at the impacted site. The differences observed between the spatial distributions of the fishing-impacted vs. the non-impacted site reflect similar findings for other components of these two mudflat ecosystems, suggesting common community-level responses to prolonged mechanical perturbation: a decrease in naturally-occurring aggregation. This change may have consequences for basic biological characteristics such as reproduction, recruitment, growth, and feeding.

  4. Subcellular distribution and uptake mechanism of di-n-butyl phthalate in roots of pumpkin (Cucurbita moschata) seedlings.

    Science.gov (United States)

    Lin, Qingqi; Yang, Xiuhong; Huang, Xiongfei; Wang, Shizhong; Chao, Yuanqing; Qiu, Rongliang

    2016-01-01

    Phthalate acid esters (PAEs) are of particular concern due to their potential environmental risk to human and nonhuman organisms. Although uptake of PAEs by plants has been reported by several researchers, information about the intracellular distribution and uptake mechanisms of PAEs is still lacking. In this study, a series of hydroponic experiments using intact pumpkin (Cucurbita moschata) seedlings was conducted to investigate how di-n-butyl phthalate (DnBP), one of the most frequently identified PAEs in the environment, enters and is distributed in roots. DnBP was transported into subcellular tissues rapidly in the initial uptake period (<12 h). More than 80% of DnBP was detected in the cell walls and organelles, which suggests that DnBP is primarily accumulated in these two fractions due to their high affinity to DnBP. The kinetics of DnBP uptake were fitted well with the Michaelis-Menten equation, suggesting that a carrier-mediated process was involved. The application of 2,4-dinitrophenol and sodium vanadate reduced the uptake of DnBP by 37 and 26%, respectively, while aquaporin inhibitors, silver and glycerol, had no effect on DnBP uptake. These data demonstrated that the uptake of DnBP included a carrier-mediated and energy-dependent process without the participation of aquaporins.

  5. Salt stress-induced seedling growth inhibition coincides with differential distribution of serotonin and melatonin in sunflower seedling roots and cotyledons.

    Science.gov (United States)

    Mukherjee, Soumya; David, Anisha; Yadav, Sunita; Baluška, František; Bhatla, Satish Chander

    2014-12-01

    Indoleamines regulate a variety of physiological functions during the growth, morphogenesis and stress-induced responses in plants. Present investigations report the effect of NaCl stress on endogenous serotonin and melatonin accumulation and their differential spatial distribution in sunflower (Helianthus annuus) seedling roots and cotyledons using HPLC and immunohistochemical techniques, respectively. Exogenous serotonin and melatonin treatments lead to variable effect on hypocotyl elongation and root growth under NaCl stress. NaCl stress for 48 h increases endogenous serotonin and melatonin content in roots and cotyledons, thus indicating their involvement in salt-induced long distance signaling from roots to cotyledons. Salt stress-induced accumulation of serotonin and melatonin exhibits differential distribution in the vascular bundles and cortex in the differentiating zones of the primary roots, suggesting their compartmentalization in the growing region of roots. Serotonin and melatonin accumulation in oil body rich cells of salt-treated seedling cotyledons correlates with longer retention of oil bodies in the cotyledons. Present investigations indicate the possible role of serotonin and melatonin in regulating root growth during salt stress in sunflower. Effect of exogenous serotonin and melatonin treatments (15 μM) on sunflower seedlings grown in the absence or presence of 120 mM NaCl substantiates their role on seedling growth. Auxin and serotonin biosynthesis are coupled to the common precursor tryptophan. Salt stress-induced root growth inhibition, thus pertains to partial impairment of auxin functions caused by increased serotonin biosynthesis. In seedling cotyledons, NaCl stress modulates the activity of N-acetylserotonin O-methyltransferase (HIOMT; EC 2.1.1.4), the enzyme responsible for melatonin biosynthesis from N-acetylserotonin.

  6. Influence of land crabs Gecarcinus quadratus (Gecarcinidae on distributions of organic carbon and roots in a Costa Rican rain forest

    Directory of Open Access Journals (Sweden)

    Peter M Sherman

    2006-03-01

    Full Text Available In Costa Rica’s Corcovado National Park,the fossorial land crab, Gecarcinus quadratus (Gecarcinidae, densely populates (1-6 m-2 a region of forest extending from the Park’s Pacific coastline inland to ca.600 m. Throughout this coastal forest (‘crabzone’, crabs selectively forage for fallen leaves and relocate them to subterranean burrow chambers. Comparisons between surface soils (0 -15 cm sampled from the crabzone and forest lying immediately inland that is naturally devoid of crabs (‘crabless zone’ suggest that crabzone top soils contained less organic carbon and fewer fine and very fine roots. In contrast, soils sampled from 70 -100 cm depths in the crabzone contained twice the carbon of the crabless zone during the dry season but similar values during the wet season. Two years of experimental crab exclusion from 25 m² replicates established in the crabzone resulted in 16% more organic carbon content in surface soils relative to baseline conditions (n.s. and 22% more carbon than final control values (P El cangrejo Gecarcinus quadratus (Gecarcinidae habita madrigueras terrestres y afecta el retorno de carbón orgánico a los suelos de los bosques lluviosos al reducir la acumulación de hojarasca y alterar su proceso de descomposición. En el Parque Nacional Corcovado en Costa Rica, G. quadratus vive en altas densidades (de 1-6 cangrejos m-2 en una franja boscosa que se extiende desde la costa del Océano Pacífico hasta 600 m tierra adentro. En esta región de bosque costero (‘zona cangrejera’, los cangrejos buscan alimento selectivamente en la hojarasca, trasladando lo que recolectan a sus cuevas de más de 1 m de profundidad. Comparaciones entre la superficie de los suelos de la zona cangrejera y los de la región inmediata pero más lejana a la costa y sin cangrejos (‘zona no-cangrejera’, revelan que la capa superficial del suelo (a 10 cm en la zona cangrejera contiene 39% menos carbono orgánico, 72% menos ra

  7. The unseen iceberg: plant roots in arctic tundra.

    Science.gov (United States)

    Iversen, Colleen M; Sloan, Victoria L; Sullivan, Patrick F; Euskirchen, Eugenie S; McGuire, A David; Norby, Richard J; Walker, Anthony P; Warren, Jeffrey M; Wullschleger, Stan D

    2015-01-01

    Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits - including distribution, chemistry, anatomy and resource partitioning - play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions.

  8. The unseen iceberg: Plant roots in arctic tundra

    Science.gov (United States)

    Iverson, Colleen M.; Sloan, Victoria L.; Sullivan, Patrick F.; Euskirchen, E.S.; McGuire, Anthony; Norby, Richard J.; Walker, Anthony P.; Warren, Jeffrey M.; Wullschleger, Stan D.

    2015-01-01

    Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits – including distribution, chemistry, anatomy and resource partitioning – play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions.

  9. RAD genotyping reveals fine-scale genetic structuring and provides powerful population assignment in a widely distributed marine species, the American lobster (Homarus americanus).

    Science.gov (United States)

    Benestan, Laura; Gosselin, Thierry; Perrier, Charles; Sainte-Marie, Bernard; Rochette, Rémy; Bernatchez, Louis

    2015-07-01

    Deciphering genetic structure and inferring connectivity in marine species have been challenging due to weak genetic differentiation and limited resolution offered by traditional genotypic methods. The main goal of this study was to assess how a population genomics framework could help delineate the genetic structure of the American lobster (Homarus americanus) throughout much of the species' range and increase the assignment success of individuals to their location of origin. We genotyped 10 156 filtered SNPs using RAD sequencing to delineate genetic structure and perform population assignment for 586 American lobsters collected in 17 locations distributed across a large portion of the species' natural distribution range. Our results revealed the existence of a hierarchical genetic structure, first separating lobsters from the northern and southern part of the range (FCT  = 0.0011; P-value = 0.0002) and then revealing a total of 11 genetically distinguishable populations (mean FST  = 0.00185; CI: 0.0007-0.0021, P-value < 0.0002), providing strong evidence for weak, albeit fine-scale population structuring within each region. A resampling procedure showed that assignment success was highest with a subset of 3000 SNPs having the highest FST . Applying Anderson's (Molecular Ecology Resources, 2010, 10, 701) method to avoid 'high-grading bias', 94.2% and 80.8% of individuals were correctly assigned to their region and location of origin, respectively. Lastly, we showed that assignment success was positively associated with sample size. These results demonstrate that using a large number of SNPs improves fine-scale population structure delineation and population assignment success in a context of weak genetic structure. We discuss the implications of these findings for the conservation and management of highly connected marine species, particularly regarding the geographic scale of demographic independence.

  10. Toxic effects of Cu{sup 2+} on growth, nutrition, root morphology, and distribution of Cu in roots of Sabi grass

    Energy Technology Data Exchange (ETDEWEB)

    Kopittke, P.M., E-mail: p.kopittke@uq.edu.au [School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), The University of Queensland, St. Lucia, Queensland 4072 (Australia); Asher, C.J. [School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072 (Australia); Blamey, F.P.C.; Menzies, N.W. [School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland 4072 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), The University of Queensland, St. Lucia, Queensland 4072 (Australia)

    2009-08-01

    Sabi grass (Urochloa mosambicensis (Hack.) Dandy) (a C4 species of Poaceae) is commonly used to revegetate disturbed sites in low-rainfall environments, but comparatively little is known regarding copper (Cu) toxicity in this species. A dilute nutrient solution culture experiment was conducted for 10 d to examine the effects of elevated Cu{sup 2+} activities ({l_brace}Cu{sup 2+}{r_brace}) on the growth of Sabi grass. Growth was inhibited by high Cu in solution, with a 50% reduction in the relative fresh mass occurring at 1.0 {mu}M {l_brace}Cu{sup 2+}{r_brace} for the roots and 1.2 {mu}M {l_brace}Cu{sup 2+}{r_brace} for the shoots. In solutions containing 1.2-1.9 {mu}M {l_brace}Cu{sup 2+}{r_brace}, many of the roots ruptured due to the tearing and separation of the rhizodermis and outer cortex from the underlying tissues. Transmission electron microscopy revealed that Cu-rich deposits were found to accumulate predominantly within vacuoles. Due to limited translocation of Cu from the roots to the shoots, phytotoxicity is likely to be more of a problem in remediation of Cu-toxic sites than is Cu toxicity of fauna consuming the above-ground biomass.

  11. Nerve root distribution of deltoid and biceps brachii muscle in cervical spondylotic myelopathy: a potential risk factor for postoperative shoulder muscle weakness after posterior decompression.

    Science.gov (United States)

    Yonemura, Hiroshi; Kaneko, Kazuo; Taguchi, Toshihiko; Fujimoto, Hideaki; Toyoda, Kouichiro; Kawai, Shinya

    2004-01-01

    To investigate the nerve root distribution of deltoid and biceps brachii muscle, compound muscle action potentials (CMAPs) were recorded intraoperatively following nerve root stimulation in cervical spondylotic myelopathy. A total of 19 upper limbs in 12 patients aged 55-72 years (mean, 65.5 years) with cervical spondylotic myelopathy were examined. CMAPs were recorded from deltoid and biceps brachii muscle following C5 and C6 root stimulation. Although both C5 and C6 roots were innervated for deltoid and biceps brachii muscle in all subjects, the amplitude ratio of CMAPs (C5/C6) differed individually depending on the symptomatic intervertebral levels of the spinal cord. The C5 root predominantly innervated both deltoid and biceps brachii in patients with symptomatic cord lesions at the C4-C5 intervertebral level compared to patients with symptomatic cord lesions at the C5-C6 intervertebral level. Although no patients sustained postoperative radiculopathy in our study, severe weakness and unfavorable recovery are expected when the C5 root in patients with C4-C5 myelopathy is damaged. From the electrophysiological aspect, C4-C5 cord lesions are likely to be a potential risk factor for postoperative shoulder muscle weakness in patients with compressive cervical myelopathy.

  12. 氮、水交互对长白山阔叶红松林细根形态及生产量的影响%Effects of nitrogen﹣water interaction on fine root morphology and production in a mi.ed Pinus koraiensis forest in Changbai Mountains, northeastern China

    Institute of Scientific and Technical Information of China (English)

    郭伟; 宫浩; 韩士杰; 金阳; 王译焓; 冯圆; 王存国

    2016-01-01

    Changing soil nutrient and water profoundly influence carbon allocation in the forest ecosystem, and then impact morphology and production of tree fine roots. We studied the responses of fine root morphology and production in scenarios of increased nitrogen deposition (50 kg/( ha·yr) ) and decreased precipitation (30% throughfall, about 210 mm/yr) in a broadleaf﹣Pinus koraiensis forest in Changbai Mountains, northeastern China. Results demonstrated that various factors ( treatment, sampling date, soil layer) collectively influenced the morphology and production of fine roots. Nitrogen fertilization ( N ) significantly decreased the diameter, but increased specific root length of fine roots in 0 -10 cm soil layer;the root length density in dry treatment plots ( D) had been raised by 1. 55-2. 44 times and the production of fine roots increased by 104 g/( m2·yr) as compared with CK plots; decreased throughfall and nitrogen fertilization ( DN) significantly increased the diameter and production of fine roots in 10-20 cm soil layer. Thus, there might be the functional differentiation on nitrogen and water uptake of fine roots in different soil layers in the mixed Pinus koraiensis forest, and the spatial﹣temporal variations of fine root morphology and production are activated by nitrogen deposition, changed precipitation and their interactions.%土壤养分和水分的变化深刻影响着森林生态系统的碳分配,进而影响树木细根形态结构和生产量。本文以我国长白山阔叶红松林为研究对象,研究氮沉降增加(50 kg/(hm2·a))和降雨量减少(30%穿透雨,约210 mm/a)情形下,细根形态结构和生产量的时空响应特征。结果表明,细根形态结构和生产量受多种因素(处理、取样时间、取样层次)的共同影响。施氮样地( N)显著降低了0~10 cm土壤层细根直径,从而增加了比根长;减少降雨样地(D)细根根长密度增加了1.55~3.24倍,细根生产量增加了104 g

  13. Concentration levels and spatial distribution of sulphur and metals in fine-grained sediments in western Finland

    Directory of Open Access Journals (Sweden)

    M. ÅSTRÖM

    2008-12-01

    Full Text Available On the coastal plains of Finland, widespread Holocene marine and lacustrine sediments have developed into acid sulphate soil as a result of extensive artificial drainage for agricultural purposes. This has caused a variety of environmental problems. The aim of this study was to determine the concentration levels and spatial distribution of sulphur, carbon and metals [titanium, vanadium, chromium, manganese (Mn, iron, cobalt (Co, nickel (Ni, copper (Cu, zinc (Zn] in these sediments, in order to increase the geochemical understanding of the parent materials from which acid sulphate soil develops. Sediment samples were collected at 317 sites from a depth of 1.5–3 m. While the sediments have high S (sulphide concentrations (median = 0.54% and thus a strong acidification potential, they carry transition metals mainly in smallsized silicates close to “background concentrations” far below contamination limits. The previously documented extensive release of Co, Cu, Mn, Ni and Zn from oxidised and acidified layers of these sediments (i.e. acid sulphate soil is thus not explained by anomalously high natural or anthropogenic metal concentrations of the soils/sediments, but by an inherent highly mobile metal pool. Spatial-distribution maps highlight areas of elevated S and Mn concentrations, where it is likely that ditching and subsequent oxidation will result in an exceptionally large release of protons and Mn respectively.;

  14. NEW RSW & Wall Fine Fully Tetrahedral Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — NEW RSW Fine Fully Tetrahedral Grid with Viscous Wind Tunnel wall at the root. This grid is for a node-based unstructured solver. Note that the CGNS file is very...

  15. NEW RSW & Wall Fine Mixed Element Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — RSW Fine Mixed Element Grid with viscous root wind tunnel wall. This grid is for a node-based unstructured solver. Quad Surface Faces= 38016 Tria Surface Faces=...

  16. Distribution of ibogaine and noribogaine in a man following a poisoning involving root bark of the Tabernanthe iboga shrub.

    Science.gov (United States)

    Kontrimaviciūte, Violeta; Mathieu, Olivier; Mathieu-Daudé, Jean-Claude; Vainauskas, Paulius; Casper, Thierry; Baccino, Eric; Bressolle, Françoise M M

    2006-09-01

    In the present paper, we report for the first time the tissue distribution of ibogaine and noribogaine, the main metabolite of ibogaine, in a 48-year-old Caucasian male, with a history of drug abuse, found dead at his home after a poisoning involving the ingestion of root bark from the shrub Tabernanthe iboga. Ibogaine and noribogaine were quantified in tissues and fluids using a fully validated liquid chromatography-electrospray mass spectrometry method. Apart from cardiac tissue, ibogaine and noribogaine were identified in all matrices investigated. The highest concentrations were found in spleen, liver, brain, and lung. The tissue/subclavian blood concentration ratios averaged 1.78, 3.75, 1.16, and 4.64 for ibogaine and 0.83, 2.43, 0.90, and 2.69 for noribogaine for spleen, liver, brain, and lung, respectively. Very low concentrations of the two drugs were found in the prostatic tissue. Both ibogaine and noribogaine are secreted in the bile and cross the blood-brain barrier. Four other compounds were detected in most of the studied matrices. One of them was identified as ibogamine. Unfortunately, we were not able to positively identify the other three compounds because of the unavailability of reference substances. Two of them could possibly be attributed to the following oxidation products: iboluteine and desmethoxyiboluteine. The third compound could be ibogaline.

  17. Studies on the endoplasmic reticulum. IV. Its form and distribution during mitosis in cells of onion root tip.

    Science.gov (United States)

    PORTER, K R; MACHADO, R D

    1960-02-01

    Cells of onion and garlic root tips were examined under the electron and phase contrast microscopes after fixation in KMnO(4). Special attention was focused on the distribution and behavior of the endoplasmic reticulum (ER) during the several phases of mitosis. Slender profiles, recognized as sections through thin lamellar units of the ER (most prominent in KMnO(4)-fixed material), are distributed more or less uniformly in the cytoplasm of interphase cells and show occasional continuity with the nuclear envelope. In late prophase the nuclear envelope breaks down and its remnants plus cytoplasmic elements of the ER, which are morphologically identical, surround the spindle in a zone from which mitochondria, etc., are excluded. During metaphase these ER elements persist and concentrate as two separate systems in the polar caps or zones of the spindle. At about this same time they begin to proliferate and to invade the ends of the spindle. The invading lamellar units form drape-like partitions between the anaphase chromosomes. In late anaphase, their advancing margins reach the middle zone of the spindle and begin to fray out. Finally, in telophase, while elements of the ER in the poles of the spindle coalesce around the chromosomes to form the new envelope, the advancing edges of those in the middle zone reticulate at the level of the equator to form a close lattice of tubular elements. Within this, which is identified as the phragmoplast, the earliest signs of the cell plate appear in the form of small vesicles. These subsequently grow and fuse to complete the separation of the two protoplasts. Other morphological units apparently participating in mitosis are described. Speculation is provided on the equal division or not of the nuclear envelope and the contribution the envelope fragments make to the ER of the new cell.

  18. Synchrotron micro-scale measurement of metal distributions in Phragmites australis and Typha latifolia root tissue from an urban brownfield site.

    Science.gov (United States)

    Feng, Huan; Qian, Yu; Gallagher, Frank J; Zhang, Weiguo; Yu, Lizhong; Liu, Changjun; Jones, Keith W; Tappero, Ryan

    2016-03-01

    Liberty State Park in New Jersey, USA, is a "brownfield" site containing various levels of contaminants. To investigate metal uptake and distributions in plants on the brownfield site, Phragmites australis and Typha latifolia were collected in Liberty State Park during the growing season (May-September) in 2011 at two sites with the high and low metal loads, respectively. The objective of this study was to understand the metal (Fe, Mn, Cu, Pb and Zn) concentration and spatial distributions in P. australis and T. latifolia root systems with micro-meter scale resolution using synchrotron X-ray microfluorescence (μXRF) and synchrotron X-ray computed microtomography (μCMT) techniques. The root structure measurement by synchrotron μCMT showed that high X-ray attenuation substance appeared in the epidermis. Synchrotron μXRF measurement showed that metal concentrations and distributions in the root cross-section between epidermis and vascular tissue were statistically different. Significant correlations were found between metals (Cu, Mn, Pb and Zn) and Fe in the epidermis, implying that metals were scavenged by Fe oxides. The results from this study suggest that the expression of metal transport and accumulation within the root systems may be element specific. The information derived from this study can improve our current knowledge of the wetland plant ecological function in brownfield remediation. Copyright © 2015. Published by Elsevier B.V.

  19. The distribution of glutathione and homoglutathione in leaf, root and seed tissue of 73 species across the three sub-families of the Leguminosae.

    Science.gov (United States)

    Colville, Louise; Sáez, Clara M Blanco; Lewis, Gwilym P; Kranner, Ilse

    2015-07-01

    Homoglutathione (γ-glutamyl-cysteinyl-β-alanine) is a homologue of glutathione (γ-glutamyl-cysteinyl-glycine), which is a ubiquitous and indispensable tripeptide in eukaryotes with multi-facetted functions, many of which relate to cellular redox regulation. Homoglutathione is unique to the Leguminosae family, but studies of its occurrence have been restricted to the Papilionoideae subfamily, and almost exclusively to crop species. To determine whether the distribution of homoglutathione in the Leguminosae has a phylogenetic basis the occurrence of homoglutathione was investigated in the leaves, roots and seeds of 73 wild species of Leguminosae, representing 30 tribes across the Caesalpinioideae, Mimosoideae and Papilionoideae subfamilies. Homoglutathione was found only in the Papilionoideae, and was generally restricted to the 'Old World Clade'. It is proposed that homoglutathione may have arisen following a whole genome duplication event after the divergence of the Old World Clade. Homoglutathione is believed to fulfil the same functional roles as glutathione, but this study showed that homoglutathione and glutathione have different tissue-specific distribution patterns. Homoglutathione tended to occur more frequently in root tissue, and higher concentrations were found in leaves and roots, whereas glutathione tended to be present at the highest concentrations in seeds. This may reflect a distinct role for homoglutathione, particularly in roots, or an inability of homoglutathione to functionally replace glutathione in reproductive tissues. However, no relationships with environmental factors or nodulation were observed. Greater understanding of the factors that influence homoglutathione distribution may help to elucidate its unique function in some legume species.

  20. Distribution of fish, crustacea and zooplankton at different distances from mangrove prop roots within a semi-isolated lagoon

    National Research Council Canada - National Science Library

    J Jaxion-Harm; C Pien; J E Saunders; M R Speight

    2013-01-01

    ... of adjacent seagrass and coral-reef habitats. In this study, visual surveys, minnow traps and plankton tows, which were deployed at abutting mangrove prop roots and on macro-algal beds 5 and 15 m away from the prop roots, were used to study...

  1. Anne Fine

    Directory of Open Access Journals (Sweden)

    Philip Gaydon

    2015-04-01

    Full Text Available An interview with Anne Fine with an introduction and aside on the role of children’s literature in our lives and development, and our adult perceptions of the suitability of childhood reading material.Since graduating from Warwick in 1968 with a BA in Politics and History, Anne Fine has written over fifty books for children and eight for adults, won the Carnegie Medal twice (for Goggle-Eyes in 1989 and Flour Babies in 1992, been a highly commended runner-up three times (for Bill’s New Frock in 1989, The Tulip Touch in 1996, and Up on Cloud Nine in 2002, been shortlisted for the Hans Christian Andersen Award (the highest recognition available to a writer or illustrator of children’s books, 1998, undertaken the positon of Children’s Laureate (2001-2003, and been awarded an OBE for her services to literature (2003. Warwick presented Fine with an Honorary Doctorate in 2005.Philip Gaydon’s interview with Anne Fine was recorded as part of the ‘Voices of the University’ oral history project, co-ordinated by Warwick’s Institute of Advanced Study.

  2. Ion distribution measured by electron probe X-ray microanalysis in apoplastic and symplastic pathways in root cells in sunflower plants grown in saline medium

    Indian Academy of Sciences (India)

    Reza Ebrahimi; S C Bhatla

    2012-09-01

    Little is known about how salinity affects ions distribution in root apoplast and symplast. Using x-ray microanalysis, ions distribution and the relative contribution of apoplastic and symplastic pathways for delivery of ions to root xylem were studied in sunflower plants exposed to moderate salinity (EC=6). Cortical cells provided a considerably extended Na+ and Cl− storage facility. Their contents are greater in cytoplasm (root symplast) as compared to those in intercellular spaces (root apoplast). Hence, in this level of salinity, salt damage in sunflower is not dehydration due to extracellular accumulation of sodium and chloride ions, as suggested in the Oertli hypothesis. On the other hand, reduction in calcium content due to salinity in intercellular space is less than reduction in the cytoplasm of cortical cells. It seems that sodium inhibits the radial movement of calcium in symplastic pathway more than in the apoplastic pathway. The cell wall seems to have an important role in providing calcium for the apoplastic pathway. Redistribution of calcium from the cell wall to intercellular space is because of its tendency towards xylem through the apoplastic pathway. This might be a strategy to enhance loading of calcium to xylem elements and to reduce calcium deficiency in young leaves under salinity. This phenomenon may be able to increase salt tolerance in sunflower plants. Supplemental calcium has been found to be effective in reducing radial transport of Na+ across the root cells and their loading into the xylem, but not sodium absorption. Supplemental calcium enhanced Ca2+ uptake and influx into roots and transport to stele.

  3. Ion distribution measured by electron probe X-ray microanalysis in apoplastic and symplastic pathways in root cells in sunflower plants grown in saline medium.

    Science.gov (United States)

    Ebrahimi, Reza; Bhatla, S C

    2012-09-01

    Little is known about how salinity affects ions distribution in root apoplast and symplast. Using x-ray microanalysis, ions distribution and the relative contribution of apoplastic and symplastic pathways for delivery of ions to root xylem were studied in sunflower plants exposed to moderate salinity (EC=6). Cortical cells provided a considerably extended Na(+) and Cl(-) storage facility. Their contents are greater in cytoplasm (root symplast) as compared to those in intercellular spaces (root apoplast). Hence, in this level of salinity, salt damage in sunflower is not dehydration due to extracellular accumulation of sodium and chloride ions, as suggested in the Oertli hypothesis. On the other hand, reduction in calcium content due to salinity in intercellular space is less than reduction in the cytoplasm of cortical cells. It seems that sodium inhibits the radial movement of calcium in symplastic pathway more than in the apoplastic pathway. The cell wall seems to have an important role in providing calcium for the apoplastic pathway. Redistribution of calcium from the cell wall to intercellular space is because of its tendency towards xylem through the apoplastic pathway. This might be a strategy to enhance loading of calcium to xylem elements and to reduce calcium deficiency in young leaves under salinity. This phenomenon may be able to increase salt tolerance in sunflower plants. Supplemental calcium has been found to be effective in reducing radial transport of Na(+) across the root cells and their loading into the xylem, but not sodium absorption. Supplemental calcium enhanced Ca(2+) uptake and influx into roots and transport to stele.

  4. Spatial distribution of arsenic and heavy metals in willow roots from a contaminated floodplain soil measured by X-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zimmer, Dana, E-mail: dana.zimmer@uni-rostock.de [Soil Science, University of Rostock, Justus-von-Liebig-Weg 6, D-18051 Rostock (Germany); Kruse, Jens; Baum, Christel [Soil Science, University of Rostock, Justus-von-Liebig-Weg 6, D-18051 Rostock (Germany); Borca, Camelia [Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen PSI (Switzerland); Laue, Michael [Electron Microscopy Centre, University of Rostock, Medical Faculty, Strempelstr. 14, D-18057 Rostock (Germany); Hause, Gerd [Microscopy Unit, Biocenter of the University of Halle, Weinbergweg 22, D-06120 Halle/Saale (Germany); Meissner, Ralph [UFZ-Helmholtz Centre for Environmental Research, Department of Soil Physics, Lysimeter Station, Dorfstrasse 55, D-39615 Falkenberg (Germany); Leinweber, Peter [Soil Science, University of Rostock, Justus-von-Liebig-Weg 6, D-18051 Rostock (Germany)

    2011-09-01

    Under changing redox conditions some plants create plaques at their root surface, which may affect the mobility and uptake of As and heavy metals but it is unknown to what extent this also holds true for willows in contaminated floodplain soils. Therefore, willow roots were sampled from a phytoremediation trial in the contaminated floodplain of the river Elbe (Germany), cryofixed, freeze-dried, and cross sections were mapped for the distribution of As, Ca, Cu, Fe, K, Mn, Ni, S and Zn by synchrotron based X-ray fluorescence spectroscopy. The elements Ca, Cu, Ni, S and Zn were concentrated in the aerenchymatic tissue, and not associated with Fe and Mn. Mixed Fe-Mn plaques covered the surface of the willow roots and As was accumulated in these plaques. The observed association pattern between As and Fe was explained by the different sorption/desorption properties of As(III) and As(V). The Cu and Zn intensities were not associated with the intensity of Fe in the plaque, which seems to be a willow-specific difference compared to other wetland plants. These results suggested that willows are especially suited to stabilize low-phytoextractable elements like Cu and As in their roots and rhizosphere. Thus, short rotation coppicing of willows may be a practical approach to mitigate the adverse effects of floodplain soil contamination. - Research highlights: {yields} Elemental distributions were mapped on willow roots for the first time by synchrotron-based X-ray fluorescence. {yields} Ca, Cu, Ni, S and Zn were enriched in the aerenchyma but As, Fe and Mn formed root plaques. {yields} The Cu and Zn enrichments in aerenchyma but absence in plaques appeared to be willow-specific. {yields} In the plaques were three groups of pixels which strongly differed in the As to Fe and As to Mn ratios. {yields} This indicated different species of these redox-sensitive elements.

  5. 不同沙地生境下黄柳(Salix gordejevii)的根系分布和冠层结构特征%Root distribution and canopy structure of Salix gordejevii in different sandy land habitats

    Institute of Scientific and Technical Information of China (English)

    任安芝; 高玉葆; 王金龙

    2001-01-01

    Root distribution and canopy structure parameters of S. gordejevii in semi-fixed sand dunes, fixed sand dunes and inter-dunes lowland were investigated. The population in the semi-fixed sand dunes had the most developed root systems, followed by the population in the fixed sand dunes, and that in the inter-dunes lowland was the last. The number of thick roots was closely related to the soil water content and volume weight of the soil, while that of fine roots closely related to the soil compactness and volume weight. The population in the semi-fixed sand dunes had a greater leaf area index and longer first-year shoots whose frequency distribution followed a Normal Distribution Model. The population in the inter-dunes lowland had a lower leaf area index and shorter first-year shoots, whose frequency distribution tended to follow a Logarithmic Normal Distribution Model. The population in fixed sand dunes was rather intermediary between the above two and the frequency distribution of the first-year shoot lengths followed a Weibull Distribution Model.%对分布于3种不同沙地生境(半固定沙丘、固定沙丘、丘间低地)黄柳灌丛的根系分布(根的数目与深度分布)和冠层结构特征(叶面积指数、平均叶倾角以及当年枝长度分布)进行了研究。半固定沙丘上的黄柳根系最发达(根系分布深,数量大),固定沙丘的黄柳明显不及前者,而丘间低地的黄柳根系最不发达。粗根(Φ≥5mm)的分布与土壤水分和土壤容重呈显著相关性,细根(Φ<5mm)的分布与土壤容重和紧实度呈极显著相关。不同程度的根系发育导致地上部分的繁茂程度不同:分布于半固定沙丘上的黄柳灌丛叶面积指数较大,当年枝平均长度较大,枝长频度分布趋于正态分布;丘间低地的黄柳灌丛叶面积指数较小,当年枝平均长度较小,枝长频度分布趋于对数正态分布;固定沙丘上灌丛的上述

  6. 中亚热带6种不同更新方式森林0-5mm根系直径频率分布%Diameter frequency distribution for 0-5mm roots in six mid-subtropical forests subject to different regeneration approaches

    Institute of Scientific and Technical Information of China (English)

    胡双成; 熊德成; 黄锦学; 王韦韦; 黄超超; 邓飞; 陈云玉; 陈光水

    2015-01-01

    forest of Castanopsis carlesii through natural regeneration ( NR) , the secondary forest of Castanopsis carlesii through natural regeneration with anthropogenic promotion ( AR ) , the Castanopsis carlesii plantation ( CC ) , the Pinus massoniana plantation ( PM) , and the Cunninghamia lanceolata plantation ( CL) , in Sanming, Fujian Province. Because it is different to differentiate between the roots of different species, the study was conducted at the community level. There were three main conclusions in this study. First, root length density ( RLD) and root biomass density ( RBD) for all the three diameter ranges (≤1 mm,≤2 mm, and ≤5 mm) decreased from NF, NR, AR, to CC. Out of the three plantations, the highest RLD and RBD wereobtained in CC, while the lowest RLD and RBD was obtained in PM. Second, out of roots with 0—5mm diameter, 87%—98% and 65%—88% were represented by 0—2 mm and 0—1 mm diameter roots, respectively. The roots of NF, CC, and CL had the similar root diameter frequency distributions, with a maximum frequency of 0.7 mm diameter. The root diameter frequency distribution of AR, NR, and PM was also similar, with a maximum frequency of 0. 3mm diameter. The root diameter frequency distribution for all six stands was unimodal, and fitted well with the cumulative lognormal distribution function, with the determination coefficient R2 being above 0. 99 for all stands. Third, the fitting parameters of μ and σ in the cumulative lognormal distribution function represented different foraging strategies for soil resources in different stands. μandσwere strongly negatively correlated, which showed a trade-off in the fine root resource acquisition strategy. With the increasing tree species diversity,μtends to be smaller, whileσtends to be larger, reflecting the growing competition for nutrition and water among the roots of different trees species. μ and σ were distinctly different among different plantation tree species, showing differences in

  7. Plant roots and anti-scourability of soils in the Shangshe Catchment, Dabie Mountains, Anhui Province, Eastern China

    Institute of Scientific and Technical Information of China (English)

    Jiayao ZHUANG; Jinchi ZHANG; Bo ZHANG; Hongyan LUO; Xiaying HUANG; Jun FU

    2009-01-01

    The distribution of root biomass was studied in different soil layers (0-10, 10-20, 20-30, 30-40 cm) by means of a "study plot" method for various plant species in the Shangshe Catchment area in the Dabie Mountains, Anhui Province. The number and lengths of root samples were recorded. In each study plot, anti-scourability of soils in corresponding soil layers was measured with a C.C. Suoboliefu anti-scourability instrument. The results showed the following: 1) The root system was largely distributed in the 0-40 cm soil layer and the number of roots was the largest in the surface soil layer. Fine roots < 1 mm in diameter predominated in root length. 2) In the same section, the anti-scourability indices of the surface soil layer were larger than those of other soil layers in the various plant species. The tree root system, especially the fine roots < 1 mm in diameter, are highly instrumental in controlling soil losses. Correlation coefficients of length, number and density of fine roots and the anti-scourability index were 0.8173, 0.7159 and 0.6434, respectively. The length of fine root is a key factor in the anti-scourability soil index. This index is closely correlated with the non-capillarity of each soil type, indicating that forests have a strong soil stabilizing function, because their root systems improve physical soil properties and ultimately are responsible for the establishment of a biosoil system with an anti-scourability index.

  8. Impact of soil quality on elemental uptake by, and distribution in, Colocasia esculenta (Amadumbe), an edible root.

    Science.gov (United States)

    Reddy, Mageshni; Moodley, Roshila; Kindness, Andrew; Jonnalagadda, Sreekanth B

    2011-01-01

    In this study the elemental distribution of selected essential (Ca, Mg, Al, Mn, Cu, Fe, Co, Cr, Zn, Ni and Se) and the non-essential (Pb, Hg and As) elements were determined in the bulb and peel of Amadumbe (Colocasia esculenta) samples from eight different sites in KwaZulu-Natal, South Africa. The concentration of Se and As in the soil and in the Amadumbe bulbs were below the detection limit of 0.09 μg g⁻¹. The total and bioavailable concentrations of the elements in conjunction with pH, soil organic matter (SOM) and cation exchange capacity (CEC) were determined in the soil samples from the eight sites. Statistical analysis was done to evaluate the impact of soil quality parameters on the chemical composition of the Amadumbe root. The results show accumulation or exclusion of certain elements by the bulb as evidenced by the noticeable increase or decrease of the concentrations of elements, respectively. Ca and Mg were found to be major elements in the range (2000-12000 μg g⁻¹), whilst Mn, Zn, Fe and Al were found to be minor elements in the range (20-400 μg g⁻¹). A general trend observed was that the plant favours the absorption of Zn over Cu. A positive correlation between Mg & Ca, Cu & Fe and Co & Ni was also observed. Statistical analysis revealed that the plant tended to accumulate Mg, Ca, Co, Cr and Pb whilst it excluded Hg and Fe, to a lesser extent.

  9. Phosphate Distribution and Movement in Soil—Root Interface Zone:Ⅱ.The Influence of Soil Water Content and Application Rates of Phosphate

    Institute of Scientific and Technical Information of China (English)

    XUMING-GANG; ZHANGYI-PING; 等

    1995-01-01

    The phosphate in the soil-root interface zone under various soil water contents and application rates of phosphate was still of depletion distribution which could be described by a power function in the form of C/Co=axb(C/Co is the relative content of fertilized phosphate in a distance from the root surface x,a and b are the regression constants).The depletion rate of phosphate in soil near the root surface was higher and the depletion range was narrower under lower soil moisture.On the contrary,at higher soil water content the depletion range was wider,generally.The application rate of phosphate led to the greater depletion intensity of phosphorus was higher in the heavier texture soils.In general,the depletion intensity in the soils,which decreased with increasing clay content or in creasing buffering power of soil,decreased in the order as loessal soil and black lou soil>lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in the form of KH2PO4,This result indicated that the phosphate distribution and its movement in the soil-root interface zone closely related with the buffering capacity of soil.

  10. Grapevine root distribution in drip and microsprinkler irrigation Distribuição radicular de videiras irrigadas por gotejamento e microaspersão

    Directory of Open Access Journals (Sweden)

    Luis Henrique Bassoi

    2003-01-01

    Full Text Available Grape (Vitis vinifera L. yield and its quality are dependent of the status of the root system. Root distribution information is also valuable for soil and water management. An analysis of methods to evaluate the root distribution of grapevines for both, drip and microsprinkler irrigation in a Typic Acrustox is presented for the table grape cv. Italia grafted on the rootstock IAC-313, in northeastern Brazil. Measured root parameters using the monolith method were root dry weight (Dw and root length density (Lv, while root area (Ap was estimated using the soil profile method in combination with digital image analysis. For both irrigation systems, roots were present to the 1 m soil depth and extended laterally to 1 m distance from the trunk, but grapevines irrigated by microsprinkler showed greater root presence as the distance from the trunk increased. Values of Ap were reasonably well correlated to Dw and Lv. However, correlation values were higher when fractional root distribution was used. The soil profile method in combination with image analysis techniques, allows proper grapevine root distribution evaluation.A produção de uva (Vitis vinifera L. em termos quantitativos e qualitativos depende do estado das raízes. Além disso, informações sobre a distribuição radicular são úteis para o manejo de solo e água. Por isso, uma análise de métodos para a avaliação da distribuição radicular de videiras cv. Itália / IAC 313 num Latossolo Vermelho Amarelo irrigadas por gotejamento e microaspersão foi realizada em Petrolina – PE e Juazeiro - BA, no Vale do São Francisco. Os parâmetros medidos pelo método do monolito foram a matéria seca (Dw e densidade de comprimento de raízes (Lv, enquanto a área de raízes (Ap foi estimada pelo método do perfil de solo combinado com a análise de imagens digitais. Para ambos os sistemas de irrigação, as raízes estiveram presentes até 1 m de profundidade e estenderam-se lateralmente até 1

  11. Identified particle distributions in pp and Au+Au collisions at square root of (sNN)=200 GeV.

    Science.gov (United States)

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gutierrez, T D; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; de Toledo, A Szanto; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2004-03-19

    Transverse mass and rapidity distributions for charged pions, charged kaons, protons, and antiprotons are reported for square root of [sNN]=200 GeV pp and Au+Au collisions at Relativistic Heary Ion Collider (RHIC). Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.

  12. Fine-scale spatial and temporal plankton distributions in the Southern California Bight: lessons from in situ microscopes and broadband echosounders

    Science.gov (United States)

    Briseno-Avena, Christian

    Phytoplankton and zooplankton are important components of marine ecosystems, and play a major role in the biological pump, affecting carbon transport in the global oceans. Their dynamic heterogeneous spatial and temporal distributions require special tools for observing them at the ecological scales relevant to the individual organisms. In this work, I used optic and acoustic methods to study plankton organisms at spatial scales of meters and temporal scales ranging from minutes to months. Using two in situ microscopes I described the fine-scale vertical distribution of phytoplankton and several zooplankton taxa in a coastal location in the Southern California Bight. Highly resolved spatial observations revealed cryptic maxima of fluorescent particles not observed with traditional fluorometers. Furthermore, this high sampling resolution revealed that water density, and not depth, regulated the vertical position, and interactions between observed phytoplankton and zooplankton distributions. Underwater acoustic echosounders can be powerful tools to observe in situ plankton distributions. Interpreting the acoustic echoes, however, requires highly calibrated instruments and ground-truthing experiments to identify the source of acoustic signals. This work presents the description of a novel combination of a broadband, high-frequency (1.5-2.5 MHz) echosounder and a stereoscopic camera --combined, these systems can localize the echo produced by an individual target while simultaneously providing visual identification of the target. This work has provided one of the first comparisons of in situ measured broadband target strength (BTS) and the expected signal using a physical model. The results of this experiment revealed unexpected, important differences between measured and modeled BTS. This system was also used to make in situ observations of individual fragile gelatinous organisms, marine snow particles and phytoplankton, providing evidence of their significant acoustic

  13. Diversity and distribution patterns of root-associated fungi on herbaceous plants in alpine meadows of southwestern China.

    Science.gov (United States)

    Gao, Qian; Yang, Zhu L

    2016-01-01

    The diversity of root-associated fungi associated with four ectomycorrhizal herbaceous species, Kobresia capillifolia, Carex parva, Polygonum macrophyllum and Potentilla fallens, collected in three sites of alpine meadows in southwestern China, was estimated based on internal transcribed spacer (ITS) rDNA sequence analysis of root tips. Three hundred seventy-seven fungal sequences sorted to 154 operational taxonomical units (sequence similarity of ≥ 97% across the ITS) were obtained from the four plant species across all three sites. Similar taxa (in GenBank with ≥ 97% similarity) were not found in GenBank and/or UNITE for most of the OTUs. Ectomycorrhiz a made up 64% of the fungi operational taxonomic units (OTUs), endophytes constituted 4% and the other 33% were unidentified root-associated fungi. Fungal OTUs were represented by 57% basidiomycetes and 43% ascomycetes. Inocybe, Tomentella/Thelophora, Sebacina, Hebeloma, Pezizomycotina, Cenococcum geophilum complex, Cortinarius, Lactarius and Helotiales were OTU-rich fungal lineages. Across the sites and host species the root-associated fungal communities generally exhibited low host and site specificity but high host and sampling site preference. Collectively our study revealed noteworthy diversity and endemism of root-associated fungi of alpine plants in this global biodiversity hotspot.

  14. Distribution of moderately volatile trace elements in fine-grained chondrule rims in the unequilibrated CO3 chondrite, ALH A77307.

    Science.gov (United States)

    Brearley, A J; Bajt, S; Sutton, S R

    1995-10-01

    The concentrations of Ni, Cu, Zn, Ga, Ge, and Se in five, fine-grained chondrule rims in the highly unequilibrated CO3 chondrite ALH A77307 (3.0) have been determined for the first time by synchrotron X-ray fluorescence (SXRF) microprobe at Brookhaven National Laboratory. These elements are especially useful for tracing the role of condensation and evaporation processes which occurred at moderate temperatures in the solar nebula. Understanding the distribution of moderately volatile elements between matrix and chondrules is extremely important for evaluating the different models for the volatile depletions in chondritic meteorites. The data show that the trace element chemistry of rims on different chondrules is remarkably similar, consistent with data obtained for the major and minor elements by electron microprobe. These results support the idea that rims are not genetically related to individual chondrules, but all sampled the same reservoir of homogeneously mixed dust. Of the trace elements analyzed, Zn and Ga show depletions relative to CI chondrite values, but in comparison with bulk CO chondrites all the elements are enriched by approximately 1.5 to 3.5 x CO. The abundance patterns for moderately volatile elements in ALH A77307 chondrule rims closely mimic those observed in the bulk chondrite, indicating that matrix is the major reservoir for these elements. The close matching of the patterns for the volatile depleted bulk chondrite and enriched matrix is especially striking for Na, which is anomalously depleted in ALH A77307 in comparison with average CO chondrite abundances. The depletion in Na is probably attributable to the effects of leaching in Antarctica. With the exception of Na, the volatile elements show a relatively smooth decrease in abundance as a function of condensation temperature, indicating that their behavior is largely controlled by their volatility.

  15. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy for mapping nano-scale distribution of organic carbon forms in soil: Application to black carbon particles

    Science.gov (United States)

    Lehmann, Johannes; Liang, Biqing; Solomon, Dawit; Lerotic, Mirna; LuizãO, Flavio; Kinyangi, James; SchäFer, Thorsten; Wirick, Sue; Jacobsen, Chris

    2005-03-01

    Small-scale heterogeneity of organic carbon (C) forms in soils is poorly quantified since appropriate analytical techniques were not available up to now. Specifically, tools for the identification of functional groups on the surface of micrometer-sized black C particles were not available up to now. Scanning Transmission X-ray Microscopy (STXM) using synchrotron radiation was used in conjunction with Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy to investigate nano-scale distribution (50-nm resolution) of C forms in black C particles and compared to synchrotron-based FTIR spectroscopy. A new embedding technique was developed that did not build on a C-based embedding medium and did not pose the risk of heat damage to the sample. Elemental sulfur (S) was melted to 220°C until it polymerized and quenched with liquid N2 to obtain a very viscous plastic S in which the black C could be embedded until it hardened to a noncrystalline state and was ultrasectioned. Principal component and cluster analysis followed by singular value decomposition was able to resolve distinct areas in a black carbon particle. The core of the studied biomass-derived black C particles was highly aromatic even after thousands of years of exposure in soil and resembled the spectral characteristics of fresh charcoal. Surrounding this core and on the surface of the black C particle, however, much larger proportions of carboxylic and phenolic C forms were identified that were spatially and structurally distinct from the core of the particle. Cluster analysis provided evidence for both oxidation of the black C particle itself as well as adsorption of non-black C. NEXAFS spectroscopy has great potential to allow new insight into black C properties with important implications for biogeochemical cycles such as mineralization of black C in soils and sediments, and adsorption of C, nutrients, and pollutants as well as transport in the geosphere, hydrosphere, and atmosphere.

  16. Effects of Stand Vegetation Factors and Soil Nitrogen on Fine Root Biomass in Evergreen Broad-leaved Secondary Forests in Lower Subtropical China%植被因子和土壤氮对南亚热带常绿阔叶次生林细根生物量的影响

    Institute of Scientific and Technical Information of China (English)

    徐伟强; 周璋; 李意德; 李健容; 张霞; 徐大平

    2016-01-01

    The relationship between fine root biomass and tree basal area at breast height, and how fine roots would respond to soil nitrogen (N) in the forests with high atmospheric N deposition both are still not clear. Therefore, a study on the relationships of fine root biomass with total tree basal area at breast height, the ratio of basal area for big trees (diameter at breast height, DBH≥30 cm) to total trees, tree density, understory biomass, soil nitrogen concentration, and soil N/C ratio was conducted in lower subtropical evergreen broad-leaved secondary forests in Guangzhou. Forty-eight forest plots with mostly 1 200 m2 area were set up and investigated. These forests, called ecological forests, were protected from commercial use and human disturbance for about 40 years. This study was aim to estimate the effects of the stand vegetation factors and soil N on fine root biomass. Our results showed that:(1) Both of fine root biomass in 0~20 cm (topsoil) and 20~40 cm soil layers (subsoil) were not correlated to total tree basal area at breast height, but were negatively correlated to the ratio of basal area for big trees to total trees. (2) The correlation between fine root biomass and understory biomass was not significant in topsoil, but was negatively significant in subsoil. (3) The correlations between fine root biomass in each soil layers and the according soil N concentration or N concentration per unit carbon concentration (N/C ratio) were negatively significant, except that for fine root biomass in topsoil and soil N concentration. These results indicated that the ratio of basal area for big trees (DBH≥30 cm) to total trees rather than the total tree basal area affect fine root biomass in these secondary forests with large different tree DBH composition. The negative correlations between fine root biomass and soil N concentration indicate that forest plants still respond to soil N even in these evergreen broad-leaved forests in lower subtropical China with

  17. 植物吸收根的增殖和生长与养分变异的关系——臭椿、翠菊、加拿大一枝黄花分根实验的启示%Proliferation and growth of plant fine roots and the influences from nutrient variation——implications from the split-root experiments of Ailanthus altissima, Callistephus chinensis and Solidago canadensis

    Institute of Scientific and Technical Information of China (English)

    胡凤琴; 牟溥

    2013-01-01

    Aims Modular theory of plants considers plant roots are relatively independent in resource absorbing and responding to heterogeneous soil environments, particularly resource environments. According to the cost-benefit theory, proliferation, growth and death of individual absorbing roots (modules) depend upon their resource uptake related to the carbon costs of their construction and maintenance, with a certain time-lag. Thus we hypothesized that: 1) a root will die when available nutrients are below a certain low threshold and last for a certain period and 2) new roots will emerge when available nutrients are above a certain high threshold and last for a certain period. Methods We designed a greenhouse split-root experiment using three plant species: Ailanthus altissima, Callistephus chinensis and Solidago canadensis. The plants were grown individually in pots, and then three fine roots (uptaking roots) per plant were carefully sorted and placed in three plastic vessels of about 70 mL with one root per vessel. Three nutrient levels of 0, 20 and 200 ug N·g-1 soil were applied in the three vessels. These roots were carefully exposed and photographed every four days, and the numbers of lateral roots, the length of 1st order laterals and the root length were evaluated. Repeated-measure ANOVA was used for statistical analysis. Important findings The numbers of laterals and total root length differed significantly among the three species and under the three N levels. Both lateral numbers and total root length were the least in the 0 ug N·g-1 treatment for A. altissima, and the highest in the 200 μg N·g-1 level for S. canadensis. The length of 1st order laterals was less responsive than the other two measures. No fine roots were found dead during the experiment. These results demonstrated that the different species had different growth rates of fine roots under the same N treatments as expected, and indicated that different species may have different N thresholds

  18. Modeling root reinforcement using root-failure Weibull survival function

    Directory of Open Access Journals (Sweden)

    M. Schwarz

    2013-03-01

    Full Text Available Root networks contribute to slope stability through complicated interactions that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamic of root turnover, the quantification of root reinforcement on steep slope is challenging and consequently the calculation of slope stability as well. Although the considerable advances in root reinforcement modeling, some important aspect remain neglected. In this study we address in particular to the role of root strength variability on the mechanical behaviors of a root bundle. Many factors may contribute to the variability of root mechanical properties even considering a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw. The results show that, for both laboratory and field datasets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the tensile force and the elasticity of the roots are the most important equations, as well as the root distribution. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root

  19. MASA TOTAL Y CONTENIDO DE NUTRIENTES EN RAÍCES FINAS DE ECOSISTEMAS FORESTALES (Pinus patula Schltdl y Cham Cupressus lusitanica Mill y Quercus humboldtii Bonpl. DE PIEDRAS BLANCAS, ANTIOQUIA-COLOMBIA TOTAL FINE ROOT MASS AND NUTRIENT CONTENT IN FOREST ECOSYSTEMS (Pinus patula Schltdl and Cham Cupressus lusitanica Mill and Quercus humboldtii Bonpl. FROM PIEDRAS BLANCAS, ANTIOQUIA-COLOMBIA

    Directory of Open Access Journals (Sweden)

    Luis Hernán Barreto Sánchez

    2005-12-01

    Full Text Available En la región de Piedras Blancas, Antioquia - Colombia, se realizó un muestreo de raíces finas (£ 5 mm en tres parcelas permanentes establecidas en bosques de pino pátula (Pinus patula Schltdl y Cham, ciprés (Cupressus lusitanica Mill y roble (Quercus humboldtii Bonpl. a diferentes profundidades: 0-30, 30-50 y 50- 80 cm, con el fin de determinar la masa de raíces, y la concentración y contenido de nutrientes en cada cobertura vegetal. La masa de raíces finas disminuyó rápidamente a medida que aumentaba la profundidad, encontrándose en la parcela de ciprés el 83 % de las raíces en los primeros 30 cm de profundidad, en pino pátula el 75 % y en roble el 68 %. Los elementos con mayor participación en las raíces finas fueron calcio y potasio, siendo el primero de ellos mucho mayor en la cobertura de ciprés con respecto a las parcelas restantes, seguido en abundancia del potasio, a excepción de la parcela de roble en donde la concentración de un oligoelemento como Fe, fue incluso superior a la de calcio. Los elementos Ca, Mg, K, P, Mn, Cu y Zn acumulados en las raíces finas, hasta los 80 cm de profundidad, fueron superiores en la cobertura de ciprés, con la única excepción de Fe, que fue superior en la parcela de roble. En las parcelas de pino pátula y ciprés, el patrón de abundancia siguió la secuencia decreciente Ca > K Mg > Fe > P. En este trabajo se pretendió resaltar la importancia de las raíces finas y la concentración de los elementos, en los ecosistemas forestales naturales y plantados y su relación con el ciclo de nutrientes. Para ello, la aproximación metodológica comprendió la masa total de raíces, esto es raíces vivas y muertas en conjunto.In the Piedras Blancas region, Antioquia-Colombia, a sampling of fine roots (£ 5 mm was conducted in three permanent plots established in forest ecosystems of pine (Pinus patula Schltdl, cypress (Cupressus lusitanica Mill and oak (Quercus humboldtii Bonpl., at

  20. Multiplicity distribution and spectra of negatively charged hadrons in Au+Au collisions at square root of (sNN) = 130 GeV.

    Science.gov (United States)

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Bland, L C; Blyth, C O; Bonner, B E; Bossingham, R; Boucham, A; Brandin, A; Caines, H; Calderón De La Barca Sánchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chattopadhyay, S; Chen, M L; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Conin, L; Cormier, T M; Cramer, J G; Crawford, H J; DeMello, M; Deng, W S; Derevschikov, A A; Didenko, L; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grabski, J; Grachov, O; Greiner, D; Grigoriev, V; Guedon, M; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Heffner, M; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Hümmler, H; Igo, G; Ishihara, A; Ivanshin, Y I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T; Lednický, R; Leontiev, V M; Leszczynski, P; LeVine, M J; Li, Q; Li, Q; Lindenbaum, S J; Lisa, M A; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lynn, D; Majka, R; Maliszewski, A; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; McShane, T S; Meissner, F; Melnick, Y; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; de Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Pinganaud, W; Platner, E; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schweda, K; Schmitz, N; Schroeder, L S; Schüttauf, A; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Shvetcov, V S; Skoro, G; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Stroebele, H; Struck, C; Suaide, A A; Sugarbaker, E; Suire, C; Sumbera, M; Symons, T J; Szanto De Toledo, A; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Tikhomirov, V; Trainor, T A; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vanyashin, A; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2001-09-10

    The minimum-bias multiplicity distribution and the transverse momentum and pseudorapidity distributions for central collisions have been measured for negative hadrons ( h(-)) in Au+Au interactions at square root of ([s(NN)]) = 130 GeV. The multiplicity density at midrapidity for the 5% most central interactions is dN(h(-))/d(eta)/(eta = 0) = 280+/-1(stat)+/-20(syst), an increase per participant of 38% relative to pp collisions at the same energy. The mean transverse momentum is 0.508+/-0.012 GeV/c and is larger than in central Pb+Pb collisions at lower energies. The scaling of the h(-) yield per participant is a strong function of p( perpendicular). The pseudorapidity distribution is almost constant within /eta/<1.

  1. Study of the spatial distribution of mercury in roots of vetiver grass (Chrysopogon zizanioides) by micro-pixe spectrometry.

    Science.gov (United States)

    Lomonte, Cristina; Wang, Yaodong; Doronila, Augustine; Gregory, David; Baker, Alan J M; Siegele, Rainer; Kolev, Spas D

    2014-01-01

    Localization of Hg in root tissues of vetivergrass (Chrysopogon zizanioides) was investigated by micro-Proton Induced X-ray Emission (PIXE) spectrometry to gain a better understanding of Hg uptake and its translocation to the aerial plant parts. Tillers of C. zizanioides were grown in a hydroponic culture for 3 weeks under controlled conditions and then exposed to Hg for 10 days with or without the addition of the chelators (NH(4))(2)S(2)O(3) or KI. These treatments were used to study the effects of these chelators on localization of Hg in the root tissues to allow better understanding of Hg uptake during its assisted-phytoextraction. Qualitative elemental micro-PIXE analysis revealed that Hg was mainly localized in the root epidermis and exodermis, tissues containing suberin in all Hg treatments. Hg at trace levels was localized in the vascular bundle when plants were treated with a mercury solution only. However, higher Hg concentrations were found when the solution also contained (NH(4))(2)S(2)O(3) or KI. This finding is consistent with the observed increase in Hg translocation to the aerial parts of the plants in the case of chemically induced Hg phytoextraction.

  2. Theoretical distribution of gutta-percha within root canals filled using cold lateral compaction based on numeric calculus.

    Science.gov (United States)

    Min, Yi; Song, Ying; Gao, Yuan; Dummer, Paul M H

    2016-08-01

    This study aimed to present a new method based on numeric calculus to provide data on the theoretical volume ratio of voids when using the cold lateral compaction technique in canals with various diameters and tapers. Twenty-one simulated mathematical root canal models were created with different tapers and sizes of apical diameter, and were filled with defined sizes of standardized accessory gutta-percha cones. The areas of each master and accessory gutta-percha cone as well as the depth of their insertion into the canals were determined mathematically in Microsoft Excel. When the first accessory gutta-percha cone had been positioned, the residual area of void was measured. The areas of the residual voids were then measured repeatedly upon insertion of additional accessary cones until no more could be inserted in the canal. The volume ratio of voids was calculated through measurement of the volume of the root canal and mass of gutta-percha cones. The theoretical volume ratio of voids was influenced by the taper of canal, the size of apical preparation and the size of accessory gutta-percha cones. Greater apical preparation size and larger taper together with the use of smaller accessory cones reduced the volume ratio of voids in the apical third. The mathematical model provided a precise method to determine the theoretical volume ratio of voids in root-filled canals when using cold lateral compaction.

  3. 3D analysis of mitosis distribution highlights the longitudinal zonation and diarch symmetry in proliferation activity of the Arabidopsis thaliana root meristem.

    Science.gov (United States)

    Lavrekha, V V; Pasternak, T; Ivanov, V B; Palme, K; Mironova, V V

    2017-09-16

    To date CYCB1;1 marker and cortex cell lengths are conventionally used to determine the proliferation activity of the Arabidopsis root meristem. By creating a 3D map of mitosis distribution we showed that these markers overlooked that stele and endodermis save their potency to divide longer than cortex and epidermis. Cessation of cell divisions is not a random process, so that the mitotic activity within the endodermis and stele shows a diarch pattern. Mitotic activity of all root tissues peaked at the same distance from the quiescent center (QC); however, different tissues stopped dividing at different distances, with cells of the protophloem exiting the cell cycle first and the procambial cells being the last. The robust profile of mitotic activity in the root tip defines the longitudinal zonation in the meristem with the proliferation domain, where all cells are able to divide; and the transition domain, where the cell files cease to divide. 3D analysis of cytokinin deficient and cytokinin signaling mutants showed that their proliferation domain is similar to the wild type, but the transition domain is much longer. Our data suggests a strong inhibitory effect of cytokinin on anticlinal cell divisions in the stele. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  4. Evaluating the Effects of Mulch and Irrigation Amount on Soil Water Distribution and Root Zone Water Balance Using HYDRUS-2D

    Directory of Open Access Journals (Sweden)

    Ming Han

    2015-05-01

    Full Text Available Water scarcity is the most critical constraint for sustainable cotton production in Xinjiang Province, northwest China. Drip irrigation under mulch is a major water-saving irrigation method that has been widely practiced for cotton production in Xinjiang. The performance of such an irrigation system should be evaluated for proper design and management. Therefore, a field experiment and a simulation study were conducted to (1 determine a modeling approach that can be applied to manage drip irrigation under mulch for cotton production in this region; and (2 examine the effects of irrigation amount and mulch on soil water distribution and root zone water balance components. In the experiment, four irrigation treatments were used: T1, 166.5 m3; T2, 140.4 m3; T3, 115.4 m3; and T4: 102.3 m3. The HYDRUS-2D model was calibrated, validated, and applied with the data obtained in this experiment. Soil water balance in the 0–70 cm soil profile was simulated. Results indicate that the observed soil water content and the simulated results obtained with HYDRUS-2D are in good agreement. The radius of the wetting pattern, root water uptake, and evaporation decreased as the amount of irrigation was reduced from T1 to T4, while a lot of stored soil water in the root zone was utilized and a huge amount of water was recharged from the layer below 70 cm to compensate for the decrease in irrigation amount. Mulch significantly reduced evaporation by 11.7 mm and increased root water uptake by 11.2 mm. Our simulation study suggests that this model can be applied to provide assistance in designing drip irrigation systems and developing irrigation strategies.

  5. Roots of pioneer trees in the lower sub-tropical area of Dinghushan, Guangdong, China

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-ru; PENG Shao-lin; MO Jiang-ming; LIU Xin-wei; CHEN Zhuo-quan; ZHOU Kai; WU Jin-rong

    2006-01-01

    Representative pioneer tree root systems in the subtropical area of South China were examined with regard to their structure, underground stratification and biomass distribution. Excavation of skeleton roots and observation of fine roots of seven species including the Euphorbiaceae, Theaceae, Melastomataceae, Lauraceae and Fagaceae families was carried out. The results showed that: (1) Pioneer tree roots in the first stage of natural succession were of two types, one characterized by taproot system with bulky plagiotropic branches; the other characterized by flat root system with several tabular roots. The late mesophilous tree roots were characterized by one obvious taproot and tactic braches roots up and down. Shrub species roots were characterized by heart fibrous root type featured both by horizontally and transversally growing branches. Root shapes varied in different dominant species at different stages of succession. (2) Roots of the different species varied in the external features-color, periderm and structure of freshly cut slash. (3) In a set of successional stages the biomass of tree roots increased linearly with the age of growth. During monsoon, the total root biomass amounted to 115.70 t/ha in the evergreen broad-leaved forest; 50.61t/ha in needle and broad-leaved mixed forest dominated by coniferous forest; and 64.20 t/ha in broad-and needle-leaved mixed forest dominated by broad-leaved heliophytes, and are comparable to the underground biomass observed in similar tropical forests. Thisis the first report about roots characteristics of forest in the lower sub-tropical area of Dinghushan, Guangdong, China.

  6. Root architecture simulation improves the inference from seedling root phenotyping towards mature root systems.

    Science.gov (United States)

    Zhao, Jiangsan; Bodner, Gernot; Rewald, Boris; Leitner, Daniel; Nagel, Kerstin A; Nakhforoosh, Alireza

    2017-02-01

    Root phenotyping provides trait information for plant breeding. A shortcoming of high-throughput root phenotyping is the limitation to seedling plants and failure to make inferences on mature root systems. We suggest root system architecture (RSA) models to predict mature root traits and overcome the inference problem. Sixteen pea genotypes were phenotyped in (i) seedling (Petri dishes) and (ii) mature (sand-filled columns) root phenotyping platforms. The RSA model RootBox was parameterized with seedling traits to simulate the fully developed root systems. Measured and modelled root length, first-order lateral number, and root distribution were compared to determine key traits for model-based prediction. No direct relationship in root traits (tap, lateral length, interbranch distance) was evident between phenotyping systems. RootBox significantly improved the inference over phenotyping platforms. Seedling plant tap and lateral root elongation rates and interbranch distance were sufficient model parameters to predict genotype ranking in total root length with an RSpearman of 0.83. Parameterization including uneven lateral spacing via a scaling function substantially improved the prediction of architectures underlying the differently sized root systems. We conclude that RSA models can solve the inference problem of seedling root phenotyping. RSA models should be included in the phenotyping pipeline to provide reliable information on mature root systems to breeding research. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  7. Root hairs

    NARCIS (Netherlands)

    Grierson, C.; Nielsen, E.; Ketelaar, T.; Schiefelbein, J.

    2014-01-01

    Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair

  8. Fine-mapping of qRL6.1, a major QTL for root length of rice seedlings grown under a wide range of NH4+ concentrations in hydroponic conditions

    Science.gov (United States)

    Tamura, Wataru; Ebitani, Takeshi; Yano, Masahiro; Sato, Tadashi; Yamaya, Tomoyuki

    2010-01-01

    Root system development is an important target for improving yield in cereal crops. Active root systems that can take up nutrients more efficiently are essential for enhancing grain yield. In this study, we attempted to identify quantitative trait loci (QTL) involved in root system development by measuring root length of rice seedlings grown in hydroponic culture. Reliable growth conditions for estimating the root length were first established to renew nutrient solutions daily and supply NH4+ as a single nitrogen source. Thirty-eight chromosome segment substitution lines derived from a cross between ‘Koshihikari’, a japonica variety, and ‘Kasalath’, an indica variety, were used to detect QTL for seminal root length of seedlings grown in 5 or 500 μM NH4+. Eight chromosomal regions were found to be involved in root elongation. Among them, the most effective QTL was detected on a ‘Kasalath’ segment of SL-218, which was localized to the long-arm of chromosome 6. The ‘Kasalath’ allele at this QTL, qRL6.1, greatly promoted root elongation under all NH4+ concentrations tested. The genetic effect of this QTL was confirmed by analysis of the near-isogenic line (NIL) qRL6.1. The seminal root length of the NIL was 13.5–21.1% longer than that of ‘Koshihikari’ under different NH4+ concentrations. Toward our goal of applying qRL6.1 in a molecular breeding program to enhance rice yield, a candidate genomic region of qRL6.1 was delimited within a 337 kb region in the ‘Nipponbare’ genome by means of progeny testing of F2 plants/F3 lines derived from a cross between SL-218 and ‘Koshihikari’. Electronic supplementary material The online version of this article (doi:10.1007/s00122-010-1328-3) contains supplementary material, which is available to authorized users. PMID:20390245

  9. Desenvolvimento do sistema radicular do algodoeiro na camada arável do solo Distribution of cotton roots in the upper soil layers at three different time intervals

    Directory of Open Access Journals (Sweden)

    A. C. Magalhães

    1962-01-01

    Full Text Available Sabe-se que o sistema radicular do algodoeiro se situa predominantemente na região compreendida pelos primeiros 20 cm de profundidade do solo. Como a cultura exige intensas práticas culturais, torna-se útil conhecer a distribuição progressiva do sistema radicular naquela região, sobretudo nos primeiros meses do ciclo vegetative época em que a cultura exige a intensificação das capinas. Estudos sôbre a questão foram efetuados em um ensaio de campo com a variedade IAC 12-57/566, em solo tipo terra-roxa-misturado, fozendo-se observações aos 42, 61 e 81 dias após a germinação das sementes. Os dados mostraram maior concentração de raízes na camada de 3 a 15 cm de profundidade do solo e até a uma distância aproximada de 25 cm lateralmente às plantas. O ritmo de crescimento do sistema radicular do algodoeiro foi mais intenso do 42.° ao 61.° dia após a germinação. A má utilização dos implementos agrícolas nesse período mais critico, poderá pois, provocar grandes danos à cultura, principalmente se forem empregados cultivos profundos.The distribution of the cotton plant root system in the upper 20 cm layer of soil was studied at three different times (42, 61 ond 81-day old plants. These studies were carried out in a cotton field of the variety IAC 12-57/566 planted on a "terra-roxa-misturada" type of soil. The spacing was 80 cm between rows and 15 cm between plants in the row. The method employed consisted in excavating a ditch at a right angle to the plant rows, including four plants, and then removing the soil as blocks. Five loyers of soil blocks were taken: the first and second were 3 cm thick; the third, 4 cm thick; and the fourth and fifth, 5 cm thick. After washing off the soil of each block, the roots in it were air dried and weighed. A representation of the root distribution os encountered is given in figure 2. Far the cotton field studied, most of the roots were found between 3 and 15 cm of depth up to a

  10. The distribution of arsenate and arsenite in shoots and roots of Holcus lanatus is influenced by arsenic tolerance and arsenate and phosphate supply.

    Science.gov (United States)

    Quaghebeur, Mieke; Rengel, Zdenko

    2003-07-01

    The recent discovery that phytochelatins are important for arsenic (As) detoxification in terrestrial plants results in the necessity to understand As speciation and metabolism in plant material. A hydroponic study was therefore conducted to examine the effects of different levels of phosphate and arsenate [As(V)] on As speciation and distribution in tolerant and non-tolerant clones of Holcus lanatus. Speciation of As in tissue (using high-performance liquid chromatography-inductively coupled plasma mass spectrometry) revealed that the predominant species present were the inorganic As species (As(V) and arsenite [As(III)]), although small levels (<1%) of organic As species (dimethylarsinic acid and monomethylarsonic acid) were detected in shoot material. In roots, the proportion of total As present as As(III) generally increased with increasing levels of As(V) in the nutrient solution, whereas in shoots, the proportion of total As present as As(III) generally decreased with increasing levels of As(V). H. lanatus plants growing in the high-phosphorus (P) (100 micro M) solution contained a higher proportion of As(V) (with regard to total As) in both roots and shoots than plants supplied with low P (10 micro M); in addition, tolerant clones generally contained a higher proportion of As(V) with regard to total As than non-tolerant clones. The study further revealed that As(V) can be reduced to As(III) in both roots and shoots. Although the reduction capacity was limited, the reduction was closely regulated by As influx for all treatments. The results therefore provide a new understanding about As metabolism in H. lanatus.

  11. Granulation of fine powder

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ching-Fong

    2016-08-09

    A mixture of fine powder including thorium oxide was converted to granulated powder by forming a first-green-body and heat treating the first-green-body at a high temperature to strengthen the first-green-body followed by granulation by crushing or milling the heat-treated first-green-body. The granulated powder was achieved by screening through a combination of sieves to achieve the desired granule size distribution. The granulated powder relies on the thermal bonding to maintain its shape and structure. The granulated powder contains no organic binder and can be stored in a radioactive or other extreme environment. The granulated powder was pressed and sintered to form a dense compact with a higher density and more uniform pore size distribution.

  12. Influence of temperature and soil drying on respiration of individual roots in citrus: integrating greenhouse observations into a predictive model for the field

    NARCIS (Netherlands)

    Bryla, D.R.; Bouma, T.J.; Hartmond, U.; Eissenstat, D.M.

    2001-01-01

    In citrus, the majority of fine roots are distributed near the soil surface - a region where conditions are frequently dry and temperatures fluctuate considerably. To develop a better understanding of the relationship between changes in soil conditions and a plant's below-ground respiratory costs,

  13. Transverse-momentum and pseudorapidity distributions of charged hadrons in pp collisions at square root of s = 7 TeV.

    Science.gov (United States)

    Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Fabjan, C; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kiesenhofer, W; Krammer, M; Liko, D; Mikulec, I; Pernicka, M; Rohringer, H; Schöfbeck, R; Strauss, J; Taurok, A; Teischinger, F; Waltenberger, W; Walzel, G; Widl, E; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Benucci, L; Ceard, L; De Wolf, E A; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Roland, B; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; Devroede, O; Kalogeropoulos, A; Maes, J; Maes, M; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Gay, A P R; Hammad, G H; Marage, P E; Vander Velde, C; Vanlaer, P; Wickens, J; Costantini, S; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Walsh, S; Zaganidis, N; Basegmez, S; Bruno, G; Caudron, J; De Favereau De Jeneret, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Hollar, J; Lemaitre, V; Militaru, O; Ovyn, S; Pagano, D; Pin, A; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Caebergs, T; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; Da Costa, E M; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Torres Da Silva De Araujo, F; Dias, F A; Dias, M A F; Fernandez Perez Tomei, T R; Gregores, E M; Marinho, F; Novaes, S F; Padula, Sandra S; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dyulendarova, M; Hadjiiska, R; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Bian, J G; Chen, G M; Chen, H S; Jiang, C H; Liang, D; Liang, S; Wang, J; Wang, J; Wang, X; Wang, Z; Yang, M; Zang, J; Zhang, Z; Ban, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Cabrera, A; Carrillo Montoya, C A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Sanabria, J C; Godinovic, N; Lelas, D; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Attikis, A; Fereos, R; Galanti, M; Mousa, J; Nicolaou, C; Papadakis, A; Ptochos, F; Razis, P A; Rykaczewski, H; Tsiakkouri, D; Zinonos, Z; Mahmoud, M; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Azzolini, V; Eerola, P; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Tuominen, E; Tuominiemi, J; Tuovinen, E; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Sillou, D; Besancon, M; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Broutin, C; Busson, P; Charlot, C; Dobrzynski, L; Elgammal, S; Granier de Cassagnac, R; Haguenauer, M; Kalinowski, A; Miné, P; Paganini, P; Sabes, D; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J-L; Besson, A; Bloch, D; Bodin, D; Brom, J-M; Cardaci, M; Conte, E; Drouhin, F; Ferro, C; Fontaine, J-C; Gelé, D; Goerlach, U; Greder, S; Juillot, P; Karim, M; Le Bihan, A-C; Mikami, Y; Speck, J; Van Hove, P; Fassi, F; Mercier, D; Baty, C; Beaupere, N; Bedjidian, M; Bondu, O; Boudoul, G; Boumediene, D; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; El Mamouni, H; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Mirabito, L; Perries, S; Tosi, S; Tschudi, Y; Verdier, P; Xiao, H; Roinishvili, V; Anagnostou, G; Edelhoff, M; Feld, L; Heracleous, N; Hindrichs, O; Jussen, R; Klein, K; Merz, J; Mohr, N; Ostapchuk, A; Perieanu, A; Raupach, F; Sammet, J; Schael, S; Sprenger, D; Weber, H; Weber, M; Wittmer, B; Actis, O; Ata, M; Bender, W; Biallass, P; Erdmann, M; Frangenheim, J; Hebbeker, T; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Magass, C; Merschmeyer, M; Meyer, A; Papacz, P; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Heydhausen, D; Kress, T; Kuessel, Y; Linn, A; Nowack, A; Perchalla, L; Pooth, O; Sauerland, P; Stahl, A; Thomas, M; Tornier, D; Zoeller, M H; Aldaya Martin, M; Behrenhoff, W; Behrens, U; Bergholz, M; Borras, K; Campbell, A; Castro, E; Dammann, D; Eckerlin, G; Flossdorf, A; Flucke, G; Geiser, A; Hauk, J; Jung, H; Kasemann, M; Katkov, I; Kleinwort, C; Kluge, H

    2010-07-09

    Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at square root of s = 7  TeV are measured with the inner tracking system of the CMS detector at the LHC. The charged-hadron yield is obtained by counting the number of reconstructed hits, hit pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapidity dN(ch)/dη|(|η|<0.5) = 5.78 ± 0.01(stat) ± 0.23(syst) for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from square root of s = 0.9 to 7 TeV is [66.1 ± 1.0(stat) ± 4.2(syst)]%. The mean transverse momentum is measured to be 0.545 ± 0.005(stat) ± 0.015(syst)  GeV/c. The results are compared with similar measurements at lower energies.

  14. Fine-root production in two secondary forest sites with distinct ages in Eastern Amazon Produção de raízes finas em dois sítios de floresta secundária com diferentes idades na Amazônia Oriental

    Directory of Open Access Journals (Sweden)

    Tâmara Thaiz Santana Lima

    2012-03-01

    Full Text Available The objective of this work was to assess the fine-root (≤ 2 mm diameter production dynamics of two forest regrowths at different ages. Fine-root production was monitored by the ingrowth core method in one 18-year-old site (2 ha and one 10-year-old site (0.5 ha, both localized in the Apeú region, Northern Pará State, Brazil. The sites were abandoned after successive shifting cultivation, beginning in 1940. Monthly production of live fine-root was similar between sites and was influenced by rainfall seasonality, with higher production during the dry season than the wet season for mass and length. However, mortality in terms of mass was higher in the 10-year-old site than in the 18-year-old site. The seasonality influenced mortality only in the 18-year old site following the pattern observed for live fine-root. The influence seasonal on mortality in terms of length was different between sites, with higher mortality during the wet season in the 10-year-old site and higher mortality during the dry season in the 18-year-old site. Specific root length was higher during the wet season and at the 10-year-old site. Fine-root production was not influenced by the chronosequence of the sites studied, probably fine-root production may have already stabilized in the sites or it depended more on climate and soil conditions. The production of fine-roots mass and length were indicators that generally showed the same pattern.O objetivo deste trabalho foi avaliar a dinâmica de produção de raízes finas (diâmetro ≤ 2 mm em duas áreas de floresta secundária com diferentes idades. A produção de raízes finas foi monitorada utilizando a técnica de ingrowth core em um sítio com 18 anos de idade (2 ha e um outro sítio com 10 anos de idade (0,5 ha, localizados na região de Apeú, nordeste do Estado do Pará. Os sítios foram abandonados depois de sucessivos ciclos agrícolas, iniciados em 1940. A produção mensal de raízes vivas foi semelhante entre os

  15. Root development during soil genesis: effects of root-root interactions, mycorrhizae, and substrate

    Science.gov (United States)

    Salinas, A.; Zaharescu, D. G.

    2015-12-01

    A major driver of soil formation is the colonization and transformation of rock by plants and associated microbiota. In turn, substrate chemical composition can also influence the capacity for plant colonization and development. In order to better define these relationships, a mesocosm study was set up to analyze the effect mycorrhizal fungi, plant density and rock have on root development, and to determine the effect of root morphology on weathering and soil formation. We hypothesized that plant-plant and plant-fungi interactions have a stronger influence on root architecture and rock weathering than the substrate composition alone. Buffalo grass (Bouteloua dactyloides) was grown in a controlled environment in columns filled with either granular granite, schist, rhyolite or basalt. Each substrate was given two different treatments, including grass-microbes and grass-microbes-mycorrhizae and incubated for 120, 240, and 480 days. Columns were then extracted and analyzed for root morphology, fine fraction, and pore water major element content. Preliminary results showed that plants produced more biomass in rhyolite, followed by schist, basalt, and granite, indicating that substrate composition is an important driver of root development. In support of our hypothesis, mycorrhizae was a strong driver of root development by stimulating length growth, biomass production, and branching. However, average root length and branching also appeared to decrease in response to high plant density, though this trend was only present among roots with mycorrhizal fungi. Interestingly, fine fraction production was negatively correlated with average root thickness and volume. There is also slight evidence indicating that fine fraction production is more related to substrate composition than root morphology, though this data needs to be further analyzed. Our hope is that the results of this study can one day be applied to agricultural research in order to promote the production of crops

  16. Evolving technologies for growing, imaging and analyzing 3D root system architecture of crop plants

    Institute of Scientific and Technical Information of China (English)

    Miguel A Pineros; Pierre-Luc Pradier; Nathanael M Shaw; Ithipong Assaranurak; Susan R McCouch; Craig Sturrock; Malcolm Bennett; Leon V Kochian; Brandon G Larson; Jon E Shaff; David J Schneider; Alexandre Xavier Falcao; Lixing Yuan; Randy T Clark; Eric J Craft; Tyler W Davis

    2016-01-01

    A plant’s ability to maintain or improve its yield under limiting conditions, such as nutrient deficiency or drought, can be strongly influenced by root system architec-ture (RSA), the three-dimensional distribution of the different root types in the soil. The ability to image, track and quantify these root system attributes in a dynamic fashion is a useful tool in assessing desirable genetic and physiological root traits. Recent advances in imaging technology and phenotyp-ing software have resulted in substantive progress in describing and quantifying RSA. We have designed a hydroponic growth system which retains the three-dimen-sional RSA of the plant root system, while allowing for aeration, solution replenishment and the imposition of nutrient treatments, as well as high-quality imaging of the root system. The simplicity and flexibility of the system allows for modifications tailored to the RSA of different crop species and improved throughput. This paper details the recent improvements and innovations in our root growth and imaging system which allows for greater image sensitivity (detection of fine roots and other root details), higher efficiency, and a broad array of growing conditions for plants that more closely mimic those found under field conditions.

  17. Root fractures

    DEFF Research Database (Denmark)

    Andreasen, Jens Ove; Christensen, Søren Steno Ahrensburg; Tsilingaridis, Georgios

    2012-01-01

    The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed.......The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed....

  18. A Bi-Modal Distribution of ALHA77307 Matrix Olivine: Evidence for Fine-Grained Mixing from Multiple Reservoirs in the CO Formation Zone

    Science.gov (United States)

    Frank, D.; Zolensky, Michael E.; Brearley, A.; Le, L.

    2011-01-01

    The CO 3.0 chondrite ALHA77307 is thought to be the least metamorphosed of all the CO chondrites [1]. As such, the fine-grained (olivine found in its matrix is a valuable resource for investigating the CO formation environment since its compositions should be primary. In the CO matrix, we indeed find a wide range of major element compositions (Fa(0.5-71)). However, more importantly, we find that the olivines make up two compositionally distinct populations (Fa(0.5-5) and Fa(21-71)). Grains from both populations are found within an extremely close proximity and we see no obvious evidence of two distinct lithologies within our samples. Therefore, we conclude that the olivine grains found in the ALHA77307 matrix must have crystallized within two unique formation conditions and were later mixed at a very fine scale during the accretion epoch. Here, we propose a possible explanation based on Cr and Mn concentrations in the olivine.

  19. Artificial Root Exudate System (ARES): a field approach to simulate tree root exudation in soils

    Science.gov (United States)

    Lopez-Sangil, Luis; Estradera-Gumbau, Eduard; George, Charles; Sayer, Emma

    2016-04-01

    The exudation of labile solutes by fine roots represents an important strategy for plants to promote soil nutrient availability in terrestrial ecosystems. Compounds exuded by roots (mainly sugars, carboxylic and amino acids) provide energy to soil microbes, thus priming the mineralization of soil organic matter (SOM) and the consequent release of inorganic nutrients into the rhizosphere. Studies in several forest ecosystems suggest that tree root exudates represent 1 to 10% of the total photoassimilated C, with exudation rates increasing markedly under elevated CO2 scenarios. Despite their importance in ecosystem functioning, we know little about how tree root exudation affect soil carbon dynamics in situ. This is mainly because there has been no viable method to experimentally control inputs of root exudates at field scale. Here, I present a method to apply artificial root exudates below the soil surface in small field plots. The artificial root exudate system (ARES) consists of a water container with a mixture of labile carbon solutes (mimicking tree root exudate rates and composition), which feeds a system of drip-tips covering an area of 1 m2. The tips are evenly distributed every 20 cm and inserted 4-cm into the soil with minimal disturbance. The system is regulated by a mechanical timer, such that artificial root exudate solution can be applied at frequent, regular daily intervals. We tested ARES from April to September 2015 (growing season) within a leaf-litter manipulation experiment ongoing in temperate deciduous woodland in the UK. Soil respiration was measured monthly, and soil samples were taken at the end of the growing season for PLFA, enzymatic activity and nutrient analyses. First results show a very rapid mineralization of the root exudate compounds and, interestingly, long-term increases in SOM respiration, with negligible effects on soil moisture levels. Large positive priming effects (2.5-fold increase in soil respiration during the growing

  20. Tissue-Specific Regulation of Gibberellin Signaling Fine-Tunes Arabidopsis Iron-Deficiency Responses.

    Science.gov (United States)

    Wild, Michael; Davière, Jean-Michel; Regnault, Thomas; Sakvarelidze-Achard, Lali; Carrera, Esther; Lopez Diaz, Isabel; Cayrel, Anne; Dubeaux, Guillaume; Vert, Grégory; Achard, Patrick

    2016-04-18

    Iron is an essential element for most living organisms. Plants acquire iron from the rhizosphere and have evolved different biochemical and developmental responses to adapt to a low-iron environment. In Arabidopsis, FIT encodes a basic helix-loop-helix transcription factor that activates the expression of iron-uptake genes in root epidermis upon iron deficiency. Here, we report that the gibberellin (GA)-signaling DELLA repressors contribute substantially in the adaptive responses to iron-deficient conditions. When iron availability decreases, DELLAs accumulate in the root meristem, thereby restraining root growth, while being progressively excluded from epidermal cells in the root differentiation zone. Such DELLA exclusion from the site of iron acquisition relieves FIT from DELLA-dependent inhibition and therefore promotes iron uptake. Consistent with this mechanism, expression of a non-GA-degradable DELLA mutant protein in root epidermis interferes with iron acquisition. Hence, spatial distribution of DELLAs in roots is essential to fine-tune the adaptive responses to iron availability.

  1. Pharmacokinetics, tissue distribution and excretion study of dictamnine, a major bioactive component from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae).

    Science.gov (United States)

    Wang, Pei; Sun, Jianbo; Xu, Jingyao; Yan, Qin; Gao, Enze; Qu, Wei; Zhao, Yunli; Yu, Zhiguo

    2013-12-30

    Dictamnine is an herbal ingredient isolated from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae). The present study was aimed at the development of an ultra-high performance liquid chromatography-tandem mass spectrometry method to quantify the concentration of dictamnine in rat plasma and tissues for the in vivo pharmacokinetics, tissue distribution and excretion study. Biological samples were processed with protein precipitation. Skimmianine was chosen as internal standard. The chromatographic separation was carried out on a Thermo Syncronis C18 column (2.1mm×50mm, 1.7μm) with an isocratic mobile phase consisting of methanol and 0.1% formic acid water (75:25, v/v). The detection was accomplished by using positive ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions were monitored at m/z 200.0→129.0 for dictamnine and 260.3→227.1 for IS, respectively. An excellent linearity was observed over the concentration range from 0.5 to 250ng/mL. The lower limit of quantification (LLOQ) was 0.5ng/mL for dictamnine. The developed method was rapid, accurate, and highly sensitive and selective. It was successfully applied to the in vivo pharmacokinetics, tissue distribution and excretion study of dictamnine in rats after oral or intravenous administration of dictamnine.

  2. Flooding impairs Fe uptake and distribution in Citrus due to the strong down-regulation of genes involved in Strategy I responses to Fe deficiency in roots.

    Directory of Open Access Journals (Sweden)

    Mary-Rus Martínez-Cuenca

    Full Text Available This work determines the ffects of long-term anoxia conditions--21 days--on Strategy I responses to iron (Fe deficiency in Citrus and its impact on Fe uptake and distribution. The study was carried out in Citrus aurantium L. seedlings grown under flooding conditions (S and in both the presence (+Fe and absence of Fe (-Fe in nutritive solution. The results revealed a strong down-regulation (more than 65% of genes HA1 and FRO2 coding for enzymes proton-ATPase and Ferric-Chelate Reductase (FC-R, respectively, in -FeS plants when compared with -Fe ones. H+-extrusion and FC-R activity analyses confirmed the genetic results, indicating that flooding stress markedly repressed acidification and reduction responses to Fe deficiency (3.1- and 2.0-fold, respectively. Waterlogging reduced by half Fe concentration in +FeS roots, which led to 30% up-regulation of Fe transporter IRT1, although this effect was unable to improve Fe absorption. Consequently, flooding inhibited 57Fe uptake in +Fe and -Fe seedlings (29.8 and 66.2%, respectively and 57Fe distribution to aerial part (30.6 and 72.3%, respectively. This evidences that the synergistic action of both enzymes H+-ATPase and FC-R is the preferential regulator of the Fe acquisition system under flooding conditions and, hence, their inactivation implies a limiting factor of citrus in their Fe-deficiency tolerance in waterlogged soils.

  3. MES buffer affects Arabidopsis root apex zonation and root growth by suppressing superoxide generation in root apex

    Directory of Open Access Journals (Sweden)

    Tomoko eKagenishi

    2016-02-01

    Full Text Available In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species. MES, 2-(N-morpholinoethanesulfonic acid as one of the Good’s buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8. However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone. Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the reactive oxygen species (ROS homeostasis in root apex.

  4. Effects of acid deposition on tree roots

    Energy Technology Data Exchange (ETDEWEB)

    Persson, H. [Swedish Univ. of Agricultural Sciences (Sweden). Dept. of Ecology and Environmental Research

    1995-12-31

    Large forest regions in SW Sweden have been exposed to high levels of acid deposition for many decades, causing soil acidification in forest soils. Historically, SO{sub 2} has been the major acidification agent, but lately nitrogen compounds increasingly have become important. The amount and chemical form of nitrogen strongly affects the pH in the rhizosphere and rhizoplane. Many forest stands show a positive growth response to increased nitrogen input, even in heavily N-loaded areas. Nitrogen fertilization experiments suggest that part of the increased forest production is caused by a translocation of biomass production from below-ground to above-ground parts. At the same time fine-root growth dynamics are strongly affected by the high N supply. Deficiencies of various nutrients (Mg,Ca,K,Mn and Zn) obtained from needle analyses have been reported from different Picea abies stands. In areas with more extensive acidification and nutrient leaching, a decline in tree vitality has been observed. Although deficiency symptoms in forest trees may be reflected in nitrogen/cation ratios in fine roots, few attempts have been made to explain forest damage symptoms from fine-root chemistry. Root damage is often described as a decline in the amount of living fine roots, an increase in the amount of dead versus live fine roots (a lower live/dead ratio) and an increasing amount of dead medium and coarse roots. The primary objectives of the present presentation were to analyse available data on the effects of high nitrogen and sulphur deposition on mineral nutrient balance in tree fine roots and to evaluate the risk of Al interference with cation uptake by roots

  5. Growth of plant root cultures in liquid- and gas-dispersed reactor environments.

    Science.gov (United States)

    McKelvey, S A; Gehrig, J A; Hollar, K A; Curtis, W R

    1993-01-01

    The growth of Agrobacterium transformed "hairy root" cultures of Hyoscyamus muticus was examined in various liquid- and gas-dispersed bioreactor configurations. Reactor runs were replicated to provide statistical comparisons of nutrient availability on culture performance. Accumulated tissue mass in submerged air-sparged reactors was 31% of gyratory shake-flask controls. Experiments demonstrate that poor performance of sparged reactors is not due to bubble shear damage, carbon dioxide stripping, settling, or flotation of roots. Impaired oxygen transfer due to channeling and stagnation of the liquid phase are the apparent causes of poor growth. Roots grown on a medium-perfused inclined plane grew at 48% of gyratory controls. This demonstrates the ability of cultures to partially compensate for poor liquid distribution through vascular transport of nutrients. A reactor configuration in which the medium is sprayed over the roots and permitted to drain down through the root tissue was able to provide growth rates which are statistically indistinguishable (95% T-test) from gyratory shake-flask controls. In this type of spray/trickle-bed configuration, it is shown that distribution of the roots becomes a key factor in controlling the rate of growth. Implications of these results regarding design and scale-up of bioreactors to produce fine chemicals from root cultures are discussed.

  6. Arbuscular mycorrhizal infection in two morphological root types of Araucaria araucana (Molina) K. Koch.

    Science.gov (United States)

    Diehl, P; Fontenla, S B

    2010-01-01

    Araucaria araucana (Molina) K. Koch is a conifer distributed in the Andean-Patagonian forests in the south of Argentina and Chile. The main objective of this work was to relate the different root classes appearing in A. araucana to mycorrhizal behavior. Samples were collected in three different sites in the Lanín National Park (NW Patagonia, Argentina). Two different root classes were present in A. araucana: longitudinal fine roots (LFR) and globular short roots (GSR). Both had extensive mycorrhizal arbuscular symbiosis (AM) and presented abundant hyphae and coils in root cells, a characteristic of the anatomical Paris-type. Dark septate fungal endophytes were also observed. Values of total AM colonization were high, with similar partial AM% values for each root class. Seasonal differences were found for total and partial colonization, with higher values in spring compared to autumn. Regarding the percentage of fungal structures between root classes, values were similar for vesicles and arbuscules, but higher coil percentages were observed in GSR compared to LFR. The percentages of vesicles increased in autumn, whereas the arbuscule percentages increased in spring, coinciding with the plant growth peak. Results show that both root classes of A. araucana in Andean-Patagonian forests are associated with AM fungi, which may have ecological relevance in terms of the importance of this symbiosis, in response to soil nutrient-deficiencies, especially high P-retention.

  7. 基于EDS的煤中微细粒矿物相分布研究%Research on phase distribution of coal fine minerals based on energy disperse spectroscopy

    Institute of Scientific and Technical Information of China (English)

    于冰; 卢兆林; 王帅; 王震威; 于建勇

    2013-01-01

    Fine minerals mostly distribute in the organism of coal in the form of particulate,dissemination and irregular fine granular.The difficulty of mineral phase analysis,mineral formation time and the relation of organic matter are closely related to each other.The premise of selecting and establishing the analysis method is to divide the mineral phase boundaries.This paper presents a method which quantitatively combines low vaccum secondary electron image of scanning electron microscope (SEM),backscattered electron image technology and surface distribution and phase distribution of energy disperse spectroscopy (EDS) to assay the composition of the different micro fine granular minerals,phase distribution and the relationship of coal organic matter.The feasibility of distinguishing the type of clay minerals according to the relative content of major oxides in coal is analyzed.%煤中微细粒矿物大多数以微粒状、浸染状或不规则状细粒分布于有机基体中,矿物的相分析难度与矿物质形成时间以及与有机质的形成关系密切相关,能够准确划分矿物相的相界是选择和建立分析方法的前提.本文提出了一种采用扫描电镜(SEM)低真空二次电子像技术、背散射电子像技术结合能谱仪(EDS)面分布、相分布技术相结合的方法,来定量测定煤中不同微细粒矿物的组成、相分布以及与煤有机质的结构关系;分析了依据EDS获取粘土矿物主要氧化物相对含量数据来判别粘土矿物类型的可行性.

  8. Mise en oeuvre de carottages de sol et de minirhizotrons pour l'étude à long terme de la réponse des fines racines d'épicéa (Picea abies (L. Karst. à l'augmentation de la concentration en CO2 dans l'atmosphère et la nutrition minérale

    Directory of Open Access Journals (Sweden)

    Geneviève Pissart

    2004-01-01

    Full Text Available Use of soil cores and minirhizotrons for the long-term study of the response of Norway spruce fine roots (Picea abies (L. Karst. to the increase in CO2 concentration in the atmosphere and nutrition. The fine root biomass of Norway spruce (Picea abies (L. Karst. grown in open top chambers (OTCs under elevated CO2 since 1987 was investigated with soil cores and minirhizotrons, at Vielsalm (Ardenne, Belgium. Four levels of CO2 concentration (700, 580, 470 and 350 µmol.mol-1 CO2 were applied in combination with two nutrition regimes: the optimal nutrition and the nutrition corresponding to the local brown forest soil. First soil coring was performed in 1997 to describe the root biomass and root distribution according depth, at the initial stage of this study. Soil coring was repeated in 2003. Two observation and measurement campaigns using minirhizotrons were carried out in 2001 and in 2002. These latter measurements shown a very large proportion of very fine roots within the root classes classically reported in the literature: ]0-1 mm], ]1-2 mm], ]2-5 mm] and > 5 mm. Among the 2252 roots we regularly observed in minirhizotrons, more than 90 % were thinner than 0.5 mm in diameter, less than 2 % were in the range [1-3 mm[ in diameter and their mean was 0.28 mm. Calculations on the 42 Biotechnol. Agron. Soc. Environ. 2004 8 (1, 41-53 Lebègue C., Laita É., Perrin D., Pissart G. roots observed with minirhizotrons shown that root biomass under elevated atmospheric CO2 concentrations (580 and 700 µmol.mol-1 CO2 were two times higher than root biomass under ambient concentration (350 µmol.mol-1 CO2. As these figures are based on specific root length (SRL, they are supposed to be largely underestimated. A larger proportion of these roots were exploring the upper soil horizons under elevated CO2. Norway spruce showed an annual production cycle of fine roots, independent from the atmospheric CO2 concentration. Increased CO2 affected root branching. Under

  9. Approach for simultaneous measurement of two-dimensional angular distribution of charged particles. III. Fine focusing of wide-angle beams in multiple lens systems

    Science.gov (United States)

    Matsuda, Hiroyuki; Daimon, Hiroshi; Tóth, László; Matsui, Fumihiko

    2007-04-01

    This paper provides a way of focusing wide-angle charged-particle beams in multiple lens systems. In previous papers [H. Matsuda , Phys. Rev. E 71, 066503 (2005); 74, 036501 (2006)], it was shown that an ellipsoidal mesh, combined with electrostatic lenses, enables correction of spherical aberration over wide acceptance angles up to ±60° . In this paper, practical situations where ordinary electron lenses are arranged behind the wide-angle electrostatic lenses are taken into account using ray tracing calculation. For practical realization of the wide-angle lens systems, the acceptance angle is set to ±50° . We note that the output beams of the wide-angle electrostatic lenses have somewhat large divergence angles which cause unacceptable or non-negligible spherical aberration in additional lenses. A solution to this problem is presented showing that lens combinations to cancel spherical aberration are available, whereby wide-angle charged-particle beams can be finely focused with considerably reduced divergence angles less than ±5° .

  10. Distribuição de raízes de laranja "Pêra" sob sequeiro e irrigação por microaspersão em solo arenoso Root distribution of "Pêra" orange trees under non-irrigated and irrigated conditions in a sandy soil

    Directory of Open Access Journals (Sweden)

    Eugênio Ferreira Coelho

    2002-05-01

    Full Text Available O trabalho teve por objetivo avaliar a distribuição de raízes de laranja "Pêra" sob condições não-irrigadas e irrigadas por microaspersão em solo arenoso de tabuleiro costeiro. As raízes foram extraídas em trincheiras, a partir do tronco, nas direções longitudinal e ortogonal à fileira de plantas, pelo método do monolito. Uma vez separadas, foram digitalizadas com uso de computador e scanner, para obter, com o uso do software Rootedge, os comprimentos e diâmetros dos segmentos de raízes de todas as amostras, que foram mapeados nos perfis amostrados. O sistema radicular sob irrigação por microaspersão apresentou maior expansão, tanto em profundidade como em distância radial do tronco, do que o sistema radicular sob condições não-irrigadas. Houve maior porcentagem de raízes finas nos perfis de solo sob microaspersão, em relação à condição não-irrigada, indicando a possibilidade de maior atividade do sistema radicular nesse sistema de irrigação. As posições mais adequadas para instalação de sensores de água do solo para a cultura da laranja sob microaspersão estão entre 0 e 2,5 m de distância radial a partir do tronco, em profundidades entre 0 e 1,0 m.The objective of this work was to evaluate root distribution of orange cv. Pêra under non-irrigated and under microsprinkler irrigated conditions in a Coastal Plain Sandy Soil. Root samples were collected by monolith method from trenches, which were dug aside, the plant trunk at longitudinal and orthogonal directions to plant rows. After separation from soil, roots were scanned and digitized in a PC computer. Root length and diameter were determined using Rootedge software that allowed mapping root distribution on sampled soil profiles. Results showed that root system of microsprinkler irrigated trees occupied higher volume in the soil compared to the one under non-irrigated conditions. Higher amounts of fine roots were found in the profiles of microsprinkler

  11. Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH(X{sup ~}/A{sup ~}) products in the B-band photodissociation of H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Linsen [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Xie, Daiqian, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-03-28

    A detailed quantum mechanical characterization of the photodissociation dynamics of H{sub 2}O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH(X{sup ~}/A{sup ~}) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH(X{sup ~}, v = 0) exhibit very different characteristics. The A′ states, produced mostly via the B{sup ~}→X{sup ~} conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B{sup ~}→A{sup ~} Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH(X{sup ~}) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B{sup ~}→X{sup ~} non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH(A{sup ~}) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

  12. Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH( X ˜ / A ˜ ) products in the B-band photodissociation of H2O

    Science.gov (United States)

    Zhou, Linsen; Xie, Daiqian; Guo, Hua

    2015-03-01

    A detailed quantum mechanical characterization of the photodissociation dynamics of H2O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH( X ˜ / A ˜ ) product fine-structure populations a