ABOVE GROUND BIOMASS MICRONUTRIENTS IN A SEASONAL SUBTROPICAL FOREST

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Hamilton Luiz Munari Vogel

2015-06-01

Full Text Available In the above ground biomass of a native forest or plantation are stored large quantities of nutrients, with few studies in the literature, especially concerning micronutrients. The present work aimed to quantify the micronutrients in above ground biomass in a Seasonal Subtropical forest in Itaara-RS, Brazil. For the above ground biomass evaluation, 20 trees of five different diameter classes were felled. The above ground biomass was separated in the following compartments: stem wood, stem bark, branches and leaves. The contents of B, Cu, Fe, Mn and Zn in the biomass samples were determined. The stock of micronutrients in the biomass for each component was obtained based on the estimated dry biomass, multiplied by the nutrient content. The total production of above ground biomass was estimated at 210.0 Mg.ha-1. The branches, stem wood, stem bark and leaves corresponded to 48.8, 43.3, 5.4 and 2.4% of the above ground biomass. The lower levels of B, Cu, Fe and Mn are in stem wood, except for Zn; in the branches and trunk wood are the largest stocks of B, Cu, Fe and Mn. In the branches, leaves and trunk bark are stored most micronutrients, pointing to the importance of these to remain on the soil.

How to restore dry forest ecosystems

OpenAIRE

Nalvarte, Jaime

2012-01-01

AIDER is a Peruvian non-governmental organization working since 1992 on forest management activities, watershed management and urban forest management on tropical humid and dry forest at a national level. AIDER and the José Ignacio Távara Pasapera rural community have been working on dry forest management and recovery since 1992. This paper summarizes the activity of AIDER in the dry forests for the purpose of recovering degraded forest areas and conserve existing forests by developing sustai...

Response of Termite (Blattodea: Termitoidae) Assemblages to Lower Subtropical Forest Succession: A Case Study in Dinghushan Biosphere Reserve, China.

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Li, Zhi-Qiang; Ke, Yun-Ling; Zeng, Wen-Hui; Zhang, Shi-Jun; Wu, Wen-Jing

2016-02-01

Termite (Blattodea: Termitoidae) assemblages have important ecological functions and vary in structure between habitats, but have not been studied in lower subtropical forests. To examine whether differences in the richness and relative abundance of termite species and functional groups occur in lower subtropical regions, termite assemblages were sampled in Dinghushan Biosphere Reserve, China, among pine forest, pine and broad-leaved mixed forest (mixed forest), and monsoon evergreen broad-leaved forest (monsoon forest). The dominant functional group was wood-feeding termites (family Termitidae), and the mixed forest hosted the greatest richness and relative abundance. Soil-feeding termites were absent from the lower subtropical system, while humus-feeding termites were sporadically distributed in mixed forest and monsoon forest. The species richness and functional group abundance of termites in our site may be linked to the forest succession. Altitude, soil temperature, air temperature, surface air relative humidity, and litter depth were significant influences on species and functional group diversity.

[Characteristics of floor litter and soil arthropod community in different types ot subtropical forest in Ailao Mountain of Yunnan, Southwest China].

Science.gov (United States)

Yang, Zhao; Yang, Xiao-Dong

2011-11-01

By using line transect method, an investigation was conducted on the floor litter and soil arthropod community in a mid mountain wet evergreen broad-leaved forest, a mossy dwarf forest, and a Populus bonatii forest in Ailao Mountain of Yunnan in April (dry and hot season), June (rainy season), and December (dry and cold season), 2005. In both dry and rainy seasons, the existing floor litter mass, C storage, and C/N ratio in the three forests all increased in the order of mossy dwarf forest > P. bonatii forest > evergreen broad-leaved forest, but the N storage had less difference. In the floor litter layer of the forests, Acari and Collembola were the dominant groups of soil arthropod community, while Diptera larvae, Coleoptera, ants, and Homoptera were the common groups. The Sorenson coefficients of soil arthropod community in the three forests were extremely great. No significant differences were observed in the soil arthropod density (ind x m(-2)) in the floor litter layer among the three forests, but the relative density (ind x g(-1)) of soil arthropods was higher in the evergreen broad-leaved forest and P. bonatii forest than in the mossy dwarf forest. In the three forests, the density of soil arthropods was significantly higher in dry season than in rainy season, but the Shannon diversity index had less difference. There were significant positive correlations between the existing floor litter mass and the individual density (ind x m(-2)) and dominant groups of soil arthropod communities in dry and hot season (April), but negative correlations between the existing floor litter mass and the relative density (ind x g(-1)) of soil arthropod communities and Acari in dry and cold season (December). The individual densities of Collembola and Coleoptera also had positive correlations with the N storage of the existing floor litter mass in the three forests. It was considered that the floor litter and the development of soil arthropod community in the litter layer of

Tree diversity promotes insect herbivory in subtropical forests of south-east China.

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Schuldt, Andreas; Baruffol, Martin; Böhnke, Martin; Bruelheide, Helge; Härdtle, Werner; Lang, Anne C; Nadrowski, Karin; von Oheimb, Goddert; Voigt, Winfried; Zhou, Hongzhang; Assmann, Thorsten; Fridley, Jason

2010-07-01

1.Insect herbivory can strongly affect ecosystem processes, and its relationship with plant diversity is a central topic in biodiversity-functioning research. However, very little is known about this relationship from complex ecosystems dominated by long-lived individuals, such as forests, especially over gradients of high plant diversity.2.We analysed insect herbivory on saplings of 10 tree and shrub species across 27 forest stands differing in age and tree species richness in an extraordinarily diverse subtropical forest ecosystem in China. We tested whether plant species richness significantly influences folivory in these highly diverse forests or whether other factors play a more important role at such high levels of phytodiversity.3.Leaf damage was assessed on 58 297 leaves of 1284 saplings at the end of the rainy season in 2008, together with structural and abiotic stand characteristics.4.Species-specific mean damage of leaf area ranged from 3% to 16%. Herbivory increased with plant species richness even after accounting for potentially confounding effects of stand characteristics, of which stand age-related aspects most clearly covaried with herbivory. Intraspecific density dependence or other abiotic factors did not significantly influence overall herbivory across forest stands.5.Synthesis.The positive herbivory-plant diversity relationship indicates that effects related to hypotheses of resource concentration, according to which a reduction in damage by specialized herbivores might be expected as host plant concentration decreases with increasing plant diversity, do not seem to be major determinants for overall herbivory levels in our phytodiverse subtropical forest ecosystem. We discuss the potential role of host specificity of dominant herbivores, which are often expected to show a high degree of specialization in many (sub)tropical forests. In the forest system we studied, a much higher impact of polyphagous species than traditionally assumed might

Biodiversity promotes tree growth during succession in subtropical forest.

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Martin Barrufol

Full Text Available Losses of plant species diversity can affect ecosystem functioning, with decreased primary productivity being the most frequently reported effect in experimental plant assemblages, including tree plantations. Less is known about the role of biodiversity in natural ecosystems, including forests, despite their importance for global biogeochemical cycling and climate. In general, experimental manipulations of tree diversity will take decades to yield final results. To date, biodiversity effects in natural forests therefore have only been reported from sample surveys or meta-analyses with plots not initially selected for diversity. We studied biomass and growth of subtropical forests stands in southeastern China. Taking advantage of variation in species recruitment during secondary succession, we adopted a comparative study design selecting forest plots to span a gradient in species richness. We repeatedly censored the stem diameter of two tree size cohorts, comprising 93 species belonging to 57 genera and 33 families. Tree size and growth were analyzed in dependence of species richness, the functional diversity of growth-related traits, and phylogenetic diversity, using both general linear and structural equation modeling. Successional age covaried with diversity, but differently so in the two size cohorts. Plot-level stem basal area and growth were positively related with species richness, while growth was negatively related to successional age. The productivity increase in species-rich, functionally and phylogenetically diverse plots was driven by both larger mean sizes and larger numbers of trees. The biodiversity effects we report exceed those from experimental studies, sample surveys and meta-analyses, suggesting that subtropical tree diversity is an important driver of forest productivity and re-growth after disturbance that supports the provision of ecological services by these ecosystems.

Distribution of functional traits in subtropical trees across environmental and forest use gradients

Science.gov (United States)

Blundo, Cecilia; Malizia, Lucio R.; González-Espinosa, Mario

2015-11-01

The relationship between functional traits and environmental factors contribute to understanding community structure and predicting which species will be able to elude environmental filters in different habitats. We selected 10 functional traits related to morphology, demography and regeneration niche in 54 subtropical premontane tree species to describe their main axes of functional differentiation. We derived species traits, environmental variables and species abundance data from 20 1-ha permanent plots established in a seasonal subtropical premontane forest in northwestern Argentina. We analyzed the relationship between species functional traits and environmental factors through RLQ and fourth-corner analyzes. We found an axis of structural differentiation that segregates understory from canopy species, and an axis of functional differentiation that segregates species that maximize resource acquisition from those that promote resource conservation. Environmental and forest use gradients operate hierarchically over subtropical premontane tree species influencing the distribution of demographic and morphological traits. The interaction between climatic and topographic factors influences the distribution of species functional traits at the regional scale. In addition, the history of forest use seems to operate at the landscape scale and explains the distribution of species traits reflecting a trade-off between resource acquisition and resource conservation strategies in secondary forests across different successional stages. Our results support the idea that functional traits may be used to analyze community structure and dynamics through niche differentiation and environmental filtering processes.

Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

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J. Zhu

2013-03-01

Full Text Available Subtropical forests in southern China have received chronically large amounts of atmogenic nitrogen (N, causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O. We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4 at Tieshanping (Chongqing, SW China and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hillslope (HS and a hydrologically connected, terraced groundwater discharge zone (GDZ in the valley bottom. High emission rates of up to 1800 μg N2O-N m−2 h−1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than on HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature (ST and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3− in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3− decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.54 and 0.43 g N2O-N m−2 yr−1 for a year with a wet and a dry summer, respectively are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8–10% of the annual atmogenic N deposition, suggesting that forests on acid soils in southern China are an important, hitherto overlooked component of the anthropogenic N2O budget.

Propagation of Native Tree Species to Restore Subtropical Evergreen Broad-Leaved Forests in SW China

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Yang Lu

2016-01-01

Full Text Available Subtropical evergreen broad-leaved forest (EBLF is a widespread vegetation type throughout East Asia that has suffered extensive deforestation and fragmentation. Selection and successful propagation of native tree species are important for improving ecological restoration of these forests. We carried out a series of experiments to study the propagation requirements of indigenous subtropical tree species in Southwest China. Seeds of 21 tree species collected from the natural forest were materials for the experiment. This paper examines the seed germination and seedling growth performance of these species in a nursery environment. Germination percentages ranged from 41% to 96% and were ≥50% for 19 species. The median length of germination time (MLG ranged from 24 days for Padus wilsonii to 144 days for Ilex polyneura. Fifteen species can reach the transplant size (≥15 cm in height within 12 months of seed collection. Nursery-grown seedlings for each species were planted in degraded site. Two years after planting, the seedling survival rate was >50% in 18 species and >80% in 12 species. Based on these results, 17 species were recommended as appropriate species for nursery production in forest restoration projects. Our study contributes additional knowledge regarding the propagation techniques for various native subtropical tree species in nurseries for forest restoration.

Temporal dynamics of a subtropical urban forest in San Juan, Puerto Rico, 2001-2010

Science.gov (United States)

J. M. Tucker Lima; C. L. Staudhammer; T. J. Brandeis; F. J. Escobedo; W. Zipperer

2013-01-01

Several studies report urban tree growth and mortality rates as well as species composition, structural dynamics, and other characteristics of urban forests in mostly temperate, inland urban areas. Temporal dynamics of urban forests in subtropical and tropical forest regions are, until now, little explored and represent a new and important direction for study and...

Impacts of disturbance initiated by road construction in a subtropical cloud forest in the Luquillo Experimental Forest, Puerto Rico

Science.gov (United States)

Lydia P. Olander; F.N Scatena; Whendee L. Silver

1998-01-01

The impacts of road construction and the spread of exotic vegetation, which are common threats to upper elevation tropical forests, were evaluated in the subtropical cloud forests of Puerto Rico. The vegetation, soil and microclimate of 6-month-old road®lls, 35-year-old road®lls and mature forest with and without grass understories were compared. Recent road®lls had...

Perception of beekeepers about the melliferous plants from the Dry Forest of the Northwest (Dominican Republic).

OpenAIRE

Thomas May; Sesar Rodríguez

2012-01-01

The melliferous flora honey and its flowering in the subtropical dry forest area of the Northwest, of the Dominican Republic were studied. A survey of 30 local beekeepers as well as four semi-structured interviews on important plants for beekeeping were applied. Plants were scored according to their importance by observation is confirmed in the field visits bees species observed and consulted information secondary on flowering dates and features honey, secondary data, and applied the index Ja...

Analyzing the efficacy of subtropical urban forests in offsetting carbon emissions from cities

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Francisco Escobedo; Sebastian Varela; Min Zhao; John E. Wagner; Wayne Zipperer

2010-01-01

Urban forest management and policies have been promoted as a tool to mitigate carbon dioxide (CO2) emissions. This study used existing CO2 reduction measures from subtropical Miami-Dade and Gainesville, USA and modeled carbon storage and sequestration by trees to analyze policies that use urban forests to offset carbon emissions. Field data were analyzed, modeled, and...

Effect of Simulated N Deposition on Soil Exchangeable Cations in Three Forest Types of Subtropical China

Institute of Scientific and Technical Information of China (English)

LU Xian-Kai; MO Jiang-Ming; P.GUNDERSERN; ZHU Wei-Xing; ZHOU Guo-Yi; LI De-Jun; ZHANG Xu

2009-01-01

The effects of simulated nitrogen (N) deposition on soil exchangeable cations were studied in three forest types of subtropical China.Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest):control (0 kg N ha-1 year-1),low N (50 kg N ha-1 year-1),medium N (100 kg N ha-1 year-1) and high N (150 kg N ha-1 ycar-1),and only three treatments (i.e.,control,low N,medium N) were established for the pine and mixed forests.Nitrogen had been applied continuously for 26 months before the measurement.The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests,and exhibited some significant negative symptoms,e.g.,soil acidification,Al mobilization and leaching of base cations from soil.The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations.Response of soil exchangeable cations to N deposition varied in the forests of subtropical China,depending on soil N status and land-nse history.

Experimental evidence for a phylogenetic Janzen-Connell effect in a subtropical forest

NARCIS (Netherlands)

Liu, Xubing; Liang, Minxia; Etienne, Rampal S.; Wang, Yongfan; Staehelin, Christian; Yu, Shixiao

Observational evidence increasingly suggests that the JanzenConnell effect extends beyond the species boundary. However, this has not been confirmed experimentally. Herein, we present both observational and experimental evidence for a phylogenetic JanzenConnell effect. In a subtropical forest in

Phylogenetic classification of the world's tropical forests.

Science.gov (United States)

Slik, J W Ferry; Franklin, Janet; Arroyo-Rodríguez, Víctor; Field, Richard; Aguilar, Salomon; Aguirre, Nikolay; Ahumada, Jorge; Aiba, Shin-Ichiro; Alves, Luciana F; K, Anitha; Avella, Andres; Mora, Francisco; Aymard C, Gerardo A; Báez, Selene; Balvanera, Patricia; Bastian, Meredith L; Bastin, Jean-François; Bellingham, Peter J; van den Berg, Eduardo; da Conceição Bispo, Polyanna; Boeckx, Pascal; Boehning-Gaese, Katrin; Bongers, Frans; Boyle, Brad; Brambach, Fabian; Brearley, Francis Q; Brown, Sandra; Chai, Shauna-Lee; Chazdon, Robin L; Chen, Shengbin; Chhang, Phourin; Chuyong, George; Ewango, Corneille; Coronado, Indiana M; Cristóbal-Azkarate, Jurgi; Culmsee, Heike; Damas, Kipiro; Dattaraja, H S; Davidar, Priya; DeWalt, Saara J; Din, Hazimah; Drake, Donald R; Duque, Alvaro; Durigan, Giselda; Eichhorn, Karl; Eler, Eduardo Schmidt; Enoki, Tsutomu; Ensslin, Andreas; Fandohan, Adandé Belarmain; Farwig, Nina; Feeley, Kenneth J; Fischer, Markus; Forshed, Olle; Garcia, Queila Souza; Garkoti, Satish Chandra; Gillespie, Thomas W; Gillet, Jean-Francois; Gonmadje, Christelle; Granzow-de la Cerda, Iñigo; Griffith, Daniel M; Grogan, James; Hakeem, Khalid Rehman; Harris, David J; Harrison, Rhett D; Hector, Andy; Hemp, Andreas; Homeier, Jürgen; Hussain, M Shah; Ibarra-Manríquez, Guillermo; Hanum, I Faridah; Imai, Nobuo; Jansen, Patrick A; Joly, Carlos Alfredo; Joseph, Shijo; Kartawinata, Kuswata; Kearsley, Elizabeth; Kelly, Daniel L; Kessler, Michael; Killeen, Timothy J; Kooyman, Robert M; Laumonier, Yves; Laurance, Susan G; Laurance, William F; Lawes, Michael J; Letcher, Susan G; Lindsell, Jeremy; Lovett, Jon; Lozada, Jose; Lu, Xinghui; Lykke, Anne Mette; Mahmud, Khairil Bin; Mahayani, Ni Putu Diana; Mansor, Asyraf; Marshall, Andrew R; Martin, Emanuel H; Calderado Leal Matos, Darley; Meave, Jorge A; Melo, Felipe P L; Mendoza, Zhofre Huberto Aguirre; Metali, Faizah; Medjibe, Vincent P; Metzger, Jean Paul; Metzker, Thiago; Mohandass, D; Munguía-Rosas, Miguel A; Muñoz, Rodrigo; Nurtjahy, Eddy; de Oliveira, Eddie Lenza; Onrizal; Parolin, Pia; Parren, Marc; Parthasarathy, N; Paudel, Ekananda; Perez, Rolando; Pérez-García, Eduardo A; Pommer, Ulf; Poorter, Lourens; Qie, Lan; Piedade, Maria Teresa F; Pinto, José Roberto Rodrigues; Poulsen, Axel Dalberg; Poulsen, John R; Powers, Jennifer S; Prasad, Rama Chandra; Puyravaud, Jean-Philippe; Rangel, Orlando; Reitsma, Jan; Rocha, Diogo S B; Rolim, Samir; Rovero, Francesco; Rozak, Andes; Ruokolainen, Kalle; Rutishauser, Ervan; Rutten, Gemma; Mohd Said, Mohd Nizam; Saiter, Felipe Z; Saner, Philippe; Santos, Braulio; Dos Santos, João Roberto; Sarker, Swapan Kumar; Schmitt, Christine B; Schoengart, Jochen; Schulze, Mark; Sheil, Douglas; Sist, Plinio; Souza, Alexandre F; Spironello, Wilson Roberto; Sposito, Tereza; Steinmetz, Robert; Stevart, Tariq; Suganuma, Marcio Seiji; Sukri, Rahayu; Sultana, Aisha; Sukumar, Raman; Sunderland, Terry; Supriyadi; Suresh, H S; Suzuki, Eizi; Tabarelli, Marcelo; Tang, Jianwei; Tanner, Ed V J; Targhetta, Natalia; Theilade, Ida; Thomas, Duncan; Timberlake, Jonathan; de Morisson Valeriano, Márcio; van Valkenburg, Johan; Van Do, Tran; Van Sam, Hoang; Vandermeer, John H; Verbeeck, Hans; Vetaas, Ole Reidar; Adekunle, Victor; Vieira, Simone A; Webb, Campbell O; Webb, Edward L; Whitfeld, Timothy; Wich, Serge; Williams, John; Wiser, Susan; Wittmann, Florian; Yang, Xiaobo; Adou Yao, C Yves; Yap, Sandra L; Zahawi, Rakan A; Zakaria, Rahmad; Zang, Runguo

2018-02-20

Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: ( i ) Indo-Pacific, ( ii ) Subtropical, ( iii ) African, ( iv ) American, and ( v ) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests. Copyright © 2018 the Author(s). Published by PNAS.

Tropical savannas and dry forests.

Science.gov (United States)

Pennington, R Toby; Lehmann, Caroline E R; Rowland, Lucy M

2018-05-07

In the tropics, research, conservation and public attention focus on rain forests, but this neglects that half of the global tropics have a seasonally dry climate. These regions are home to dry forests and savannas (Figures 1 and 2), and are the focus of this Primer. The attention given to rain forests is understandable. Their high species diversity, sheer stature and luxuriance thrill biologists today as much as they did the first explorers in the Age of Discovery. Although dry forest and savanna may make less of a first impression, they support a fascinating diversity of plant strategies to cope with stress and disturbance including fire, drought and herbivory. Savannas played a fundamental role in human evolution, and across Africa and India they support iconic megafauna. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Early responses of soil fauna in three typical forests of south subtropical China to simulated N deposition addition].

Science.gov (United States)

Xu, Guolian; Mo, Jiangming; Zhou, Guoyi

2005-07-01

In this paper, simulated N deposition addition (0, 50, 100 and 150 kg x hm(-2) x yr(-1)) by spreading water or NH4NO3 was conducted to study the early responses of soil fauna in three typical native forests (monsoon evergreen broadleaf forest, pine forest, and broadleaf-pine mixed forest) of subtropical China. The results showed that in monsoon evergreen broadleaf forest, N deposition addition had an obviously negative effect on the three indexes for soil fauna, but in pine forest, the positive effect was significant (P soil fauna community could reach the level in mixed forest, even that in monsoon evergreen broadleaf forest at sometime. The responses in mixed forest were not obvious. In monsoon evergreen broadleaf forest, the negative effects were significant (P soil fauna groups. The results obtained might imply the N saturation-response mechanisms of forest ecosystems in subtropical China, and the conclusions from this study were also consisted with some related researches.

Mapping the occurrence of Chromolaena odorata (L.) in subtropical forest gaps using environmental and remote sensing data

CSIR Research Space (South Africa)

Malahlela, OE

2015-07-01

Full Text Available Globally, subtropical forests are rich in biodiversity. However, the native biodiversity in these forests is threatened by the presence of invasive species such as Chromolaena odorata (L.) King and Robinson, which thrives in forest canopy gaps. Our...

Plant trait-species abundance relationships vary with environmental properties in subtropical forests in eastern china.

Directory of Open Access Journals (Sweden)

En-Rong Yan

Full Text Available Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivariate (PCA axes environmental properties such as air humidity, soil moisture content, soil temperature, soil pH, and soil organic matter, nitrogen (N and phosphorus (P contents. At the landscape scale, plant maximum height, and twig and stem wood densities were positively correlated, whereas mean leaf area (MLA, leaf N concentration (LN, and total leaf area per twig size (TLA were negatively correlated with species abundance. At the plot scale, plant maximum height, leaf and twig dry matter contents, twig and stem wood densities were positively correlated, but MLA, specific leaf area, LN, leaf P concentration and TLA were negatively correlated with species abundance. Plant trait-species abundance relationships shifted over the range of seven single environmental properties and along multivariate environmental axes in a similar way. In conclusion, strong relationships between plant traits and species abundance existed among and within communities. Significant shifts in plant trait-species abundance relationships in a range of environmental properties suggest strong environmental filtering processes that influence species abundance and rarity in the studied subtropical forests.

Ground Monitoring Neotropical Dry Forests: A Sensor Network for Forest and Microclimate Dynamics in Semi-Arid Environments (Enviro-Net°)

Science.gov (United States)

Rankine, C. J.; Sánchez-Azofeifa, G.

2011-12-01

In the face of unprecedented global change driven by anthropogenic pressure on natural systems it has become imperative to monitor and better understand potential shifts in ecosystem functioning and services from local to global scales. The utilization of automated sensors technologies offers numerous advantages over traditional on-site ecosystem surveying techniques and, as a result, sensor networks are becoming a powerful tool in environmental monitoring programs. Tropical forests, renowned for their biodiversity, are important regulators of land-atmosphere fluxes yet the seasonally dry tropical forests, which account for 40% of forested ecosystems in the American tropics, have been severely degraded over the past several decades and not much is known of their capacity to recover. With less than 1% of these forests protected, our ability to monitor the dynamics and quantify changes in the remaining primary and recovering secondary tropical dry forests is vital to understanding mechanisms of ecosystem stress responses and climate feedback with respect to annual productivity and desertification processes in the tropics. The remote sensing component of the Tropi-Dry: Human and Biophysical Dimensions of Tropical Dry Forests in the Americas research network supports a network of long-term tropical ecosystem monitoring platforms which focus on the dynamics of seasonally dry tropical forests in the Americas. With over 25 sensor station deployments operating across a latitudinal gradient in Mexico, Costa Rica, Brazil, and Argentina continuously collecting hyper-temporal sensory input based on standardized deployment parameters, this monitoring system is unique among tropical environments. Technologies used in the network include optical canopy phenology towers, understory wireless sensing networks, above and below ground microclimate stations, and digital cameras. Sensory data streams are uploaded to a cyber-infrastructure initiative, denominated Enviro-Net°, for data

Phylogenetic classification of the world’s tropical forests

Science.gov (United States)

Franklin, Janet; Arroyo-Rodríguez, Víctor; Field, Richard; Aguilar, Salomon; Aguirre, Nikolay; Ahumada, Jorge; Aiba, Shin-Ichiro; K, Anitha; Avella, Andres; Mora, Francisco; Aymard C., Gerardo A.; Báez, Selene; Balvanera, Patricia; Bastian, Meredith L.; Bastin, Jean-François; Bellingham, Peter J.; van den Berg, Eduardo; da Conceição Bispo, Polyanna; Boeckx, Pascal; Boehning-Gaese, Katrin; Bongers, Frans; Boyle, Brad; Brearley, Francis Q.; Brown, Sandra; Chai, Shauna-Lee; Chazdon, Robin L.; Chen, Shengbin; Chhang, Phourin; Chuyong, George; Ewango, Corneille; Coronado, Indiana M.; Cristóbal-Azkarate, Jurgi; Culmsee, Heike; Damas, Kipiro; Dattaraja, H. S.; Davidar, Priya; DeWalt, Saara J.; Din, Hazimah; Drake, Donald R.; Durigan, Giselda; Eichhorn, Karl; Eler, Eduardo Schmidt; Enoki, Tsutomu; Ensslin, Andreas; Fandohan, Adandé Belarmain; Farwig, Nina; Feeley, Kenneth J.; Fischer, Markus; Forshed, Olle; Garcia, Queila Souza; Garkoti, Satish Chandra; Gillespie, Thomas W.; Gillet, Jean-Francois; Gonmadje, Christelle; Granzow-de la Cerda, Iñigo; Griffith, Daniel M.; Grogan, James; Hakeem, Khalid Rehman; Harris, David J.; Harrison, Rhett D.; Hector, Andy; Hemp, Andreas; Hussain, M. Shah; Ibarra-Manríquez, Guillermo; Hanum, I. Faridah; Imai, Nobuo; Jansen, Patrick A.; Joly, Carlos Alfredo; Joseph, Shijo; Kartawinata, Kuswata; Kearsley, Elizabeth; Kelly, Daniel L.; Kessler, Michael; Killeen, Timothy J.; Kooyman, Robert M.; Laumonier, Yves; Laurance, William F.; Lawes, Michael J.; Letcher, Susan G.; Lovett, Jon; Lozada, Jose; Lu, Xinghui; Lykke, Anne Mette; Mahmud, Khairil Bin; Mahayani, Ni Putu Diana; Mansor, Asyraf; Marshall, Andrew R.; Martin, Emanuel H.; Calderado Leal Matos, Darley; Meave, Jorge A.; Melo, Felipe P. L.; Mendoza, Zhofre Huberto Aguirre; Metali, Faizah; Medjibe, Vincent P.; Metzger, Jean Paul; Metzker, Thiago; Mohandass, D.; Munguía-Rosas, Miguel A.; Muñoz, Rodrigo; Nurtjahy, Eddy; de Oliveira, Eddie Lenza; Onrizal; Parolin, Pia; Parren, Marc; Parthasarathy, N.; Paudel, Ekananda; Perez, Rolando; Pérez-García, Eduardo A.; Pommer, Ulf; Poorter, Lourens; Qie, Lan; Piedade, Maria Teresa F.; Pinto, José Roberto Rodrigues; Poulsen, Axel Dalberg; Poulsen, John R.; Powers, Jennifer S.; Prasad, Rama Chandra; Puyravaud, Jean-Philippe; Rangel, Orlando; Reitsma, Jan; Rocha, Diogo S. B.; Rolim, Samir; Rovero, Francesco; Ruokolainen, Kalle; Rutishauser, Ervan; Rutten, Gemma; Mohd. Said, Mohd. Nizam; Saiter, Felipe Z.; Saner, Philippe; Santos, Braulio; dos Santos, João Roberto; Sarker, Swapan Kumar; Schoengart, Jochen; Schulze, Mark; Sheil, Douglas; Sist, Plinio; Souza, Alexandre F.; Spironello, Wilson Roberto; Sposito, Tereza; Steinmetz, Robert; Stevart, Tariq; Suganuma, Marcio Seiji; Sukri, Rahayu; Sukumar, Raman; Sunderland, Terry; Supriyadi; Suresh, H. S.; Suzuki, Eizi; Tabarelli, Marcelo; Tang, Jianwei; Tanner, Ed V. J.; Targhetta, Natalia; Theilade, Ida; Thomas, Duncan; Timberlake, Jonathan; de Morisson Valeriano, Márcio; van Valkenburg, Johan; Van Do, Tran; Van Sam, Hoang; Vandermeer, John H.; Verbeeck, Hans; Vetaas, Ole Reidar; Adekunle, Victor; Vieira, Simone A.; Webb, Campbell O.; Webb, Edward L.; Whitfeld, Timothy; Wich, Serge; Williams, John; Wiser, Susan; Wittmann, Florian; Yang, Xiaobo; Adou Yao, C. Yves; Yap, Sandra L.; Zahawi, Rakan A.; Zakaria, Rahmad; Zang, Runguo

2018-01-01

Knowledge about the biogeographic affinities of the world’s tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world’s tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests. PMID:29432167

Photo series for quantifying forest fuels in Mexico: montane subtropical forests of the Sierra Madre del Sur and temperate forests and montane shrubland of the northern Sierra Madre Oriental

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Jorge E. Morfin-Rios; Ernesto Alvarado-Celestino; Enrique J. Jardel-Pelaez; Robert E. Vihnanek; David K. Wright; Jose M. Michel-Fuentes; Clinton S. Wright; Roger D. Ottmar; David V. Sandberg; Andres Najera-Diaz

2008-01-01

Single wide-angle and stereo photographs display a range of forest ecosystems conditions and fuel loadings in montane subtropical forests of the Sierra Madre del Sur and temperate forests and montane shrubland of the northern Sierra Madre Oriental of Mexico. Each group of photographs includes inventory information summarizing overstory vegetation composition and...

Characterization of Unexplored Deadwood Mycobiome in Highly Diverse Subtropical Forests Using Culture-independent Molecular Technique.

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Purahong, Witoon; Pietsch, Katherina A; Lentendu, Guillaume; Schöps, Ricardo; Bruelheide, Helge; Wirth, Christian; Buscot, François; Wubet, Tesfaye

2017-01-01

The deadwood mycobiome, also known as wood-inhabiting fungi (WIF), are among the key players in wood decomposition, having a large impact on nutrient cycling in forest soils. However, our knowledge of WIF richness and distribution patterns in different forest biomes is limited. Here, we used pyrotag sequencing of the fungal internal transcribed spacer (ITS2) region to characterize the deadwood mycobiome of two tree species with greatly different wood characteristics ( Schima superba and Pinus massoniana ) in a Chinese subtropical forest ecosystem. Specifically, we tested (i) the effects of tree species and wood quality properties on WIF OTU richness and community composition; (ii) the role of biotic and abiotic factors in shaping the WIF communities; and (iii) the relationship between WIF OTU richness, community composition and decomposition rates. Due to different wood chemical properties, we hypothesized that the WIF communities derived from the two tree species would be correlated differently with biotic and abiotic factors. Our results show that deadwood in subtropical forests harbors diverse fungal communities comprising six ecological functional groups. We found interesting colonization patterns for this subtropical biome, where Resinicium spp. were highly detected in both broadleaved and coniferous deadwood. In addition, the members of Xylariales were frequently found in Schima . The two deadwood species differed significantly in WIF OTU richness ( Pinus > Schima ) and community composition ( P < 0.001). Variations in WIF community composition of both tree species were significantly explained by wood pH and ecological factors (biotic: deadwood species, basal area and abiotic: soil pH), but the WIF communities derived from each tree species correlated differently with abiotic factors. Interestingly, we found that deadwood decomposition rate significantly correlated with WIF communities and negatively correlated with WIF OTU richness. We conclude that the

Accuracy of LiDAR-based tree height estimation and crown recognition in a subtropical evergreen broad-leaved forest in Okinawa, Japan

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Azita Ahmad Zawawi

2015-04-01

Full Text Available Aim of study: To present an approach for estimating tree heights, stand density and crown patches using LiDAR data in a subtropical broad-leaved forest. Area of study: The study was conducted within the Yambaru subtropical evergreen broad-leaved forest, Okinawa main island, Japan. Materials and methods: A digital canopy height model (CHM was extracted from the LiDAR data for tree height estimation and a watershed segmentation method was applied for the individual crown delineation. Dominant tree canopy layers were estimated using multi-scale filtering and local maxima detection. The LiDAR estimation results were then compared to the ground inventory data and a high resolution orthophoto image for accuracy assessment. Main results: A Wilcoxon matched pair test suggests that LiDAR data is highly capable of estimating tree height in a subtropical forest (z = 4.0, p = 0.345, but has limitation to detect small understory trees and a single tree delineation. The results show that there is a statistically significant different type of crown detection from LiDAR data over forest inventory (z = 0, p = 0.043. We also found that LiDAR computation results underestimated the stand density and overestimated the crown size. Research highlights: Most studies involving crown detection and tree height estimation have focused on the analysis of plantations, boreal forests and temperate forests, and less was conducted on tropical and/or subtropical forests. Our study tested the capability of LiDAR as an effective application for analyzing a highly dense forest

Growth responses of trees and understory plants to nitrogen fertilization in a subtropical forest in China

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Tian, Di; Li, Peng; Fang, Wenjing; Xu, Jun; Luo, Yongkai; Yan, Zhengbing; Zhu, Biao; Wang, Jingjing; Xu, Xiaoniu; Fang, Jingyun

2017-07-01

Reactive nitrogen (N) increase in the biosphere has been a noteworthy aspect of global change, producing considerable ecological effects on the functioning and dynamics of the terrestrial ecosystems. A number of observational studies have explored responses of plants to experimentally simulated N enrichment in boreal and temperate forests. Here we investigate how the dominant trees and different understory plants respond to experimental N enrichment in a subtropical forest in China. We conducted a 3.4-year N fertilization experiment in an old-aged subtropical evergreen broad-leaved forest in eastern China with three treatment levels applied to nine 20 m × 20 m plots and replicated in three blocks. We divided the plants into trees, saplings, shrubs (including tree seedlings), and ground-cover plants (ferns) according to the growth forms, and then measured the absolute and relative basal area increments of trees and saplings and the aboveground biomass of understory shrubs and ferns. We further grouped individuals of the dominant tree species, Castanopsis eyrei, into three size classes to investigate their respective growth responses to the N fertilization. Our results showed that the plot-averaged absolute and relative growth rates of basal area and aboveground biomass of trees were not affected by N fertilization. Across the individuals of C. eyrei, the small trees with a DBH (diameter at breast height) of 5-10 cm declined by 66.4 and 59.5 %, respectively, in N50 (50 kg N ha-1 yr-1) and N100 fertilized plots (100 kg N ha-1 yr-1), while the growth of median and large trees with a DBH of > 10 cm did not significantly change with the N fertilization. The growth rate of small trees, saplings, and the aboveground biomass of understory shrubs and ground-cover ferns decreased significantly in the N-fertilized plots. Our findings suggested that N might not be a limiting nutrient in this mature subtropical forest, and that the limitation of other nutrients in the forest

Growth responses of trees and understory plants to nitrogen fertilization in a subtropical forest in China

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D. Tian

2017-07-01

Full Text Available Reactive nitrogen (N increase in the biosphere has been a noteworthy aspect of global change, producing considerable ecological effects on the functioning and dynamics of the terrestrial ecosystems. A number of observational studies have explored responses of plants to experimentally simulated N enrichment in boreal and temperate forests. Here we investigate how the dominant trees and different understory plants respond to experimental N enrichment in a subtropical forest in China. We conducted a 3.4-year N fertilization experiment in an old-aged subtropical evergreen broad-leaved forest in eastern China with three treatment levels applied to nine 20 m  ×  20 m plots and replicated in three blocks. We divided the plants into trees, saplings, shrubs (including tree seedlings, and ground-cover plants (ferns according to the growth forms, and then measured the absolute and relative basal area increments of trees and saplings and the aboveground biomass of understory shrubs and ferns. We further grouped individuals of the dominant tree species, Castanopsis eyrei, into three size classes to investigate their respective growth responses to the N fertilization. Our results showed that the plot-averaged absolute and relative growth rates of basal area and aboveground biomass of trees were not affected by N fertilization. Across the individuals of C. eyrei, the small trees with a DBH (diameter at breast height of 5–10 cm declined by 66.4 and 59.5 %, respectively, in N50 (50 kg N ha−1 yr−1 and N100 fertilized plots (100 kg N ha−1 yr−1, while the growth of median and large trees with a DBH of  >  10 cm did not significantly change with the N fertilization. The growth rate of small trees, saplings, and the aboveground biomass of understory shrubs and ground-cover ferns decreased significantly in the N-fertilized plots. Our findings suggested that N might not be a limiting nutrient in this mature subtropical

Caribbean dry forest networking: an opportunity for conservation

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K. Banda-Rodriguez; J. Weintritt; R.T. Pennington

2016-01-01

Seasonally dry tropical forest is the most threatened tropical forest in the world. Though its overall plant species diversity is lower than in neighboring biomes such as rain forest, species endemism can be high, and its conservation has often been neglected. Caribbean dry forests face diverse threats including tourism, agriculture, and climate change. The Latin...

Altitudinal variation in soil organic carbon stock in coniferous subtropical and broadleaf temperate forests in Garhwal Himalaya

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Kumar Munesh

2009-08-01

Full Text Available Abstract Background The Himalayan zones, with dense forest vegetation, cover a fifth part of India and store a third part of the country reserves of soil organic carbon (SOC. However, the details of altitudinal distribution of these carbon stocks, which are vulnerable to forest management and climate change impacts, are not well known. Results This article reports the results of measuring the stocks of SOC along altitudinal gradients. The study was carried out in the coniferous subtropical and broadleaf temperate forests of Garhwal Himalaya. The stocks of SOC were found to be decreasing with altitude: from 185.6 to 160.8 t C ha-1 and from 141.6 to 124.8 t C ha-1 in temperature (Quercus leucotrichophora and subtropical (Pinus roxburghii forests, respectively. Conclusion The results of this study lead to conclusion that the ability of soil to stabilize soil organic matter depends negatively on altitude and call for comprehensive theoretical explanation

Nutrient limitation on ecosystem productivity and processes of mature and old-growth subtropical forests in China.

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Enqing Hou

Full Text Available Nitrogen (N is considered the dominant limiting nutrient in temperate regions, while phosphorus (P limitation frequently occurs in tropical regions, but in subtropical regions nutrient limitation is poorly understood. In this study, we investigated N and P contents and N:P ratios of foliage, forest floors, fine roots and mineral soils, and their relationships with community biomass, litterfall C, N and P productions, forest floor turnover rate, and microbial processes in eight mature and old-growth subtropical forests (stand age >80 yr at Dinghushan Biosphere Reserve, China. Average N:P ratios (mass based in foliage, litter (L layer and mixture of fermentation and humus (F/H layer, and fine roots were 28.3, 42.3, 32.0 and 32.7, respectively. These values are higher than the critical N:P ratios for P limitation proposed (16-20 for foliage, ca. 25 for forest floors. The markedly high N:P ratios were mainly attributed to the high N concentrations of these plant materials. Community biomass, litterfall C, N and P productions, forest floor turnover rate and microbial properties were more strongly related to measures of P than N and frequently negatively related to the N:P ratios, suggesting a significant role of P availability in determining ecosystem production and productivity and nutrient cycling at all the study sites except for one prescribed disturbed site where N availability may also be important. We propose that N enrichment is probably a significant driver of the potential P limitation in the study area. Low P parent material may also contribute to the potential P limitation. In general, our results provided strong evidence supporting a significant role for P availability, rather than N availability, in determining ecosystem primary productivity and ecosystem processes in subtropical forests of China.

Phylogenetic Structure of Tree Species across Different Life Stages from Seedlings to Canopy Trees in a Subtropical Evergreen Broad-Leaved Forest.

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Jin, Yi; Qian, Hong; Yu, Mingjian

2015-01-01

Investigating patterns of phylogenetic structure across different life stages of tree species in forests is crucial to understanding forest community assembly, and investigating forest gap influence on the phylogenetic structure of forest regeneration is necessary for understanding forest community assembly. Here, we examine the phylogenetic structure of tree species across life stages from seedlings to canopy trees, as well as forest gap influence on the phylogenetic structure of forest regeneration in a forest of the subtropical region in China. We investigate changes in phylogenetic relatedness (measured as NRI) of tree species from seedlings, saplings, treelets to canopy trees; we compare the phylogenetic turnover (measured as βNRI) between canopy trees and seedlings in forest understory with that between canopy trees and seedlings in forest gaps. We found that phylogenetic relatedness generally increases from seedlings through saplings and treelets up to canopy trees, and that phylogenetic relatedness does not differ between seedlings in forest understory and those in forest gaps, but phylogenetic turnover between canopy trees and seedlings in forest understory is lower than that between canopy trees and seedlings in forest gaps. We conclude that tree species tend to be more closely related from seedling to canopy layers, and that forest gaps alter the seedling phylogenetic turnover of the studied forest. It is likely that the increasing trend of phylogenetic clustering as tree stem size increases observed in this subtropical forest is primarily driven by abiotic filtering processes, which select a set of closely related evergreen broad-leaved tree species whose regeneration has adapted to the closed canopy environments of the subtropical forest developed under the regional monsoon climate.

Responses of Soil Acid Phosphomonoesterase Activity to Simulated Nitrogen Deposition in Three Forests of Subtropical China

Institute of Scientific and Technical Information of China (English)

HUANG Wen-Juan; LIU Shi-Zhong; CHU Guo-Wei; ZHANG De-Qiang; LI Yue-Lin; LU Xian-Kai; ZHANG Wei; HUANG Juan; D. OTIENO; Z. H. XU; LIU Ju-Xiu

2012-01-01

Soil acid phosphomonoesterase activity (APA) plays a vital role in controlling phosphorus (P) cycling and reflecting the current degree of P limitation Responses of soil APA to elevating nitrogen (N) deposition are important because of their potential applications in addressing the relationship between N and P in forest ecosystems.A study of responses of soll APA to simulated N deposition was conducted in three succession forests of subtropical China.The three forests include a Masson pine (Pinus massoniana) forest (MPF)—pioneer community,a coniferous and broad-leaved mixed forest (MF)—transition community and a monsoon evergreen broadleaved forest (MEBF)—climax community.Four N treatments were designed for MEBF:control (without N added),low-N (50 kg N ha-1 year-1),and medium-N (100 kg N ha-1 year-1) and high-N (150 kg N ha-1 year-1),and only three N treatments (i.e.,control,low-N,mediun-N) were established for MPF and MF.Results showed that soil APA was highest in MEBF.followed by MPF and MF.Soil APAs in both MPF and MF were not influenced by low-N treatments but depressed in medium-N trcatments.However,soil APA in MEBF exhibited negative responses to high N additions,indicating that the environment of enhanced N depositions would reduce P supply for the mature forest ecosystem.Soil APA and its responses to N additions in subtropical forests were closely related to the succession stages in the forests.

High NDVI and Potential Canopy Photosynthesis of South American Subtropical Forests despite Seasonal Changes in Leaf Area Index and Air Temperature

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Piedad M. Cristiano

2014-02-01

Full Text Available The canopy photosynthesis and carbon balance of the subtropical forests are not well studied compared to temperate and tropical forest ecosystems. The main objective of this study was to assess the seasonal dynamics of Normalized Difference Vegetation Index (NDVI and potential canopy photosynthesis in relation to seasonal changes in leaf area index (LAI, chlorophyll concentration, and air temperatures of NE Argentina subtropical forests throughout the year. We included in the analysis several tree plantations (Pinus, Eucalyptus and Araucaria species that are known to have high productivity. Field studies in native forests and tree plantations were conducted; stem growth rates, LAI and leaf chlorophyll concentration were measured. MODIS satellite-derived LAI (1 km SIN Grid and NDVI (250m SIN Grid from February 2000 to 2012 were used as a proxy of seasonal dynamics of potential photosynthetic activity at the stand level. The remote sensing LAI of the subtropical forests decreased every year from 6 to 5 during the cold season, similar to field LAI measurements, when temperatures were 10 °C lower than during the summer. The yearly maximum NDVI values were observed during a few months in autumn and spring (March through May and November, respectively because high and low air temperatures may have a small detrimental effect on photosynthetic activity during both the warm and the cold seasons. Leaf chlorophyll concentration was higher during the cold season than the warm season which may have a compensatory effect on the seasonal variation of the NDVI values. The NDVI of the subtropical forest stands remained high and fairly constant throughout the year (the intra-annual coefficient of variation was 1.9%, and were comparable to the values of high-yield tree plantations. These results suggest that the humid subtropical forests in NE Argentina potentially could maintain high canopy photosynthetic activity throughout the year and thus this ecosystem may

Spatial and seasonal variations of leaf area index (LAI) in subtropical secondary forests related to floristic composition and stand characters

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Zhu, Wenjuan; Xiang, Wenhua; Pan, Qiong; Zeng, Yelin; Ouyang, Shuai; Lei, Pifeng; Deng, Xiangwen; Fang, Xi; Peng, Changhui

2016-07-01

Leaf area index (LAI) is an important parameter related to carbon, water, and energy exchange between canopy and atmosphere and is widely applied in process models that simulate production and hydrological cycles in forest ecosystems. However, fine-scale spatial heterogeneity of LAI and its controlling factors have yet to be fully understood in Chinese subtropical forests. We used hemispherical photography to measure LAI values in three subtropical forests (Pinus massoniana-Lithocarpus glaber coniferous and evergreen broadleaved mixed forests, Choerospondias axillaris deciduous broadleaved forests, and L. glaber-Cyclobalanopsis glauca evergreen broadleaved forests) from April 2014 to January 2015. Spatial heterogeneity of LAI and its controlling factors were analysed using geostatistical methods and the generalised additive models (GAMs) respectively. Our results showed that LAI values differed greatly in the three forests and their seasonal variations were consistent with plant phenology. LAI values exhibited strong spatial autocorrelation for the three forests measured in January and for the L. glaber-C. glauca forest in April, July, and October. Obvious patch distribution pattern of LAI values occurred in three forests during the non-growing period and this pattern gradually dwindled in the growing season. Stem number, crown coverage, proportion of evergreen conifer species on basal area basis, proportion of deciduous species on basal area basis, and forest types affected the spatial variations in LAI values in January, while stem number and proportion of deciduous species on basal area basis affected the spatial variations in LAI values in July. Floristic composition, spatial heterogeneity, and seasonal variations should be considered for sampling strategy in indirect LAI measurement and application of LAI to simulate functional processes in subtropical forests.

Phytogeography and conservation of neotropical dry forest with emphasis on Columbia

OpenAIRE

Banda Rodriguez, Karina Paola

2017-01-01

Dry forest is one of the most threatened tropical forests in the world. Human impact has caused its massive transformation but conservation of dry forest has often been neglected across Latin America. In Colombia, less than 10% of the original extension of dry forest remains. This thesis studies the phytogeography of neotropical dry forest and its relevance for conservation using data from 1602 tree species inventories made in dry forests across Latin America and the Caribbean ...

A study of the dry forest communities in the Dominican Republic.

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García-Fuentes, Antonio; Torres-Cordero, Juan A; Ruiz-Valenzuela, Luis; Lendínez-Barriga, María Lucía; Quesada-Rincón, Juan; Valle-Tendero, Francisco; Veloz, Alberto; León, Yolanda M; Salazar-Mendías, Carlos

2015-03-01

This paper is a floristic and phytosociological study of the dry forest communities of the Dominican Republic. A total of 69 relevés in dry forest biotopes were carried out. The samples were subsequently subjected to Detrended Correspondence Analysis for the determination and study of possible groupings. The study does not cover tree formations growing on serpentines, nor the so-called semideciduous forests, peculiar to areas with higher rainfall. A total of nine phytocoenoses were identified. The most significant results led to the description of six new phytosociological associations: Simaroubetum berteroani (thorny dry forest on coastal dunes), Phyllostylo rhamnoidis-Prosopidetum juliflorae (southern Dominican disturbed dry forest), Consoleo moniliformis-Camerarietum linearifoliae (dry forest on hard limestones), Lemaireocereo hystricis-Prosopidetum juliflorae (northern Dominican disturbed dry forest), Lycio americani-Prosopidetum juliflorae (disturbed dry forest on saline soils) and Guettardo ellipticae-Guapiretum discoloris (dry forest on flat-topped hillocks in Montecristi). This is an important step forward in the phytosociological and floristic studies of the Caribbean territories.

A study of the dry forest communities in the Dominican Republic

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Antonio García-Fuentes

2015-03-01

Full Text Available This paper is a floristic and phytosociological study of the dry forest communities of the Dominican Republic. A total of 69 relevés in dry forest biotopes were carried out. The samples were subsequently subjected to Detrended Correspondence Analysis for the determination and study of possible groupings. The study does not cover tree formations growing on serpentines, nor the so-called semideciduous forests, peculiar to areas with higher rainfall. A total of nine phytocoenoses were identified. The most significant results led to the description of six new phytosociological associations: Simaroubetum berteroani(thorny dry forest on coastal dunes, Phyllostylo rhamnoidis-Prosopidetum juliflorae (southern Dominican disturbed dry forest, Consoleo moniliformis-Camerarietum linearifoliae(dry forest on hard limestones, Lemaireocereo hystricis-Prosopidetum juliflorae(northern Dominican disturbed dry forest, Lycio americani-Prosopidetum juliflorae (disturbed dry forest on saline soils and Guettardo ellipticae-Guapiretum discoloris (dry forest on flat-topped hillocks in Montecristi. This is an important step forward in the phytosociological and floristic studies of the Caribbean territories.

Sixty-two years of change in subtropical wet forest structure and composition at El Verde, Puerto Rico

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A.P. Drew; J.D. Boley; Y. Zhao; F.H. Wadsworth

2009-01-01

A plot established in 1943 in a subtropical wet forest at the Luquillo Experimental Forest of Puerto Rico has been assessed periodically for changes in species and size of all trees >4cm diameter. Forest dynamics on a 0.72ha plot (EV-3) at 400masl at El Verde show recovery principally from hurricanes of 1928 and 1932, timber stand improvement in 1958, and from...

The arboreal component of a dry forest in Northeastern Brazil

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M. J. N. Rodal

Full Text Available The dry forests of northeastern Brazil are found near the coastal zone and on low, isolated mountains inland amid semi-arid vegetation. The floristic composition of these dry montane forests, as well as their relationship to humid forests (Atlantic forest sensu stricto and to the deciduous thorn woodlands (Caatinga sensu stricto of the Brazilian northeast are not yet well known. This paper sought to determine if the arboreal plants in a dry forest growing on a low mountain in the semi-arid inland region (Serra Negra, 8° 35’ - 8° 38’ S and 38° 02’ - 38° 04’ W between the municipalities of Floresta and Inajá, state of Pernambuco have the same floristic composition and structure as that seen in other regional forests. In fifty 10 x 20 m plots all live and standing dead trees with trunk measuring > 5 cm diameter at breast height were measured. Floristic similarities between the forest studied and other regional forests were assessed using multivariate analysis. The results demonstrate that the dry forest studied can be classified into two groups that represent two major vegetational transitions: (1 a humid forest/dry forest transition; and (2 a deciduous thorn-woodland/ dry forest transition.

The arboreal component of a dry forest in Northeastern Brazil.

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Rodal, M J N; Nascimento, L M

2006-05-01

The dry forests of northeastern Brazil are found near the coastal zone and on low, isolated mountains inland amid semi-arid vegetation. The floristic composition of these dry montane forests, as well as their relationship to humid forests (Atlantic forest sensu stricto) and to the deciduous thorn woodlands (Caatinga sensu stricto) of the Brazilian northeast are not yet well known. This paper sought to determine if the arboreal plants in a dry forest growing on a low mountain in the semi-arid inland region (Serra Negra, 8 degrees 35 - 8 degrees 38 S and 38 degrees 02 - 38 degrees 04 W) between the municipalities of Floresta and Inajá, state of Pernambuco have the same floristic composition and structure as that seen in other regional forests. In fifty 10 x 20 m plots all live and standing dead trees with trunk measuring > 5 cm diameter at breast height were measured. Floristic similarities between the forest studied and other regional forests were assessed using multivariate analysis. The results demonstrate that the dry forest studied can be classified into two groups that represent two major vegetational transitions: (1) a humid forest/dry forest transition; and (2) a deciduous thorn-woodland/ dry forest transition.

Soil-atmospheric exchange of CO2, CH4, and N2O in three subtropical forest ecosystems in southern China

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Tang, X.; Liu, S.; Zhou, G.; Zhang, Dongxiao; Zhou, C.

2006-01-01

The magnitude, temporal, and spatial patterns of soil-atmospheric greenhouse gas (hereafter referred to as GHG) exchanges in forests near the Tropic of Cancer are still highly uncertain. To contribute towards an improvement of actual estimates, soil-atmospheric CO2, CH4, and N2O fluxes were measured in three successional subtropical forests at the Dinghushan Nature Reserve (hereafter referred to as DNR) in southern China. Soils in DNR forests behaved as N2O sources and CH4 sinks. Annual mean CO2, N2O, and CH4 fluxes (mean ?? SD) were 7.7 ?? 4.6MgCO2-Cha-1 yr-1, 3.2 ?? 1.2 kg N2ONha-1 yr-1, and 3.4 ?? 0.9 kgCH4-Cha-1 yr-1, respectively. The climate was warm and wet from April through September 2003 (the hot-humid season) and became cool and dry from October 2003 through March 2004 (the cool-dry season). The seasonality of soil CO2 emission coincided with the seasonal climate pattern, with high CO2 emission rates in the hot-humid season and low rates in the cool-dry season. In contrast, seasonal patterns of CH4 and N2O fluxes were not clear, although higher CH4 uptake rates were often observed in the cool-dry season and higher N2O emission rates were often observed in the hot-humid season. GHG fluxes measured at these three sites showed a clear increasing trend with the progressive succession. If this trend is representative at the regional scale, CO2 and N2O emissions and CH4 uptake in southern China may increase in the future in light of the projected change in forest age structure. Removal of surface litter reduced soil CO2 effluxes by 17-44% in the three forests but had no significant effect on CH4 absorption and N2O emission rates. This suggests that microbial CH4 uptake and N2O production was mainly related to the mineral soil rather than in the surface litter layer. ?? 2006 Blackwell Publishing Ltd.

Abiotic factors influencing tropical dry forests regeneration

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Ceccon Eliane

2006-01-01

Full Text Available Tropical dry forests represent nearly half the tropical forests in the world and are the ecosystems registering the greatest deterioration from the anthropogenic exploitation of the land. This paper presents a review on the dynamics of tropical dry forests regeneration and the main abiotic factors influencing this regeneration, such as seasonal nature, soil fertility and humidity, and natural and anthropic disturbances. The main purpose is to clearly understand an important part of TDF succession dynamics.

Mercury dynamics and mass balance in a subtropical forest, southwestern China

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M. Ma

2016-04-01

Full Text Available The mid-subtropical forest area in southwest China was affected by anthropogenic mercury (Hg emissions over the past 3 decades. We quantified mercury dynamics on the forest field and measured fluxes and pools of Hg in litterfall, throughfall, stream water and forest soil in an evergreen broadleaved forest field in southwestern China. Total Hg (THg input by the throughfall and litterfall was assessed at 32.2 and 42.9 µg m−2 yr−1, respectively, which was remarkably higher than those observed from other forest fields in the background of North America and Europe. Hg fluxes across the soil–air interface (18.6 mg m−2 yr−1 and runoff and/or stream flow (7.2 µg m−2 yr−1 were regarded as the dominant ways for THg export from the forest field. The forest field hosts an enormous amount of atmospheric Hg, and its reserves is estimated to be 25 341 µg m2. The ratio of output to input Hg fluxes (0.34 is higher compared with other study sites. The higher output / input ratio may represent an important ecological risk for the downstream aquatic ecosystems, even if the forest field could be an effective sink of Hg.

The arboreal component of a dry forest in Northeastern Brazil

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Rodal,M. J. N.; Nascimento,L. M.

2006-01-01

The dry forests of northeastern Brazil are found near the coastal zone and on low, isolated mountains inland amid semi-arid vegetation. The floristic composition of these dry montane forests, as well as their relationship to humid forests (Atlantic forest sensu stricto) and to the deciduous thorn woodlands (Caatinga sensu stricto) of the Brazilian northeast are not yet well known. This paper sought to determine if the arboreal plants in a dry forest growing on a low mountain in the semi-arid ...

Epiphytic and endophytic bacteria that promote growth of ethnomedicinal plants in the subtropical forests of Meghalaya, India

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Fenella Mary War Nongkhlaw

2014-12-01

Full Text Available The present study was aimed to investigate the endophytic and epiphytic bacteria associated with selected ethnomedicinal plants from the pristine subtropical forests of Meghalaya and analyse them for plant growth promotion and antagonistic ability. This study is an attempt to explore plant associated bacteria which are beneficial to host plants, and thus aid in the conservation of ethnomedicinal plants of the studied subtropical forests, which are dwindling due to exploitation. The plant growth promotion parameters like indole acetic acid (IAA production, mineral phosphate solubilisation, acid phosphatase activity, presence of 1-aminocyclopropane-1-carboxylic acid deaminase (ACC gene, nitrogen fixation, cellulose digestion, chitin and pectin degradation were screened among the isolates. The study revealed significant differences in bacterial population not only between the epiphytic and endophytic microhabitats, but also amongst the host plants. Out of the 70 isolated plant associated bacteria, Bacillus sp., Serratia sp., Pseudomonas sp., Pantoea sp., and Lysinibacillus sp. showed potent plant growth promotion properties. Bacillus siamensis C53 and B. subtilis cenB showed significant antagonistic activity against the tested pathogens. This study indicated the isolates inhabiting the plants prevalent in the subtropical sacred forests could be explored for use as plant growth promoters while practising the cultivation and conservation of ethnomedicinal plants. Rev. Biol. Trop. 62 (4: 1295-1308. Epub 2014 December 01.

Atmospheric deposition of nitrogen at five subtropical forested sites in South China

International Nuclear Information System (INIS)

Chen, Xi Yun; Mulder, Jan

2007-01-01

Elevated concentrations of reactive nitrogen (N) in precipitation have been reported for many cities in China. Due to increased use of fossil fuels and expansion in agriculture, further increases in deposition of ammonia (NH x ) and reactive N oxides (NO y ) are predicted. Increased deposition of reactive N is likely to affect N dynamics and N runoff in forest ecosystems. Yet, in China little work has been done to quantify the levels of atmospheric N deposition in such systems. Here, we assess the deposition of inorganic N (ammonium, NH 4 + and nitrate, NO 3 - ) for five subtropical forest ecosystems in remote and urban areas of South China. Annual volume-weighted concentrations in bulk precipitation range from 0.18 to 1.55 mg NH 4 + -N L - 1 and from 0.12 to 0.74 mg NO 3 - -N L - 1 . These values are large and several times greater than those reported for remote sites of the world. The fluxes of total inorganic N (TIN) in wet-only deposition range from 0.8 to 2.3 g N m - 2 yr - 1 , with NH 4 + -N contributing 54% to 77%. Both the tree canopy and the ground vegetation layer are important in determining the net N flux reaching the forest floor, but the net effect varies from site to site. At TieShanPing (TSP), close to Chongqing city, and at CaiJiaTang (CJT), near Shaoshan (Hunan province), the canopy represents a net source of N, probably due to dry deposition. At the other three sites (LiuChongGuan (LCG), LeiGongShan (LGS), both in Guizhou province, and LiuXiHe (LXH) in Guangdong), a net loss of reactive N from precipitation water occurs in the canopy, probably due to uptake processes. The total annual atmospheric TIN load is estimated to range from at least 0.8 g N m - 2 yr - 1 to 4.0 g N m - 2 yr - 1 , with a considerable contribution from dry deposition. Concentrations and fluxes of inorganic N in tree canopy throughfall are greater than those in North America. Also the contribution of NH 4 + -N to TIN fluxes in throughfall (40% to 70%) is greater than in North

Throughfall patterns of a Subtropical Atlantic Forest in Brazil

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Macedo Sá, João Henrique; Borges Chaffe, Pedro Luiz; Yuimi de Oliveira, Debora; Nery Giglio, Joana; Kobiyama, Masato

2017-04-01

The interception process is responsible for the spatial and temporal redistribution of the precipitation that reaches the ground. This process is important especially in forested areas since it influences recycling of moisture from the air and also the amount of water that effectively reaches the ground. The contact of the precipitation with the canopy influences on the water quality, increasing the concentration of various nutrients in the throughfall (Tf) and stemflow (Sf). Brazil, only about 8% of the original Atlantic Forest cover remains. That is an important biome and little is known about the characteristics of rainfall interception of this forest. The total interception loss in forested areas is usually formulated as the gross precipitation (P) minus the sum of the throughfall (Tf) and the stemflow (Sf). The stems characteristics influence on Sf, meanwhile, the value of Tf strongly depends on the canopy and leaf structures. Because of the complex structure of the canopy, these characteristics are usually expressed by the simpler Leaf Area Index (LAI) or the Canopy Cover Fraction (CCF). The Araponga river experimental catchment (ARA) with 5.3 ha is on the northern plateau of Santa Catarina State, southern Brazil. It is an area completely covered by secondary subtropical Atlantic Forest, the regional climate is the Köppen Cfb type, i.e., temperate climate without dry season and with warm summer (the mean temperature of the hottest month is always under 22°C). The objectives of the present study were (i) to evaluate the spatial and temporal variation of canopy cover; (ii) to influence of the interception process on the precipitation quality; and (iii) to explore the relation between canopy cover and throughfall. Inside the catchment, 9 Tf gauges were installed 40 cm above the soil surface in order to include the interception by shrub. 28 hand-made gauges were installed on a circular area of 3 m radius to analyze the spatial variability of throughfall. During

Tree Diversity Enhances Stand Carbon Storage but Not Leaf Area in a Subtropical Forest.

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Castro-Izaguirre, Nadia; Chi, Xiulian; Baruffol, Martin; Tang, Zhiyao; Ma, Keping; Schmid, Bernhard; Niklaus, Pascal A

2016-01-01

Research about biodiversity-productivity relationships has focused on herbaceous ecosystems, with results from tree field studies only recently beginning to emerge. Also, the latter are concentrated largely in the temperate zone. Tree species diversity generally is much higher in subtropical and tropical than in temperate or boreal forests, with reasons not fully understood. Niche overlap and thus complementarity in the use of resources that support productivity may be lower in forests than in herbaceous ecosystems, suggesting weaker productivity responses to diversity change in forests. We studied stand basal area, vertical structure, leaf area, and their relationship with tree species richness in a subtropical forest in south-east China. Permanent forest plots of 30 x 30 m were selected to span largely independent gradients in tree species richness and secondary successional age. Plots with higher tree species richness had a higher stand basal area. Also, stand basal area increases over a 4-year census interval were larger at high than at low diversity. These effects translated into increased carbon stocks in aboveground phytomass (estimated using allometric equations). A higher variability in tree height in more diverse plots suggested that these effects were facilitated by denser canopy packing due to architectural complementarity between species. In contrast, leaf area was not or even negatively affected by tree diversity, indicating a decoupling of carbon accumulation from leaf area. Alternatively, the same community leaf area might have assimilated more C per time interval in more than in less diverse plots because of differences in leaf turnover and productivity or because of differences in the display of leaves in vertical and horizontal space. Overall, our study suggests that in species-rich forests niche-based processes support a positive diversity-productivity relationship and that this translates into increased carbon storage in long-lived woody

Climatology and forest decay - stresses caused by dry periods

International Nuclear Information System (INIS)

Havlik, D.

1991-01-01

In the discussion of forest decline in the Eighties, stresses due to dry weather is often named as a secondary cause. The concept of 'climatological dry periods' is introduced in this article and applied to records for the Basel and Aachen regions. The time distribution of dry periods of different length and different water deficiency (40 mm, 60 mm, 100 mm) is analyzed. In the case of the Basel data, the dry periods are related to the 'forest damage caused by draught' recorded for the Basel region since 1930. The results support the theory that increasingly larger and more frequent dry periods with water shortage have contributed significantly to forest damage in the last 15 years. Apart from the 'dry stress' itself, also the enhanced production of photooxidants is a damaging mechanism. (orig.) [de

Botanical and ecological basis for the resilience of Antillean dry forests

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A.E. Lugo; E. Medina; J. Carlos Trejo Torres; E. Helmer

2006-01-01

Dry forest environments limit the number of species that can survive there. Antillean dry forests have low floristic diversity and stature, high density of small and medium-sized trees, and are among the least conserved of the tropical forests. Their canopies are smooth with no emergent trees and have high species dominance. Antillean dry forests occur mostly on...

Analyzing the edge effects in a Brazilian seasonally dry tropical forest.

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Arruda, D M; Eisenlohr, P V

2016-02-01

Due to the deciduous nature of dry forests (widely known as seasonally dry tropical forests) they are subject to microclimatic conditions not experienced in other forest formations. Close examinations of the theory of edge effects in dry forests are still rare and a number of questions arise in terms of this topic. In light of this situation we examined a fragment of the dry forest to respond to the following questions: (I) Are there differences in canopy cover along the edge-interior gradient during the dry season? (II) How does the microclimate (air temperature, soil temperature, and relative humidity) vary along that gradient? (III) How does the microclimate influence tree species richness, evenness and abundance along that gradient? (IV) Are certain tree species more dominant closer to the forest edges? Regressions were performed to address these questions. Their coefficients did not significantly vary from zero. Apparently, the uniform openness of the forest canopy caused a homogeneous internal microclimate, without significant differentiation in habitats that would allow modifications in biotic variables tested. We conclude that the processes of edge effect commonly seen in humid forests, not was shared with the dry forest assessed.

Forest structure in low diversity tropical forests: a study of Hawaiian wet and dry forests

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R. Ostertag; F. Inman-Narahari; S. Cordell; C.P. Giardina; L. Sack

2014-01-01

The potential influence of diversity on ecosystem structure and function remains a topic of significant debate, especially for tropical forests where diversity can range widely. We used Center for Tropical Forest Science (CTFS) methodology to establish forest dynamics plots in montane wet forest and lowland dry forest on Hawai‘i Island. We compared the species...

Forest response to heat waves at the dry timberline

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Yakir, D.; Rotenberg, E.; Tatrinov, F.; Ogee, J.; Maseyk, K.

2012-04-01

Predictions of climate change consistently indicate continuous warming and drying for the entire Mediterranean basin and other regions during the next century. Investigating forest functioning at the current dry and hot "timberline" has therefore implications for predicting future forest distribution. In such investigations we should consider the forest adjustments to extreme conditions both at the long-term average climate basis, as at the time-scale of episodic extreme events, such as heat waves and droughts. Investigating both aspects in a 45-yr old semi-arid pine forest at the dry timberline (MuSICA) was used to test our understandings of underlying processes, and our ability to account for such differential responses.

DRY DEPOSITION OF POLLUTANTS TO FORESTS

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We report on the results of an extensive field campaign to measure dry deposition of ozone and sulfur dioxide to a sample of forest types in the United States. Measurements were made for full growing seasons over a deciduous forest in Pennsylvania and a mixed deciduous-conifer...

Efficient way back litters nutrient potential of a tropical forest of bank. Sierra Nevada of Santa Marta Colombia

International Nuclear Information System (INIS)

Fuentes Molina, Natalia; Rodriguez Barrios, Javier Alfredo

2012-01-01

In three representative forests along the River Gaira, (subtropical wet forest, subtropical moist forest and tropical thorn mount), were measured over six months (wet and dry seasons) fluxes of nitrogen and phosphorus through the litter. Concentrations of nutrients (nitrogen and phosphorus) in the litter were relatively similar in the three Nevada de Santa Marta Colombia. Fuentes, Rodriguez. vegetation types (1.71% n and 0.12% p for the subtropical moist forest, followed by the tropical thorn mount with 1.50% n and 0.10% p and the subtropical wet forest with 1.39% n and 0.08% p), with the most significant differences found for nitrogen, which is the major nutrient with the absolute maximum in the subtropical rain forest set in the middle stretch of the basin. The greatest returns on biomass and nutrients occurred in the subtropical moist forest and tropical thorn mount set in the middle and lower reaches of the basin. The leaves showed high concentration of n and consequently, given the high production values of the different fractions, a high potential return of n (78.6 kg ha-1 yr-1). The foliar p concentration showed a potential return of 4.9 kgha1yr-1 and high values of the indices of efficiency in their use (iev: 2888.5) and foliar resorption (ern: 98.2), was the nutrient most limiting.

Community-weighted mean of leaf traits and divergence of wood traits predict aboveground biomass in secondary subtropical forests.

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Ali, Arshad; Yan, En-Rong; Chang, Scott X; Cheng, Jun-Yang; Liu, Xiang-Yu

2017-01-01

Subtropical forests are globally important in providing ecological goods and services, but it is not clear whether functional diversity and composition can predict aboveground biomass in such forests. We hypothesized that high aboveground biomass is associated with high functional divergence (FDvar, i.e., niche complementarity) and community-weighted mean (CWM, i.e., mass ratio; communities dominated by a single plant strategy) of trait values. Structural equation modeling was employed to determine the direct and indirect effects of stand age and the residual effects of CWM and FDvar on aboveground biomass across 31 plots in secondary forests in subtropical China. The CWM model accounted for 78, 20, 6 and 2% of the variation in aboveground biomass, nitrogen concentration in young leaf, plant height and specific leaf area of young leaf, respectively. The FDvar model explained 74, 13, 7 and 0% of the variation in aboveground biomass, plant height, twig wood density and nitrogen concentration in young leaf, respectively. The variation in aboveground biomass, CWM of leaf nitrogen concentration and specific leaf area, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf explained by the joint model was 86, 20, 13, 7, 2 and 0%, respectively. Stand age had a strong positive direct effect but low indirect positive effects on aboveground biomass. Aboveground biomass was negatively related to CWM of nitrogen concentration in young leaf, but positively related to CWM of specific leaf area of young leaf and plant height, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf. Leaf and wood economics spectra are decoupled in regulating the functionality of forests, communities with diverse species but high nitrogen conservative and light acquisitive strategies result in high aboveground biomass, and hence, supporting both the mass ratio and niche complementarity hypotheses in secondary subtropical forests

Water use efficiency in a primary subtropical evergreen forest in Southwest China.

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Song, Qing-Hai; Fei, Xue-Hai; Zhang, Yi-Ping; Sha, Li-Qing; Liu, Yun-Tong; Zhou, Wen-Jun; Wu, Chuan-Sheng; Lu, Zhi-Yun; Luo, Kang; Gao, Jin-Bo; Liu, Yu-Hong

2017-02-20

We calculated water use efficiency (WUE) using measures of gross primary production (GPP) and evapotranspiration (ET) from five years of continuous eddy covariance measurements (2009-2013) obtained over a primary subtropical evergreen broadleaved forest in southwestern China. Annual mean WUE exhibited a decreasing trend from 2009 to 2013, varying from ~2.28 to 2.68 g C kg H 2 O -1 . The multiyear average WUE was 2.48 ± 0.17 (mean ± standard deviation) g C kg H 2 O -1 . WUE increased greatly in the driest year (2009), due to a larger decline in ET than in GPP. At the diurnal scale, WUE in the wet season reached 5.1 g C kg H 2 O -1 in the early morning and 4.6 g C kg H 2 O -1 in the evening. WUE in the dry season reached 3.1 g C kg H 2 O -1 in the early morning and 2.7 g C kg H 2 O -1 in the evening. During the leaf emergence stage, the variation of WUE could be suitably explained by water-related variables (relative humidity (RH), soil water content at 100 cm (SWC_100)), solar radiation and the green index (Sgreen). These results revealed large variation in WUE at different time scales, highlighting the importance of individual site characteristics.

Breeding biology of passerines in a subtropical montane forest in northwestern Argentina

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Auer, S.K.; Bassar, R.D.; Fontaine, J.J.; Martin, T.E.

2007-01-01

The breeding ecology of south temperate bird species is less widely known than that of north temperate species, yet because they comprise a large portion of the world's avian diversity, knowledge of their breeding ecology can contribute to a more comprehensive understanding of the geographic diversity of avian reproductive traits and life history strategies. We provide the first detailed examination of the reproductive strategies of 18 forest passerines of subtropical, northwestern Argentina. Mean clutch sizes were smaller and egg mass was greater than for north temperate birds, but differed among species and nest types, with cavity-nesters having larger clutches than species with open-cup and enclosed nests. Across all species, the average breeding season duration was 50 days; thus, the common perception that southern species have smaller clutch sizes because of longer breeding seasons is not supported in this community. Daily nest predation rates were influenced by nest type, cavity nests suffering the least from predation, as found in north temperate systems. Only females incubated eggs in all but one species, whereas both parents fed and cared for nestlings in all species. Mean nest attentiveness was low compared to north temperate passerines. Mean hourly nestling feeding rates differed among species and were negatively related to nest predation risk. In short, coexisting species in this subtropical forest varied in their life history strategies, in part correlated with variation in nest predation risk, but also differing from north temperate species. ?? The Cooper Ornithological Society 2007.

Bet-hedging dry-forest resilience to climate-change threats in the western USA based on historical forest structure

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William Lawrence Baker

2015-01-01

Full Text Available Dry forests are particularly subject to wildfires, insect outbreaks, and droughts that likely will increase with climate change. Efforts to increase resilience of dry forests often focus on removing most small trees to reduce wildfire risk. However, small trees often survive other disturbances and could provide broader forest resilience, but small trees are thought to have been historically rare. We used direct records by land surveyors in the late-1800s along 22,206 km of survey lines in 1.7 million ha of dry forests in the western USA to test this idea. These systematic surveys (45,171 trees of historical forests reveal that small trees dominated (52-92% of total trees dry forests. Historical forests also included diverse tree sizes and species, which together provided resilience to several types of disturbances. Current risk to dry forests from insect outbreaks is 5.6 times the risk of higher-severity wildfires, with small trees increasing forest resilience to insect outbreaks. Removal of most small trees to reduce wildfire risk may compromise the bet-hedging resilience, provided by small trees and diverse tree sizes and species, against a broad array of unpredictable future disturbances.

Are variations in heterotrophic soil respiration related to changes in substrate availability and microbial biomass carbon in the subtropical forests?

Science.gov (United States)

Wei, Hui; Chen, Xiaomei; Xiao, Guoliang; Guenet, Bertrand; Vicca, Sara; Shen, Weijun

2015-01-01

Soil temperature and moisture are widely-recognized controlling factors on heterotrophic soil respiration (Rh), although they often explain only a portion of Rh variability. How other soil physicochemical and microbial properties may contribute to Rh variability has been less studied. We conducted field measurements on Rh half-monthly and associated soil properties monthly for two years in four subtropical forests of southern China to assess influences of carbon availability and microbial properties on Rh. Rh in coniferous forest was significantly lower than that in the other three broadleaf species-dominated forests and exhibited obvious seasonal variations in the four forests (P < 0.05). Temperature was the primary factor influencing the seasonal variability of Rh while moisture was not in these humid subtropical forests. The quantity and decomposability of dissolved organic carbon (DOC) were significantly important to Rh variations, but the effect of DOC content on Rh was confounded with temperature, as revealed by partial mantel test. Microbial biomass carbon (MBC) was significantly related to Rh variations across forests during the warm season (P = 0.043). Our results suggest that DOC and MBC may be important when predicting Rh under some conditions, and highlight the complexity by mutual effects of them with environmental factors on Rh variations. PMID:26670822

Impacts of increasing typhoons on the structure and function of a subtropical forest: reflections of a changing climate.

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Lin, Kuo-Chuan; Hamburg, Steven P; Wang, Lixin; Duh, Chin-Tzer; Huang, Chu-Mei; Chang, Chung-Te; Lin, Teng-Chiu

2017-07-07

Due to their destructive and sporadic nature, it is often difficult to evaluate and predict the effects of typhoon on forest ecosystem patterns and processes. We used a 21-yr record of litterfall rates to explore the influence of typhoon frequency and intensity, along with other meteorological variables, on ecosystem dynamics in a subtropical rainforest. Over the past half century there has been an increasing frequency of strong typhoons (category 3; >49.6 m s -1 ; increase of 1.5 typhoons/decade) impacting the Fushan Experimental Forest, Taiwan. At Fushan strong typhoons drive total litterfall mass with an average of 1100 kg ha -1 litterfall typhoon -1 . While mean typhoon season litterfall has been observed to vary by an order of magnitude, mean litterfall rates associated with annual leaf senescence vary by typhoon frequency, total annual litter mass increased gradually over the 21-year record following three major typhoons in 1994. Monthly maximum wind speed was predictive of monthly litterfall, yet the influence of precipitation and temperature was only evident in non-typhoon affected months. The response of this subtropical forest to strong typhoons suggests that increasing typhoon frequency has already shifted ecosystem structure and function (declining carbon sequestration and forest stature).

Effect of fragmentation on the Costa Rican dry forest avifauna

OpenAIRE

Barrantes, Gilbert; Ocampo, Diego; Ram?rez-Fern?ndez, Jos? D.; Fuchs, Eric J.

2016-01-01

Deforestation and changes in land use have reduced the tropical dry forest to isolated forest patches in northwestern Costa Rica. We examined the effect of patch area and length of the dry season on nestedness of the entire avian community, forest fragment assemblages, and species occupancy across fragments for the entire native avifauna, and for a subset of forest dependent species. Species richness was independent of both fragment area and distance between fragments. Similarity in bird comm...

Carbon and water vapore balance in a primary subtropical evergreen forest in Southewest China under a changing climate

Science.gov (United States)

Song, Q. H.; Zhang, Y. P.

2017-12-01

The Ailaoshan Nature Reserve in Yunnan province, southwestern China hosts about 5000 ha of primary subtropical evergreen mountain cloud forest. A widespread and severe drought occurred in southwestern China in 2009 and 2010, providing a unique opportunity to directly evaluate how water use efficiency (WUE) changes with drought stress in the primary subtropical forest. We calculated WUE using measures of gross primary production (GPP) and evapotranspiration (ET) from five years of continuous eddy covariance measurements (2009-2013) obtained over a primary subtropical evergreen broadleaved forest in southwestern China. Annual mean WUE exhibited a decreasing trend from 2009 to 2013, varying from 2.28 to 2.68 g C kg H2O-1. The multiyear average WUE was 2.48 ± 0.17 (mean ± standard deviation) g C kg H2O-1. WUE increased greatly in the driest year (2009), due to a larger decline in ET than in GPP. Unfortunately, the same study site experienced a particularly extreme climate anomaly during January 2015, with a heavy snow of up to 50 cm in depth, which led to severe forest damage. The forest canopy was severely damaged by the heavy snow, and the leaf area index (LAI) decreased significantly from January to July 2015. GPP, net ecosystem exchange (NEE), and Ecosystem respiration (Reco) all sharply decreased in 2015 after the heavy snow. On average, a strong decrease of 544 g C m-2 year-1 in annual NEE in 2015 was associated with a decrease of 829 g C m-2 year-1 in annual GPP and a decrease of 285 g C m-2 year-1 in annual Reco. Overall, annual net C uptake in 2015 was reduced by 76% compared to the mean C uptake of the previous four years. A sharp increase in carbon uptake was also observed in 2016, indicating that long-term, continuous measurements should be carried out to evaluate the overall response to the disturbance.

Diversity and Spatial Structure of Belowground Plant–Fungal Symbiosis in a Mixed Subtropical Forest of Ectomycorrhizal and Arbuscular Mycorrhizal Plants

Science.gov (United States)

Toju, Hirokazu; Sato, Hirotoshi; Tanabe, Akifumi S.

2014-01-01

Plant–mycorrhizal fungal interactions are ubiquitous in forest ecosystems. While ectomycorrhizal plants and their fungi generally dominate temperate forests, arbuscular mycorrhizal symbiosis is common in the tropics. In subtropical regions, however, ectomycorrhizal and arbuscular mycorrhizal plants co-occur at comparable abundances in single forests, presumably generating complex community structures of root-associated fungi. To reveal root-associated fungal community structure in a mixed forest of ectomycorrhizal and arbuscular mycorrhizal plants, we conducted a massively-parallel pyrosequencing analysis, targeting fungi in the roots of 36 plant species that co-occur in a subtropical forest. In total, 580 fungal operational taxonomic units were detected, of which 132 and 58 were probably ectomycorrhizal and arbuscular mycorrhizal, respectively. As expected, the composition of fungal symbionts differed between fagaceous (ectomycorrhizal) and non-fagaceous (possibly arbuscular mycorrhizal) plants. However, non-fagaceous plants were associated with not only arbuscular mycorrhizal fungi but also several clades of ectomycorrhizal (e.g., Russula) and root-endophytic ascomycete fungi. Many of the ectomycorrhizal and root-endophytic fungi were detected from both fagaceous and non-fagaceous plants in the community. Interestingly, ectomycorrhizal and arbuscular mycorrhizal fungi were concurrently detected from tiny root fragments of non-fagaceous plants. The plant–fungal associations in the forest were spatially structured, and non-fagaceous plant roots hosted ectomycorrhizal fungi more often in the proximity of ectomycorrhizal plant roots. Overall, this study suggests that belowground plant–fungal symbiosis in subtropical forests is complex in that it includes “non-typical” plant–fungal combinations (e.g., ectomycorrhizal fungi on possibly arbuscular mycorrhizal plants) that do not fall within the conventional classification of mycorrhizal symbioses, and in

Diversity and spatial structure of belowground plant-fungal symbiosis in a mixed subtropical forest of ectomycorrhizal and arbuscular mycorrhizal plants.

Science.gov (United States)

Toju, Hirokazu; Sato, Hirotoshi; Tanabe, Akifumi S

2014-01-01

Plant-mycorrhizal fungal interactions are ubiquitous in forest ecosystems. While ectomycorrhizal plants and their fungi generally dominate temperate forests, arbuscular mycorrhizal symbiosis is common in the tropics. In subtropical regions, however, ectomycorrhizal and arbuscular mycorrhizal plants co-occur at comparable abundances in single forests, presumably generating complex community structures of root-associated fungi. To reveal root-associated fungal community structure in a mixed forest of ectomycorrhizal and arbuscular mycorrhizal plants, we conducted a massively-parallel pyrosequencing analysis, targeting fungi in the roots of 36 plant species that co-occur in a subtropical forest. In total, 580 fungal operational taxonomic units were detected, of which 132 and 58 were probably ectomycorrhizal and arbuscular mycorrhizal, respectively. As expected, the composition of fungal symbionts differed between fagaceous (ectomycorrhizal) and non-fagaceous (possibly arbuscular mycorrhizal) plants. However, non-fagaceous plants were associated with not only arbuscular mycorrhizal fungi but also several clades of ectomycorrhizal (e.g., Russula) and root-endophytic ascomycete fungi. Many of the ectomycorrhizal and root-endophytic fungi were detected from both fagaceous and non-fagaceous plants in the community. Interestingly, ectomycorrhizal and arbuscular mycorrhizal fungi were concurrently detected from tiny root fragments of non-fagaceous plants. The plant-fungal associations in the forest were spatially structured, and non-fagaceous plant roots hosted ectomycorrhizal fungi more often in the proximity of ectomycorrhizal plant roots. Overall, this study suggests that belowground plant-fungal symbiosis in subtropical forests is complex in that it includes "non-typical" plant-fungal combinations (e.g., ectomycorrhizal fungi on possibly arbuscular mycorrhizal plants) that do not fall within the conventional classification of mycorrhizal symbioses, and in that

Effects of forest conversion on the assemblages' structure of aquatic insects in subtropical regions

Directory of Open Access Journals (Sweden)

Tiago R.N. Bertaso

2015-03-01

Full Text Available The effects of forest conversion to agricultural land uses on assemblages of aquatic insects were analyzed in subtropical streams. Organisms and environmental variables were collected in six low-order streams: three streams located in a forested area, and three in areas converted to agricultural land uses. We expected that the aquatic insects' assemblage attributes would be significantly affected by forest conversion, as well as by environmental variables. Streams in converted areas presented lower species richness, abundance and proportion of sensitive insect taxa. The ANOSIM test evidenced strong difference in EPT assemblage structure between streams of forested and converted areas. The ISA test evidenced several EPT genera with high specificity to streams in forested areas and only one genus related to streams in converted areas. Thus, the impacts of the conversion of forested area to agricultural land uses have significantly affected the EPT assemblages, while environmental variables were not affected. We suggest that the effects detected can be influenced by two processes related to vegetation cover: i lower input of allochthonous material, and ii increased input of fine sediments in streams draining converted areas.

Comparison of bacterial and fungal communities between natural and planted pine forests in subtropical China.

Science.gov (United States)

Nie, Ming; Meng, Han; Li, Ke; Wan, Jia-Rong; Quan, Zhe-Xue; Fang, Chang-Ming; Chen, Jia-Kuan; Li, Bo

2012-01-01

To improve our understanding of the changes in bacterial and fungal diversity in natural pine and planted forests in subtropical region of China, we examined bacterial and fungal communities from a native and a nearby planted pine forest of the Mt. Lushan by constructing clone libraries of 16S and 18S rRNA genes. For bacterial communities, Proteobacteria and Acidobacteria were dominant bacterial taxa in both two types of forest soils. The Shannon-Wiener diversity index, rarefaction curve analysis, and LibShuff analysis suggest that these two forests contained similar diversity of bacterial communities. Low soil acidity (pH ≈ 4) of our study forests might be one of the most important selection factors determining growth of acidophilic Acidobacteria and Proteobacteria. However, the natural forest harbored greater level of fungal diversity than the planted forest according to the Shannon-Wiener diversity index and rarefaction curve analysis. Basidiomycota and Ascomycota were dominant fungal taxa in the soils of natural and planted forests, respectively. Our results suggest that fungal community was more sensitive than the bacterial community in characterizing the differences in plant cover impacts on the microbial flora in the natural and planted forests. The natural and planted forests may function differently due to the differences in soil fungal diversity and relative abundance.

Forest structure in low-diversity tropical forests: a study of Hawaiian wet and dry forests.

Science.gov (United States)

Ostertag, Rebecca; Inman-Narahari, Faith; Cordell, Susan; Giardina, Christian P; Sack, Lawren

2014-01-01

The potential influence of diversity on ecosystem structure and function remains a topic of significant debate, especially for tropical forests where diversity can range widely. We used Center for Tropical Forest Science (CTFS) methodology to establish forest dynamics plots in montane wet forest and lowland dry forest on Hawai'i Island. We compared the species diversity, tree density, basal area, biomass, and size class distributions between the two forest types. We then examined these variables across tropical forests within the CTFS network. Consistent with other island forests, the Hawai'i forests were characterized by low species richness and very high relative dominance. The two Hawai'i forests were floristically distinct, yet similar in species richness (15 vs. 21 species) and stem density (3078 vs. 3486/ha). While these forests were selected for their low invasive species cover relative to surrounding forests, both forests averaged 5->50% invasive species cover; ongoing removal will be necessary to reduce or prevent competitive impacts, especially from woody species. The montane wet forest had much larger trees, resulting in eightfold higher basal area and above-ground biomass. Across the CTFS network, the Hawaiian montane wet forest was similar to other tropical forests with respect to diameter distributions, density, and aboveground biomass, while the Hawai'i lowland dry forest was similar in density to tropical forests with much higher diversity. These findings suggest that forest structural variables can be similar across tropical forests independently of species richness. The inclusion of low-diversity Pacific Island forests in the CTFS network provides an ∼80-fold range in species richness (15-1182 species), six-fold variation in mean annual rainfall (835-5272 mm yr(-1)) and 1.8-fold variation in mean annual temperature (16.0-28.4°C). Thus, the Hawaiian forest plots expand the global forest plot network to enable testing of ecological theory for

Forest structure in low-diversity tropical forests: a study of Hawaiian wet and dry forests.

Directory of Open Access Journals (Sweden)

Rebecca Ostertag

Full Text Available The potential influence of diversity on ecosystem structure and function remains a topic of significant debate, especially for tropical forests where diversity can range widely. We used Center for Tropical Forest Science (CTFS methodology to establish forest dynamics plots in montane wet forest and lowland dry forest on Hawai'i Island. We compared the species diversity, tree density, basal area, biomass, and size class distributions between the two forest types. We then examined these variables across tropical forests within the CTFS network. Consistent with other island forests, the Hawai'i forests were characterized by low species richness and very high relative dominance. The two Hawai'i forests were floristically distinct, yet similar in species richness (15 vs. 21 species and stem density (3078 vs. 3486/ha. While these forests were selected for their low invasive species cover relative to surrounding forests, both forests averaged 5->50% invasive species cover; ongoing removal will be necessary to reduce or prevent competitive impacts, especially from woody species. The montane wet forest had much larger trees, resulting in eightfold higher basal area and above-ground biomass. Across the CTFS network, the Hawaiian montane wet forest was similar to other tropical forests with respect to diameter distributions, density, and aboveground biomass, while the Hawai'i lowland dry forest was similar in density to tropical forests with much higher diversity. These findings suggest that forest structural variables can be similar across tropical forests independently of species richness. The inclusion of low-diversity Pacific Island forests in the CTFS network provides an ∼80-fold range in species richness (15-1182 species, six-fold variation in mean annual rainfall (835-5272 mm yr(-1 and 1.8-fold variation in mean annual temperature (16.0-28.4°C. Thus, the Hawaiian forest plots expand the global forest plot network to enable testing of ecological

Transfer of 137Cs from soil to plants in a wet montane forest in subtropical Taiwan

International Nuclear Information System (INIS)

Chih-Yu Chiu

1999-01-01

The distribution of 137 Cs in an undisturbed, multistoried, subtropical wet montane forest ecosystem surrounding Yuanyang Lake (lake surface level ca. 1670 m, in northeastern Taiwan), was investigated. The mossy forest here represents a currently-rare perhumid temperate environment in subtropical region. The radioactivity concentration of 137 Cs was determined by γ-spectroscopy with a Ge(Li) detector. Although the soil is extremely acidic (pH 3.3 to 3.6) and the rainfall is high, 137 Cs is evidently retained in the organic layer. The radioactivity concentration of 137 Cs in surface soil ranges from 28 to 71 Bq x kg -1 . The concentrations of 137 Cs in the ground moss layer and litter were much lower than that in the soil organic layer; this suggests that 137 Cs detected is not from the newly deposited radioactive fallout. The radioactivity concentration and transfer factor (TF) of 137 Cs varied with plant species. Shrubs and ferns have higher values than a coniferous tree (Taiwan cedar). The TF in this ecosystem is as high as 0.21 to 1.88. The high values of TF is attributed to the abundance of the organic matter in the forest soils. The rapid recycling of 137 Cs through the soil-plant system of this undisturbed multistoried ecosystem suggests the existence of an internal cycling that help the accumulation of 137 Cs in this ecosystem. (author)

Emergence of nutrient limitation in tropical dry forests: hypotheses from simulation models

Science.gov (United States)

Medvigy, D.; Waring, B. G.; Xu, X.; Trierweiler, A.; Werden, L. K.; Wang, G.; Zhu, Q.; Powers, J. S.

2017-12-01

It is unclear to what extent tropical dry forest productivity may be limited by nutrients. Direct assessment of nutrient limitation through fertilization experiments has been rare, and paradigms pertaining to other ecosystems may not extend to tropical dry forests. For example, because dry tropical forests have a lower water supply than moist tropical forests, dry forests can have lower decomposition rates, higher soil carbon and nitrogen concentrations, and a more open nitrogen cycle than moist forests. We used a mechanistic, numerical model to generate hypotheses about nutrient limitation in tropical dry forests. The model dynamically couples ED2 (vegetation dynamics), MEND (biogeochemistry), and N-COM (plant-microbe competition for nutrients). Here, the MEND-component of the model has been extended to include nitrogen (N) and phosphorus (P) cycles. We focus on simulation of sixteen 25m x 25m plots in Costa Rica where a fertilization experiment has been underway since 2015. Baseline simulations are characterized by both nitrogen and phosphorus limitation of vegetation. Fertilization with N and P increased vegetation biomass, with N fertilization having a somewhat stronger effect. Nutrient limitation was also sensitive to climate and was more pronounced during drought periods. Overflow respiration was identified as a key process that mitigated nutrient limitation. These results suggest that, despite often having richer soils than tropical moist forests, tropical dry forests can also become nutrient-limited. If the climate becomes drier in the next century, as is expected for Central America, drier soils may decrease microbial activity and exacerbate nutrient limitation. The importance of overflow respiration underscores the need for appropriate treatment of microbial dynamics in ecosystem models. Ongoing and new nutrient fertilization experiments will present opportunities for testing whether, and how, nutrient limitation may indeed be emerging in tropical dry

Forest composition modifies litter dynamics and decomposition in regenerating tropical dry forest.

Science.gov (United States)

Schilling, Erik M; Waring, Bonnie G; Schilling, Jonathan S; Powers, Jennifer S

2016-09-01

We investigated how forest composition, litter quality, and rainfall interact to affect leaf litter decomposition across three successional tropical dry forests in Costa Rica. We monitored litter stocks and bulk litter turnover in 18 plots that exhibit substantial variation in soil characteristics, tree community structure, fungal communities (including forests dominated by ecto- or arbuscular mycorrhizal host trees), and forest age. Simultaneously, we decomposed three standard litter substrates over a 6-month period spanning an unusually intense drought. Decay rates of standard substrates depended on the interaction between litter identity and forest type. Decomposition rates were correlated with tree and soil fungal community composition as well as soil fertility, but these relationships differed among litter types. In low fertility soils dominated by ectomycorrhizal oak trees, bulk litter turnover rates were low, regardless of soil moisture. By contrast, in higher fertility soils that supported mostly arbuscular mycorrhizal trees, bulk litter decay rates were strongly dependent on seasonal water availability. Both measures of decomposition increased with forest age, as did the frequency of termite-mediated wood decay. Taken together, our results demonstrate that soils and forest age exert strong control over decomposition dynamics in these tropical dry forests, either directly through effects on microclimate and nutrients, or indirectly by affecting tree and microbial community composition and traits, such as litter quality.

Changes in carbon pool and stand structure of a native subtropical mangrove forest after inter-planting with exotic species Sonneratia apetala.

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Lu, Weizhi; Yang, Shengchang; Chen, Luzhen; Wang, Wenqing; Du, Xiaona; Wang, Canmou; Ma, Yan; Lin, Guangxuan; Lin, Guanghui

2014-01-01

In this study, we compared stand structure, biomass and soil carbon pools, and litterfall production between a mixed mangrove forest consisting of Aegiceras corniculatum inter-planted with the exotic Sonneratia apetala and a native monospecific forest dominated by A. corniculatum in the intertidal area of Zhanjiang, Guangdong Province, southeast China. The goal of this study was to test the hypothesis that inter-planting fast growing exotic mangrove S. apetala into subtropical native mangrove forests will significantly increase C sequestration. Although the tree heights and basal diameters of S. apetala were significantly higher than those of A. corniculatum, the density of the 12-year-old S. apetala trees in the mixed forest was much smaller than that of A. corniculatum in the monospecific forest. In contrast to several previous studies on S. apetala forests planted directly on mangrove-free mudflats, the mixed mangrove forest showed no significant difference in either standing biomass or soil carbon pools from the native monospecific mangrove forest (p = 0.294 and 0.073, respectively) twelve years after inter-planting with S. apetala. Moreover, carbon cycling was likely speeded up after inter-planting S. apetala due to higher litterfall input and lower C/N ratio. Thus, inter-planting fast-growing S. apetala into native mangrove forest is not an effective way to increase carbon sequestration in this subtropical mangrove forest. Given that exotic plant species may exert negative impact on native mangrove species and related epifauna, this fast-growing mangrove species is not suitable for mangrove plantation projects aiming mainly at enhancing carbon sequestration.

76 FR 71342 - Proposed CERCLA Administrative Cost Recovery Settlement; River Forest Dry Cleaners Site, River...

Science.gov (United States)

2011-11-17

... Settlement; River Forest Dry Cleaners Site, River Forest, Cook County, IL AGENCY: Environmental Protection... response costs concerning the River Forest Dry Cleaners site in River Forest, Cook County, Illinois with... code: C-14J, Chicago, Illinois 60604. Comments should reference the River Forest Dry Cleaners Site...

An Old-Growth Definition for Dry and Dry-Mesic Oak-Pine Forests.

Science.gov (United States)

David L. White; F. Thomas. Lloyd

1998-01-01

Dry and dry-mesic oak-pine forests are widely distributed from New Jersey to Texas, but representative old-growth stands are rare. Historical accounts of composition, along with information from existing old-growth stands, were used to characterize this type. Shortleaf pine and white oak were the most widely distributed trees across all old-growth stands. Shortleaf was...

[A comparative study on soil fauna in native secondary evergreen broad-leaved forest and Chinese fir plantation forests in subtropics].

Science.gov (United States)

Yan, Shaokui; Wang, Silong; Hu, Yalin; Gao, Hong; Zhang, Xiuyong

2004-10-01

In this study, we investigated the response of soil animal communities to the replacement of native secondary forest by Chinese fir plantation forest and successive rotation of Chinese fir in subtropics. Three adjacent forest stands, i.e., native secondary evergreen broad-leaved forest stand (control) and Chinese fir plantation stands of first (20 yr) and second (20 yr) rotations were selected for the comparison of soil fauna. All animals were extracted from the floor litter and 0-15 cm soil layer of the stands in Summer, 2003 by using Tullgren method, wet funnel method and hand-sorting method. Compared to two Chinese fir plantation forests, the native secondary evergreen broad-leaved forest had a higher abundance and a higher taxonomic diversity of animals in soil and litter, but there were no significant differences in the biomass and productivity of soil fauna between all study stands. The abundance or diversity did not differ significantly between the first rotation and second rotation stands, too. The results supported that vegetation cover might be one of the main forces driving the development of soil animal communities, and the effect of successive rotation of Chinese fir on the development of soil fauna was a slow-running process.

Deforestation trends of tropical dry forests in central Brazil

Science.gov (United States)

Bianchi, Carlos A.; Haig, Susan M.

2013-01-01

Tropical dry forests are the most threatened forest type in the world yet a paucity of research about them stymies development of appropriate conservation actions. The Paranã River Basin has the most significant dry forest formations in the Cerrado biome of central Brazil and is threatened by intense land conversion to pastures and agriculture. We examined changes in Paranã River Basin deforestation rates and fragmentation across three time intervals that covered 31 yr using Landsat imagery. Our results indicated a 66.3 percent decrease in forest extent between 1977 and 2008, with an annual rate of forest cover change of 3.5 percent. Landscape metrics further indicated severe forest loss and fragmentation, resulting in an increase in the number of fragments and reduction in patch sizes. Forest fragments in flatlands have virtually disappeared and the only significant forest remnants are mostly found over limestone outcrops in the eastern part of the basin. If current patterns persist, we project that these forests will likely disappear within 25 yr. These patterns may be reversed with creation of protected areas and involvement of local people to preserve small fragments that can be managed for restoration.

Strong hydrological control on nutrient cycling of subtropical rainforests

Science.gov (United States)

Lin, T. C.; Chang, C. T.; Huang, J. C.; Wang, L.; Lin, N. H.

2016-12-01

Forest nutrient cycling is strongly controlled by both biological and hydrological factors. However, based on a close examination of earlier reports, we highlight the role of hydrological control on nutrient cycling at a global scale and is more important at humid tropical and subtropical forests. we analyzed the nutrient budget of precipitation input and stream water output from 1994 to 2013 in a subtropical forest in Taiwan and conducted a data synthesis using results from 32 forests across the globe. The results revealed that monthly input and output of ions were positively correlated with water quantity, indicating hydrological control on nutrient cycling. Hydrological control is also evident from the greater ions export via stream water during the warm and wet growing season. The synthesis also illustrates that strong hydrological control leads to lower nitrogen retention and greater net loss of base cations in humid regions, particularly in the humid tropical and subtropical forests. Our result is of great significance in an era of global climate change because climate change could directly affect ecosystem nutrient cycling particularly in the tropics through changes in patterns of precipitation regime.

Phosphorus addition mitigates N2O and CH4 emissions in N-saturated subtropical forest, SW China

Directory of Open Access Journals (Sweden)

L. Yu

2017-06-01

Full Text Available Chronically elevated nitrogen (N deposition has led to severe nutrient imbalance in forest soils. Particularly in tropical and subtropical forest ecosystems, increasing N loading has aggravated phosphorus (P limitation of biomass production, and has resulted in elevated emissions of nitrous oxide (N2O and reduced uptake of methane (CH4, both of which are important greenhouse gases. Yet, the interactions of N and P and their effects on greenhouse gas emissions remain elusive. Here, we report N2O and CH4 emissions together with soil N and P data for a period of 18 months following a single P addition (79 kg P ha−1, as NaH2PO4 powder to an N-saturated, Masson pine-dominated forest soil at TieShanPing (TSP, Chongqing, south-western (SW China. We observed a significant decline in both nitrate (NO3− concentrations in soil water (5 and 20 cm depths and in soil N2O emissions, following P application. We hypothesise that enhanced N uptake by plants in response to P addition, resulted in less available NO3− for denitrification. By contrast to most other forest ecosystems, TSP is a net source of CH4. P addition significantly decreased CH4 emissions and turned the soil from a net source into a net sink. Based on our observation and previous studies in South America and China, we believe that P addition relieves N inhibition of CH4 oxidation. Within the 1.5 years after P addition, no significant increase of forest growth was observed and P stimulation of forest N uptake by understorey vegetation remains to be confirmed. Our study indicates that P fertilisation of N-saturated, subtropical forest soils may mitigate N2O and CH4 emissions, in addition to alleviating nutrient imbalances and reducing losses of N through NO3− leaching.

Towards restoration of Hawaiian tropical dry forests: the Kaupulehu outplanting programme

Science.gov (United States)

Susan Cordell; Moana McClellan; Yvonne Yarber Carter; Lisa J. Hadway

2008-01-01

Hawaiian tropical dry forests contain diverse assemblages of woody canopy species, including many endemic and endangered species that warrant conservation attention before completely disappearing. Today, tropical dry forests in Hawaii are not viable ecosystems. Poor land use practices, fragmentation, non-native plant invasions, and inadequate native vegetation...

Temporal dynamics and leaf trait variability in Neotropical dry forests

Science.gov (United States)

Hesketh, Michael Sean

This thesis explores the variability of leaf traits resulting from changes in season, ecosystem successional stage, and site characteristics. In chapter two, I present a review of the use of remote sensing analysis for the evaluation of Neotropical dry forests. Here, I stress the conclusion, drawn from studies on land cover characterization, biodiversity assessment, and evaluation of forest structural characteristics, that addressing temporal variability in spectral properties is an essential element in the monitoring of these ecosystems. Chapter three describes the effect of wet-dry seasonality on spectral classification of tree and liana species. Highly accurate classification (> 80%) was possible using data from either the wet or dry season. However, this accuracy decreased by a factor of ten when data from the wet season was classified using an algorithm trained on the dry, or vice versa. I also address the potential creation of a spectral taxonomy of species, but found that any clustering based on spectral properties resulted in markedly different arrangements in the wet and dry seasons. In chapter 4, I address the variation present in both physical and spectral leaf traits according to changes in forest successional stage at dry forest sites in Mexico and Costa Rica. I found significant differences in leaf traits between successional stages, but more strongly so in Costa Rica. This variability deceased the accuracy of spectral classification of tree species by a factor of four when classifying data using an algorithm trained on a different successional stage. Chapter 5 shows the influence of seasonality and succession on trait variability in Mexico. Differences in leaf traits between successional stages were found to be greater during the dry season, but were sufficient in both seasons to negatively influence spectral classification of tree species. Throughout this thesis, I show clear and unambiguous evidence of the variability of key physical and spectral

Effect of urbanization on the structure and functional traits of remnant subtropical evergreen broad-leaved forests in South China

Science.gov (United States)

Liujing Huang; Hongfeng Chen; Hai Ren; Jun Wang; Qinfeng Guo

2013-01-01

We investigated the effects of major environmental drivers associated with urbanization on species diversity and plant functional traits (PFTs) in the remnant subtropical evergreen broad-leaved forests in Metropolitan Guangzhou (Guangdong, China). Twenty environmental factors including topography, light, and soil properties were used to quantify the effects of...

Seed ecology and regeneration in dry Afromontane forests of Ethiopia

Energy Technology Data Exchange (ETDEWEB)

Teketay, D. [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Forest Vegetation Ecology

1996-12-31

Various aspects of seed and regeneration ecology: germination requirements of seeds, seed longevity in the soil, soil seed banks in forests, gaps and arable land as well as density, survival and growth of seedlings were investigated within the dry Afromontane region in Ethiopia. In laboratory germination tests, 60% of the species studied exhibited some degree of initial dormancy and the optimum constant temperature for germination was between 20 and 25 deg C in the majority of the species. A few species showed a requirement for fluctuating temperatures and germination was suppressed or completely inhibited in several, mainly small-seeded, species when they were incubated in darkness or in light filtered through green leaves. Hard-seeded species required scarification treatments to improve germination, indicating seed-coat imposed dormancy. Dry storage reduced the germinability of seeds in a few species, suggesting a recalcitrant behaviour, while seeds of many species remained unaffected. During four years of storage in forest soils, seeds of 2 out of 8 species germinated in the soil almost completely within a year, 2 of the species maintained nearly full viability, while 4 were intermediate. The generally high levels of dormancy and somewhat extended viability of seeds in the soil may have been selected for under a climate of seasonal drought and unreliable rainfall that characterizes the dry Afromontane region. Dry Afromontane forests have a potential to recover in relatively short time after natural and man-made disturbances, e.g. after carefully managed selective cutting. However, the common practice of clearing forests and converting them into permanent arable land destroys the sources of regrowth thereby preventing regeneration of the forest vegetation. Therefore, the fate of dry Afromontane forests depends on the protection, careful management and conservation of the remaining patches. 102 refs, 4 figs, 1 tab

Bushy-tailed woodrat abundance in dry forests of eastern Washington.

Science.gov (United States)

John F. Lehmkuhl; Keith D. Kistler; James S. Begley

2006-01-01

We studied bushy-tailed woodrats (Neotonza cinerea occidentalis) in the eastern Washington Cascade Range to estimate their density and survival in 3 typical dry forest cover types. We predicted woodrat density to be high, moderate, and low in mature mixed-conifer forests, young mixed-conifer forests, and open ponderosa pine forests, respectively....

Phylogenetic classification of the world's tropical forests

DEFF Research Database (Denmark)

Slik, J. W. Ferry; Franklin, Janet; Arroyo-Rodriguez, Victor

2018-01-01

-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between......Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern...... phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal...

Rapid structural and compositional change in an old-growth subtropical forest: using plant traits to identify probable drivers.

Science.gov (United States)

Malizia, Agustina; Easdale, Tomás A; Grau, H Ricardo

2013-01-01

Recent studies have shown directional changes in old-growth tropical forests, but changes are complex and diverse, and their drivers unclear. Here, we report rapid net structural and compositional changes in an old-growth subtropical forest and we assess the functional nature of these changes to test hypothetical drivers including recovery from past disturbances, reduction in ungulate browsing, CO2 fertilization, and increases in rainfall and temperature. The study relies on 15 years of demographic monitoring within 8 ha of subtropical montane forest in Argentina. Between 1992 and 2007, stem density markedly increased by 50% (12 stems ha(-1) y(-1)) and basal area by 6% (0.13 m(2) ha(-1) y(-1)). Increased stem density resulted from enhanced recruitment of understory treelets (Piper tucumanum, Eugenia uniflora, Allophylus edulis) into small size classes. Among 27 common tree species, net population growth was negatively correlated with maximum tree size and longevity, and positively correlated with leaf size and leaf nutrient content, especially so when initial population size was controlled for. Changes were inconsistent with predictions derived from past disturbances (no increase in shade-tolerant or long-lived late-succesional species), rainfall or temperature increase (no increase in evergreen or deciduous species, respectively). However, the increase in nutrient-rich soft-leaved species was consistent with exclusion of large herbivores two decades before monitoring started; and CO2 fertilization could help explain the disproportionate increase in small stems. Reductions in populations of large vertebrates have been observed in many otherwise undisturbed tropical forests, and our results suggest they can have important structural and functional repercussions in these forests.

Soil Effects on Forest Structure and Diversity in a Moist and a Dry Tropical Forest

NARCIS (Netherlands)

Peña-Claros, M.; Poorter, L.; Alarcon, A.; Blate, G.; Choque, U.; Fredericksen, T.S.; Justiniano, J.; Leaño, C.; Licona, J.C.; Pariona, W.; Putz, F.E.; Quevedo, L.; Toledo, M.

2012-01-01

Soil characteristics are important drivers of variation in wet tropical forest structure and diversity, but few studies have evaluated these relationships in drier forest types. Using tree and soil data from 48 and 32 1 ha plots, respectively, in a Bolivian moist and dry forest, we asked how soil

Carbon stocks assessment in subtropical forest types of Kashmir Himalayas

International Nuclear Information System (INIS)

Shaheen, H.; Khan, R.W.A.; Hussain, K.; Ullah, T.S.; Mehmood, A.

2016-01-01

Estimation of carbon sequestration in forest ecosystem is necessary to mitigate impacts of climate change. Current research project was focused to assess the Carbon contents in standing trees and soil of different subtropical forest sites in Kashmir. Tree biomass was estimated by using allometric equations whereas Soil carbon was calculated by Walkey-Black titration method. Total carbon stock was computed as 186.27 t/ha with highest value of 326 t/ha recorded from Pinus roxburghii forest whereas lowest of 75.86 t/ha at mixed forest. Average biomass carbon was found to be 151.38 t/ha with a maximum value of 294.7 t/ha and minimum of 43.4 t/ha. Pinus roxburghii was the most significant species having biomass value of 191.8 t/ha, followed by Olea cuspidata (68.9 t/ha), Acacia modesta (12.71 t/ha), Dalbergia sissoo (12.01 t/ha), Broussonetia papyrifera (5.93 t/ha), Punica granatum (2.27 t/ha), Mallotus philippensis (2.2 t/ha), Albizia lebbeck (1.8t/ha), Ficus palmata (1.51 t/ha), Acacia arabica (1.4 t/ha), Melia azedarach, (1.14 t/ha) and Ficus carica (1.07 t/ha) respectively. Recorded value of tree density was 492/ha; average DBH was 87.27 cm; tree height was 13.3m; and regeneration value was 83 seedlings/ha. Soil carbon stocks were found to be 34.89 t/ha whereas agricultural soil carbon was calculated as 27.18 t/ha. Intense deforestation was represented by a stump density of 147.4/ha. The results of Principal Component Analysis (PCA) revealed the distinct species clusters on the basis of location, biomass and Carbon stock values. Pinus roxburghii and Olea cuspidata were found to be the major contributors of carbon stock having maximum vector lengths in the PCA Biplot. Forest in the area needs to be managed in a sustainable manner to increase its carbon sequestration potential. (author)

Dynamics of ecosystem services provided by subtropical forests in Southeast China during succession as measured by donor and receiver value

Science.gov (United States)

The trends in the provision of ecosystem services during restoration and succession of subtropical forests and plantations were quantified, in terms of both receiver and donor values, based on a case study of a 3-step secondary succession series that included a 400-year-old subtr...

Persistent Soil Seed Banks for Natural Rehabilitation of Dry Tropical Forests in Northern Ethiopia

OpenAIRE

Gebrehiwot, K.; Heyn, M.; Reubens, B.; Hermy, M.; Muys, B.

2007-01-01

Dry tropical forests are threatened world-wide by conversion to grazing land, secondary forest, savannah or arable land. In Ethiopia, natural dry forest cover has been decreasing at an alarming rate over the last decennia and has reached a critical level. Efforts like the rehabilitation of dry forests to curb this ecological degradation, need a stronger scientific basis than currently available. The aim of the present research was to test the hypothesis whether soil seed banks can contribute ...

Inorganic and organic nitrogen acquisition by a fern Dicranopteris dichotoma in a subtropical forest in South China.

Directory of Open Access Journals (Sweden)

Xingliang Xu

Full Text Available The fern Dicranopteris dichotoma is an important pioneer species of the understory in Masson pine (Pinus massoniana forests growing on acidic soils in the subtropical and tropical China. To improve our understanding of the role of D. dichotoma in nitrogen (N uptake of these forests, a short-term (15N experiment was conducted at mountain ridge (MR, with low N level and mountain foot (MF, with high N level. We injected (15N tracers as (15NH4, (15NO3 or (15N-glycine into the soil surrounding each plant at both MR and MF sites. Three hours after tracer injection, the fern D. dichotoma took up 15NH4+ significantly faster at MF than at MR, but it showed significantly slower uptake of (15NO3- at MF than at MR. Consequently, (15NO3- made greater contribution to the total N uptake (50% to the total N uptake at MR than at MF, but (15N-glycine only contributed around 11% at both sites. Twenty-four hours after tracer injection, D. dichotoma preferred (15NH4+ (63% at MR, whereas it preferred (15NO3- (47% at MF. We concluded that the D. dichotoma responds distinctly in its uptake pattern for three available N species over temporal and spatial scales, but mainly relies on inorganic N species in the subtropical forest. This suggests that the fern employs different strategies to acquire available N which depends on N levels and time.

Plant diversity patterns in neotropical dry forests and their conservation implications.

Science.gov (United States)

Banda-R, Karina; Delgado-Salinas, Alfonso; Dexter, Kyle G; Linares-Palomino, Reynaldo; Oliveira-Filho, Ary; Prado, Darién; Pullan, Martin; Quintana, Catalina; Riina, Ricarda; Rodríguez M, Gina M; Weintritt, Julia; Acevedo-Rodríguez, Pedro; Adarve, Juan; Álvarez, Esteban; Aranguren B, Anairamiz; Arteaga, Julián Camilo; Aymard, Gerardo; Castaño, Alejandro; Ceballos-Mago, Natalia; Cogollo, Álvaro; Cuadros, Hermes; Delgado, Freddy; Devia, Wilson; Dueñas, Hilda; Fajardo, Laurie; Fernández, Ángel; Fernández, Miller Ángel; Franklin, Janet; Freid, Ethan H; Galetti, Luciano A; Gonto, Reina; González-M, Roy; Graveson, Roger; Helmer, Eileen H; Idárraga, Álvaro; López, René; Marcano-Vega, Humfredo; Martínez, Olga G; Maturo, Hernán M; McDonald, Morag; McLaren, Kurt; Melo, Omar; Mijares, Francisco; Mogni, Virginia; Molina, Diego; Moreno, Natalia Del Pilar; Nassar, Jafet M; Neves, Danilo M; Oakley, Luis J; Oatham, Michael; Olvera-Luna, Alma Rosa; Pezzini, Flávia F; Dominguez, Orlando Joel Reyes; Ríos, María Elvira; Rivera, Orlando; Rodríguez, Nelly; Rojas, Alicia; Särkinen, Tiina; Sánchez, Roberto; Smith, Melvin; Vargas, Carlos; Villanueva, Boris; Pennington, R Toby

2016-09-23

Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale. Copyright © 2016, American Association for the Advancement of Science.

Long-term Seedling Dynamics of Tree Species in a Subtropical Rain Forest, Taiwan

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Chia-Hao Chang-Yang

2013-03-01

Full Text Available Knowledge of demographical rates at seedling stage is critical for understanding forest composition and dynamics. We monitored the seedling dynamics of tree species in a subtropical rain forest in Fushan, northern Taiwan (24°45’ N, 121°35’ E during an 8-yr period (2003–2010. There were great temporal fluctuations in the seedling density, which might be largely driven by the pulses of seedling recruitment. Interspecific variation in the seedling abundance, however, was not related to the reproductive adult abundance. Previous studies showed that frequent typhoon disturbances contributed to the high canopy openness and high understory light availability at Fushan, which might benefit tree regeneration. But our results do not support this idea. Most of the newly recruited seedlings died within six months and only grew 1.55 ± 0.20 cm per year, which might be suppressed by the dense understory vegetation. Our results suggested that the majority of tree species in Fushan were recruitment limited, which might have important consequences for species coexistence. High temporal variability in recruitment density and low growth rates of seedlings emphasize the importance of long-term studies to our understandings of forest dynamics.

Paratrechina longicornis ants in a tropical dry forest harbor specific Actinobacteria diversity.

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Reyes, Ruth D Hernández; Cafaro, Matías J

2015-01-01

The diversity of Actinobacteria associated with Paratrechina longicornis, an ant species that prefers a high protein diet, in a subtropical dry forest (Guánica, Puerto Rico) was determined by culture methods and by 16S rDNA clone libraries. The results of both methodologies were integrated to obtain a broader view of the diversity. Streptomyces, Actinomadura, Nocardia, Ornithinimicrobium, Tsukamurella, Brevibacterium, Saccharopolyspora, Nocardioides, Microbacterium, Leifsonia, Pseudonocardia, Corynebacterium, Geodermatophilus, Amycolatopsis, and Nonomuraea were found associated with the ants. The genera Streptomyces and Actinomadura were the most abundant. Also, the diversity of Actinobacteria associated with the soil surrounding the nest was determined using 16S rDNA clone libraries. In total, 27 genera of Actinobacteria were associated with the nest soils. A dominant genus was not observed in any of the soil samples. We compared statistically the Actinobacteria communities among P. longicornis nests and each nest with its surrounding soil using the clone libraries data. We established that the communities associated with the ants were consistent and significantly different from those found in the soil in which the ants live. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diameter growth of subtropical trees in Puerto Rico

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Thomas J. Brandeis

2009-01-01

Puerto Rico’s forests consist of young, secondary stands still recovering from a long history of island-wide deforestation that largely abated in the mid-20th century. Limited knowledge about growth rates of subtropical tree species in these forests makes it difficult to accurately predict forest yield, biomass accumulation, and carbon...

Can lowland dry forests represent a refuge from avian malaria for native Hawaiian birds?

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Tucker-Mohl, Katherine; Hart, Patrick; Atkinson, Carter T.

2010-01-01

Hawaii's native birds have become increasingly threatened over the past century. Introduced mosquito borne diseases such as avian malaria may be responsible for the near absence of endemic Hawaiian forest birds in low-elevation habitats. The recent recognition that some native Hawaiian forest birds may be repopulating moist lowland habitats as a result of evolved resistance to this disease has increased the conservation value of these areas. Here, we investigate whether remnant low elevation dry forests on Hawaii Island provide natural 'refuges' from mosquito-transmitted malaria by nature of their low rainfall and absence of suitable natural sources of water for mosquito breeding. Unlike lowland wet forests where high rates of disease transmission may be selecting for disease resistance, lowland dry forests may provide some refuge for native forest birds without natural resistance to malaria. We mistnetted forest birds in two lowland dry forests and tested all native birds by microscopy and serology for avian malaria caused by the Plasmodium relictum parasite. We also conducted surveys for standing water and mosquito larvae. Overall prevalence of infections with Plasmodium relictum in the Hawaii Amakihi Hemignathus virens virens was 15%. Most infected birds had lowlevel parasitemias, suggesting chronic infections. Although avian malaria is present in these lowland dry forest Amakihi populations, infection rates are significantly lower than in wet forest populations at similar elevations. Sources of breeding mosquitoes in these forests appeared to be largely anthropogenic; thus, there is potential to manage dry forests as mosquito-free habitat for Hawaii Amakihi and other Hawaiian forest birds.

Tropical dry forest recovery : processes and causes of change

NARCIS (Netherlands)

Lebrija Trejos, E.E.

2009-01-01

Seasonally dry areas are one of the preferred zones for human inhabitance in the tropics. Large forest areas are converted to other land uses and many are covered by secondary forests that grow naturally after cessation of disturbance. Surprisingly, secondary succession in these strongly seasonal

Disentangling the environmental heterogeneity, floristic distinctiveness and current threats of tropical dry forests in Colombia

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González-M, Roy; García, Hernando; Isaacs, Paola; Cuadros, Hermes; López-Camacho, René; Rodríguez, Nelly; Pérez, Karen; Mijares, Francisco; Castaño-Naranjo, Alejandro; Jurado, Rubén; Idárraga-Piedrahíta, Álvaro; Rojas, Alicia; Vergara, Hernando; Pizano, Camila

2018-04-01

Tropical dry forests (TDFs) have been defined as a single biome occurring mostly in the lowlands where there is a marked period of drought during the year. In the Neotropics, dry forests occur across contrasting biogeographical regions that contain high beta diversity and endemism, but also strong anthropogenic pressures that threaten their biodiversity and ecological integrity. In Colombia, TDFs occur across six regions with contrasting soils, climate, and anthropogenic pressures, therefore being ideal for studying how these variables relate to dry forest species composition, successional stage and conservation status. Here, we explore the variation in climate and soil conditions, floristic composition, forest fragment size and shape, successional stage and anthropogenic pressures in 571 dry forest fragments across Colombia. We found that TDFs should not be classified solely on rainfall seasonality, as high variation in precipitation and temperature were correlated with soil characteristics. In fact, based on environmental factors and floristic composition, the dry forests of Colombia are clustered in three distinctive groups, with high species turnover across and within regions, as reported for other TDF regions of the Neotropics. Widely distributed TDF species were found to be generalists favored by forest disturbance and the early successional stages of dry forests. On the other hand, TDF fragments were not only small in size, but highly irregular in shape in all regions, and comprising mostly early and intermediate successional stages, with very little mature forest left at the national level. At all sites, we detected at least seven anthropogenic disturbances with agriculture, cattle ranching and human infrastructure being the most pressing disturbances throughout the country. Thus, although environmental factors and floristic composition of dry forests vary across regions at the national level, dry forests are equally threatened by deforestation, degradation

Associations between soil variables and vegetation structure and composition of Caribbean dry forests

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Elvia M. Melendez-Ackerman; Julissa Rojas-Sandoval; Danny S. Fernandez; Grizelle Gonzalez; Hana Lopez; Jose Sustache; Mariely Morales; Miguel Garcia-Bermudez; Susan Aragon

2016-01-01

Soil–vegetation associations have been understudied in tropical dry forests when compared to the amount of extant research on this issue in tropical wet forests. Recent studies assert that vegetation in tropical dry forests is highly heterogeneous and that soil variability may be a contributing factor. In this study, we evaluated the relationship between soil variables...

Dominant Species in Subtropical Forests Could Decrease Photosynthetic N Allocation to Carboxylation and Bioenergetics and Enhance Leaf Construction Costs during Forest Succession.

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Xiao, Yihua; Liu, Shirong; Tong, Fuchun; Chen, Bufeng; Kuang, Yuanwen

2018-01-01

It is important to understand how eco-physiological characteristics shift in forests when elucidating the mechanisms underlying species replacement and the process of succession and stabilization. In this study, the dominant species at three typical successional stages (early-, mid-, and late-succession) in the subtropical forests of China were selected. At each stage, we compared the leaf construction costs (CC), payback time (PBT), leaf area based N content ( N A ), maximum CO 2 assimilation rate ( P max ), specific leaf area (SLA), photosynthetic nitrogen use efficiency (PNUE), and leaf N allocated to carboxylation ( N C ), and to bioenergetics ( N B ). The relationships between these leaf functional traits were also determined. The results showed that the early-succession forest is characterized with significantly lower leaf CC, PBT, N A , but higher P max , SLA, PNUE, N C , and N B , in relation to the late-succession forest. From the early- to the late-succession forests, the relationship between P max and leaf CC strengthened, whereas the relationships between N B , N C , PNUE, and leaf CC weakened. Thus, the dominant species are able to decrease the allocation of the photosynthetic N fraction to carboxylation and bioenergetics during forest succession. The shift in these leaf functional traits and their linkages might represent a fundamental physiological mechanism that occurs during forest succession and stabilization.

The Influence of Forest Management Regimes on Deforestation in a Central Indian Dry Deciduous Forest Landscape

OpenAIRE

Shivani Agarwal; Harini Nagendra; Rucha Ghate

2016-01-01

This research examines the impact of forest management regimes, with various degrees of restriction, on forest conservation in a dry deciduous Indian forest landscape. Forest change is mapped using Landsat satellite images from 1977, 1990, 1999, and 2011. The landscape studied has lost 1478 km2 of dense forest cover between 1977 and 2011, with a maximum loss of 1002 km2 of dense forest between 1977 and 1990. The number of protected forest areas has increased, concomitant with an increase in r...

FLORULA URBAN FRAGMENT OF TROPICAL DRY FOREST

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Willington Barranco-Pérez

2016-01-01

Full Text Available The aim of this study was to record the composition of plant species in an urban fragment of tropical dry forest of secondary regeneration (bs-T to generate information that can be used in the planning and management of green spaces in the city of Santa Marta. Transects of 2 x 50 m were established equivalent to 0.1 ha and all species were counted >1.0 cm DBH (Diameter at Breast Height: 1.3m. 100 species of angiosperms were recorded of which 47% have herbaceous habit. The number of species recorded in this study represents 39.6% of the species reported for the hills of Santa Marta and 3.8% for the dry forests of Colombia. It is suggested to isolate this type of secondary formations of any intervention and contemplate the reintroduction of individuals and conservation strategies.

Breeding birds in riparian and upland dry forests of the Cascade Range

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John F. Lehmkuhl; E. Dorsey Burger; Emily K. Drew; John P. Lindsey; Maryellen Haggard; Kent Z. Woodruff

2007-01-01

We quantified breeding bird abundance, diversity, and indicator species in riparian and upland dry forests along six third- to fourth-order streams on the east slope of the Cascade Range, Washington, USA. Upland mesic forest on southerly aspects was dominated by open ponderosa pine (Pinus ponderosa) and dry Douglas-fir (Pseudotsuga menziesii...

[Diversity, structure and regeneration of the seasonally dry tropical forest of Yucatán Peninsula, Mexico].

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Hernández-Ramírez, Angélica María; García-Méndez, Socorro

2015-09-01

Seasonally dry tropical forests are considered as the most endangered ecosystem in lowland tropics. The aim of this study was to characterize the floristic composition, richness, diversity, structure and regeneration of a seasonally dry tropical forest landscape constituted by mature forest, secondary forest and seasonally inundated forest located in the Northeastern part of the Yucatán Peninsula, Mexico. We used the Gentry's standard inventory plot methodology (0.1 ha per forest type in 2007) for facilitating comparison with other Mesoamerican seasonally dry tropical forests. A total of 77 species belonging to 32 families were observed in the study area. Fabaceae and Euphorbiaceae were the families with the largest taxonomic richness in the three forest types. Low levels of β diversity were observed among forest types (0.19-0.40), suggesting a high turnover of species at landscape level. The non-regenerative species were dominant (50-51 %), followed by regenerative species (30- 28 %), and colonizer species (14-21 %) in the three forest types. Zoochory was the most common dispersal type in the study area. The 88 % of the observed species in the study area were distributed in Central America. Some floristic attributes of the seasonally dry tropical forest of the Yucatán Peninsula, fall into the values reported for Mesoamerican seasonally dry tropical forests. Natural disturbances contributed to explain the high number of individuals, the low number of liana species, as well as the low values of basal area observed in this study. Our results suggested that the seasonally dry tropical forest of Yucatán Peninsula seems to be resilient to natural disturbances (hurricane) in terms of the observed number of species and families, when compared with the reported values in Mesoamerican seasonally dry tropical forests. Nonetheless, the recovery and regeneration of vegetation in long-term depends on animal-dispersed species. This study highlights the importance of

Exploring tree-habitat associations in a Chinese subtropical forest plot using a molecular phylogeny generated from DNA barcode loci.

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Nancai Pei

Full Text Available Elucidating the ecological mechanisms underlying community assembly in subtropical forests remains a central challenge for ecologists. The assembly of species into communities can be due to interspecific differences in habitat associations, and there is increasing evidence that these associations may have an underlying phylogenetic structure in contemporary terrestrial communities. In other words, by examining the degree to which closely related species prefer similar habitats and the degree to which they co-occur, ecologists are able to infer the mechanisms underlying community assembly. Here we implement this approach in a diverse subtropical tree community in China using a long-term forest dynamics plot and a molecular phylogeny generated from three DNA barcode loci. We find that there is phylogenetic signal in plant-habitat associations (i.e. closely related species tend to prefer similar habitats and that patterns of co-occurrence within habitats are typically non-random with respect to phylogeny. In particular, we found phylogenetic clustering in valley and low-slope habitats in this forest, indicating a filtering of lineages plays a dominant role in structuring communities in these habitats and we found evidence of phylogenetic overdispersion in high-slope, ridge-top and high-gully habitats, indicating that distantly related species tended to co-occur in these high elevation habitats and that lineage filtering is less important in structuring these communities. Thus we infer that non-neutral niche-based processes acting upon evolutionarily conserved habitat preferences explain the assembly of local scale communities in the forest studied.

Avian relationships with wildfire at two dry forest locations with different historical fire regimes

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Quresh Latif; Jamie Sanderlin; Vicki Saab; William Block; Jonathan Dudley

2016-01-01

Wildfire is a key factor influencing bird community composition in western North American forests. We need to understand species and community responses to wildfire and how responses vary regionally to effectively manage dry conifer forests for maintaining biodiversity. We compared avian relationships with wildfire burn severity between two dry forest...

Composition and biogeography of forest patches on the inland mountains of the southern Cape

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C. J. Geldenhuys

1997-10-01

Full Text Available Patterns in species richness of 23 small, isolated forests on the inland mountains of the southern Cape were studied. Species richness of woody plants and vines of the Kouga-Baviaanskloof Forests was higher than in the western mountain complexes, where species richness in the more southern Rooiberg and Kamanassie Mountains was higher than in the Swartberg range. The Rooiberg, a dry mountain with small forests far away from the coastal source area, had more species than, and contained many species which are absent from, the larger, moister forests of the Kamanassie which are closest to the coastal source areas. Neither altitude nor distance from the source area, the forests south of the coastal mountains, nor long-distance dispersal, adequately explained the variation in species richness. The variations are best explained in terms of dispersal corridors along the Gouritz and Gamtoos River systems which connect the coastal forests with the inland mountains. The distribution patterns of four species groups in relation to the geomorphological history of the two river systems provide relative dates for the expansion and contraction of temperate forest, subtropical forest and subtropical transitional thicket in the southern Cape.

Preliminary Response of Soil Fauna to Simulated N Deposition in Three Typical Subtropical Forests

Institute of Scientific and Technical Information of China (English)

XU Guo-Liang; MO Jiang-Ming; ZHOU Guo-Yi; FU Sheng-Lei

2006-01-01

A field-scale experiment arranged in a complete randomized block design with three N addition treatments including a control (no addition of N), a low N (5 g m-2 year-1), and a medium N (10 g m-2 year-1) was performed in each of the three typical forests, a pine (Pinus massoniana Lamb.) forest (PF), a pine-broadleaf mixed forest (MF) and a mature monsoon evergreen broadleaf forest (MEBF), of the Dinghushan Biosphere Reserve in subtropical China to study the response of soil fauna community to additions of N. Higher NH4+ and NO3- concentrations and a lower soil pH occurred in the medium N treatment of MEBF, whereas the NO3- concentration was the lowest in PF after the additions of N. The response of the density, group abundance and diversity index of soil fauna to addition of N varied with the forest type,and all these variables decreased with increasing N under MEBF but the trend was opposite under PF. The N treatments had no significant effects on these variables under MF. Compared with the control plots, the medium N treatment had significant negative effect on soil fauna under MEBF. The group abundance of soil fauna increased significantly with additions of higher N rates under PF. These results suggested that the response of soil fauna to N deposition varied with the forest type and N deposition rate, and soil N status is one of the important factors affecting the response of soil fauna to N deposition.

Different Patterns of Changes in the Dry Season Diameter at Breast Height of Dominant and Evergreen Tree Species in a Mature Subtropical Forest in South China

Institute of Scientific and Technical Information of China (English)

Jun-Hua Yan; Guo-Yi Zhou; De-Qiang Zhang; Xu-Li Tang; Xu Wang

2006-01-01

Information on changes in diameter at breast height (DBH) is important for net primary production (NPP)estimates, timing of forest inventory, and forest management. In the present study, patterns of DBH change were measured under field conditions during the dry season for three dominant and native tree species in a monsoon evergreen broad-leaved forest in the Dinghushan Biosphere Reserve. For each tree species,different patterns of DBH change were observed. In the case of the fast-growing tree species Castanopsis chinensis Hance, large diurnal fluctuations occur, with a peak DBH in the early morning (around 05:00 h) that decreases to a minimum by about 14:00 h. Both Schima superba Gardn. et Chemp and Cryptocarya chinensis (Hance) Hemsl. exhibited less diurnal swelling and shrinkage. Diurnal fluctuations for these species were observed on a few occasions over the period of observation. Graphical comparisons and statistical analysis of changes in DBH with meteorological variables indicate that for different trees, the different changes in DBH observed responded to different meteorological variables. Large stem changes were found to occur for Ca. chinensis trees that were associated with variations in solar radiation. However, both S. superba and Cr. chinensis were found to be less sensitive to solar radiation. Changes in the DBH of these two species were found to be controlled mainly by soil temperature and soil moisture. During the later dry season, with a lower soil temperature and soil moisture, all three tree species stopped growing and only negligible shrinkage, expansion, or fluctuation occurred, suggesting that the optimum time to measure tree growth in the Dinghushan Biosphere Reserve is the later dry season.

Indirect approach for estimation of forest degradation in non-intact dry forest

DEFF Research Database (Denmark)

Dons, Klaus; Bhattarai, Sushma; Meilby, Henrik

2016-01-01

Background Implementation of REDD+ requires measurement and monitoring of carbon emissions from forest degradation in developing countries. Dry forests cover about 40 % of the total tropical forest area, are home to large populations, and hence often display high disturbance levels....... They are susceptible to gradual but persistent degradation and monitoring needs to be low cost due to the low potential benefit from carbon accumulation per unit area. Indirect remote sensing approaches may provide estimates of subsistence wood extraction, but sampling of biomass loss produces zero-inflated continuous...... data that challenges conventional statistical approaches. We introduce the use of Tweedie Compound Poisson distributions from the exponential dispersion family with Generalized Linear Models (CPGLM) to predict biomass loss as a function of distance to nearest settlement in two forest areas in Tanzania...

Dynamics of soil inorganic nitrogen and their responses to nitrogen additions in three subtropical forests, south China

Institute of Scientific and Technical Information of China (English)

FANG Yun-ting; ZHU Wei-xing; MO Jiang-ming; ZHOU Guo-yi; GUNDERSEN Per

2006-01-01

Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions.Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine (Pinus massoniana) and pine-broadleaf mixed forests, both originated from the 1930's clear-cut and pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching,and higher soil C/N ratios. Mineral soil extractable NH4+-N and NO3--N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH4+-N in the mature forest. In contrast, inorganic N (both NH4+-N and NO3--N) in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%-70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region.

Impacts of tropical cyclones on hydrochemistry of a subtropical forest

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C. T. Chang

2013-10-01

Full Text Available Tropical cyclones (typhoons/hurricanes have major impacts on the biogeochemistry of forest ecosystems, but the stochastic nature and the long intervals between storms means that there are limited data on their effects. We characterised the impacts of 14 typhoons over six years on hydrochemistry of a subtropical forest plantation in Taiwan, a region experiencing frequent typhoons. Typhoons contributed 1/3 of the annual rainfall on average, but ranged from 4 to 55%. The stochastic nature of annual typhoon related precipitation poses a challenge with respect to managing the impacts of these extreme events. This challenge is exacerbated by the fact that typhoon-related rainfall is not significantly correlated with wind velocity, the current focus of weather forecasts. Thus, little advance warning is provided for the hydrological impacts of these storms. The typhoons we studied contributed approximately one third of the annual input and output of most nutrients (except nitrogen during an average 9.5 day yr−1 period, resulting in nutrient input/output rates an order of magnitude greater than during non-typhoon months. Nitrate output balanced input during the non-typhoon period, but during the typhoon period an average of 10 kg ha−1 yr−1 nitrate was lost. Streamwater chemistry exhibited similarly high variability during typhoon and non-typhoon periods and returned to pre-typhoon levels one to three weeks following each typhoon. The streamwater chemistry appears to be very resilient in response to typhoons, resulting in minimal loss of nutrients.

Carbon isotope characterization of vegetation and soil organic matter in subtropical forests in Luquillo, Puerto Rico

International Nuclear Information System (INIS)

Fischer, J.C. von; Tieszen, L.L.

1995-01-01

We examined natural abundances of 13 C in vegetation and soil organic maner (SOM) of subtropical wet and rain forests to characterize the isotopic enrichment through decomposition that has been reported for temperate forests. Soil cores and vegetative samples from the decomposition continuum (leaves, new litter, old liner, wood, and roots) were taken from each of four forest types in the Luquillo Experimental Forest, Puerto Rico. SOM δ 13 C was enriched 1.60/00 relative to aboveground litter. We found no further enrichment within the soil profile. The carbon isotope ratios of vegetation varied among forests, ranging from -28.20/00 in the Colorado forest to -26.90/00 in the Palm forest. Isotope ratios of SOM differed between forests primarily in the top 20 em where the Colorado forest was again most negative at -28.00/00, and the Palm forest was most positive at -26.50/00. The isotopic differences between forests are likely attributable to differences in light regimes due to canopy density variation, soil moisture regimes, and/or recycling of CO 2 . Our data suggest that recalcitrant SOM is not derived directly from plant lignin since plant lignin is even more 13 C depleted than the bulk vegetation. We hypothesize that the anthropogenic isotopic depletion of atmospheric CO 2 , (ca 1.50/00 in the last 150 years) accounts for some of the enrichment observed in the SOM relative to the more modern vegetation in this study and others. This study also supports other observations that under wet or anaerobic soil environments there is no isotopic enrichment during decomposition or with depth in the active profile. (author)

Carbon isotope characterization of vegetation and soil organic matter in subtropical forests in Luquillo, Puerto Rico

Energy Technology Data Exchange (ETDEWEB)

Fischer, J.C. von [Cornell University, Ithaca, NY (United States); Tieszen, L. L.

1995-06-15

We examined natural abundances of {sup 13}C in vegetation and soil organic maner (SOM) of subtropical wet and rain forests to characterize the isotopic enrichment through decomposition that has been reported for temperate forests. Soil cores and vegetative samples from the decomposition continuum (leaves, new litter, old liner, wood, and roots) were taken from each of four forest types in the Luquillo Experimental Forest, Puerto Rico. SOM δ{sup 13}C was enriched 1.60/00 relative to aboveground litter. We found no further enrichment within the soil profile. The carbon isotope ratios of vegetation varied among forests, ranging from -28.20/00 in the Colorado forest to -26.90/00 in the Palm forest. Isotope ratios of SOM differed between forests primarily in the top 20 em where the Colorado forest was again most negative at -28.00/00, and the Palm forest was most positive at -26.50/00. The isotopic differences between forests are likely attributable to differences in light regimes due to canopy density variation, soil moisture regimes, and/or recycling of CO{sub 2}. Our data suggest that recalcitrant SOM is not derived directly from plant lignin since plant lignin is even more {sup 13}C depleted than the bulk vegetation. We hypothesize that the anthropogenic isotopic depletion of atmospheric CO{sub 2}, (ca 1.50/00 in the last 150 years) accounts for some of the enrichment observed in the SOM relative to the more modern vegetation in this study and others. This study also supports other observations that under wet or anaerobic soil environments there is no isotopic enrichment during decomposition or with depth in the active profile. (author)

[Estimating individual tree aboveground biomass of the mid-subtropical forest using airborne LiDAR technology].

Science.gov (United States)

Liu, Feng; Tan, Chang; Lei, Pi-Feng

2014-11-01

Taking Wugang forest farm in Xuefeng Mountain as the research object, using the airborne light detection and ranging (LiDAR) data under leaf-on condition and field data of concomitant plots, this paper assessed the ability of using LiDAR technology to estimate aboveground biomass of the mid-subtropical forest. A semi-automated individual tree LiDAR cloud point segmentation was obtained by using condition random fields and optimization methods. Spatial structure, waveform characteristics and topography were calculated as LiDAR metrics from the segmented objects. Then statistical models between aboveground biomass from field data and these LiDAR metrics were built. The individual tree recognition rates were 93%, 86% and 60% for coniferous, broadleaf and mixed forests, respectively. The adjusted coefficients of determination (R(2)adj) and the root mean squared errors (RMSE) for the three types of forest were 0.83, 0.81 and 0.74, and 28.22, 29.79 and 32.31 t · hm(-2), respectively. The estimation capability of model based on canopy geometric volume, tree percentile height, slope and waveform characteristics was much better than that of traditional regression model based on tree height. Therefore, LiDAR metrics from individual tree could facilitate better performance in biomass estimation.

Dry forest resilience varies under simulated climate‐management scenarios in a central Oregon, USA landscape.

Science.gov (United States)

Halofsky, Joshua S; Halofsky, Jessica E; Burcsu, Theresa; Hemstrom, Miles A

Determining appropriate actions to create or maintain landscapes resilient to climate change is challenging because of uncertainty associated with potential effects of climate change and their interactions with land management. We used a set of climate-informed state-and-transition models to explore the effects of management and natural disturbances on vegetation composition and structure under different future climates. Models were run for dry forests of central Oregon under a fire suppression scenario (i.e., no management other than the continued suppression of wildfires) and an active management scenario characterized by light to moderate thinning from below and some prescribed fire, planting, and salvage logging. Without climate change, area in dry province forest types remained constant. With climate change, dry mixed-conifer forests increased in area (by an average of 21–26% by 2100), and moist mixed-conifer forests decreased in area (by an average of 36–60% by 2100), under both management scenarios. Average area in dry mixed-conifer forests varied little by management scenario, but potential decreases in the moist mixed-conifer forest were lower with active management. With changing climate in the dry province of central Oregon, our results suggest the likelihood of sustaining current levels of dense, moist mixed-conifer forests with large-diameter, old trees is low (less than a 10% chance) irrespective of management scenario; an opposite trend was observed under no climate change simulations. However, results also suggest active management within the dry and moist mixed-conifer forests that creates less dense forest conditions can increase the persistence of larger-diameter, older trees across the landscape. Owing to projected increases in wildfire, our results also suggest future distributions of tree structures will differ from the present. Overall, our projections indicate proactive management can increase forest resilience and sustain some societal

Testing Dragonflies as Species Richness Indicators in a Fragmented Subtropical Atlantic Forest Environment.

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Renner, S; Sahlén, G; Périco, E

2016-06-01

We surveyed 15 bodies of water among remnants of the Atlantic Forest biome in southern Brazil for adult dragonflies and damselflies to test whether an empirical selection method for diversity indicators could be applied in a subtropical ecosystem, where limited ecological knowledge on species level is available. We found a regional species pool of 34 species distributed in a nested subset pattern with a mean of 11.2 species per locality. There was a pronounced difference in species composition between spring, summer, and autumn, but no differences in species numbers between seasons. Two species, Homeoura chelifera (Selys) and Ischnura capreolus (Hagen), were the strongest candidates for regional diversity indicators, being found only at species-rich localities in our surveyed area and likewise in an undisturbed national forest reserve, serving as a reference site for the Atlantic Forest. Using our selection method, we found it possible to obtain a tentative list of diversity indicators without having detailed ecological information of each species, providing a reference site is available for comparison. The method thus allows for indicator species to be selected in blanco from taxonomic groups that are little known. We hence argue that Odonata can already be incorporated in ongoing assessment programs in the Neotropics, which would also increase the ecological knowledge of the group and allow extrapolation to other taxa.

Restoring dry and moist forests of the inland northwestern United States [Chapter 23

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Theresa B. Jain; Russell T. Graham

2015-01-01

The complex topography of the Inland Northwestern United States (58.4 million ha) interacts with soils and a highly variable climate to provide a mosaic of dry and moist mixed conifer forest settings. Approximately 20% of the area is covered by dry forests dominated by Pinus ponderosa, Pseudotsuga menziesii and contains a diversity of lower vegetation ranging from a...

Broadcast seeding as a potential tool to reestablish native species in degraded dry forest ecosystems in Hawaii

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S. Brooks; S. Cordell; L. Perry

2009-01-01

Hawaiian dry forests currently occupy a small fraction of their former range, and worldwide tropical dry forests are one of the most human-altered systems. Many small-scale projects have been successful in restoring native dry forests in abandoned pastures and degraded woodlands by outplanting after invasive species removal, but this is a costly approach. In this...

Species associations in a species-rich subtropical forest were not well-explained by stochastic geometry of biodiversity.

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Wang, Qinggang; Bao, Dachuan; Guo, Yili; Lu, Junmeng; Lu, Zhijun; Xu, Yaozhan; Zhang, Kuihan; Liu, Haibo; Meng, Hongjie; Jiang, Mingxi; Qiao, Xiujuan; Huang, Handong

2014-01-01

The stochastic dilution hypothesis has been proposed to explain species coexistence in species-rich communities. The relative importance of the stochastic dilution effects with respect to other effects such as competition and habitat filtering required to be tested. In this study, using data from a 25-ha species-rich subtropical forest plot with a strong topographic structure at Badagongshan in central China, we analyzed overall species associations and fine-scale species interactions between 2,550 species pairs. The result showed that: (1) the proportion of segregation in overall species association analysis at 2 m neighborhood in this plot followed the prediction of the stochastic dilution hypothesis that segregations should decrease with species richness but that at 10 m neighborhood was higher than the prediction. (2) The proportion of no association type was lower than the expectation of stochastic dilution hypothesis. (3) Fine-scale species interaction analyses using Heterogeneous Poisson processes as null models revealed a high proportion (47%) of significant species effects. However, the assumption of separation of scale of this method was not fully met in this plot with a strong fine-scale topographic structure. We also found that for species within the same families, fine-scale positive species interactions occurred more frequently and negative ones occurred less frequently than expected by chance. These results suggested effects of environmental filtering other than species interaction in this forest. (4) We also found that arbor species showed a much higher proportion of significant fine-scale species interactions (66%) than shrub species (18%). We concluded that the stochastic dilution hypothesis only be partly supported and environmental filtering left discernible spatial signals in the spatial associations between species in this species-rich subtropical forest with a strong topographic structure.

Species associations in a species-rich subtropical forest were not well-explained by stochastic geometry of biodiversity.

Directory of Open Access Journals (Sweden)

Qinggang Wang

Full Text Available The stochastic dilution hypothesis has been proposed to explain species coexistence in species-rich communities. The relative importance of the stochastic dilution effects with respect to other effects such as competition and habitat filtering required to be tested. In this study, using data from a 25-ha species-rich subtropical forest plot with a strong topographic structure at Badagongshan in central China, we analyzed overall species associations and fine-scale species interactions between 2,550 species pairs. The result showed that: (1 the proportion of segregation in overall species association analysis at 2 m neighborhood in this plot followed the prediction of the stochastic dilution hypothesis that segregations should decrease with species richness but that at 10 m neighborhood was higher than the prediction. (2 The proportion of no association type was lower than the expectation of stochastic dilution hypothesis. (3 Fine-scale species interaction analyses using Heterogeneous Poisson processes as null models revealed a high proportion (47% of significant species effects. However, the assumption of separation of scale of this method was not fully met in this plot with a strong fine-scale topographic structure. We also found that for species within the same families, fine-scale positive species interactions occurred more frequently and negative ones occurred less frequently than expected by chance. These results suggested effects of environmental filtering other than species interaction in this forest. (4 We also found that arbor species showed a much higher proportion of significant fine-scale species interactions (66% than shrub species (18%. We concluded that the stochastic dilution hypothesis only be partly supported and environmental filtering left discernible spatial signals in the spatial associations between species in this species-rich subtropical forest with a strong topographic structure.

Attaining the canopy in dry and moist tropical forests: strong differences in tree growth trajectories reflect variation in growing conditions.

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Brienen, Roel J W; Zuidema, Pieter A; Martínez-Ramos, Miguel

2010-06-01

Availability of light and water differs between tropical moist and dry forests, with typically higher understorey light levels and lower water availability in the latter. Therefore, growth trajectories of juvenile trees--those that have not attained the canopy--are likely governed by temporal fluctuations in light availability in moist forests (suppressions and releases), and by spatial heterogeneity in water availability in dry forests. In this study, we compared juvenile growth trajectories of Cedrela odorata in a dry (Mexico) and a moist forest (Bolivia) using tree rings. We tested the following specific hypotheses: (1) moist forest juveniles show more and longer suppressions, and more and stronger releases; (2) moist forest juveniles exhibit wider variation in canopy accession pattern, i.e. the typical growth trajectory to the canopy; (3) growth variation among dry forest juveniles persists over longer time due to spatial heterogeneity in water availability. As expected, the proportion of suppressed juveniles was higher in moist than in dry forest (72 vs. 17%). Moist forest suppressions also lasted longer (9 vs. 5 years). The proportion of juveniles that experienced releases in moist forest (76%) was higher than in dry forest (41%), and releases in moist forests were much stronger. Trees in the moist forest also had a wider variation in canopy accession patterns compared to the dry forest. Our results also showed that growth variation among juvenile trees persisted over substantially longer periods of time in dry forest (>64 years) compared to moist forest (12 years), most probably because of larger persistent spatial variation in water availability. Our results suggest that periodic increases in light availability are more important for attaining the canopy in moist forests, and that spatial heterogeneity in water availability governs long-term tree growth in dry forests.

Okinawan Subtropical Plants as a Promising Resource for Novel Chemical Treasury.

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Matsunami, Katsuyoshi; Otsuka, Hideaki

2018-01-01

The Okinawa Islands are a crescent-shaped archipelago and their natural forests hold a huge variety of unique subtropical plants with relatively high endemism. We have performed phytochemical study on Okinawan subtropical plants for many years. In this review, we describe our recent research progress on the isolation of new compounds and their various bioactivities.

Seasonal Precipitation Variability Effects on Carbon Exchange in a Tropical Dry Forest of Northwest Mexico

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Verduzco, V.; Garatuza-Payan, J.; Yépez, E. A.; Watts, C. J.; Rodriguez, J. C.; Robles-Morua, A.; Vivoni, E. R.

2015-12-01

The Tropical Dry Forest (TDF) cover a large area in tropical and subtropical regions in the Americas and its productivity is thought to have an important contribution to the atmospheric carbon fluxes. However, due to this ecosystem complex dynamics, our understanding about the mechanisms controlling net ecosystem exchange is limited. In this study, five years of continue water and carbon fluxes measurements from eddy covariance complemented with remotely sensed vegetation greenness were used to investigate the ecosystem carbon balance of a TDF in the North American Monsoon region under different hydro climatic conditions. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer a predominant heterotrophic control owed to high decomposition of accumulated labile soil organic matter from prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production over the year, but can be overwhelmed by the strength of the primary productivity during the monsoon season. Precipitation characteristics during the monsoon have significant controls on sustaining carbon fixation in the TDF ecosystem into the fall season. A threshold of ~350 to 400 mm of summer precipitation was identify to switch the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This research points at the needs for understanding the potential effects of changing seasonal precipitation patterns on ecosystem dynamics and carbon sequestration in subtropical regions.

Bryophyte-dominated biological soil crusts mitigate soil erosion in an early successional Chinese subtropical forest

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S. Seitz

2017-12-01

Full Text Available This study investigated the development of biological soil crusts (biocrusts in an early successional subtropical forest plantation and their impact on soil erosion. Within a biodiversity and ecosystem functioning experiment in southeast China (biodiversity and ecosystem functioning (BEF China, the effect of these biocrusts on sediment delivery and runoff was assessed within micro-scale runoff plots under natural rainfall, and biocrust cover was surveyed over a 5-year period. Results showed that biocrusts occurred widely in the experimental forest ecosystem and developed from initial light cyanobacteria- and algae-dominated crusts to later-stage bryophyte-dominated crusts within only 3 years. Biocrust cover was still increasing after 6 years of tree growth. Within later-stage crusts, 25 bryophyte species were determined. Surrounding vegetation cover and terrain attributes significantly influenced the development of biocrusts. Besides high crown cover and leaf area index, the development of biocrusts was favoured by low slope gradients, slope orientations towards the incident sunlight and the altitude of the research plots. Measurements showed that bryophyte-dominated biocrusts strongly decreased soil erosion, being more effective than abiotic soil surface cover. Hence, their significant role in mitigating sediment delivery and runoff generation in mesic forest environments and their ability to quickly colonise soil surfaces after disturbance are of particular interest for soil erosion control in early-stage forest plantations.

Bryophyte-dominated biological soil crusts mitigate soil erosion in an early successional Chinese subtropical forest

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Seitz, Steffen; Nebel, Martin; Goebes, Philipp; Käppeler, Kathrin; Schmidt, Karsten; Shi, Xuezheng; Song, Zhengshan; Webber, Carla L.; Weber, Bettina; Scholten, Thomas

2017-12-01

This study investigated the development of biological soil crusts (biocrusts) in an early successional subtropical forest plantation and their impact on soil erosion. Within a biodiversity and ecosystem functioning experiment in southeast China (biodiversity and ecosystem functioning (BEF) China), the effect of these biocrusts on sediment delivery and runoff was assessed within micro-scale runoff plots under natural rainfall, and biocrust cover was surveyed over a 5-year period. Results showed that biocrusts occurred widely in the experimental forest ecosystem and developed from initial light cyanobacteria- and algae-dominated crusts to later-stage bryophyte-dominated crusts within only 3 years. Biocrust cover was still increasing after 6 years of tree growth. Within later-stage crusts, 25 bryophyte species were determined. Surrounding vegetation cover and terrain attributes significantly influenced the development of biocrusts. Besides high crown cover and leaf area index, the development of biocrusts was favoured by low slope gradients, slope orientations towards the incident sunlight and the altitude of the research plots. Measurements showed that bryophyte-dominated biocrusts strongly decreased soil erosion, being more effective than abiotic soil surface cover. Hence, their significant role in mitigating sediment delivery and runoff generation in mesic forest environments and their ability to quickly colonise soil surfaces after disturbance are of particular interest for soil erosion control in early-stage forest plantations.

Forests growing under dry conditions have higher hydrological resilience to drought than do more humid forests.

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Helman, David; Lensky, Itamar M; Yakir, Dan; Osem, Yagil

2017-07-01

More frequent and intense droughts are projected during the next century, potentially changing the hydrological balances in many forested catchments. Although the impacts of droughts on forest functionality have been vastly studied, little attention has been given to studying the effect of droughts on forest hydrology. Here, we use the Budyko framework and two recently introduced Budyko metrics (deviation and elasticity) to study the changes in the water yields (rainfall minus evapotranspiration) of forested catchments following a climatic drought (2006-2010) in pine forests distributed along a rainfall gradient (P = 280-820 mm yr -1 ) in the Eastern Mediterranean (aridity factor = 0.17-0.56). We use a satellite-based model and meteorological information to calculate the Budyko metrics. The relative water yield ranged from 48% to 8% (from the rainfall) in humid to dry forests and was mainly associated with rainfall amount (increasing with increased rainfall amount) and bedrock type (higher on hard bedrocks). Forest elasticity was larger in forests growing under drier conditions, implying that drier forests have more predictable responses to drought, according to the Budyko framework, compared to forests growing under more humid conditions. In this context, younger forests were shown more elastic than older forests. Dynamic deviation, which is defined as the water yield departure from the Budyko curve, was positive in all forests (i.e., less-than-expected water yields according to Budyko's curve), increasing with drought severity, suggesting lower hydrological resistance to drought in forests suffering from larger rainfall reductions. However, the dynamic deviation significantly decreased in forests that experienced relatively cooler conditions during the drought period. Our results suggest that forests growing under permanent dry conditions might develop a range of hydrological and eco-physiological adjustments to drought leading to higher hydrological

Altered dynamics of broad-leaved tree species in a Chinese subtropical montane mixed forest: the role of an anomalous extreme 2008 ice storm episode.

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Ge, Jielin; Xiong, Gaoming; Wang, Zhixian; Zhang, Mi; Zhao, Changming; Shen, Guozhen; Xu, Wenting; Xie, Zongqiang

2015-04-01

Extreme climatic events can trigger gradual or abrupt shifts in forest ecosystems via the reduction or elimination of foundation species. However, the impacts of these events on foundation species' demography and forest dynamics remain poorly understood. Here we quantified dynamics for both evergreen and deciduous broad-leaved species groups, utilizing a monitoring permanent plot in a subtropical montane mixed forest in central China from 2001 to 2010 with particular relevance to the anomalous 2008 ice storm episode. We found that both species groups showed limited floristic alterations over the study period. For each species group, size distribution of dead individuals approximated a roughly irregular and flat shape prior to the ice storm and resembled an inverse J-shaped distribution after the ice storm. Furthermore, patterns of mortality and recruitment displayed disequilibrium behaviors with mortality exceeding recruitment for both species groups following the ice storm. Deciduous broad-leaved species group accelerated overall diameter growth, but the ice storm reduced evergreen small-sized diameter growth. We concluded that evergreen broad-leaved species were more susceptible to ice storms than deciduous broad-leaved species, and ice storm events, which may become more frequent with climate change, might potentially threaten the perpetuity of evergreen-dominated broad-leaved forests in this subtropical region in the long term. These results underscore the importance of long-term monitoring that is indispensible to elucidate causal links between forest dynamics and climatic perturbations.

Leaf traits show different relationships with shade tolerance in moist versus dry tropical forests.

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Poorter, Lourens

2009-03-01

Shade tolerance is the central paradigm for understanding forest succession and dynamics, but there is considerable debate as to what the salient features of shade tolerance are, whether adult leaves show similar shade adaptations to seedling leaves, and whether the same leaf adaptations are found in forests under different climatic control. Here, adult leaf and metamer traits were measured for 39 tree species from a tropical moist semi-evergreen forest (1580 mm rain yr(-1)) and 41 species from a dry deciduous forest (1160 mm yr(-1)) in Bolivia. Twenty-six functional traits were measured and related to species regeneration light requirements.Adult leaf traits were clearly associated with shade tolerance. Different, rather than stronger, shade adaptations were found for moist compared with dry forest species. Shade adaptations exclusively found in the evergreen moist forest were related to tough and persistent leaves, and shade adaptations in the dry deciduous forest were related to high light interception and water use.These results suggest that, for forests differing in rainfall seasonality, there is a shift in the relative importance of functional leaf traits and performance trade-offs that control light partitioning. In the moist evergreen forest leaf traits underlying the growth-survival trade-off are important, whereas in the seasonally deciduous forest leaf traits underlying the growth trade-off between low and high light might become important.

Effects of reforestation on ammonia-oxidizing microbial community composition and abundance in subtropical acidic forest soils.

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Wu, Ruo-Nan; Meng, Han; Wang, Yong-Feng; Gu, Ji-Dong

2018-06-01

Forest ecosystems have great ecological values in mitigation of climate change and protection of biodiversity of flora and fauna; re-forestry is commonly used to enhance the sequestration of atmospheric CO 2 into forest storage biomass. Therefore, seasonal and spatial dynamics of the major microbial players in nitrification, ammonia-oxidizing archaea (AOA) and bacteria (AOB), in acidic soils of young and matured revegetated forests were investigated to elucidate the changes of microbial communities during forest restoration, and compared to delineate the patterns of community shifts under the influences of environmental factors. AOA were more abundant than AOB in both young and matured revegetated forest soils in both summer and winter seasons. In summer, however, the abundance of amoA-AOA decreased remarkably (p < 0.01), ranging from 1.90 (± 0.07) × 10 8 copies per gram dry soil in matured forest to 5.04 (± 0.43) × 10 8 copies per gram dry soil in young forest, and amoA-AOB was below detection limits to obtain any meaningful values. Moreover, exchangeable Al 3+ and organic matter were found to regulate the physiologically functional nitrifiers, especially AOA abundance in acidic forest soils. AOB community in winter showed stronger correlation with the restoration status of revegetated forests and AOA community dominated by Nitrosotalea devanaterra, in contrast, was more sensitive to the seasonal and spatial variations of environmental factors. These results enrich the current knowledge of nitrification during re-forestry and provide valuable information to developmental status of revegetated forests for management through microbial analysis.

Effects of growth form and functional traits on response of woody plants to clearing and fragmentation of subtropical rainforest.

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Kooyman, R M; Zanne, A E; Gallagher, R V; Cornwell, W; Rossetto, M; O'Connor, P; Parkes, E A; Catterall, C F; Laffan, S W; Lusk, C H

2013-12-01

The conservation implications of large-scale rainforest clearing and fragmentation on the persistence of functional and taxonomic diversity remain poorly understood. If traits represent adaptive strategies of plant species to particular circumstances, the expectation is that the effect of forest clearing and fragmentation will be affected by species functional traits, particularly those related to dispersal. We used species occurrence data for woody plants in 46 rainforest patches across 75,000 ha largely cleared of forest by the early 1900s to determine the combined effects of area reduction, fragmentation, and patch size on the taxonomic structure and functional diversity of subtropical rainforest. We compiled species trait values for leaf area, seed dry mass, wood density, and maximum height and calculated species niche breadths. Taxonomic structure, trait values (means, ranges), and the functional diversity of assemblages of climbing and free-standing plants in remnant patches were quantified. Larger rainforest patches had higher species richness. Species in smaller patches were taxonomically less related than species in larger patches. Free-standing plants had a high percentage of frugivore dispersed seeds; climbers had a high proportion of small wind-dispersed seeds. Connections between the patchy spatial distribution of free-standing species, larger seed sizes, and dispersal syndrome were weak. Assemblages of free-standing plants in patches showed more taxonomic and spatial structuring than climbing plants. Smaller isolated patches retained relatively high functional diversity and similar taxonomic structure to larger tracts of forest despite lower species richness. The response of woody plants to clearing and fragmentation of subtropical rainforest differed between climbers and slow-growing mature-phase forest trees but not between climbers and pioneer trees. Quantifying taxonomic structure and functional diversity provides an improved basis for

Multi-Temporal Monitoring Of Ecological Succession In Tropical Dry Forests Using Angular - Hyperspectral Data (Chris/Proba)

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Garcia Millan, V. E.

2015-12-01

The tropical dry forest is the largest and most threatened ecosystem in Latin America. Remote sensing can effectively contribute to the surveillance of conservation measurements and laws through the monitoring of natural protected areas, at the required temporal and spatial scales. CHRIS/PROBA is the only satellite that presents quasi-simultaneous multi-angular pointing and hyperspectral spectroscopy. These two characteristics permit the study of structural and compositional traces of successional stages within the tropical dry forest. The current study presents the results of mapping the succession of tropical dry forest in the Parque Estadual de la Mata-Seca, in Minas Gerais, Brazil, using a temporal analysis of CHRIS/PROBA images in a time frame of 7 years, between 2008 and 2014. For the purpose the -55° angle of observation has been used, which enhances spectral differences between successional stages. Spectral Angle Mapper has been used for mapping succession of tropical dry forest and afterwards Change Detection Analysis has been performed. Based on our observations, the tropical dry forest in the Parque Estadual de la Mataseca recovers at a fast rate, for the observed period (2008-2014). More than the 50% of the early and intermediate forests has been recovered to a mature forest. Significantly, around a 12% of old pastures have been converted into forest. The spatial analysis also reveals that the areas that recover most rapidly are located in the east of the Park, close to mature forests. The provision of seeds from these forests might be the cause for the fast recovery.

Water flow and energy balance for a tropical dry semideciduous forest

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Andrade, J. L.; Garruña-Hernandez, R.; Leon-Palomo, M.; Us-Santamaria, R.; Sima, J. L.

2013-05-01

Tropical forests cool down locally because increase water evaporation from the soil to the atmosphere, reduce albedo and help forming clouds that reflect solar radiation back to the atmosphere; this, aligned to the carbon catchment, increase forests value. We will present an estimation of the sap flow and energy balance for the tropical dry semideciduous forest at Kiuic, Yucatan, Mexico during a year. We use a meteorological tower equipped with a rain gauge, temperature and relative humidity, heat flow plates, thermocouples and volumetric soil water content. We recorded net radiation and soil heat flux and estimated sensible heat and latent heat. Besides, we estimated latent heat by measuring sap flow directly in tres using disispation constant heat probes during the rainy season. Results show the influence of the seasonality on net radiation, air temperatura and vapor pressure deficit, because during the dry season his variables were higher and with more duation than during the rainy and early dry season. Sap flow was different for trees belonging to the family Fabaceae compared to trees from other families.

SRTM-DEM and Landsat ETM+ data for mapping tropical dry forest cover and biodiversity assessment in Nicaragua

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S.E. Sesnie; S.E. Hagell; S.M. Otterstrom; C.L. Chambers; B.G. Dickson

2008-01-01

Tropical dry and deciduous forest comprises as much as 42% of the world’s tropical forests, but has received far less attention than forest in wet tropical areas. Land use change threatens to greatly reduce the extent of dry forest that is known to contain high levels of plant and animal diversity. Forest fragmentation may further endanger arboreal mammals that play...

Forest structure, diversity and soil properties in a dry tropical forest in Rajasthan, Western India

OpenAIRE

J. I. Nirmal Kumar,; Kanti Patel,; Rohit Bhoi Kumar

2011-01-01

Structure, species composition, and soil properties of a dry tropical forest in Rajasthan Western India, were examined by establishment of 25 plots. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 995 stems ha-1 (≥ 3.0 cm DBH); 52% of those stems were smaller than 10 cm DBH. The total basal area was 46.35 m2ha-1, of which Tectona grandis L. contributed 48%. The fo...

[Regenerative morphological traits in a woody species community in Tumbesian tropical dry forest].

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Romero-Saritama, José Miguel; Pérez-Rúuz, César

2016-06-01

The study of functional morphological traits enables us to know fundamental aspects of the dynamics of plant communities in local and global habitats. Regenerative morphological traits play an important role in defining plant history and ecological behavior. Seed and fruit characteristics determine to a large extent the patterns for dispersal, germination, establishment and seedling recruitment a given species exhibits on its natural habitat. Despite their prominent role, seed and fruit traits have been poorly studied at the community level of woody plant species in neo-tropical dry forests. In the present study we aimed at i) evaluate the functional role of morphological traits of seeds, fruits and embryo in woody plant species; ii) determine which are the morphological patterns present in seeds collected from the community of woody species that occur in neo-tropical dry forests; and iii) compare woody plant species seed mass values comparatively between neo-tropical dry and tropical forests. To do so, mature seeds were collected from 79 plant species that occur in the Tumbesian forest of Southwest Ecuador. The studied species included the 42 and 37 most representative tree and shrubbery species of the Tumbesian forest respectively. A total of 18 morphological traits (seven quantitative and 11 qualitative) were measured and evaluated in the seeds, fruits and embryos of the selected species, and we compared the seeds mass with other forest types. Our results showed a huge heterogeneity among traits values in the studied species. Seed mass, volume and number were the traits that vary the most at the community level, i.e. seed length ranged from 1.3 to 39 mm, and seed width from 0.6 to 25 mm. Only six embryo types were found among the 79 plant species. In 40 % of the cases, fully developed inverted embryos with large and thick cotyledons to store considerable amount of nutrients were recorded. We concluded that highly variable and functionally complementary

Soil water storage, rainfall and runoff relationships in a tropical dry forest catchment

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Farrick, Kegan K.; Branfireun, Brian A.

2014-12-01

In forested catchments, the exceedance of rainfall and antecedent water storage thresholds is often required for runoff generation, yet to our knowledge these threshold relationships remain undescribed in tropical dry forest catchments. We, therefore, identified the controls of streamflow activation and the timing and magnitude of runoff in a tropical dry forest catchment near the Pacific coast of central Mexico. During a 52 day transition phase from the dry to wet season, soil water movement was dominated by vertical flow which continued until a threshold soil moisture content of 26% was reached at 100 cm below the surface. This satisfied a 162 mm storage deficit and activated streamflow, likely through lateral subsurface flow pathways. High antecedent soil water conditions were maintained during the wet phase but had a weak influence on stormflow. We identified a threshold value of 289 mm of summed rainfall and antecedent soil water needed to generate >4 mm of stormflow per event. Above this threshold, stormflow response and magnitude was almost entirely governed by rainfall event characteristics and not antecedent soil moisture conditions. Our results show that over the course of the wet season in tropical dry forests the dominant controls on runoff generation changed from antecedent soil water and storage to the depth of rainfall.

Pan tropical biomass equations for Mexico's dry forests

Directory of Open Access Journals (Sweden)

José Návar

2014-12-01

Full Text Available This study reports a set of robust regional M-tree allometric equations for Mexico's tropical dry forests and their application to a forest inventory dataset for the States of Durango and Sinaloa, Mexico. Calculated M data from 15 reported equations were fitted, applied and validated for regional and global models. Proposed theoretical models, empirically derived equations, as well as global and local reported equations were fitted and applied to calculated M-tree data using wood specific gravity, diameter at breast height, and top height as exogenous variables. Empirically-derived, computer-based equations assessed the M-tree evaluations slightly better than the theoretical, the global and the local models. However, the theoretical models projected compatible M-tree values and deserve further attention once wood specific gravity data are collected in the field. Using the best fit equation, mean M plot density values of 30, 41 and 35 Mg ha-1 were estimated from 57 plots (1,600 m² each, 217 plots (1,000 m² each and 166 plots (1,000 m² each in the tropical dry forests of the States of Durango, Tiniaquis and Vado Hondo (Sinaloa, respectively. The large sample size, the richness of the tested allometric models, the economic and ecological importance of this data-source, and the spatial coverage of these equations made this dataset uniquely useful for biomass, charcoal, and other bio-energy estimations, as well as for understanding the inherent heterogeneity of the stand-structure in dynamic tropical forest environments.

The effects of forest-savanna-grassland gradients on bird communities of Chiquitano Dry Forests domain, in western Brazil.

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Godoi, Mauricio N; Souza, Edivaldo O DE

2016-01-01

Different vegetation types are distributed in mountains according to altitude, topography and soil. The composition and structure of bird communities in these areas can change in relation to the vegetation gradient, with particular communities occupying each habitat type. In this study we present the changes in composition, species richness and bird abundance over the gradient of forests, savannas and altitudinal grasslands of Maciço do Urucum, a mountainous region located in the Chiquitano Dry Forests domain in western Brazil. We recorded 165 bird species through qualitative and quantitative methods. Forested savannas, riparian forests and submontane forests presented the highest richness and abundance of birds, while arboreal savannas and altitudinal grasslands had intermediate and low values, respectively. The bird composition was similar between riparian and submontane forests, while other vegetation types present more dissimilar bird communities. Our results show differences in composition, richness and bird abundance among the vegetation types present at Maciço do Urucum, and highlight an important function of vegetation gradients for the conservation of bird communities in mountains. Additionally, this is the first study of the bird communities in the Brazilian Chiquitano Dry Forests, an important domain in the west of Brazil which has been poorly studied.

Are variations in heterotrophic soil respiration related to changes in substrate availability and microbial biomass carbon in the subtropical forests?

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Wei, Hui; Chen, Xiaomei; Xiao, Guoliang; Guenet, Bertrand; Vicca, Sara; Shen, Weijun

2015-12-16

Soil temperature and moisture are widely-recognized controlling factors on heterotrophic soil respiration (Rh), although they often explain only a portion of Rh variability. How other soil physicochemical and microbial properties may contribute to Rh variability has been less studied. We conducted field measurements on Rh half-monthly and associated soil properties monthly for two years in four subtropical forests of southern China to assess influences of carbon availability and microbial properties on Rh. Rh in coniferous forest was significantly lower than that in the other three broadleaf species-dominated forests and exhibited obvious seasonal variations in the four forests (P forests. The quantity and decomposability of dissolved organic carbon (DOC) were significantly important to Rh variations, but the effect of DOC content on Rh was confounded with temperature, as revealed by partial mantel test. Microbial biomass carbon (MBC) was significantly related to Rh variations across forests during the warm season (P = 0.043). Our results suggest that DOC and MBC may be important when predicting Rh under some conditions, and highlight the complexity by mutual effects of them with environmental factors on Rh variations.

Functional trait strategies of trees in dry and wet tropical forests are similar but differ in their consequences for succession.

Science.gov (United States)

Lohbeck, Madelon; Lebrija-Trejos, Edwin; Martínez-Ramos, Miguel; Meave, Jorge A; Poorter, Lourens; Bongers, Frans

2014-01-01

Global plant trait studies have revealed fundamental trade-offs in plant resource economics. We evaluated such trait trade-offs during secondary succession in two species-rich tropical ecosystems that contrast in precipitation: dry deciduous and wet evergreen forests of Mexico. Species turnover with succession in dry forest largely relates to increasing water availability and in wet forest to decreasing light availability. We hypothesized that while functional trait trade-offs are similar in the two forest systems, the successful plant strategies in these communities will be different, as contrasting filters affect species turnover. Research was carried out in 15 dry secondary forest sites (5-63 years after abandonment) and in 17 wet secondary forest sites (dry and wet forest and compare trait trade-offs. We evaluated whether multivariate plant strategies changed during succession, by calculating a 'Community-Weighted Mean' plant strategy, based on species scores on the first two PCA-axes. Trait spectra reflected two main trade-off axes that were similar for dry and wet forest species: acquisitive versus conservative species, and drought avoiding species versus evergreen species with large animal-dispersed seeds. These trait associations were consistent when accounting for evolutionary history. Successional changes in the most successful plant strategies reflected different functional trait spectra depending on the forest type. In dry forest the community changed from having drought avoiding strategies early in succession to increased abundance of evergreen strategies with larger seeds late in succession. In wet forest the community changed from species having mainly acquisitive strategies to those with more conservative strategies during succession. These strategy changes were explained by increasing water availability during dry forest succession and increasing light scarcity during wet forest succession. Although similar trait spectra were observed among dry and

Epizoochory in dry forest iguanas: an overlooked seed dispersal mechanism?

Directory of Open Access Journals (Sweden)

Eloisa Lasso

2015-01-01

Full Text Available The role of animals as seed dispersal vectors is widely acknowledged, including dispersal by reptiles (saurochory. Most reports of saurochory have been via endozoochory, through feces deposition. We present the first evidence of epizoochory in Iguanas from a dry forest in Colombia via seeds attached to the snout. Our results show that seeds of a cactus Melocactus curvispinus ingested by iguana suffers from their passage through the digestive tract while seeds transported while attached to the snout germinate faster and in higher numbers. Our data suggest that we may have overlooked an alternative means of seed dispersal by lizards that does not comprise a passage through their digestive tract, and that deserves further attention for the understanding of dry forest ecology.

[Effect of seasonal high temperature and drought on carbon flux of bamboo forest ecosystem in subtropical region].

Science.gov (United States)

Chen, Xiao-feng; Jiang, Hong; Niu, Xiao-dong; Zhang, Jin-meng; Liu, Yu-li; Fang, Cheng-yuan

2016-02-01

The carbon flux of subtropical bamboo forest ecosystem was continuously measured using eddy covariance technique in Anji County of Zhejiang Province, China. The monthly net ecosystem productivity (NEP), ecosystem respiration (Re) and gross ecosystem productivity (GEP) data from 2011 to 2013 were selected to analyze the impacts of seasonal high temperature and drought on the carbon flux of bamboo forest ecosystem. The results showed that there were big differences among annual NEP of bamboo forest from 2011 to 2013. Because of the asynchronization of precipitation and heat, the seasonal high temperature and drought in July and August of 2013 caused significant decline in NEP by 59.9% and 80.0% when compared with the same months in 2011. Correlation analysis of the NEP, Re, GEP and environmental factors suggested that the atmosphere temperatures were significantly correlated with Re and GEP in 2011 and 2013 (P<0.05). However, to air and soil moisture, Re and GEP had different responses, that was, GEP was more vulnerable by the decrease of the soil moisture compared with Re. Besides, the raising of saturation vapour pressure promoted the Re modestly but inhibited the GEP, which was supposed to be the main reason for NEP decrease of bamboo forest ecosystem in Anji, from July to August in 2013.

SRTM-DEM AND LANDSAT ETM+ DATA FOR MAPPING TROPICAL DRY FOREST COVER AND BIODIVERSITY ASSESSMENT IN NICARAGUA

OpenAIRE

Brett G. Dickson; Carol L. Chambers; Sarah M. Otterstrom; Suzanne E. Hagell; Steven E. Sesnie

2008-01-01

Tropical dry and deciduous forest comprises as much as 42% of the world’s tropical forests, but hasreceived far less attention than forest in wet tropical areas. Land use change threatens to greatly reducethe extent of dry forest that is known to contain high levels of plant and animal diversity. Forest fragmentationmay further endanger arboreal mammals that play principal role in the dispersal of large seeded fruits, plantcommunity assembly and diversity in these systems. Data on the spatial...

Recovery of Biomass Following Shifting Cultivation in Dry Tropical Forests of the Yucatan

OpenAIRE

Read, L; Lawrence, Deborah; Foster, David Russell

2003-01-01

Land-use change in the tropics is creating secondary forest at an unprecedented rate. In the tropical Americas, mature dry tropical forest is rapidly being converted to secondary forest during the fallow period of shifting cultivation. This study addresses changes in forest biomass during forest recovery following shifting cultivation of maize (corn) in the Southern Yucatan Peninsular Region (SYPR), Mexico. We sampled stems .1 cm diameter at breast height at 36 study sites in t...

Soil emissions of nitric oxide in a seasonally dry tropical forest of Mexico

Science.gov (United States)

Davidson, Eric A.; Vitousek, Peter M.; Riley, Ralph; Matson, Pamela A.; Garcia-Mendez, Georgina; Maass, J. M.

1991-01-01

Soil emissions of NO were measured at the Chamela Biological Station, Mexico, using soil covers and a field apparatus of NO detection based on CrO3 conversion of NO to NO2 and detection of NO2 by chemiluminescence with Luminol. Mean NO fluxes from forest soils ranged from 0.14 to 0.52 ng NO-N/sq cm/hr during the dry season and from 0.73 to 1.27 ng NO-N/sq cm/hr during the wet season. A fertilized floodplain pasture exhibited higher fluxes, but an unfertilized upland pasture, which represents the fastest growing land use in the region, had flux rates similar to the forest sites. Wetting experiments at the end of the dry season caused large pulses of NO flux, equaling 10 percent to 20 percent of the estimated annual NO emissions of 0.5-1.0 kg N/ha from the forest sites. Absence of a forest canopy during the dry season and the first wet season rain probably results in substantial NO(x) export from the forest system that may be important to regional atmospheric chemical processes. Wetting experiments during the wet season and a natural rain event had little or no stimulatory effect on NO flux rates.

Taboos and forest governance: informal protection of hot spot dry forest in southern Madagascar.

Science.gov (United States)

Tengö, Maria; Johansson, Kristin; Rakotondrasoa, Fanambinantsoa; Lundberg, Jakob; Andriamaherilala, Jean-Aimé; Rakotoarisoa, Jean-Aimé; Elmqvist, Thomas

2007-12-01

In the dry forest of southern Madagascar, a region of global conservation priority, formally protected areas are nearly totally absent. We illustrate how the continued existence of unique forest habitats in the Androy region is directly dependent on informal institutions, taboos, regulating human behavior. Qualitative interviews to map and analyze the social mechanisms underlying forest protection have been combined with vegetation analyses of species diversity and composition. Of 188 forest patches, 93% were classified as protected, and in Southern Androy all remaining forest patches larger than 5 ha were protected. Eight different types of forests, with a gradient of social fencing from open access to almost complete entry prohibitions, were identified. Transgressions were well enforced with strong sanctions of significant economic as well as religious importance. Analyses of species diversity between protected and unprotected forests were complicated because of size differences and access restrictions. However, since, for example, in southern Androy >90% of the total remaining forest cover is protected through taboos, these informal institutions represent an important, and presently the only, mechanism for conservation of the highly endemic forest species. We conclude that social aspects, such as local beliefs and legitimate sanctioning systems, need to be analyzed and incorporated along with biodiversity studies for successful conservation.

Wildfires, Ecosystem Services, and Biodiversity in Tropical Dry Forest in India

Science.gov (United States)

Schmerbeck, Joachim; Fiener, Peter

2015-08-01

This review is intended to contribute to the understanding of the interlinkage between wildfire in India's tropical dry forest (TDF) and selected ecosystem services (ES), namely forest provisioning and water regulating services, as well as biodiversity. TDF covers approximately 146,000 km2 (4.4 %) of India, whereas according to the MODIS fire product about 2200 km2 (1.4 %) burns per year. As studies on wildfire effects upon ESs and biodiversity in Indian TDFs are rare we partly transferred findings from other (dry) forest areas to the environmental situation in India. In India (intentionally lit) wildfires have a very important connection to local livelihoods and the availability of non-wood forest products. Very important adverse long-term effects are the deterioration of forest ecosystems and soil degradation. The potential for TDF to regulate hydrological cycles is expected to be greater in the absence of fire than with it. A general judgment on the effect of fire on biodiversity is difficult as it depends on the community and species involved but a loss of biodiversity under regular burnings is apparent. Consequently, forest managers need sound knowledge regarding the interplay of wildfires and ecosystem behavior in general and more specific knowledge regarding the effects on taxa being considered for conservation efforts. Generally, much more research is needed to understand the trade-offs between the short-term benefits gained from forest provisioning services and long-term adverse effects.

Wildfires, Ecosystem Services, and Biodiversity in Tropical Dry Forest in India.

Science.gov (United States)

Schmerbeck, Joachim; Fiener, Peter

2015-08-01

This review is intended to contribute to the understanding of the interlinkage between wildfire in India's tropical dry forest (TDF) and selected ecosystem services (ES), namely forest provisioning and water regulating services, as well as biodiversity. TDF covers approximately 146,000 km(2) (4.4%) of India, whereas according to the MODIS fire product about 2200 km(2) (1.4%) burns per year. As studies on wildfire effects upon ESs and biodiversity in Indian TDFs are rare we partly transferred findings from other (dry) forest areas to the environmental situation in India. In India (intentionally lit) wildfires have a very important connection to local livelihoods and the availability of non-wood forest products. Very important adverse long-term effects are the deterioration of forest ecosystems and soil degradation. The potential for TDF to regulate hydrological cycles is expected to be greater in the absence of fire than with it. A general judgment on the effect of fire on biodiversity is difficult as it depends on the community and species involved but a loss of biodiversity under regular burnings is apparent. Consequently, forest managers need sound knowledge regarding the interplay of wildfires and ecosystem behavior in general and more specific knowledge regarding the effects on taxa being considered for conservation efforts. Generally, much more research is needed to understand the trade-offs between the short-term benefits gained from forest provisioning services and long-term adverse effects.

Opposing Responses of Bird Functional Diversity to Vegetation Structural Diversity in Wet and Dry Forest.

Directory of Open Access Journals (Sweden)

Holly Sitters

Full Text Available Disturbance regimes are changing worldwide, and the consequences for ecosystem function and resilience are largely unknown. Functional diversity (FD provides a surrogate measure of ecosystem function by capturing the range, abundance and distribution of trait values in a community. Enhanced understanding of the responses of FD to measures of vegetation structure at landscape scales is needed to guide conservation management. To address this knowledge gap, we used a whole-of-landscape sampling approach to examine relationships between bird FD, vegetation diversity and time since fire. We surveyed birds and measured vegetation at 36 landscape sampling units in dry and wet forest in southeast Australia during 2010 and 2011. Four uncorrelated indices of bird FD (richness, evenness, divergence and dispersion were derived from six bird traits, and we investigated responses of these indices and species richness to both vertical and horizontal vegetation diversity using linear mixed models. We also considered the extent to which the mean and diversity of time since fire were related to vegetation diversity. Results showed opposing responses of FD to vegetation diversity in dry and wet forest. In dry forest, where fire is frequent, species richness and two FD indices (richness and dispersion were positively related to vertical vegetation diversity, consistent with theory relating to environmental variation and coexistence. However, in wet forest subject to infrequent fire, the same three response variables were negatively associated with vertical diversity. We suggest that competitive dominance by species results in lower FD as vegetation diversity increases in wet forest. The responses of functional evenness were opposite to those of species richness, functional richness and dispersion in both forest types, highlighting the value of examining multiple FD metrics at management-relevant scales. The mean and diversity of time since fire were uncorrelated

Opposing Responses of Bird Functional Diversity to Vegetation Structural Diversity in Wet and Dry Forest.

Science.gov (United States)

Sitters, Holly; York, Alan; Swan, Matthew; Christie, Fiona; Di Stefano, Julian

2016-01-01

Disturbance regimes are changing worldwide, and the consequences for ecosystem function and resilience are largely unknown. Functional diversity (FD) provides a surrogate measure of ecosystem function by capturing the range, abundance and distribution of trait values in a community. Enhanced understanding of the responses of FD to measures of vegetation structure at landscape scales is needed to guide conservation management. To address this knowledge gap, we used a whole-of-landscape sampling approach to examine relationships between bird FD, vegetation diversity and time since fire. We surveyed birds and measured vegetation at 36 landscape sampling units in dry and wet forest in southeast Australia during 2010 and 2011. Four uncorrelated indices of bird FD (richness, evenness, divergence and dispersion) were derived from six bird traits, and we investigated responses of these indices and species richness to both vertical and horizontal vegetation diversity using linear mixed models. We also considered the extent to which the mean and diversity of time since fire were related to vegetation diversity. Results showed opposing responses of FD to vegetation diversity in dry and wet forest. In dry forest, where fire is frequent, species richness and two FD indices (richness and dispersion) were positively related to vertical vegetation diversity, consistent with theory relating to environmental variation and coexistence. However, in wet forest subject to infrequent fire, the same three response variables were negatively associated with vertical diversity. We suggest that competitive dominance by species results in lower FD as vegetation diversity increases in wet forest. The responses of functional evenness were opposite to those of species richness, functional richness and dispersion in both forest types, highlighting the value of examining multiple FD metrics at management-relevant scales. The mean and diversity of time since fire were uncorrelated with vegetation

Simulated dry deposition of nitric acid near forest edges

NARCIS (Netherlands)

DeJong, JJM; Klaassen, W; Jong, J.J.M. de

1997-01-01

Dry deposition is simulated to understand and generalize observations of enhanced deposition of air pollution near forest edges. Nitric acid is taken as an example as its deposition velocity is often assumed to be determined by turbulent transport only. The simulations are based on the

Propagation of dry tropical forest trees in Mexico

Science.gov (United States)

Martha A. Cervantes Sanchez

2002-01-01

There is a distinct lack of technical information on the propagation of native tree species from the dry tropical forest ecosystem in Mexico. This ecosystem has come under heavy human pressures to obtain several products such as specialty woods for fuel, posts for fences and construction, forage, edible fruits, stakes for horticulture crops, and medicinal products. The...

Forest structure, diversity and soil properties in a dry tropical forest in Rajasthan, Western India

Directory of Open Access Journals (Sweden)

J. I. Nirmal Kumar

2011-06-01

Full Text Available Structure, species composition, and soil properties of a dry tropical forest in Rajasthan Western India, were examined by establishment of 25 plots. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 995 stems ha-1 (= 3.0 cm DBH; 52% of those stems were smaller than 10 cm DBH. The total basal area was 46.35 m2ha-1, of which Tectona grandis L. contributed 48%. The forest showed high species diversity of trees. 50 tree species (= 3.0 cm DBH from 29 families were identified in the 25 sampling plots. T. grandis (20.81% and Butea monosperma (9% were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were 1.08 for Shannon diversity index (H´, 0.71 for equitability index (J´ and 5.57 for species richness index (S´, all of which strongly declined with the increase of importance value of the dominant, T. grandis. Measures of soil nutrients indicated low fertility, extreme heterogeneity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil available P, exchangeable K+, Ca2+ (all p values < 0.001 and a negative relationship with N, C, C:N and C:P ratio. The results suggest that soil properties are major factors influencing forest composition and structure within the dry tropical forest in Rajasthan.

Former land-use and tree species affect nitrogen oxide emissions from a tropical dry forest.

Science.gov (United States)

Heather Erickson; Eric A. Davidson; Michael Keller

2002-01-01

Species composition in successional dry forests in the tropics varies widely, but the effect of this variation on biogeochemical processes is not well known. We examined fluxes of N oxides (nitrous and nitric oxide), soil N cycling, and litter chemistry (C/N ratio) in four successional dry forests on similar soils in western Puerto Rico with differing species...

Distribution patterns of the subtropical evergreen broad-leaved forests of southwestern China, as compared with those of the eastern Chinese subtropical regions

Directory of Open Access Journals (Sweden)

Tang, C. Q.

2015-12-01

Full Text Available This paper analyzes the geographic distribution patterns of the subtropical evergreen broad-leaved forests of southwestern China, and compares with other subtropical regions in the east of China in terms of forest types, pertinent species, and spatial distribution along latitudinal, longitudinal and altitudinal gradients. In general, for both the western and the eastern subtropical regions, the evergreen broad-leaved forests are dominated by species of Castanopsis, Lithocarpus, Cyclobalanopsis (Fagaceae, Machilus, Cinnamomum (Lauraceae, Schima (Theaceae, Manglietia, and Michelia, (Magnoliaceae, while in southwestern China there are more diverse forest types including semi-humid, monsoon, mid-montane moist and humid evergreen broad-leaved forests, but only monsoon and humid forests in the east. The Yunnan area has more varied species of Lithocarpus or Cyclobalanopsis or Castanopsis as dominants than does eastern China, where the chief dominant genus is Castanopsis. The upper limits of the evergreen broad-leaved forests are mainly 2400–2800 m in western Yunnan and western Sichuan, much higher than in eastern China (600–1500, but 2500 m in Taiwan. Also discussed are the environmental effects on plant diversity of the evergreen broad-leaved forest ecosystems exemplified by Yunnan and Taiwan.En este trabajo se analiza los patrones de distribución geográfica de los bosques subtropicales perennifolios de hoja ancha del suroeste de china, y se comparan con los de otras regiones subtropicales del este de China en términos de tipología de bosque, especies relevantes, y distribución espacial a lo largo de un gradiente latitudinal, longitudinal y altitudinal. De manera general, los bosques perennifolios de hoja ancha de la regiones subtropicales tanto orientales como occidentales presentan dominancia de especies de Castanopsis, Lithocarpus, Cyclobalanopsis (Fagaceae, Machilus, Cinnamomum (Lauraceae, Schima (Theaceae, Manglietia y Michelia

Functional trait strategies of trees in dry and wet tropical forests are similar but differ in their consequences for succession.

Directory of Open Access Journals (Sweden)

Madelon Lohbeck

Full Text Available Global plant trait studies have revealed fundamental trade-offs in plant resource economics. We evaluated such trait trade-offs during secondary succession in two species-rich tropical ecosystems that contrast in precipitation: dry deciduous and wet evergreen forests of Mexico. Species turnover with succession in dry forest largely relates to increasing water availability and in wet forest to decreasing light availability. We hypothesized that while functional trait trade-offs are similar in the two forest systems, the successful plant strategies in these communities will be different, as contrasting filters affect species turnover. Research was carried out in 15 dry secondary forest sites (5-63 years after abandonment and in 17 wet secondary forest sites (<1-25 years after abandonment. We used 11 functional traits measured on 132 species to make species-trait PCA biplots for dry and wet forest and compare trait trade-offs. We evaluated whether multivariate plant strategies changed during succession, by calculating a 'Community-Weighted Mean' plant strategy, based on species scores on the first two PCA-axes. Trait spectra reflected two main trade-off axes that were similar for dry and wet forest species: acquisitive versus conservative species, and drought avoiding species versus evergreen species with large animal-dispersed seeds. These trait associations were consistent when accounting for evolutionary history. Successional changes in the most successful plant strategies reflected different functional trait spectra depending on the forest type. In dry forest the community changed from having drought avoiding strategies early in succession to increased abundance of evergreen strategies with larger seeds late in succession. In wet forest the community changed from species having mainly acquisitive strategies to those with more conservative strategies during succession. These strategy changes were explained by increasing water availability during

[Soil microbial community structure of two types of forests in the mid-subtropics of China].

Science.gov (United States)

Han, Shi-zhong; Gao, Ren; Li, Ai-ping; Ma, Hong-liang; Yin, Yun-feng; Si, You-tao; Chen, Shi-dong; Zheng, Qun-rui

2015-07-01

Soil microbial community structures were analyzed by biomarker method of phospholipid fatty acid (PLFA) for a natural forest dominated by Castanopsis fabri (CF) and an adjacent plantation of Cunninghamia lanceolata (CL) in the mid-subtropics of China. The results showed that the amounts of total PLFAs, bacterial PLFAs, fungal PLFAs, gram-positive bacterial PLFAs and gramnegative bacterial PLFAs in the 0-10 cm soil layer were higher than in the 10-20 cm soil layer, and each type of PLFAs in CF were higher than in CL. In either soil layer of the two forest types, the contents of bacterial PLFAs were significantly higher than those of fungal PLFAs. In the two forests, the contents of bacterial PLFAs accounted for 44%-52% of total PLFAs, while the contents of fungal PLFAs just accounted for 6%-8%, indicating the bacteria were dominant in the soils of the two vegetation types. Principal component analysis showed that the influence of vegetation types was greater than soil depth on the microbial community structures. Correlation analysis showed that gram-negative bacterial PLFAs, gram-positive bacterial PLFAs and bacterial PLFAs were significantly negatively correlated with pH, positively with water content, and the PLFAs of main soil microorganism groups were significantly positively correlated with soil total nitrogen, organic carbon, C/N and ammonium.

Water relations and gas exchange of fan bryophytes and their adaptations to microhabitats in an Asian subtropical montane cloud forest.

Science.gov (United States)

Song, Liang; Zhang, Yong-Jiang; Chen, Xi; Li, Su; Lu, Hua-Zheng; Wu, Chuan-Sheng; Tan, Zheng-Hong; Liu, Wen-Yao; Shi, Xian-Meng

2015-07-01

Fan life forms are bryophytes with shoots rising from vertical substratum that branch repeatedly in the horizontal plane to form flattened photosynthetic surfaces, which are well suited for intercepting water from moving air. However, detailed water relations, gas exchange characteristics of fan bryophytes and their adaptations to particular microhabitats remain poorly understood. In this study, we measured and analyzed microclimatic data, as well as water release curves, pressure-volume relationships and photosynthetic water and light response curves for three common fan bryophytes in an Asian subtropical montane cloud forest (SMCF). Results demonstrate high relative humidity but low light levels and temperatures in the understory, and a strong effect of fog on water availability for bryophytes in the SMCF. The facts that fan bryophytes in dry air lose most of their free water within 1 h, and a strong dependence of net photosynthesis rates on water content, imply that the transition from a hydrated, photosynthetically active state to a dry, inactive state is rapid. In addition, fan bryophytes developed relatively high cell wall elasticity and the osmoregulatory capacity to tolerate desiccation. These fan bryophytes had low light saturation and compensation point of photosynthesis, indicating shade tolerance. It is likely that fan bryophytes can flourish on tree trunks in the SMCF because of substantial annual precipitation, average relative humidity, and frequent and persistent fog, which can provide continual water sources for them to intercept. Nevertheless, the low water retention capacity and strong dependence of net photosynthesis on water content of fan bryophytes indicate a high risk of unbalanced carbon budget if the frequency and severity of drought increase in the future as predicted.

Light-dependent leaf trait variation in 43 tropical dry forest tree species

NARCIS (Netherlands)

Markesteijn, L.; Poorter, L.; Bongers, F.J.J.M.

2007-01-01

Our understanding of leaf acclimation in relation to irradiance of fully grown or juvenile trees is mainly based on research involving tropical wet forest species. We studied sun¿shade plasticity of 24 leaf traits of 43 tree species in a Bolivian dry deciduous forest. Sampling was confined to small

Quantifying Components of Soil Respiration and Their Response to Abiotic Factors in Two Typical Subtropical Forest Stands, Southwest China

Science.gov (United States)

Yu, Lei; Wang, Yujie; Wang, Yunqi; Sun, Suqi; Liu, Liziyuan

2015-01-01

Separating the components of soil respiration and understanding the roles of abiotic factors at a temporal scale among different forest types are critical issues in forest ecosystem carbon cycling. This study quantified the proportions of autotrophic (R A) and heterotrophic (R H) in total soil (R T) respiration using trenching and litter removal. Field studies were conducted in two typical subtropical forest stands (broadleaf and needle leaf mixed forest; bamboo forest) at Jinyun Mountain, near the Three Georges Reservoir in southwest China, during the growing season (Apr.–Sep.) from 2010 to 2012. The effects of air temperature (AT), soil temperature (ST) and soil moisture (SM) at 6cm depth, solar radiation (SR), pH on components of soil respiration were analyzed. Results show that: 1) SR, AT, and ST exhibited a similar temporal trend. The observed abiotic factors showed slight interannual variability for the two forest stands. 2) The contributions of R H and R A to R T for broadleaf and needle leaf mixed forest were 73.25% and 26.75%, respectively, while those for bamboo forest were 89.02% and 10.98%, respectively; soil respiration peaked from June to July. In both stands, CO2 released from the decomposition of soil organic matter (SOM), the strongest contributor to R T, accounted for over 63% of R H. 3) AT and ST were significantly positively correlated with R T and its components (psoil respiration. 4) Components of soil respiration were significantly different between two forest stands (psoil respiration and its components. PMID:25680112

Deposition to forests in Europe: most important factors influencing dry deposition and models used for generalisation

International Nuclear Information System (INIS)

Erisman, Jan Willem; Draaijers, Geert

2003-01-01

The influence of forest characteristics on deposition can be modelled reasonably well; forest edge effects and dynamical processes are still uncertain. - Dry deposition of gases and particles to forests is influenced by factors influencing the turbulent transport, such as wind speed, tree height, canopy closure, LAI, etc. as well as by factors influencing surface condition, such as precipitation, relative humidity, global radiation, etc. In this paper, an overview of these factors is given and it is shown which are the most important determining temporal and spatial variation of dry deposition of sodium and sulphur. Furthermore, it is evaluated how well current deposition models are able to describe the temporal and spatial variation in dry deposition. It is concluded that the temporal variation is not modelled well enough, because of limited surface-wetness exchange parameterisations. The influence of forest characteristics are modelled reasonably well, provided enough data describing the forests and the spatial variation in concentration is available. For Europe these data are not available. The means to decrease the atmospheric deposition through forest management is discussed

Species composition and community structure of subtropical forest stands in western himalayan foothills of kashmir

International Nuclear Information System (INIS)

Shaheen, H.; Malik, N. M.; Dar, M. E. U. I.

2015-01-01

Lesser Himalayan subtropical forests have unique species composition due to diverse climatic and topographic factors which create numerous microhabitats. Phytosociological characteristics, structural attributes and biological spectrum of plant communities in the forests of Himalayan foothills in Kashmir were analyzed. A total of 65 species belonging to 26 plant families were recorded constituting 6 plant communities. Average value of diversity recorded for the communities was 2.44; species richness 4.01; whereas evenness was found to be 0.48. The species data indicated random distribution of species with a hump shaped diversity pattern directly correlated with increasing altitude. Themeda anathera was the dominant species with an importance value percentage of 14.7 percentage followed by Pinus roxburghii (9.6 percentage), Mallotus philippenensis (5.2 percentage), Malvastrum coromandelianum (5.1 percentage), Acacia modesta (5 percentage), Olea ferruginea (3.8 percentage) and Oxalis corniculata (3.2 percentage). Vegetation was dominated by Therophytes (30 percentage) and megaphanerophytes (23.3) with dominant leaf spectrum as leptophylls (31.6 percentage). Thirty seven percent plants had medicinal values followed by 31 percentage having fodder values where as 12 percentage used as fuel. Principal component analyses and cluster analyses revealed the association of dominant species with specific sites due to prevailing environmental conditions. The distribution of species in ordination diagrams indicated a continuous change in species composition along the altitudinal gradient. Key stone tree species were subject to immense tree felling resulting in deteriorating changes in forest structure. Visual indicators showed over grazing at all the studied sites evident from the dominance of unpalatable species. Local forest stands demand immediate attention of policy makers as well as forest management so that local diversity and floristic richness could be conserved and

Phytophthora pseudopolonica sp. nov., a new species recovered from stream water in subtropical forests of China.

Science.gov (United States)

Li, Wen-Wen; Zhao, Wen-Xia; Huai, Wen-Xia

2017-09-01

A new species of the genus Phytophthora was isolated from stream water in the subtropical forests of China during a survey of forest Phytophthora from 2011 to 2013. This new species is formally described here and named Phytophthora pseudopolonica sp. nov. This new homothallic species is distinct from other known Phytophthora species in morphology and produces nonpapillate and noncaducous sporangia with internal proliferation. Spherical hyphal swellings and thin-walled chlamydospores are abundant when the species is kept in sterile water. The P. pseudopolonica sp. nov. forms smooth oogonia with paragynous and sometimes amphigynous antheridia. The optimum growth temperature of the species is 30 °C in V8-juice agar with β-sitosterol, yet it barely grows at 5 °C and 35 °C. Based on sequences of the internal transcribed spacer and the combined β-tubulin and elongation factor 1α gene sequence data, isolates of the new species cluster together into a single branch and are close to Phytophthora polonicabelonging to clade 9.

Radiation budget changes with dry forest clearing in temperate Argentina.

Science.gov (United States)

Houspanossian, Javier; Nosetto, Marcelo; Jobbágy, Esteban G

2013-04-01

Land cover changes may affect climate and the energy balance of the Earth through their influence on the greenhouse gas composition of the atmosphere (biogeochemical effects) but also through shifts in the physical properties of the land surface (biophysical effects). We explored how the radiation budget changes following the replacement of temperate dry forests by crops in central semiarid Argentina and quantified the biophysical radiative forcing of this transformation. For this purpose, we computed the albedo and surface temperature for a 7-year period (2003-2009) from MODIS imagery at 70 paired sites occupied by native forests and crops and calculated the radiation budget at the tropopause and surface levels using a columnar radiation model parameterized with satellite data. Mean annual black-sky albedo and diurnal surface temperature were 50% and 2.5 °C higher in croplands than in dry forests. These contrasts increased the outgoing shortwave energy flux at the top of the atmosphere in croplands by a quarter (58.4 vs. 45.9 W m(-2) ) which, together with a slight increase in the outgoing longwave flux, yielded a net cooling of -14 W m(-2) . This biophysical cooling effect would be equivalent to a reduction in atmospheric CO2 of 22 Mg C ha(-1) , which involves approximately a quarter to a half of the typical carbon emissions that accompany deforestation in these ecosystems. We showed that the replacement of dry forests by crops in central Argentina has strong biophysical effects on the energy budget which could counterbalance the biogeochemical effects of deforestation. Underestimating or ignoring these biophysical consequences of land-use changes on climate will certainly curtail the effectiveness of many warming mitigation actions, particularly in semiarid regions where high radiation load and smaller active carbon pools would increase the relative importance of biophysical forcing. © 2012 Blackwell Publishing Ltd.

Phylogenetic turnover during subtropical forest succession across environmental and phylogenetic scales.

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Purschke, Oliver; Michalski, Stefan G; Bruelheide, Helge; Durka, Walter

2017-12-01

Although spatial and temporal patterns of phylogenetic community structure during succession are inherently interlinked and assembly processes vary with environmental and phylogenetic scales, successional studies of community assembly have yet to integrate spatial and temporal components of community structure, while accounting for scaling issues. To gain insight into the processes that generate biodiversity after disturbance, we combine analyses of spatial and temporal phylogenetic turnover across phylogenetic scales, accounting for covariation with environmental differences. We compared phylogenetic turnover, at the species- and individual-level, within and between five successional stages, representing woody plant communities in a subtropical forest chronosequence. We decomposed turnover at different phylogenetic depths and assessed its covariation with between-plot abiotic differences. Phylogenetic turnover between stages was low relative to species turnover and was not explained by abiotic differences. However, within the late-successional stages, there was high presence-/absence-based turnover (clustering) that occurred deep in the phylogeny and covaried with environmental differentiation. Our results support a deterministic model of community assembly where (i) phylogenetic composition is constrained through successional time, but (ii) toward late succession, species sorting into preferred habitats according to niche traits that are conserved deep in phylogeny, becomes increasingly important.

Balancing forest-regeneration probabilities and maintenance costs in dry grasslands of high conservation priority

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Bolliger, Janine; Edwards, Thomas C.; Eggenberg, Stefan; Ismail, Sascha; Seidl, Irmi; Kienast, Felix

2011-01-01

Abandonment of agricultural land has resulted in forest regeneration in species-rich dry grasslands across European mountain regions and threatens conservation efforts in this vegetation type. To support national conservation strategies, we used a site-selection algorithm (MARXAN) to find optimum sets of floristic regions (reporting units) that contain grasslands of high conservation priority. We sought optimum sets that would accommodate 136 important dry-grassland species and that would minimize forest regeneration and costs of management needed to forestall predicted forest regeneration. We did not consider other conservation elements of dry grasslands, such as animal species richness, cultural heritage, and changes due to climate change. Optimal sets that included 95–100% of the dry grassland species encompassed an average of 56–59 floristic regions (standard deviation, SD 5). This is about 15% of approximately 400 floristic regions that contain dry-grassland sites and translates to 4800–5300 ha of dry grassland out of a total of approximately 23,000 ha for the entire study area. Projected costs to manage the grasslands in these optimum sets ranged from CHF (Swiss francs) 5.2 to 6.0 million/year. This is only 15–20% of the current total estimated cost of approximately CHF30–45 million/year required if all dry grasslands were to be protected. The grasslands of the optimal sets may be viewed as core sites in a national conservation strategy.

Global-Scale Patterns of Forest Fragmentation

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Kurt Riitters

2000-12-01

Full Text Available We report an analysis of forest fragmentation based on 1-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km 2 (9 x 9 pixels, "small" scale to 59,049 km 2 (243 x 243 pixels, "large" scale were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe-Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types and Europe-Asia (four types, in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 forest types, of which only a few would be considered as "naturally patchy" (e.g., dry woodland. The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf.

Global-scale patterns of forest fragmentation

Science.gov (United States)

Riitters, K.; Wickham, J.; O'Neill, R.; Jones, B.; Smith, E.

2000-01-01

We report an analysis of forest fragmentation based on 1-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km 2 (9 ?? 9 pixels, "small" scale) to 59,049 km 2 (243 ?? 243 pixels, "large" scale) were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe - Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types) and Europe - Asia (four types), in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 forest types, of which only a few would be considered as "naturally patchy" (e.g., dry woodland). The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf. Copyright ?? 2000 by The Resilience Alliance.

Climatic Characteristics of the Subtropical Mountainous Cloud Forest at the Yuanyang Lake Long-Term Ecological Research Site, Taiwan

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I-Ling Lai

2006-12-01

Full Text Available To better understand the climatic characteristics in a subtropical mountainous cloud forest at the Yuanyang Lake long-term ecological research site, weather data collected from January 1994 to December 2004 were analyzed in the present study. The obvious seasonal changes in climatic factors were observed at this site. The annual mean air temperature was 12.7°C. The lowest temperature was recorded in February (monthly mean 5.9°C, and the highest one was taken in July (monthly mean 18.1°C. Winter featured light rain with a prolonged occurrence of fog, resulting in a large reduction of radiation. In summer, fog occurred once in the early morning and the other time from afternoon to evening. The latter one was associated with the wind direction changes and usually accompanied with short moderate to heavy convective rain. Consequently the photosynthetic photon flux density (PPFD was high in the morning but reduced drastically in the afternoon. Typhoons occurred in the summer had contributed to 37% of the annual rainfall, usually resulting in torrential rain events and sharp increases in the water level of this lake. As a matter of fact, perhumid environment of this site was attributed to abundant rainfall (mean annual precipitation 3396 mm and high frequency (up to 40% of foggy time. Such conditions would reduce the intensity of solar radiation and PPFD. The average annual solar radiation at the site was 2475 MJ m-2, and annual PPFD was 5713 mol m-2. The average degree of reduction of PPFD under foggy condition was up to 88%. Such climatic characteristics are suggested to constrain the growth of plants and play an important role in competition among plant species in this cloud forest. It is considered that the distinct seasonal fluctuation in environmental factors, perhumid and dim light conditions are the most distinguished characteristics of this subtropical mountainous cloud forest ecosystem.

Monitoring Temporal Variation to Assess Changes in the Structure of Subtropical Atlantic Forest Butterfly Communities.

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Iserhard, Cristiano Agra; Romanowski, Helena Piccoli; Richter, Aline; Mendonça, Milton de Souza

2017-08-01

The study of fauna through long-term surveys is important in unveiling how temporal patterns shape the structure of communities in tropical habitats. The butterfly assemblage of the subtropical Atlantic Forest may be considered highly diverse and shows changes in diversity and composition over time, highlighting the importance of long-term inventories. This work assessed temporal diversity patterns in the distribution and composition of butterfly assemblages in an Atlantic Forest site in southern Brazil using combined data from three years of standardized sampling with entomological nets, increasing the knowledge on this group in the Neotropics for monitoring and conservation. The butterfly fauna was analyzed in terms of richness, abundance, and composition. The inventories reached 401 species, with 14,442 butterfly individuals sampled. All the diversity parameters evaluated show significant differences between the first year of sampling compared to the second and third years. The latter had higher values of richness and abundance, followed by the first and second years. Hesperiidae was the richest family, followed by Nymphalidae and Lycaenidae, indicating a good representation of the assemblage as a whole. The results of this work are important for developing conservation programs in the Atlantic Forest and other forested environments in the neotropics, especially concerning reliable diversity assessments for the monitoring and management of protected areas. Decision making and public policy might also benefit from knowledge on temporal patterns of diversity regarding the maintenance of native habitats and integrity of biomes and their associated fauna. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Restoring and managing low-severity fire in dry-forest landscapes of the western USA.

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Baker, William L

2017-01-01

Low-severity fires that killed few canopy trees played a significant historical role in dry forests of the western USA and warrant restoration and management, but historical rates of burning remain uncertain. Past reconstructions focused on on dating fire years, not measuring historical rates of burning. Past statistics, including mean composite fire interval (mean CFI) and individual-tree fire interval (mean ITFI) have biases and inaccuracies if used as estimators of rates. In this study, I used regression, with a calibration dataset of 96 cases, to test whether these statistics could accurately predict two equivalent historical rates, population mean fire interval (PMFI) and fire rotation (FR). The best model, using Weibull mean ITFI, had low prediction error and R2adj = 0.972. I used this model to predict historical PMFI/FR at 252 sites spanning dry forests. Historical PMFI/FR for a pool of 342 calibration and predicted sites had a mean of 39 years and median of 30 years. Short ( 55 years) mean PMFI/FRs were mainly from northern New Mexico to South Dakota. Mountain sites often had a large range in PMFI/FR. Nearly all 342 estimates are for old forests with a history of primarily low-severity fire, found across only about 34% of historical dry-forest area. Frequent fire (PMFI/FR dry-forest area, with 86% having multidecadal rates of low-severity fire. Historical fuels (e.g., understory shrubs and small trees) could fully recover between multidecadal fires, allowing some denser forests and some ecosystem processes and wildlife habitat to be less limited by fire. Lower historical rates mean less restoration treatment is needed before beginning managed fire for resource benefits, where feasible. Mimicking patterns of variability in historical low-severity fire regimes would likely benefit biological diversity and ecosystem functioning.

Strong spatial structure, Pliocene diversification and cryptic diversity in the Neotropical dry forest spider Sicarius cariri.

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Magalhaes, Ivan L F; Oliveira, Ubirajara; Santos, Fabrício R; Vidigal, Teofânia H D A; Brescovit, Antonio D; Santos, Adalberto J

2014-11-01

The Brazilian Caatinga is part of the seasonally dry tropical forests, a vegetation type disjunctly distributed throughout the Neotropics. It has been suggested that during Pleistocene glacial periods, these dry forests had a continuous distribution, so that these climatic shifts may have acted as important driving forces of the Caatinga biota diversification. To address how these events affected the distribution of a dry forest species, we chose Sicarius cariri, a spider endemic to the Caatinga, as a model. We studied the phylogeography of one mitochondrial and one nuclear gene and reconstructed the paleodistribution of the species using modelling algorithms. We found two allopatric and deeply divergent clades within S. cariri, suggesting that this species as currently recognized might consist of more than one independently evolving lineage. Sicarius cariri populations are highly structured, with low haplotype sharing among localities, high fixation index and isolation by distance. Models of paleodistribution, Bayesian reconstructions and coalescent simulations suggest that this species experienced a reduction in its population size during glacial periods, rather than the expansion expected by previous hypotheses on the paleodistribution of dry forest taxa. In addition to that, major splits of intraspecific lineages of S. cariri took place in the Pliocene. Taken together, these results indicate S. cariri has a complex diversification history dating back to the Tertiary, suggesting the history of dry forest taxa may be significantly older than previously thought. © 2014 John Wiley & Sons Ltd.

Distribution and elevated soil pools of mercury in an acidic subtropical forest of southwestern China

International Nuclear Information System (INIS)

Zhou, Jun; Wang, Zhangwei; Zhang, Xiaoshan; Chen, Jian

2015-01-01

Tieshanping catchment in southwest China was supposed to a large pool of atmospheric mercury. This work was aimed to examine THg (total mercury) concentrations, pools and influence factors in the acidic forest. THg concentrations were highly elevated in the study area, which was significantly depended on TOM (total organic matter) concentrations and altitudinal elevation, whereas negatively correlated with soil pH. The pools of mercury accumulated in soils were correlated strongly with the stocks of TOM and altitude, ranged from 5.9 to 32 mg m −2 and averaged 14.5 mg m −2 , indicating that the acidic forest was a great sink of atmospheric mercury in southwest China. THg concentrations in stream waters decreased with altitude increasing and regression analyses showed that soil/air exchange flux would be increased with the decrease of altitude. Present results suggest that elevation increasing decreases THg losses as low THg concentrations in runoffs and volatilization from soils. - Highlights: • Soil THg pools and influence factors were studied at an acidic catchment in southwestern China. • THg concentrations was increased significantly with TOM concentrations and altitude increasing, decreased with pH. • THg pools in soils were highly elevated and deepened on TOM pools and altitude. • Difference in THg output by volatilization and runoff was a major reason for THg distribution at different altitudes. - Mercury pools increased with altitude increasing as mercury lost more at low elevation area in acidic subtropical forest

Wood Decomposition of Cyrilla racemiflora (Cyrillaceae) in Puerto Rican Dry and Wet Forests: A 13-year Case Study.

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Juan A. Torres; Grizelle Gonzalez

2005-01-01

We studied the decomposition of Cyrilla racemiflora logs over a 13-yr period in tropical dry and wet forests in Puerto Rico. The mean mass loss, ratio of soft to hard wood, nutrient concentrations, and the diversity of wood-inhabiting organisms were greater in logs decomposing in the dry forest than in the wet forest. Termites were also more abundant in the logs...

Modeling carbon stocks in a secondary tropical dry forest in the Yucatan Peninsula, Mexico

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Zhaohua Dai; Richard A. Birdsey; Kristofer D. Johnson; Juan Manuel Dupuy; Jose Luis Hernandez-Stefanoni; Karen. Richardson

2014-01-01

The carbon balance of secondary dry tropical forests of Mexico’s Yucatan Peninsula is sensitive to human and natural disturbances and climate change. The spatially explicit process model Forest-DeNitrification-DeComposition (DNDC) was used to estimate forest carbon dynamics in this region, including the effects of disturbance on carbon stocks. Model evaluation using...

Response of epiphytic bryophytes to simulated N deposition in a subtropical montane cloud forest in southwestern China.

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Song, Liang; Liu, Wen-Yao; Ma, Wen-Zhang; Qi, Jin-Hua

2012-11-01

A field manipulation experiment was conducted in a subtropical montane cloud forest in southwestern China to determine the possible responses of epiphytic bryophytes to increasing nitrogen (N) deposition from community to physiology level, and to find sensitive epiphytic bryophytes that may be used as indicators for assessing the degree of N pollution. N addition had significantly negative effects on species richness and cover of the epiphytic bryophyte community. Harmful effects of high N loads were recorded for chlorophyll, growth, and vitality of the species tested. The decline of some epiphytic bryophytes may result from detrimental effects on degradation to photosynthetic pigments. Bazzania himalayana (Mitt.) Schiffn., Bazzania ovistipula (Steph.) Mizut., and Homaliodendron flabellatum (Sm.) Fleisch. are candidates in atmospheric nitrogen monitoring. Epiphytic bryophytes in the montane cloud forest are very sensitive to increasing N deposition and often difficult to recover once they have been destroyed, providing early detection of enhanced N pollution for trees or even the whole forest ecosystem. The inference that increasing N pollution may lead to loss of biodiversity is a concern to the developing economy in western China, and should alert the government to the adverse impacts caused by increased industrial pollution during the process of China's West Development.

ALOS PALSAR Applications in the Tropics and Subtropics: Characterisation, Mapping and Detecting Change in Forests and Coastal Wetlands

Science.gov (United States)

Lucas, Richard; Carreiras, Joao; Proisy, Christophe; Buniting, Peter

2008-11-01

Research undertaken as part of the Japanese Space Exploration Agency (JAXA) Principal Investigator (PI) and Kyoto and Carbon (K&C) programs has focused on the regional characterization (growth stage as a function of biomass and structure) and mapping of forests across northern Australia and mangroves (including wetlands) in selected tropical regions (northern Australia, Belize, French Guiana and Brazil) using Advanced Land Observing Satellite (ALOS) Phased Array L-band SAR (PALSAR) data, either singularly or in conjunction with other remote sensing (e.g., optical) data. Comparison against existing baseline datasets has allowed these data to be used for detecting change in these tropical and subtropical regions. Regional products (e.g., forest growth stage, mangrove/wetland extent and change) generated from the K&C dual polarimetric strip data are anticipated to benefit conservation of these ecosystems and allow better assessments of carbon stocks and changes in these as a function of natural and anthropogenic drivers, thereby supporting key international conventions.

Phosphatase activity in relation to key litter and soil properties in mature subtropical forests in China.

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Hou, Enqing; Chen, Chengrong; Wen, Dazhi; Liu, Xian

2015-05-15

Phosphatase-mediated phosphorus (P) mineralization is one of the critical processes in biogeochemical cycling of P and determines soil P availability in forest ecosystems; however, the regulation of soil phosphatase activity remains elusive. This study investigated the potential extracellular activities of acid phosphomonoesterase (AcPME) and phosphodiesterase (PDE) and how they were related to key edaphic properties in the L horizon (undecomposed litter) and F/H horizon (fermented and humified litter) and the underlying mineral soil at the 0-15cm depth in eight mature subtropical forests in China. AcPME activity decreased significantly in the order of F/H horizon>L horizon>mineral soil horizon, while the order for PDE activity was L horizon=F/H horizon>mineral soil horizon. AcPME (X axis) and PDE (Y axis) activities were positively correlated in all horizons with significantly higher slope in the L and F/H horizons than in the mineral soil horizon. Both AcPME and PDE activities were positively related to microbial biomass C, moisture content and water-holding capacity in the L horizon, and were positively related to soil C:P, N:P and C:N ratios and fine root (diameter≤2mm) biomass in the mineral soil horizon. Both enzyme activities were also interactively affected by forest and horizon, partly due to the interactive effect of forest and horizon on microbial biomass. Our results suggest that modulator(s) of the potential extracellular activity of phosphatases vary with horizon, depending on the relative C, P and water availability of the horizon. Copyright © 2015 Elsevier B.V. All rights reserved.

Manual of design and installation of Forest Service water spray dry kiln

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L.V. Teesdale

1920-01-01

The best thing that can be said of any dry kiln is that when it is run by a properly informed operator the temperature, humidity, and circulation are constant and uniform. In an endeavor to produce a kiln in which each of these could be regulated independently of the others, the Forest Products Laboratory designed and developed the "Forest Service Humidity...

Measurement of the dry deposition flux of NH3 on to coniferous forest

NARCIS (Netherlands)

Duyzer, J.H.; Verhagen, H.L.M.; Weststrate, J.H.; Bosveld, F.C.

1992-01-01

The dry deposition flux of NH3 to coniferous forest was determined by the micrometeorological gradient method using a 36m high tower. Aerodynamic characteristics of the site were studied, using a second tower erected in the forest 100m from the first. Fluxes and gradients of heat and momentum

Increases in soil water content after the mortality of non-native trees in oceanic island forest ecosystems are due to reduced water loss during dry periods.

Science.gov (United States)

Hata, Kenji; Kawakami, Kazuto; Kachi, Naoki

2016-03-01

The control of dominant, non-native trees can alter the water balance of soils in forest ecosystems via hydrological processes, which results in changes in soil water environments. To test this idea, we evaluated the effects of the mortality of an invasive tree, Casuarina equisetifolia Forst., on the water content of surface soils on the Ogasawara Islands, subtropical islands in the northwestern Pacific Ocean, using a manipulative herbicide experiment. Temporal changes in volumetric water content of surface soils at 6 cm depth at sites where all trees of C. equisetifolia were killed by herbicide were compared with those of adjacent control sites before and after their mortality with consideration of the amount of precipitation. In addition, the rate of decrease in the soil water content during dry periods and the rate of increase in the soil water content during rainfall periods were compared between herbicide and control sites. Soil water content at sites treated with herbicide was significantly higher after treatment than soil water content at control sites during the same period. Differences between initial and minimum values of soil water content at the herbicide sites during the drying events were significantly lower than the corresponding differences in the control quadrats. During rainfall periods, both initial and maximum values of soil water contents in the herbicided quadrats were higher, and differences between the maximum and initial values did not differ between the herbicided and control quadrats. Our results indicated that the mortality of non-native trees from forest ecosystems increased water content of surface soils, due primarily to a slower rate of decrease in soil water content during dry periods. Copyright © 2015 Elsevier B.V. All rights reserved.

Simulating fuel treatment effects in dry forests of the western United States: testing the principles of a fire-safe forest

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Morris C. Johnson; Maureen C Kennedy; David L. Peterson

2011-01-01

We used the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) to simulate fuel treatment effects on stands in low- to midelevation dry forests (e.g., ponderosa pine (Pinus ponderosa Dougl. ex. P. & C. Laws.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) of the western United States. We...

Long-term persistence and fire resilience of oak shrubfields in dry conifer forests of northern New Mexico

Science.gov (United States)

Guiterman, Christopher H.; Margolis, Ellis; Allen, Craig D.; Falk, Donald A.; Swetnam, Thomas W.

2017-01-01

Extensive high-severity fires are creating large shrubfields in many dry conifer forests of the interior western USA, raising concerns about forest-to-shrub conversion. This study evaluates the role of disturbance in shrubfield formation, maintenance and succession in the Jemez Mountains, New Mexico. We compared the environmental conditions of extant Gambel oak (Quercus gambelii) shrubfields with adjoining dry conifer forests and used dendroecological methods to determine the multi-century fire history and successional dynamics of five of the largest shrubfields (76–340 ha). Across the study area, 349 shrubfields (5–368 ha) occur in similar topographic and climate settings as dry conifer forests. This suggests disturbance, rather than other biophysical factors, may explain their origins and persistence. Gambel oak ages and tree-ring fire scars in our sampled shrubfields indicate they historically (1664–1899) burned concurrently with adjoining conifer forests and have persisted for over 115 years in the absence of fire. Aerial imagery from 1935 confirmed almost no change in sampled shrubfield patch sizes or boundaries over the twentieth century. The largest shrubfield we identified is less than 4% the size of the largest conifer-depleted and substantially shrub-dominated area recently formed in the Jemez following extensive high-severity wildfires, indicating considerable departure from historical patterns and processes. Projected hotter droughts and increasingly large high-severity fires could trigger more forest-to-shrub transitions and maintain existing shrubfields, inhibiting conifer forest recovery. Restoration of surface fire regimes and associated historical forest structures likely could reduce the rate and patch size of dry conifer forests being converted to shrubfields.

Light Diffusion in the Tropical Dry Forest of Costa Rica

Science.gov (United States)

Calvo-Rodriguez, S.; Sanchez-Azofeifa, G. A.

2016-06-01

Leaf Area Index (LAI) has been defined as the total leaf area (one-sided) in relation to the ground. LAI has an impact on tree growth and recruitment through the interception of light, which in turn affects primary productivity. Even though many instruments exist for estimating LAI from ground, they are often laborious and costly to run continuously. Measurements of LAI from the field using traditional sensors (e.g., LAI-2000) require multiple visits to the field under very specific sky conditions, making them unsuitable to operate in inaccessible areas and forests with dense vegetation, as well as areas where persistent sunny conditions are the norm like tropical dry forests. With this context, we proposed a methodology to characterize light diffusion based on NDVI and LAI measurements taken from the field in two successional stages in the tropical dry forest of Santa Rosa National Park in Costa Rica. We estimate a "K" coefficient to characterize light diffusion by the canopy, based on field NDVI measurements derived from optical phenology instruments and MODIS NDVI. From the coefficients determined, we estimated LAI values and compared them with ground measurements of LAI. In both successional stages ground measurements of LAI had no significant difference to the tower-derived LAI and the estimated LAI from MODIS NDVI.

[Biomass allometric equations of nine common tree species in an evergreen broadleaved forest of subtropical China].

Science.gov (United States)

Zuo, Shu-di; Ren, Yin; Weng, Xian; Ding, Hong-feng; Luo, Yun-jian

2015-02-01

Biomass allometric equation (BAE) considered as a simple and reliable method in the estimation of forest biomass and carbon was used widely. In China, numerous studies focused on the BAEs for coniferous forest and pure broadleaved forest, and generalized BAEs were frequently used to estimate the biomass and carbon of mixed broadleaved forest, although they could induce large uncertainty in the estimates. In this study, we developed the species-specific and generalized BAEs using biomass measurement for 9 common broadleaved trees (Castanopsis fargesii, C. lamontii, C. tibetana, Lithocarpus glaber, Sloanea sinensis, Daphniphyllum oldhami, Alniphyllum fortunei, Manglietia yuyuanensis, and Engelhardtia fenzlii) of subtropical evergreen broadleaved forest, and compared differences in species-specific and generalized BAEs. The results showed that D (diameter at breast height) was a better independent variable in estimating the biomass of branch, leaf, root, aboveground section and total tree than a combined variable (D2 H) of D and H (tree height) , but D2H was better than D in estimating stem biomass. R2 (coefficient of determination) values of BAEs for 6 species decreased when adding H as the second independent variable into D- only BAEs, where R2 value for S. sinensis decreased by 5.6%. Compared with generalized D- and D2H-based BAEs, standard errors of estimate (SEE) of BAEs for 8 tree species decreased, and similar decreasing trend was observed for different components, where SEEs of the branch decreased by 13.0% and 20.3%. Therefore, the biomass carbon storage and its dynamic estimates were influenced largely by tree species and model types. In order to improve the accuracy of the estimates of biomass and carbon, we should consider the differences in tree species and model types.

Coalescent Simulation and Paleodistribution Modeling for Tabebuia rosealba Do Not Support South American Dry Forest Refugia Hypothesis.

Directory of Open Access Journals (Sweden)

Warita Alves de Melo

Full Text Available Studies based on contemporary plant occurrences and pollen fossil records have proposed that the current disjunct distribution of seasonally dry tropical forests (SDTFs across South America is the result of fragmentation of a formerly widespread and continuously distributed dry forest during the arid climatic conditions associated with the Last Glacial Maximum (LGM, which is known as the modern-day dry forest refugia hypothesis. We studied the demographic history of Tabebuia rosealba (Bignoniaceae to understand the disjunct geographic distribution of South American SDTFs based on statistical phylogeography and ecological niche modeling (ENM. We specifically tested the dry forest refugia hypothesis; i.e., if the multiple and isolated patches of SDTFs are current climatic relicts of a widespread and continuously distributed dry forest during the LGM. We sampled 235 individuals across 18 populations in Central Brazil and analyzed the polymorphisms at chloroplast (trnS-trnG, psbA-trnH and ycf6-trnC intergenic spacers and nuclear (ITS nrDNA genomes. We performed coalescence simulations of alternative hypotheses under demographic expectations from two a priori biogeographic hypotheses (1. the Pleistocene Arc hypothesis and, 2. a range shift to Amazon Basin and other two demographic expectances predicted by ENMs (3. expansion throughout the Neotropical South America, including Amazon Basin, and 4. retraction during the LGM. Phylogenetic analyses based on median-joining network showed haplotype sharing among populations with evidence of incomplete lineage sorting. Coalescent analyses showed smaller effective population sizes for T. roseoalba during the LGM compared to the present-day. Simulations and ENM also showed that its current spatial pattern of genetic diversity is most likely due to a scenario of range retraction during the LGM instead of the fragmentation from a once extensive and largely contiguous SDTF across South America, not supporting the

Coalescent Simulation and Paleodistribution Modeling for Tabebuia rosealba Do Not Support South American Dry Forest Refugia Hypothesis.

Science.gov (United States)

de Melo, Warita Alves; Lima-Ribeiro, Matheus S; Terribile, Levi Carina; Collevatti, Rosane G

2016-01-01

Studies based on contemporary plant occurrences and pollen fossil records have proposed that the current disjunct distribution of seasonally dry tropical forests (SDTFs) across South America is the result of fragmentation of a formerly widespread and continuously distributed dry forest during the arid climatic conditions associated with the Last Glacial Maximum (LGM), which is known as the modern-day dry forest refugia hypothesis. We studied the demographic history of Tabebuia rosealba (Bignoniaceae) to understand the disjunct geographic distribution of South American SDTFs based on statistical phylogeography and ecological niche modeling (ENM). We specifically tested the dry forest refugia hypothesis; i.e., if the multiple and isolated patches of SDTFs are current climatic relicts of a widespread and continuously distributed dry forest during the LGM. We sampled 235 individuals across 18 populations in Central Brazil and analyzed the polymorphisms at chloroplast (trnS-trnG, psbA-trnH and ycf6-trnC intergenic spacers) and nuclear (ITS nrDNA) genomes. We performed coalescence simulations of alternative hypotheses under demographic expectations from two a priori biogeographic hypotheses (1. the Pleistocene Arc hypothesis and, 2. a range shift to Amazon Basin) and other two demographic expectances predicted by ENMs (3. expansion throughout the Neotropical South America, including Amazon Basin, and 4. retraction during the LGM). Phylogenetic analyses based on median-joining network showed haplotype sharing among populations with evidence of incomplete lineage sorting. Coalescent analyses showed smaller effective population sizes for T. roseoalba during the LGM compared to the present-day. Simulations and ENM also showed that its current spatial pattern of genetic diversity is most likely due to a scenario of range retraction during the LGM instead of the fragmentation from a once extensive and largely contiguous SDTF across South America, not supporting the South

[Floristic composition and distribution of the Andean subtropical riparian forests of Lules River, Tucuman, Argentina].

Science.gov (United States)

Sirombra, Martín G; Mesa, Leticia M

2010-03-01

We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem.

Gaseous elemental mercury (GEM) fluxes over canopy of two typical subtropical forests in south China

Science.gov (United States)

Yu, Qian; Luo, Yao; Wang, Shuxiao; Wang, Zhiqi; Hao, Jiming; Duan, Lei

2018-01-01

Mercury (Hg) exchange between forests and the atmosphere plays an important role in global Hg cycling. The present estimate of global emission of Hg from natural source has large uncertainty, partly due to the lack of chronical and valid field data, particularly for terrestrial surfaces in China, the most important contributor to global atmospheric Hg. In this study, the micrometeorological method (MM) was used to continuously observe gaseous elemental mercury (GEM) fluxes over forest canopy at a mildly polluted site (Qianyanzhou, QYZ) and a moderately polluted site (Huitong, HT, near a large Hg mine) in subtropical south China for a full year from January to December in 2014. The GEM flux measurements over forest canopy in QYZ and HT showed net emission with annual average values of 6.67 and 0.30 ng m-2 h-1, respectively. Daily variations of GEM fluxes showed an increasing emission with the increasing air temperature and solar radiation in the daytime to a peak at 13:00, and decreasing emission thereafter, even as a GEM sink or balance at night. High temperature and low air Hg concentration resulted in the high Hg emission in summer. Low temperature in winter and Hg absorption by plant in spring resulted in low Hg emission, or even adsorption in the two seasons. GEM fluxes were positively correlated with air temperature, soil temperature, wind speed, and solar radiation, while it is negatively correlated with air humidity and atmospheric GEM concentration. The lower emission fluxes of GEM at the moderately polluted site (HT) when compared with that in the mildly polluted site (QYZ) may result from a much higher adsorption fluxes at night in spite of a similar or higher emission fluxes during daytime. This shows that the higher atmospheric GEM concentration at HT restricted the forest GEM emission. Great attention should be paid to forests as a crucial increasing Hg emission source with the decreasing atmospheric GEM concentration in polluted areas because of Hg

Contrasting regeneration strategies in climax and long-lived pioneer tree species in a subtropical forest.

Directory of Open Access Journals (Sweden)

Haiyang Wang

Full Text Available 1: This study investigated 15 coexisting dominant species in a humid subtropical evergreen broad-leaved forest in southwest China, consisting of long-lived pioneers and climax species occurring in natural and disturbed regimes. The authors hypothesized that there would be non-tradeoff scaling relationships between sprouting and seed size among species, with the aim of uncovering the ecological relationship between plant sprouting and seed characteristics in the two functional groups. 2: The sprouting variations of the species were initially examined using pairwise comparisons between natural and disturbed habitats within and across species and were noted to show a continuum in persistence niches across the forest dominants, which may underlie the maintenance of plant diversity. Second, a significantly positive, rather than tradeoff, relationship between sprout number and seed size across species within each of the two functional groups was observed, and an obvious elevational shift with a common slope among the two groups in their natural habitat was examined. The results indicate the following: 1 the relationship of seed size vs. sprouts in the natural habitat is more likely to be bet-hedging among species within a guild in a forest; 2 climax species tend to choose seeding rather than sprouting regeneration, and vice versa for the long-lived pioneers; and 3 the negative correlation between sprouting and seed dispersal under disturbed conditions may imply a tradeoff between dispersal and persistence in situ during the process of plant regeneration. 3: These findings may be of potential significance for urban greening using native species.

Plant diversity and regeneration in a disturbed isolated dry Afromontane forest in northern Ethiopia

DEFF Research Database (Denmark)

Aynekulu, Ermias; Aerts, Raf; Denich, Manfred

2016-01-01

We studied the diversity, community composition and natural regeneration of woody species in an isolated but relatively large (> 1,000 ha) dry Afromontane forest in northern Ethiopia to assess its importance for regional forest biodiversity conservation. The principal human-induced disturbance...... in biodiversity through local extinction of indigenous tree species. Despite the problems associated with conserving plant species diversity in small and isolated populations, this relic forest is of particular importance for regional conservation of forest biodiversity, as species with high conservation value...

Diameter distribution in a Brazilian tropical dry forest domain: predictions for the stand and species.

Science.gov (United States)

Lima, Robson B DE; Bufalino, Lina; Alves, Francisco T; Silva, José A A DA; Ferreira, Rinaldo L C

2017-01-01

Currently, there is a lack of studies on the correct utilization of continuous distributions for dry tropical forests. Therefore, this work aims to investigate the diameter structure of a brazilian tropical dry forest and to select suitable continuous distributions by means of statistic tools for the stand and the main species. Two subsets were randomly selected from 40 plots. Diameter at base height was obtained. The following functions were tested: log-normal; gamma; Weibull 2P and Burr. The best fits were selected by Akaike's information validation criterion. Overall, the diameter distribution of the dry tropical forest was better described by negative exponential curves and positive skewness. The forest studied showed diameter distributions with decreasing probability for larger trees. This behavior was observed for both the main species and the stand. The generalization of the function fitted for the main species show that the development of individual models is needed. The Burr function showed good flexibility to describe the diameter structure of the stand and the behavior of Mimosa ophthalmocentra and Bauhinia cheilantha species. For Poincianella bracteosa, Aspidosperma pyrifolium and Myracrodum urundeuva better fitting was obtained with the log-normal function.

Estimation of Black Carbon Emissions from Dry Dipterocarp Forest Fires in Thailand

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Ubonwan Chaiyo

2014-12-01

Full Text Available This study focused on the estimation of black carbon emissions from dry dipterocarp forest fires in Thailand. Field experiments were set up at the natural forest, Mae Nam Phachi wildlife sanctuary, Ratchaburi Province, Thailand. The dead leaves were the main component consumed of the surface biomass with coverage higher than 90% in volume and mass. The dead leaves load was 342 ± 190 g∙m−2 and followed by a little mass load of twig, 100 g∙m−2. The chemical analysis of the dead leaves showed that the carbon content in the experimental biomass fuel was 45.81 ± 0.04%. From the field experiments, it was found that 88.38 ± 2.02% of the carbon input was converted to carbon released to the atmosphere, while less than 10% were left in the form of residues, and returned to soil. The quantity of dead leaves consumed to produce each gram of carbon released was 2.40 ± 0.02 gdry biomass burned. From the study, the emissions factor of carbon dioxide, carbon monoxide, particulate matter (PM2.5 and black carbon amounted 1329, 90, 26.19 and 2.83 g∙kg−1dry biomass burned, respectively. In Thailand, the amount of black carbon emissions from dry dipterocarp forest fires amounted 17.43 tonnes∙y−1.

Extending the baseline of tropical dry forest loss in Ghana (1984–2015) reveals drivers of major deforestation inside a protected area

OpenAIRE

Janssen, T; Ametsisi, G; Collins, M; Adu-Bredu, S; Oliveras-Menor, I; Mitchard, ETA; Veenendaal, EM

2017-01-01

Abstract Tropical dry forests experience the highest deforestation rates on Earth, with major implications for the biodiversity of these ecosystems, as well as for its human occupants. Global remote sensing based forest cover data (2000 − 2012) point to the rapid loss of tropical dry forest in South America and Africa, also, if not foremost, inside formally protected areas. Here, we significantly extend the baseline of tropical dry forest loss inside a protected area in Ghana using a generali...

Large-scale carbon stock assessment of woody vegetation in tropical dry deciduous forest of Sathanur reserve forest, Eastern Ghats, India.

Science.gov (United States)

Gandhi, Durai Sanjay; Sundarapandian, Somaiah

2017-04-01

Tropical dry forests are one of the most widely distributed ecosystems in tropics, which remain neglected in research, especially in the Eastern Ghats. Therefore, the present study was aimed to quantify the carbon storage in woody vegetation (trees and lianas) on large scale (30, 1 ha plots) in the dry deciduous forest of Sathanur reserve forest of Eastern Ghats. Biomass of adult (≥10 cm DBH) trees was estimated by species-specific allometric equations using diameter and wood density of species whereas in juvenile tree population and lianas, their respective general allometric equations were used to estimate the biomass. The fractional value 0.4453 was used to convert dry biomass into carbon in woody vegetation of tropical dry forest. The mean aboveground biomass value of juvenile tree population was 1.86 Mg/ha. The aboveground biomass of adult trees ranged from 64.81 to 624.96 Mg/ha with a mean of 245.90 Mg/ha. The mean aboveground biomass value of lianas was 7.98 Mg/ha. The total biomass of woody vegetation (adult trees + juvenile population of trees + lianas) ranged from 85.02 to 723.46 Mg/ha, with a mean value of 295.04 Mg/ha. Total carbon accumulated in woody vegetation in tropical dry deciduous forest ranged from 37.86 to 322.16 Mg/ha with a mean value of 131.38 Mg/ha. Adult trees accumulated 94.81% of woody biomass carbon followed by lianas (3.99%) and juvenile population of trees (1.20%). Albizia amara has the greatest biomass and carbon stock (58.31%) among trees except for two plots (24 and 25) where Chloroxylon swietenia contributed more to biomass and carbon stock. Similarly, Albizia amara (52.4%) showed greater carbon storage in juvenile population of trees followed by Chloroxylon swietenia (21.9%). Pterolobium hexapetalum (38.86%) showed a greater accumulation of carbon in liana species followed by Combretum albidum (33.04%). Even though, all the study plots are located within 10 km radius, they show a significant spatial variation among

Tree diversity in the tropical dry forest of Bannerghatta National Park in Eastern Ghats, Southern India

Directory of Open Access Journals (Sweden)

Gopalakrishna S. Puttakame

2015-12-01

Full Text Available Tree species inventories, particularly of poorly known dry deciduous forests, are needed to protect and restore forests in degraded landscapes. A study of forest stand structure, and species diversity and density of trees with girth at breast height (GBH ≥10 cm was conducted in four management zones of Bannerghatta National Park (BNP in the Eastern Ghats of Southern India. We identified 128 tree species belonging to 45 families in 7.9 hectares. However, 44 species were represented by ≤ 2 individuals. Mean diversity values per site for the dry forest of BNP were: tree composition (23.8 ±7.6, plant density (100.69 ± 40.02, species diversity (2.56 ± 0.44 and species richness (10.48 ± 4.05. Tree diversity was not significantly different (P>0.05 across the four management zones in the park. However, the number of tree species identified significantly (P<0.05 increased with increasing number of sampling sites, but majority of the species were captured. Similarly, there were significant variations (p<0.05 between tree diameter class distributions. Juveniles accounted for 87% of the tree population. The structure of the forest was not homogeneous, with sections ranging from poorly structured to highly stratified configurations. The study suggests that there was moderate tree diversity in the tropical dry thorn forest of Bannerghatta National Park, but the forest was relatively young.

Soil fauna and leaf species, but not species diversity, affect initial soil erosion in a subtropical forest plantation

Science.gov (United States)

Seitz, Steffen; Goebes, Philipp; Assmann, Thorsten; Schuldt, Andreas; Scholten, Thomas

2017-04-01

In subtropical parts of China, high rainfall intensities cause continuous soil losses and thereby provoke severe harms to ecosystems. In woodlands, it is not the tree canopy, but mostly an intact forest floor that provides protection from soil erosion. Although the protective role of leaf litter covers against soil losses is known for a long time, little research has been conducted on the processes involved. For instance, the role of different leaf species and leaf species diversity has been widely disregarded. Furthermore, the impact of soil meso- and macrofauna within the litter layer on soil losses remains unclear. To investigate how leaf litter species and diversity as well as soil meso- and macrofauna affect sediment discharge in a subtropical forest ecosystem, a field experiment was carried out in Xingangshan, Jiangxi Province, PR China (BEF China). A full-factorial random design with 96 micro-scale runoff plots and seven domestic leaf species in three diversity levels and a bare ground feature were established. Erosion was initiated with a rainfall simulator. This study confirms that leaf litter cover generally protects forest soils from water erosion (-82 % sediment discharge on leaf covered plots compared to bare plots) and this protection is gradually removed as the litter layer decomposes. Different leaf species showed variable impacts on sediment discharge and thus erosion control. This effect can be related to different leaf habitus, leaf decomposition rates and food preferences of litter decomposing meso- and macrofauna. In our experiment, runoff plots with leaf litter from Machilus thunbergii in monoculture showed the highest sediment discharge (68.0 g m-2), whereas plots with Cyclobalanopsis glauca in monoculture showed the smallest rates (7.9 g m-2). At the same time, neither leaf species diversity, nor functional diversity showed any significant influence, only a negative trend could be observed. Nevertheless, the protective effect of the leaf

The importance of forest disturbance for the recruitment of the large arborescent palm Attalea maripa in a seasonally-dry Amazonian forest

OpenAIRE

Salm,Rodolfo

2005-01-01

The hypothesis that forest disturbance is important for the recruitment of the large arborescent palms Attalea maripa was tested with a natural experiment in the Pinkaití site (7º 46'S; 51º 57'W), a seasonally-dry Amazonian forest. A 8,000 m long trail, that crosses, in its lower half, an open forest along the Pinkaití stream bottomlands and, on its upper half, a dense forest on a hill, was divided in 160 0.15 ha (50x30 m) sampling units. At each unit, adult palms were counted and percentage ...

Comparative Studies on Community Ecology of Two Types of Subtropical Forests Grown in Silicate and Limestone Habitats in the Northern Part of Okinawa Island, Japan

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S. M. Feroz

2008-06-01

Full Text Available In order to compare woody species diversity, spatial distribution of trees and stand structure on the basis of the architectural stratification between two types of subtropical forests in the northern part of Okinawa Island, Japan, tree censuses in a 750 m2 plot in silicate habitat and a 1000 m2 plot in limestone habitat were performed. It was found that both subtropical forests growing in silicate and limestone habitats consisted of four architectural layers. A total of 26 families, 43 genera, 60 species and 4684 individuals larger than 0.1 m high in the silicate habitat, and 31 families, 51 genera, 62 species and 4798 individuals larger than 0.0 m high in the limestone habitat, were recorded. As a result, the floristic composition in the silicate habitat was quite different from that in the limestone habitat in terms of similarity index ( Π C = 0.07; approximately only one-sixth of the species were in common. The floristic composition among layers was more similar in the silicate habitat than in the limestone habitat. Castanopsis sieboldii (Mak. Hatusima was the most dominant species in the silicate habitat, but was completely absent in the limestone habitat where Cinnamomum japonicum Sieb. ex Nees was the most dominant species. The potential number of species in the silicate forest (62 was lower than that in the limestone forest (71. However, the woody species diversity was higher in the silicate forest than in the limestone forest. The values of H′ and J′ tended to increase from the top layer downward except for the bottom layer in the silicate forest, while this increasing trend was reversed in the limestone forest. It follows that high woody species diversity in the silicate forest depended on small-sized trees, whereas in the limestone forest it depended on big-sized trees. The spatial distribution of trees in the forests was random in each layer, except the top layer, where there existed a double-clump structure. High degree of

Carbon storage and emissions offset potential in an African dry forest, the Arabuko-Sokoke Forest, Kenya.

Science.gov (United States)

Glenday, Julia

2008-07-01

Concerns about rapid tropical deforestation, and its contribution to rising atmospheric concentrations of greenhouse gases, increase the importance of monitoring terrestrial carbon storage in changing landscapes. Emerging markets for carbon emission offsets may offer developing nations needed incentives for reforestation, rehabilitation, and avoided deforestation. However, relatively little empirical data exists regarding carbon storage in African tropical forests, particularly for those in arid or semi-arid regions. Kenya's 416 km(2) Arabuko-Sokoke Forest (ASF) is the largest remaining fragment of East African coastal dry forest and is considered a global biodiversity hotspot (Myers et al. 2000), but has been significantly altered by past commercial logging and ongoing extraction. Forest carbon storage for ASF was estimated using allometric equations for tree biomass, destructive techniques for litter and herbaceous vegetation biomass, and spectroscopy for soils. Satellite imagery was used to assess land cover changes from 1992 to 2004. Forest and thicket types (Cynometra webberi dominated, Brachystegia spiciformis dominated, and mixed species forest) had carbon densities ranging from 58 to 94 Mg C/ha. The ASF area supported a 2.8-3.0 Tg C carbon stock. Although total forested area in ASF did not change over the analyzed time period, ongoing disturbances, quantified by the basal area of cut tree stumps per sample plot, correlated with decreased carbon densities. Madunguni Forest, an adjoining forest patch, lost 86% of its forest cover and at least 76% of its terrestrial carbon stock in the time period. Improved management of wood harvesting in ASF and rehabilitation of Madunguni Forest could substantially increase terrestrial carbon sequestration in the region.

Southern Forests: a Journal of Forest Science

African Journals Online (AJOL)

Southern Hemisphere Forestry Journal. ... The journal particularly encourages contributions from South America, Africa and tropical/subtropical ... Alternative eucalypts for commercial pulpwood production at moderately dry sites in the warm ...

Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

Science.gov (United States)

Baker, William L

2015-01-01

Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984-2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984-2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046-2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in

Tree species traits but not diversity mitigate stem breakage in a subtropical forest following a rare and extreme ice storm.

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Karin Nadrowski

Full Text Available Future climates are likely to include extreme events, which in turn have great impacts on ecological systems. In this study, we investigated possible effects that could mitigate stem breakage caused by a rare and extreme ice storm in a Chinese subtropical forest across a gradient of forest diversity. We used Bayesian modeling to correct stem breakage for tree size and variance components analysis to quantify the influence of taxon, leaf and wood functional traits, and stand level properties on the probability of stem breakage. We show that the taxon explained four times more variance in individual stem breakage than did stand level properties; trees with higher specific leaf area (SLA were less susceptible to breakage. However, a large part of the variation at the taxon scale remained unexplained, implying that unmeasured or undefined traits could be used to predict damage caused by ice storms. When aggregated at the plot level, functional diversity and wood density increased after the ice storm. We suggest that for the adaption of forest management to climate change, much can still be learned from looking at functional traits at the taxon level.

Dry forests and wildland fires of the inland Northwest USA: contrasting the landscape ecology of the pre-settlement and modern eras.

Science.gov (United States)

Paul F. Hessburg; James K. Agee; Jerry F. Franklin

2005-01-01

Prior to Euro-American settlement, dry ponderosa pine and mixed conifer forests (hereafter, the "dry forests") of the Inland Northwest were burned by frequent low- or mixed-severity fires. These mostly surface fires maintained low and variable tree densities, light and patchy ground fuels, simplified forest structure, and favored fire-tolerant trees, such as...

Sympatric occurrence of four Cathartid vultures in the dry forests of ...

African Journals Online (AJOL)

dry forests of north-western Peru. Robert S R Williams. Frankfurt Zoological Society and Asociación TuTierra. rob@szfperu.org. This photograph, taken with a cameratrap, shows four species of Cathartid vultures: Andean Condor Vultur gryphus, King. Vulture Sarcoramphus papa, Turkey. Vulture Cathartes aura and Black ...

Forest vegetation as a sink for atmospheric particulates: Quantitative studies in rain and dry deposition

International Nuclear Information System (INIS)

Russel, I.J.; Choquette, C.E.; Fang, S.; Dundulis, W.P.; Pao, A.A.; Pszenny, A.A.P.

1981-01-01

Radionuclides in the atmosphere are associated with nonradioactive air particulates and hence serve to trace the fluxes of air particulates to various surfaces. Natural and artificial radioactivities found in the atmosphere have been measured in vegetation for 10 years to elucidate some of the mechanisms of acquirement by forest trees of atmospheric particulates. Whole tree analysis, in conjunction with soil assay, have served to establish the fraction of the flux of radionuclides retained by above-ground tissues of a forest stand. Interpretation is facilitated because most radionuclides in the atmosphere are superficially acquired. Typically 5--20% of the total open field flux is retained by the forest canopy in a moderately rainy climate (120 cm/year). Short-lived daughters of radon give a dry deposition velocity of particulates in the Aitken size range of 0.03--0.05 cm/s, thus permitting an estimate of transient removal by forest canopies by dry deposition of this size fraction

Urbanization effects on leaf litter decomposition, foliar nutrient dynamics and aboveground net primary productivity in the subtropics

Science.gov (United States)

Heather A. Enloe; B. Graeme Lockaby; Wayne C. Zipperer; Greg L. Somers

2015-01-01

Urbanization can alter nutrient cycling. This research evaluated how urbanization affected nutrient dynamics in the subtropics. We established 17–0.04 ha plots in five different land cover types—slash pine (Pinus elliottii) plantations (n=3), rural natural pine forests (n= 3), rural natural oak forests (n=4), urban pine forests (n=3) and urban oak forests (n=4) in the...

Edge effects and beta diversity in ground and canopy beetle communities of fragmented subtropical forest.

Science.gov (United States)

Stone, Marisa J; Catterall, Carla P; Stork, Nigel E

2018-01-01

Clearing of dry forests globally creates edges between remnant forest and open anthropogenic habitats. We used flight intercept traps to evaluate how forest beetle communities are influenced by distance from such edges, together with vertical height, spatial location, and local vegetation structure, in an urbanising region (Brisbane, Australia). Species composition (but not total abundance or richness) differed greatly between ground and canopy. Species composition also varied strongly among sites at both ground and canopy levels, but almost all other significant effects occurred only at ground level, where: species richness declined from edge to interior; composition differed between positions near edges ( 50 m); high local canopy cover was associated with greater total abundance and richness and differing composition; and greater distances to the city centre were associated with increased total abundances and altered composition. Analyses of individual indicator species associated with this variation enabled further biological interpretations. A global literature synthesis showed that most spatially well-replicated studies of edge effects on ground-level beetles within forest fragments have likewise found that positions within tens of metres from edges with open anthropogenic habitats had increased species richness and different compositions from forest interior sites, with fewer effects on abundance. Accordingly, negative edge effects will not prevent relatively small compact fragments (if >10-20 ha) from supporting forest-like beetle communities, although indirect consequences of habitat degradation remain a threat. Retention of multiple spatially scattered forest areas will also be important in conserving forest-dependent beetles, given high levels of between-site diversity.

Edge effects and beta diversity in ground and canopy beetle communities of fragmented subtropical forest

Science.gov (United States)

Catterall, Carla P.; Stork, Nigel E.

2018-01-01

Clearing of dry forests globally creates edges between remnant forest and open anthropogenic habitats. We used flight intercept traps to evaluate how forest beetle communities are influenced by distance from such edges, together with vertical height, spatial location, and local vegetation structure, in an urbanising region (Brisbane, Australia). Species composition (but not total abundance or richness) differed greatly between ground and canopy. Species composition also varied strongly among sites at both ground and canopy levels, but almost all other significant effects occurred only at ground level, where: species richness declined from edge to interior; composition differed between positions near edges ( 50 m); high local canopy cover was associated with greater total abundance and richness and differing composition; and greater distances to the city centre were associated with increased total abundances and altered composition. Analyses of individual indicator species associated with this variation enabled further biological interpretations. A global literature synthesis showed that most spatially well-replicated studies of edge effects on ground-level beetles within forest fragments have likewise found that positions within tens of metres from edges with open anthropogenic habitats had increased species richness and different compositions from forest interior sites, with fewer effects on abundance. Accordingly, negative edge effects will not prevent relatively small compact fragments (if >10–20 ha) from supporting forest-like beetle communities, although indirect consequences of habitat degradation remain a threat. Retention of multiple spatially scattered forest areas will also be important in conserving forest-dependent beetles, given high levels of between-site diversity. PMID:29494680

Measurements of ammonia concentrations, fluxes and dry deposition velocities to a spruce forest 1991-1995

DEFF Research Database (Denmark)

Andersen, H.V.; Hovmand, M.F.; Hummelshøj, P.

1999-01-01

The dry deposition velocities and fluxes of ammonia have been estimated from measurements of the vertical gradient of ammonia and micrometeorology above a spruce forest in western Jutland, Denmark. Measurements have been made in seven periods, each lasting about one week and covering all seasons...... measuring period characterized by easterly winds with dry conditions and high ammonia concentrations, and the emissions might relate to evaporation from ammonia saturated surfaces or emission from mineralization in the forest soil. In general, relatively high net deposition velocities were observed during...... at conditions with easterly winds, the air have passed central Jutland with large emission areas. Some of the relatively low deposition velocities or emissions were observed during conditions with low ammonia concentration and westerly winds. These observations might relate to a compensation point of the forest...

Extending the baseline of tropical dry forest loss in Ghana (1984–2015) reveals drivers of major deforestation inside a protected area

NARCIS (Netherlands)

Janssen, Thomas A.J.; Ametsitsi, George K.D.; Collins, Murray; Adu-Bredu, Stephen; Oliveras, Imma; Mitchard, Edward T.A.; Veenendaal, Elmar M.

2018-01-01

Tropical dry forests experience the highest deforestation rates on Earth, with major implications for the biodiversity of these ecosystems, as well as for its human occupants. Global remote sensing based forest cover data (2000 − 2012) point to the rapid loss of tropical dry forest in South America

Extending the baseline of tropical dry forest loss in Ghana (1984–2015) reveals drivers of major deforestation inside a protected area

NARCIS (Netherlands)

Janssen, Thomas A.J.; Ametsitsi, George K.D.; Collins, Murray; Adu-Bredu, Stephen; Oliveras, Imma; Mitchard, Edward T.A.; Veenendaal, Elmar M.

2018-01-01

Abstract Tropical dry forests experience the highest deforestation rates on Earth, with major implications for the biodiversity of these ecosystems, as well as for its human occupants. Global remote sensing based forest cover data (2000 − 2012) point to the rapid loss of tropical dry forest in South

Responses of photosynthetic parameters to drought in subtropical forest ecosystem of China

Science.gov (United States)

Zhou, Lei; Wang, Shaoqiang; Chi, Yonggang; Li, Qingkang; Huang, Kun; Yu, Quanzhou

2015-12-01

The mechanism underlying the effect of drought on the photosynthetic traits of leaves in forest ecosystems in subtropical regions is unclear. In this study, three limiting processes (stomatal, mesophyll and biochemical limitations) that control the photosynthetic capacity and three resource use efficiencies (intrinsic water use efficiency (iWUE), nitrogen use efficiency (NUE) and light use efficiency (LUE)), which were characterized as the interactions between photosynthesis and environmental resources, were estimated in two species (Schima superba and Pinus massoniana) under drought conditions. A quantitative limitation analysis demonstrated that the drought-induced limitation of photosynthesis in Schima superba was primarily due to stomatal limitation, whereas for Pinus massoniana, both stomatal and non-stomatal limitations generally exhibited similar magnitudes. Although the mesophyll limitation represented only 1% of the total limitation in Schima superba, it accounted for 24% of the total limitations for Pinus massoniana. Furthermore, a positive relationship between the LUE and NUE and a marginally negative relationship or trade-off between the NUE and iWUE were observed in the control plots. However, drought disrupted the relationships between the resource use efficiencies. Our findings may have important implications for reducing the uncertainties in model simulations and advancing the understanding of the interactions between ecosystem functions and climate change.

Plant diversity patterns in neotropical dry forests and their conservation implications

Science.gov (United States)

K. Banda-R; A. Delgado-Salinas; K. G. Dexter; R. Linares-Palomino; A. Oliveira-Filho; D. Prado; M. Pullan; C. Quintana; R. Riina; G. M. Rodriguez M.; J. Weintritt; P. Acevedo-Rodriguez; J. Adarve; E. Alvarez; A. Aranguren B.; J. C. Arteaga; G. Aymard; A. Castano; N. Ceballos-Mago; A. Cogollo; H. Cuadros; F. Delgado; W. Devia; H. Duenas; L. Fajardo; A. Fernandez; M. A. Fernandez; J. Franklin; E. H. Freid; L. A. Galetti; R. Gonto; R. Gonzalez-M.; R. Graveson; E. H. Helmer; A. Idarraga; R. Lopez; H. Marcano-Vega; O. G. Martinez; H. M. Maturo; M. McDonald; K. McLaren; O. Melo; F. Mijares; V. Mogni; D. Molina; N. d. P. Moreno; J. M. Nassar; D. M. Neves; L. J. Oakley; M. Oatham; A. R. Olvera-Luna; F. F. Pezzini; O. J. R. Dominguez; M. E. Rios; O. Rivera; N. Rodriguez; A. Rojas; T. Sarkinen; R. Sanchez; M. Smith; C. Vargas; B. Villanueva; R. T. Pennington

2016-01-01

Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than...

Gaseous elemental mercury (GEM fluxes over canopy of two typical subtropical forests in south China

Directory of Open Access Journals (Sweden)

Q. Yu

2018-01-01

Full Text Available Mercury (Hg exchange between forests and the atmosphere plays an important role in global Hg cycling. The present estimate of global emission of Hg from natural source has large uncertainty, partly due to the lack of chronical and valid field data, particularly for terrestrial surfaces in China, the most important contributor to global atmospheric Hg. In this study, the micrometeorological method (MM was used to continuously observe gaseous elemental mercury (GEM fluxes over forest canopy at a mildly polluted site (Qianyanzhou, QYZ and a moderately polluted site (Huitong, HT, near a large Hg mine in subtropical south China for a full year from January to December in 2014. The GEM flux measurements over forest canopy in QYZ and HT showed net emission with annual average values of 6.67 and 0.30 ng m−2 h−1, respectively. Daily variations of GEM fluxes showed an increasing emission with the increasing air temperature and solar radiation in the daytime to a peak at 13:00, and decreasing emission thereafter, even as a GEM sink or balance at night. High temperature and low air Hg concentration resulted in the high Hg emission in summer. Low temperature in winter and Hg absorption by plant in spring resulted in low Hg emission, or even adsorption in the two seasons. GEM fluxes were positively correlated with air temperature, soil temperature, wind speed, and solar radiation, while it is negatively correlated with air humidity and atmospheric GEM concentration. The lower emission fluxes of GEM at the moderately polluted site (HT when compared with that in the mildly polluted site (QYZ may result from a much higher adsorption fluxes at night in spite of a similar or higher emission fluxes during daytime. This shows that the higher atmospheric GEM concentration at HT restricted the forest GEM emission. Great attention should be paid to forests as a crucial increasing Hg emission source with the decreasing atmospheric GEM concentration

Regeneration complexities of Pinus gerardiana in dry temperate forests of Indian Himalaya.

Science.gov (United States)

Kumar, Raj; Shamet, G S; Mehta, Harsh; Alam, N M; Kaushal, Rajesh; Chaturvedi, O P; Sharma, Navneet; Khaki, B A; Gupta, Dinesh

2016-04-01

Pinus gerardiana is considered an important species in dry temperate forests of North-Western Indian Himalaya because of its influence on ecological processes and economic dependence of local people in the region. But, large numbers of biotic and abiotic factors have affected P. gerardiana in these forests; hence, there is a crucial need to understand the regeneration dynamics of this tree species. The present investigation was conducted in P. gerardiana forests to understand vegetation pattern and regeneration processes on different sites in the region. Statistical analysis was performed to know variability in growing stock and regeneration on sample plots, while correlation coefficients and regression models were developed to find the relationship between regeneration and site factors. The vegetation study showed dominance of P. gerardiana, which is followed by Cedrus deodara, Pinus wallichiana and Quercus ilex in the region. The growing stock of P. gerardiana showed steep increasing and then steadily declining trend from lower to higher diameter class. The distribution of seedling, sapling, pole and trees was not uniform at different sites and less number of plots in each site were observed to have effective conditions for continuous regeneration, but mostly showed extremely limited regeneration. Regeneration success ranging from 8.44 to 15.93 % was recorded in different sites of the region, which suggests that in different sites regeneration success is influenced by collection of cone for extracting seed, grazing/browsing and physico-chemical properties of soil. Regeneration success showed significant correlation and relationship with most of abiotic and biotic factors. The regeneration success is lower than the requirement of sustainable forest, but varies widely among sites in dry temperate forests of Himalaya. More forest surveys are required to understand the conditions necessary for greater success of P. gerardiana in the region.

Diverse patterns of stored water use among saplings in seasonally dry tropical forests.

Science.gov (United States)

Wolfe, Brett T; Kursar, Thomas A

2015-12-01

Tree species in seasonally dry tropical forests likely vary in their drought-survival mechanisms. Drought-deciduousness, which reduces water loss, and low wood density, which may permit dependence on stored water, are considered key traits. For saplings of six species at two distinct sites, we studied these and two associated traits: the seasonal amount of water released per stem volume ("water released") and the hydraulic capacitance of the stem (C). Two deciduous species with low stem density, Cavanillesia platanifolia and Bursera simaruba, had high C and high dry-season stem water potential (Ψ(stem)), but differed in dry-season water released. C. platanifolia did not use stored water during the dry season whereas B. simaruba, in a drier forest, released stored water. In both, water released was highest while flushing leaves, suggesting that stored water supports leaf flushing. In contrast, two deciduous species with intermediate stem density, Annona hayesii and Genipa americana, had intermediate C, low dry-season Ψ(stem), and high seasonal change in water released. Meanwhile, two evergreen species with intermediate stem density, Cojoba rufescens and Astronium graveolens, had relatively low C, low dry-season Ψ(stem), and intermediate seasonal change in water released. Thus, at least three, distinct stored-water-use strategies were observed. Additionally, bark relative water content (RWC) decreased along with Ψ(stem) during the dry season while xylem RWC did not change, suggesting that bark-stored water buffers Ψ(stem) seasonally. Together these results suggest that seasonal use of stored water and change in Ψ(stem) are associated with functional groups that are characterized by combinations of deciduousness and stem density.

Isometric scaling of above- and below-ground biomass at the individual and community levels in the understorey of a sub-tropical forest.

Science.gov (United States)

Cheng, Dongliang; Zhong, Quanlin; Niklas, Karl J; Ma, Yuzhu; Yang, Yusheng; Zhang, Jianhua

2015-02-01

Empirical studies and allometric partitioning (AP) theory indicate that plant above-ground biomass (MA) scales, on average, one-to-one (isometrically) with below-ground biomass (MR) at the level of individual trees and at the level of entire forest communities. However, the ability of the AP theory to predict the biomass allocation patterns of understorey plants has not been established because most previous empirical tests have focused on canopy tree species or very large shrubs. In order to test the AP theory further, 1586 understorey sub-tropical forest plants from 30 sites in south-east China were harvested and examined. The numerical values of the scaling exponents and normalization constants (i.e. slopes and y-intercepts, respectively) of log-log linear MA vs. MR relationships were determined for all individual plants, for each site, across the entire data set, and for data sorted into a total of 19 sub-sets of forest types and successional stages. Similar comparisons of MA/MR were also made. The data revealed that the mean MA/MR of understorey plants was 2·44 and 1·57 across all 1586 plants and for all communities, respectively, and MA scaled nearly isometrically with respect to MR, with scaling exponents of 1·01 for all individual plants and 0·99 for all communities. The scaling exponents did not differ significantly among different forest types or successional stages, but the normalization constants did, and were positively correlated with MA/MR and negatively correlated with scaling exponents across all 1586 plants. The results support the AP theory's prediction that MA scales nearly one-to-one with MR (i.e. MA ∝ MR (≈1·0)) and that plant biomass partitioning for individual plants and at the community level share a strikingly similar pattern, at least for the understorey plants examined in this study. Furthermore, variation in environmental conditions appears to affect the numerical values of normalization constants, but not the scaling exponents

Effect of elevated [CO2] and nutrient management on wet and dry season rice production in subtropical India

Institute of Scientific and Technical Information of China (English)

Sushree Sagarika Satapathy; Dillip Kumar Swain; Surendranath Pasupalak; Pratap Bhanu Singh Bhadoria

2015-01-01

The present experiment was conducted to evaluate the effect of elevated [CO2] with varying nutrient management on rice–rice production system. The experiment was conducted in the open field and inside open-top chambers（OTCs） of ambient [CO2]（≈ 390 μmol L-1） and elevated [CO2] environment（25% above ambient） during wet and dry seasons in 2011–2013at Kharagpur, India. The nutrient management included recommended doses of N, P, and K as chemical fertilizer（CF）, integration of chemical and organic sources, and application of increased（25% higher） doses of CF. The higher [CO2] level in the OTC increased aboveground biomass but marginally decreased filled grains per panicle and grain yield of rice, compared to the ambient environment. However, crop root biomass was increased significantly under elevated [CO2]. With respect to nutrient management, increasing the dose of CF increased grain yield significantly in both seasons. At the recommended dose of nutrients, integrated nutrient management was comparable to CF in the wet season, but significantly inferior in the dry season, in its effect on growth and yield of rice. The [CO2] elevation in OTC led to a marginal increase in organic C and available P content of soil, but a decrease in available N content. It was concluded that increased doses of nutrients via integration of chemical and organic sources in the wet season and chemical sources alone in the dry season will minimize the adverse effect of future climate on rice production in subtropical India.

Effect of elevated [CO2] and nutrient management on wet and dry season rice production in subtropical India

Institute of Scientific and Technical Information of China (English)

Sushree Sagarika Satapathy; Dillip Kumar Swain; Surendranath Pasupalak; Pratap Bhanu Singh Bhadoria

2015-01-01

The present experiment was conducted to evaluate the effect of elevated [CO2] with varying nutrient management on rice–rice production system. The experiment was conducted in the open field and inside open-top chambers (OTCs) of ambient [CO2] (≈390μmol L−1) and elevated [CO2] environment (25%above ambient) during wet and dry seasons in 2011–2013 at Kharagpur, India. The nutrient management included recommended doses of N, P, and K as chemical fertilizer (CF), integration of chemical and organic sources, and application of increased (25%higher) doses of CF. The higher [CO2] level in the OTC increased aboveground biomass but marginally decreased filled grains per panicle and grain yield of rice, compared to the ambient environment. However, crop root biomass was increased significantly under elevated [CO2]. With respect to nutrient management, increasing the dose of CF increased grain yield significantly in both seasons. At the recommended dose of nutrients, integrated nutrient management was comparable to CF in the wet season, but significantly inferior in the dry season, in its effect on growth and yield of rice. The [CO2] elevation in OTC led to a marginal increase in organic C and available P content of soil, but a decrease in available N content. It was concluded that increased doses of nutrients via integration of chemical and organic sources in the wet season and chemical sources alone in the dry season will minimize the adverse effect of future climate on rice production in subtropical India.

Amazon Forests Maintain Consistent Canopy Structure and Greenness During the Dry Season

Science.gov (United States)

Morton, Douglas C.; Nagol, Jyoteshwar; Carabajal, Claudia C.; Rosette, Jacqueline; Palace, Michael; Cook, Bruce D.; Vermote, Eric F.; Harding, David J.; North, Peter R. J.

2014-01-01

The seasonality of sunlight and rainfall regulates net primary production in tropical forests. Previous studies have suggested that light is more limiting than water for tropical forest productivity, consistent with greening of Amazon forests during the dry season in satellite data.We evaluated four potential mechanisms for the seasonal green-up phenomenon, including increases in leaf area or leaf reflectance, using a sophisticated radiative transfer model and independent satellite observations from lidar and optical sensors. Here we show that the apparent green up of Amazon forests in optical remote sensing data resulted from seasonal changes in near-infrared reflectance, an artefact of variations in sun-sensor geometry. Correcting this bidirectional reflectance effect eliminated seasonal changes in surface reflectance, consistent with independent lidar observations and model simulations with unchanging canopy properties. The stability of Amazon forest structure and reflectance over seasonal timescales challenges the paradigm of light-limited net primary production in Amazon forests and enhanced forest growth during drought conditions. Correcting optical remote sensing data for artefacts of sun-sensor geometry is essential to isolate the response of global vegetation to seasonal and interannual climate variability.

Factor contribution to fire occurrence, size, and burn probability in a subtropical coniferous forest in East China.

Science.gov (United States)

Ye, Tao; Wang, Yao; Guo, Zhixing; Li, Yijia

2017-01-01

The contribution of factors including fuel type, fire-weather conditions, topography and human activity to fire regime attributes (e.g. fire occurrence, size distribution and severity) has been intensively discussed. The relative importance of those factors in explaining the burn probability (BP), which is critical in terms of fire risk management, has been insufficiently addressed. Focusing on a subtropical coniferous forest with strong human disturbance in East China, our main objective was to evaluate and compare the relative importance of fuel composition, topography, and human activity for fire occurrence, size and BP. Local BP distribution was derived with stochastic fire simulation approach using detailed historical fire data (1990-2010) and forest-resource survey results, based on which our factor contribution analysis was carried out. Our results indicated that fuel composition had the greatest relative importance in explaining fire occurrence and size, but human activity explained most of the variance in BP. This implies that the influence of human activity is amplified through the process of overlapping repeated ignition and spreading events. This result emphasizes the status of strong human disturbance in local fire processes. It further confirms the need for a holistic perspective on factor contribution to fire likelihood, rather than focusing on individual fire regime attributes, for the purpose of fire risk management.

Light habitat, structure, diversity and dynamic of the tropical dry forest

Directory of Open Access Journals (Sweden)

Omar Melo-Cruz

2017-01-01

Full Text Available Tropical dry forests are complex and fragile ecosystems with high anthropic intervention and restricted reproductive cycles. These have unique richness, structural diversity, physiological and phenological . This research was executed  in the Upper Magdalena Valley, in four forest fragments with different successional stages. In each fragment four permanent plots of 0.25 ha were established and lighting habitat associated with richness, relative abundance and rarity of species. The forest dynamics included the mortality, recruitment and diameter growth for a period of 5.25 years. The species rischness found in the mature riparian forestis higher than that reported in other studies of similar areas in Valle del Cauca and the Atlantic coast.  The values of richness, diversity and rarity species are more evidenced  than the magnitudes found in  drier areas of Tolima. The structure, diversity and dynamics of forests were correlated with the lighting habitat, showing differences in canopy architecture and its role in the capture and absorption of radiation. Forests with dense canopy have limited availability of photosynthetically active radiation in understory related low species richness, while illuminated undergrowth are richer and heterogeneous.

Insect herbivores associated with an evergreen tree Goniorrhachis marginata Taub. (Leguminosae: Caesalpinioideae) in a tropical dry forest.

Science.gov (United States)

Silva, J O; Neves, F S

2014-08-01

Goniorrhachis marginata Taub. (Leguminosae: Caesalpinioideae) is a tree species found in Brazilian tropical dry forests that retain their leaves during the dry season. That being, we addressed the following question: i) How do insect diversity (sap-sucking and chewing), leaf herbivory and defensive traits (tannin and leaf sclerophylly) vary on the evergreen tree species G. marginata between seasons? The abundance of sap-sucking insects was higher in the dry season than in the rainy season. However, we did not verify any difference in the species richness and abundance of chewing insects between seasons. Leaf herbivory was higher in the rainy season, whereas leaf sclerophylly was higher in the dry season. However, herbivory was not related to sclerophylly. Insect herbivores likely decrease their folivory activity during the dry season due to life history patterns or changes in behaviour, possibly entering diapause or inactivity during this period. Therefore, G. marginata acts as a likely keystone species, serving as a moist refuge for the insect fauna during the dry season in tropical dry forest, and the presence of this evergreen species is crucial to conservation strategies of this threatened ecosystem.

Estimating the opportunity costs of activities that cause degradation in tropical dry forest: Implications for REDD +

NARCIS (Netherlands)

Borrego, Armonia; Skutsch, Margaret

2014-01-01

The viability of national REDD + programs will depend in part on whether funds generated from sales of carbon credits are sufficient to cover the opportunity costs (OC) of forgone uses of the forest. We present the results of a study in which OC were estimated in dry tropical forest, in western

Dispersal, isolation and diversification with continued gene flow in an Andean tropical dry forest.

Science.gov (United States)

Toby Pennington, R; Lavin, Matt

2017-07-01

The Andes are the world's longest mountain chain, and the tropical Andes are the world's richest biodiversity hot spot. The origin of the tropical Andean cordillera is relatively recent because the elevation of the mountains was relatively low (400-2500 m palaeoelevations) only 10 MYA with final uplift being rapid. These final phases of the Andean orogeny are thought to have had a fundamental role in shaping processes of biotic diversification and biogeography, with these effects reaching far from the mountains themselves by changing the course of rivers and deposition of mineral-rich Andean sediments across the massive Amazon basin. In a recent issue of Molecular Ecology, Oswald, Overcast, Mauck, Andersen, and Smith (2017) investigate the biogeography and diversification of bird species in the Andes of Peru and Ecuador. Their study is novel in its focus on tropical dry forests (Figure 1) rather than more mesic biomes such as rain forests, cloud forests and paramos, which tend to be the focus of science and conservation in the Andean hot spot. It is also able to draw powerful conclusions via the first deployment of genomic approaches to a biogeographic question in the threatened dry forests of the New World. © 2017 John Wiley & Sons Ltd.

Mapping tropical dry forest habitats integrating landsat NDVI, Ikonos imagery, and topographic information in the Caribbean island of Mona.

Science.gov (United States)

Martinuzzi, Sebastiáin; Gould, William A; Ramos Gonzalez, Olga M; Martinez Robles, Alma; Calle Maldonado, Paulina; Pérez-Buitrago, Néstor; Fumero Caban, José J

2008-06-01

Assessing the status of tropical dry forest habitats using remote sensing technologies is one of the research priorities for Neotropical forests. We developed a simple method for mapping vegetation and habitats in a tropical dry forest reserve, Mona Island, Puerto Rico, by integrating the Normalized Difference Vegetation Index (NDVI) from Landsat, topographic information, and high-resolution Ikonos imagery. The method was practical for identifying vegetation types in areas with a great variety of plant communities and complex relief, and can be adapted to other dry forest habitats of the Caribbean Islands. NDVI was useful for identifying the distribution of forests, woodlands, and shrubland, providing a natural representation of the vegetation patterns on the island. The use of Ikonos imagery allowed increasing the number of land cover classes. As a result, sixteen land-cover types were mapped over the 5500 ha area, with a kappa coefficient of accuracy equal to 79%. This map is a central piece for modeling vertebrate species distribution and biodiversity patterns by the Puerto Rico Gap Analysis Project, and it is of great value for assisting research and management actions in the island.

The Tetramerium lineage (Acanthaceae: Justicieae) does not support the Pleistocene Arc hypothesis for South American seasonally dry forests.

Science.gov (United States)

Côrtes, Ana Luiza A; Rapini, Alessandro; Daniel, Thomas F

2015-06-01

The Tetramerium lineage (Acanthaceae) presents a striking ecological structuring in South America, with groups concentrated in moist forests or in seasonally dry forests. In this study, we investigate the circumscription and relationships of the South American genera as a basis for better understanding historic interactions between dry and moist biomes in the Neotropics. We dated the ancestral distribution of the Tetramerium lineage based on one nuclear and four plastid DNA regions. Maximum parsimony, maximum likelihood, and Bayesian inference analyses were performed for this study using 104 terminals. Phylogenetic divergences were dated using a relaxed molecular clock approach and ancestral distributions obtained from dispersal-vicariance analyses. The genera Pachystachys, Schaueria, and Thyrsacanthus are nonmonophyletic. A dry forest lineage dispersed from North America to South America and reached the southwestern part of the continent between the end of the Miocene and beginning of the Pleistocene. This period coincides with the segregation between Amazonian and Atlantic moist forests that established the geographic structure currently found in the group. The South American genera Pachystachys, Schaueria, and Thyrsacanthus need to be recircumscribed. The congruence among biogeographical events found for the Tetramerium lineage suggests that the dry forest centers currently dispersed throughout South America are relatively old remnants, probably isolated since the Neogene, much earlier than the Last Glacial Maximum postulated by the Pleistocene Arc hypothesis. In addition to exploring the Pleistocene Arc hypothesis, this research also informs evolution in a lineage with numerous geographically restricted and threatened species. © 2015 Botanical Society of America, Inc.

Seasonal variation in soil and plant water potentials in a Bolivian tropical moist and dry forest

NARCIS (Netherlands)

Markesteijn, L.; Iraipi, J.; Bongers, F.; Poorter, L.

2010-01-01

We determined seasonal variation in soil matric potentials (¿soil) along a topographical gradient and with soil depth in a Bolivian tropical dry (1160 mm y-1 rain) and moist forest (1580 mm y-1). In each forest we analysed the effect of drought on predawn leaf water potentials (¿pd) and drought

Warm Dry Weather Conditions Cause of 2016 Fort McMurray Wild Forest Fire and Associated Air Quality

Science.gov (United States)

de Azevedo, S. C.; Singh, R. P.; da Silva, E. A., Sr.

2016-12-01

The climate change is evident from the increasing temperature around the world, day to day life and increasing frequency of natural hazards. The warm and dry conditions are the cause of frequent forest fires around the globe. Forest fires severely affect the air quality and human health. Multi sensor satellites and dense network of ground stations provide information about vegetation health, meteorological, air quality and atmospheric parameters. We have carried out detailed analysis of satellite and ground data of wild forest fire that occurred in May 2016 in Fort McMurray, Alberta, Canada. This wild forest fire destroyed 10 per cent of Fort McMurray's housing and forced more than 90,000 people to evacuate the surrounding areas. Our results show that the warm and dry conditions with low rainfall were the cause of Fort McMurray wild fire. The air quality parameters (particulate matter, CO, ozone, NO2, methane) and greenhouse gases measured from Atmospheric Infrared Sounder (AIRS) satellite show enhanced levels soon after the forest fire. The emissions from the forest fire affected health of population living in surrounding areas up to 300 km radius.

Seasonality in the dung beetle community in a Brazilian tropical dry forest: Do small changes make a difference?

Science.gov (United States)

Medina, Anderson Matos; Lopes, Priscila Paixão

2014-01-01

Dung beetle (Coleoptera: Scarabaeoidea: Scarabaeinae) activity is influenced by rainfall seasonality. We hypothesized that rainfall might also play a major role in regulating the community structure of this group. In this study, we describe seasonal changes in the richness, composition, and structure of the Scarabaeinae community in a Brazilian tropical dry forest. A fragment of arboreal Caatinga was sampled using baited pitfall traps during the early dry season (EDS), late dry season (LDS), early wet season (EWS), and middle wet season (MWS). We compared the dung beetle community in each season in relationship to species richness, rank-dominance, curves, and composition. We collected 1352 Scarabaeinae individuals , belonging to 15 species. Dichotomius aff. laevicollis Felsche (Coleoptera: Scarabaeidae) was the dominant species, representing 73.89% of the individuals. There were no seasonal changes in the rank dominance curves; all had a single dominant species and a few species with low abundance, typical for arid areas. Estimated richness was highest in MWS, followed by EWS. Dry-season samples (EDS and LDS) had lower richness, with no significant difference between the dry seasons. Although species richness increased as the habitat became wetter, the difference between the wet and dry seasons was small, which differs completely from the findings of other studies in Neotropical dry forests, where almost all species cease activities in the dry season. Species composition changes were found in non-metric multidimensional scaling and sustained by analysis of similarity. All the seasons had pairwise differences in composition, with the exception of EDS and MWS, which indicates that the dung beetle community in this fragment requires more than three months of drought to trigger changes in species composition; this is probably due to small changes in the forest canopy. There was no difference in composition between EDS and MWS. As in other tropical dry forests, although

Photoprotection related to xanthophyll cycle pigments in epiphytic orchids acclimated at different light microenvironments in two tropical dry forests of the Yucatan Peninsula, Mexico.

Science.gov (United States)

de la Rosa-Manzano, Edilia; Andrade, José Luis; García-Mendoza, Ernesto; Zotz, Gerhard; Reyes-García, Casandra

2015-12-01

Epiphytic orchids from dry forests of Yucatán show considerable photoprotective plasticity during the dry season, which depends on leaf morphology and host tree deciduousness. Nocturnal retention of antheraxanthin and zeaxanthin was detected for the first time in epiphytic orchids. In tropical dry forests, epiphytes experience dramatic changes in light intensity: photosynthetic photon flux density may be up to an order of magnitude higher in the dry season compared to the wet season. To address the seasonal changes of xanthophyll cycle (XC) pigments and photosynthesis that occur throughout the year, leaves of five epiphytic orchid species were studied during the early dry, dry and wet seasons in a deciduous and a semi-deciduous tropical forests at two vertical strata on the host trees (3.5 and 1.5 m height). Differences in XC pigment concentrations and photosynthesis (maximum quantum efficiency of photosystem II; F v/F m) were larger among seasons than between vertical strata in both forests. Antheraxanthin and zeaxanthin retention reflected the stressful conditions of the epiphytic microhabitat, and it is described here in epiphytes for the first time. During the dry season, both XC pigment concentrations and photosystem II heat dissipation of absorbed energy increased in orchids in the deciduous forest, while F v/F m and nocturnal acidification (ΔH(+)) decreased, clearly as a response to excessive light and drought. Concentrations of XC pigments were higher than those in orchids with similar leaf shape in semi-deciduous forest. There, only Encyclia nematocaulon and Lophiaris oerstedii showed somewhat reduced F v/F m. No changes in ΔH(+) and F v/F m were detected in Cohniella ascendens throughout the year. This species, which commonly grows in forests with less open canopies, showed leaf tilting that diminished light interception. Light conditions in the uppermost parts of the canopy probably limit the distribution of epiphytic orchids and the retention of

Phytossociology of wood community in Seasonal Dry Montane Forest in Paraiba, Brazil

Directory of Open Access Journals (Sweden)

Maria do Carmo Learth Cunha

2013-06-01

Full Text Available The Pico do Jabre Seasonally Dry Montane Forest in Paraiba state, Brazil, the highest regional elevation, 1197 m, distant 360 km the sea was assessed aiming to survey its phytosociology and woody structure. In 36 systematic sampling plots, 10x50m, individuals, Dbh > 4.8cm, had their diameters and height measured. Botanical samples were collected during five years and vouchers were deposited at the Paraiba Federal University Herbaria (JPB. It was found 2050 trees distributed in 64 species of 51 genera of 31 families, which accounted for 1138 ind.ha-1 and 22.45 m2.ha -1. Diversity and equability were assessed as H' = 3.17 nats.ind-1 and J' = 0.76 similar to some others regional seasonally dry montane forest communities. Malpighiaceae, Myrtaceae, Erythroxylaceae, Vochysiaceae, Celastraceae, Rutaceae, Sapindaceae e Fabaceae-Faboideae stood out and summed 66.72% of the total VI. Byrsonima nitidifolia, Eugenia ligustrina, Calisthene microphylla, Maytenus distichophylla and Erythroxylum mucronatum species accounted for 120.79 (40.3% of the total VI. B. nitidifolia ecological dominance is firstly reported in the Brazilian northeast region.

SENSITIVITY ANALYSIS OF BIOME-BGC MODEL FOR DRY TROPICAL FORESTS OF VINDHYAN HIGHLANDS, INDIA

OpenAIRE

M. Kumar; A. S. Raghubanshi

2012-01-01

A process-based model BIOME-BGC was run for sensitivity analysis to see the effect of ecophysiological parameters on net primary production (NPP) of dry tropical forest of India. The sensitivity test reveals that the forest NPP was highly sensitive to the following ecophysiological parameters: Canopy light extinction coefficient (k), Canopy average specific leaf area (SLA), New stem C : New leaf C (SC:LC), Maximum stomatal conductance (gs,max), C:N of fine roots (C:Nfr), All-sided to...

Spatio-Temporal Distribution of Bark and Ambrosia Beetles in a Brazilian Tropical Dry Forest.

Science.gov (United States)

Macedo-Reis, Luiz Eduardo; Novais, Samuel Matos Antunes de; Monteiro, Graziela França; Flechtmann, Carlos Alberto Hector; Faria, Maurício Lopes de; Neves, Frederico de Siqueira

2016-01-01

Bark and the ambrosia beetles dig into host plants and live most of their lives in concealed tunnels. We assessed beetle community dynamics in tropical dry forest sites in early, intermediate, and late successional stages, evaluating the influence of resource availability and seasonal variations in guild structure. We collected a total of 763 beetles from 23 species, including 14 bark beetle species, and 9 ambrosia beetle species. Local richness of bark and ambrosia beetles was estimated at 31 species. Bark and ambrosia composition was similar over the successional stages gradient, and beta diversity among sites was primarily determined by species turnover, mainly in the bark beetle community. Bark beetle richness and abundance were higher at intermediate stages; availability of wood was the main spatial mechanism. Climate factors were effectively non-seasonal. Ambrosia beetles were not influenced by successional stages, however the increase in wood resulted in increased abundance. We found higher richness at the end of the dry and wet seasons, and abundance increased with air moisture and decreased with higher temperatures and greater rainfall. In summary, bark beetle species accumulation was higher at sites with better wood production, while the needs of fungi (host and air moisture), resulted in a favorable conditions for species accumulation of ambrosia. The overall biological pattern among guilds differed from tropical rain forests, showing patterns similar to dry forest areas. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

Protozoans bacterivory in a subtropical environment during a dry/cold and a rainy/warm season

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Karina F. Hisatugo

2014-01-01

Full Text Available In aquatic ecosystems, bacteria are controlled by several organisms in the food chain, such as protozoa, that use them as food source. This study aimed to quantify the ingestion and clearance rates of bacteria by ciliates and heterotrophic nanoflagellates (HNF in a subtropical freshwater reservoir (Monjolinho reservoir -São Carlos -Brazil during one year period, in order to verify their importance as consumers and controllers of bacteria in two seasons, a dry/cold and a rainy/warm one. For this purpose, in situ bacterivory experiments were carried out bimonthly using fluorescently labeled bacteria with 5-(4,6 diclorotriazin-2yl aminofluorescein (DTAF. Although ciliates have shown the highest individual ingestion and clearance rates, bacterivory was dominated by HNF, who showed higher population ingestion rates (mean of 9,140 bacteria h-1mL-1 when compared to ciliates (mean of 492 bacteria h-1mL-1. The greater predation impact on bacterial communities was caused mainly by the small HNF (< 5 µm population, especially in the rainy season, probably due to the abundances of these organisms, the precipitation, trophic index state and water temperature that were higher in this period. Thus, the protozoan densities together with environmental variables were extremely relevant in determining the seasonal pattern of bacterivory in Monjolinho reservoir.

Microhabitat partitioning between leiuperidae and bufonidae species (amphibia: anura) in tropical dry forest areas in Colombian Caribbean

International Nuclear Information System (INIS)

Blanco Torres, Argelina; Bonilla Gomez, Maria Argenis

2010-01-01

We analyzed partitioning of microhabitats by five species of frogs in the families, Bufonidae (Rhinella marina, r. granulosa), and Leiuperidae (Engystomops pustulosus, Pleurodema brachyops and Pseudopaludicola pusilla) in six different localities of the Colombian Caribbean with tropical dry forest fragments and different land uses. We identified 29 types of microhabitats; permanent ponds in pastures with trees (CPPA) and flooded pastures without trees (PISA) were the most important environmental used. Engystomops pustulosus used the must microhabitats, and none are used by specialist species. Thus, differences in the use of resource on regional and local scales appeared. Dynamics of microhabitat uses was influenced by the climatic variations of the tropical dry forest. Microhabitats distribution as a mechanism of coexistence in these species is implemented for dry season but in rainfall season this mechanism not exists.

Effect of gamma irradiation on the qualitative characteristics of freeze dried forest fruits

International Nuclear Information System (INIS)

Nacheva, I; Miteva, P.; Metodieva, P.; Todorova, Ya.; Loginovska, K.

2012-01-01

The purpose of the present investigation was to establish the effect of a combined technological processing - freeze drying and gamma sterilization - with irradiation doses of 2 and 4 kGy on the qualitative characteristics on a set of forest fruits - blackberry, blueberry, aronia, strawberry and black elder. The results prove that the freeze drying technology and the applied irradiation dose of 2 kGy is sufficient to preserve the quality and prolong the shelf life of the studied products without damage of their physical-chemical and microbiological characteristics

Input and output of dissolved organic and inorganic nitrogen in subtropical forests of South China under high air pollution

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Y. T. Fang

2008-03-01

Full Text Available The nitrogen (N emissions to the atmosphere and N deposition to forest ecosystems are increasing rapidly in Southeast Asia, but little is known about the fates and effects of elevated N deposition in forest ecosystems in this warm and humid region. Here we report the concentrations and fluxes of dissolved inorganic (DIN and organic N (DON in precipitation, throughfall, surface runoff and soil solution for three subtropical forests in a region of South China under high air pollution over two years (2004 and 2005, to investigate how deposited N is processed, and to examine the importance of DON in the N budget. The precipitation DIN input was 32–34 kg N ha⁻¹ yr⁻¹. An additional input of 18 kg N ha⁻¹ yr⁻¹ as DON was measured in 2005, which to our knowledge is the highest DON flux ever measured in precipitation. A canopy uptake of DIN was indicated in two young conifer dominated forests (72–85% of DIN input reached the floor in throughfall, whereas no uptake occurred in an old-growth broadleaf forest. The DON fluxes in throughfall were similar to that in precipitation in all forests. In the younger forests, DIN was further retained in the soil, with 41–63% of precipitation DIN leached below the 20-cm soil depth. Additionally, about half of the DON input was retained in these forests. The N retention in two young aggrading forests (21–28 kg N ha⁻¹ yr⁻¹ was in accordance with the estimates of N accumulation in biomass and litter accretion. In the old-growth forest, no N retention occurred, but rather a net loss of 8–16 kg N ha⁻¹ yr⁻¹ from the soil was estimated. In total up to 60 kg N ha⁻¹ yr⁻¹ was leached from the old-growth forest, indicating that this forest was completely N saturated and could not retain additional anthropogenic N inputs. We found that the majority of DIN deposition as well as of DIN leaching

Impact of livestock on a mosquito community (Diptera: Culicidae) in a Brazilian tropical dry forest

OpenAIRE

Santos,Cleandson Ferreira; Borges,Magno

2015-01-01

AbstractINTRODUCTION: This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil.METHODS: Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models.RESULTS: Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition.CO...

Dry deposition of sulfur: a 23-year record for the Hubbard Brook Forest ecosystem

Energy Technology Data Exchange (ETDEWEB)

Likens, G E; Eaton, J S [Inst. of Ecosystem Studies, The New York Botanical Garden, NY (US); Bormann, F H [School of Forestry and Environmental Studies Yale Univ., New Haven, CT (US); Hedin, L O [Dept. of Biology, Yale Univ., New Haven, CT (US); Driscoll, C T [Dept. of Civil and Environmental Engineering, Syracuse, NY (US)

1990-01-01

Dry deposition of S was estimated for watershed-ecosystems of the Hubbard Brook Experimental Forest from 1964-65 through 1986-87. Two approaches, a regression analysis of bulk precipitation inputs and stream outputs and a mass-balance method, gave similar average values for Watershed 6 430 and 410 eq SO{sub 4}{sup =}/ha-yr, respectively, for this 23-year period. Dry deposition contributed about 37% of total S deposition, varying from 12% in 1964-65 to 61% in 1983-84. Long-term data from 'replicated' watershed-ecosystems showed that temporal variability in estimates of dry deposition was considerably greater than spatial (between watersheds) variability.

Bark traits and life-history strategies of tropical dry- and moist forest trees

NARCIS (Netherlands)

Poorter, L.; McNeil, A.; Hurtado, V.H.; Prins, H.H.T.; Putz, F.E.

2014-01-01

1.Bark is crucial to trees because it protects their stems against fire and other hazards and because of its importance for assimilate transport, water relationships and repair. We evaluate size-dependent changes in bark thickness for 50 woody species from a moist forest and 50 species from a dry

Post-fire regeneration in seasonally dry tropical forest fragments in southeastern Brazil.

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Costa, Mayke B; Menezes, Luis Fernando T DE; Nascimento, Marcelo T

2017-01-01

Seasonally dry tropical forest is one of the highly threatened biome. However, studies on the effect of fire on these tree communities are still scarce. In this context, a floristic and structural survey in three forest areas in the southeast of Brazil that were affected by fire between 14 and 25 years ago was performed with the objective of evaluating post-fire regeneration. In each site, five systematically placed plots (25 m x 25 m each) were established. The more recently burnt site had significantly lower values of richness and diversity than the other two sites. However, the sites did not differ in density and basal area. Annona dolabripetala, Astronium concinnum, Joannesia princeps and Polyandrococos caudescens were within the 10 most important species for the three sites. Comparing these data with adjacent mature forests, the results indicated differences both in structural and floristic aspects, suggesting that the time after fire was not sufficient for recuperation of these areas. The recovery process indicate at least 190 years for areas return to basal area values close to those observed in mature forests nearby.

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.

Serological Survey of Hantavirus in Inhabitants from Tropical and Subtropical Areas of Brazil

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Felipe Alves Morais

2016-01-01

Full Text Available Brazil has reported more than 1,600 cases of hantavirus cardiopulmonary syndrome (HPS since 1993, with a 39% rate of reported fatalities. Using a recombinant nucleocapsid protein of Araraquara virus, we performed ELISA to detect IgG antibodies against hantavirus in human sera. The aim of this study was to analyze hantavirus antibody levels in inhabitants from a tropical area (Amazon region in Rondônia state and a subtropical (Atlantic Rain Forest region in São Paulo state, Brazil. A total of 1,310 serum samples were obtained between 2003 and 2008 and tested by IgG-ELISA, and 82 samples (6.2%, of which 62 were from the tropical area (5.8% and 20 from the subtropical area (8.3%, tested positive. Higher levels of hantavirus antibody were observed in inhabitants of the populous subtropical areas compared with those from the tropical areas in Brazil.

Changes in Photosystem Ⅱ Activity and Leaf Reflectance Features of Several Subtropical Woody Plants Under Simulated SO2 Treatment

Institute of Scientific and Technical Information of China (English)

Nan Liu; Chang-Lian Peng; Zhi-Fang Lin; Gui-Zhu Lin; Ling-Ling Zhang; Xiao-Ping Pan

2006-01-01

The effects of simulated SO2 treatment on the photosynthetic apparatus were investigated in five subtropical forest plants, namely Pinus massoniana Lamb., Schima superba Gardn. et Champ., Castanopsis fissa (Champ. ex Benth.) Rehd. et Wils., Acmena acuminatissima (BI.) Merr et Perry, and Cryptocarya concinna Hance. After leaf sections had been immersed in 0, 20, 50, and 100 mmol/L NaHSO3 for 20 h, total chlorophyll (Chl) content, Chl a/b, maximal photochemical efficiency, and the photochemical quantum yields of photosystem Ⅱ of all five woody plants were reduced to different degrees, whereas lutein content (Chl base) was increased. Two protective mechanisms, namely the xanthophyll cycle (de-epoxidation) and an anti-oxidant system (1,1-diphenyl-2-picrylhydrazyl radical-scavenging capacity), showed differences in the degree of modulation under simulated SO2 treatment. Compared with control (distilled water treatment), the revised normalized difference vegetation index, a leaf reflectance index, was lowered with increasing concentrations of NaHSO3. Cryptocarya concinna, a dominant species in the late succession stage of subtropical forests in South China, exhibited less sensitivity to NaHSO3. Conversely, Pinus massoniana, the pioneer heliophyte species, was most susceptible to NaHSO3 treatment. It is suggested that SO2 pollution may accelerate the succession of subtropical forest.

How did climate drying reduce ecosystem carbon storage in the forest-steppe ecotone? A case study in Inner Mongolia, China.

Science.gov (United States)

Zhang, Yuke; Liu, Hongyan

2010-07-01

The projected recession of forests in the forest-steppe ecotone under projected climate drying would restrict the carbon sink function of terrestrial ecosystems. Previous studies have shown that the forest-steppe ecotone in the southeastern Inner Mongolia Plateau originally resulted from climate drying and vegetation shifts during the mid- to late-Holocene, but the interrelated processes of changing soil carbon storage and vegetation and soil shifts remain unclear. A total of 44 forest soil profiles and 40 steppe soil profiles were excavated to determine soil carbon storage in deciduous broadleaf forests (DBF), coniferous forests (CF) and steppe (ST) in this area. Carbon density was estimated to be 106.51 t/hm(2) (DBF), 73.20 t/hm(2) (CF), and 28.14 t/hm(2) (ST) for these ecosystems. Soil organic carbon (SOC) content was negatively correlated with sand content (R = -0.879, P ecotone. Changes in carbon storage caused by climate drying can be divided into two stages: (1) carbon storage of the ecosystem was reduced to 68.7%, mostly by soil coarsening when DBF were replaced by CF at approximately 5,900 (14)C years before present (BP); and (2) carbon storage was reduced to 26.4%, mostly by vegetation shifts when CF were replaced by ST at approximately 2,900 (14)C years BP.

Birds surveyed in the harvested and unharvested areas of a reduced-impact logged forestry concession, located in the lowland subtropical humid forests of the Department of Santa Cruz, Bolivia.

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Felton, A.

2007-01-01

Full Text Available As part of a larger study of reduced-impactlogging effects on bird community composition,we surveyed birds from December to Februaryduring the 2003-2004 wet-season within harvestedand unharvested blocks of the La Chonta forestryconcession, Department of Santa Cruz, Bolivia.The logged forest was harvested using reduced-impactlogging techniques between one and fouryears previously. During point count surveys, weidentified 5062 individual birds, belonging to 155species, and 33 families. We provide a list of birdspecies found within the harvested andunharvested blocks of the concession for thebenefit of other researchers assessing theresponses of Neotropical avifauna to disturbance,and to facilitate increased understanding of thediverse bird assemblages found within thelowland subtropical humid forests of Bolivia.

Biomass and nutrient dynamics associated with slash fires in neotropical dry forests

International Nuclear Information System (INIS)

Kauffman, J.B.; Cummings, D.L.; Sanford, R.L. Jr.; Salcedo, I.H.; Sampaio, E.V.S.B.

1993-01-01

Unprecedented rates of deforestation and biomass burning in tropical dry forests are dramatically influencing biogeochemical cycles, resulting in resource depletion, declines in biodiversity, and atmospheric pollution. We quantified the effects of deforestation and varying levels of slash-fire severity on nutrient losses and redistribution in a second-growth tropical dry forest (open-quotes Caatingaclose quotes) near Serra Talhada, Pernambuco, Brazil. Total aboveground biomass prior to burning was ∼74 Mg/ha. Nitrogen and phosphorus concentrations were highest in litter, leaves attached to slash, and fine wood debris (< O.64 cm diameter). While these components comprised only 30% of the prefire aboveground biomass, they accounted for ∼60% of the aboveground pools of N and P. Three experimental fires were conducted during the 1989 burning season. Consumption was 78, 88, and 95% of the total aboveground biomass. As much as 96% of the prefire aboveground N and C pools and 56% of the prefire aboveground P pool was lost. Nitrogen losses exceeded 500 kg/ha and P losses exceeded 20 kg/ha in the fires of the greatest severity. With increasing fire severity, the concentrations of N and P in ash decreased while the concentration of Ca increased. Greater ecosystem losses of these nutrients occurred with increasing fire severity. Following fire, up to 47% of the residual aboveground N and 84% of the residual aboveground P were in the form of ash, quickly lost from the site via wind erosion. Fires appeared to have a minor immediate effect on total N, C, or P in the soils. However, soils in forests with no history of cultivation had significantly higher concentrations of C and P than second-growth forests. It would likely require a century or more of fallow for reaccumulation to occur. However, current fallow periods in this region are 15 yr or less. 38 refs., 2 figs., 7 tabs

Succesional change and resilience of a very dry tropical deciduous forest following shifting agriculture

NARCIS (Netherlands)

Lebrija Trejos, E.E.; Bongers, F.J.J.M.; Pérez-García, E.; Meave, J.

2008-01-01

We analyzed successional patterns in a very dry tropical deciduous forest by using 15 plots differing in age after abandonment and contrasted them to secondary successions elsewhere in the tropics. We used multivariate ordination and nonlinear models to examine changes in composition and structure

Determinants of Tree Assemblage Composition at the Mesoscale within a Subtropical Eucalypt Forest

Science.gov (United States)

Hero, Jean-Marc; Butler, Sarah A.; Lollback, Gregory W.; Castley, James G.

2014-01-01

A variety of environmental processes, including topography, edaphic and disturbance factors can influence vegetation composition. The relative influence of these patterns has been known to vary with scale, however, few studies have focused on environmental drivers of composition at the mesoscale. This study examined the relative importance of topography, catchment flow and soil in influencing tree assemblages in Karawatha Forest Park; a South-East Queensland subtropical eucalypt forest embedded in an urban matrix that is part of the Terrestrial Ecosystem Research Network South-East Queensland Peri-urban SuperSite. Thirty-three LTER plots were surveyed at the mesoscale (909 ha), where all woody stems ≥1.3 m high rooted within plots were sampled. Vegetation was divided into three cohorts: small (≥1–10 cm DBH), intermediate (≥10–30 cm DBH), and large (≥30 cm DBH). Plot slope, aspect, elevation, catchment area and location and soil chemistry and structure were also measured. Ordinations and smooth surface modelling were used to determine drivers of vegetation assemblage in each cohort. Vegetation composition was highly variable among plots at the mesoscale (plots systematically placed at 500 m intervals). Elevation was strongly related to woody vegetation composition across all cohorts (R2: 0.69–0.75). Other topographic variables that explained a substantial amount of variation in composition were catchment area (R2: 0.43–0.45) and slope (R2: 0.23–0.61). Soil chemistry (R2: 0.09–0.75) was also associated with woody vegetation composition. While species composition differed substantially between cohorts, the environmental variables explaining composition did not. These results demonstrate the overriding importance of elevation and other topographic features in discriminating tree assemblage patterns irrespective of tree size. The importance of soil characteristics to tree assemblages was also influenced by topography, where ridge top sites were

Disentangling the effects of shrubs and herbivores on tree regeneration in a dry Chaco forest (Argentina).

Science.gov (United States)

Tálamo, Andrés; Barchuk, Alicia H; Garibaldi, Lucas A; Trucco, Carlos E; Cardozo, Silvana; Mohr, Federico

2015-07-01

Successful persistence of dry forests depends on tree regeneration, which depends on a balance of complex biotic interactions. In particular, the relative importance and interactive effects of shrubs and herbivores on tree regeneration are unclear. In a manipulative study, we investigated if thornless shrubs have a direct net effect, an indirect positive effect mediated by livestock, and/or an indirect negative effect mediated by small vertebrates on tree regeneration of two key species of Chaco forest (Argentina). In a spatial association study, we also explored the existence of net positive interactions from thorny and thornless shrubs. The number of Schinopsis lorentzii seedlings was highest under artificial shade with native herbivores and livestock excluded. Even excluding livestock, no seedlings were found with natural conditions (native herbivores present with natural shade or direct sunlight) at the end of the experiment. Surprisingly, seedling recruitment was not enhanced under thornless shrubs, because there was a complementary positive effect of shade and interference. Moreover, thornless shrubs had neither positive nor negative effects on regeneration of S. lorentzii. Regeneration of Aspidosperma quebracho-blanco was minimal in all treatments. In agreement with the experiment, spatial distributions of saplings of both tree species were independent of thornless shrubs, but positively associated with thorny shrubs. Our results suggest that in general thornless shrubs may have a negligible effect and thorny shrubs a net positive effect on tree regeneration in dry forests. These findings provide a conceptual framework for testing the impact of biotic interactions on seedling recruitment in other dry forests.

Temporal Changes in Forest Contexts at Multiple Extents: Three Decades of Fragmentation in the Gran Chaco (1979-2010), Central Argentina

Science.gov (United States)

Frate, Ludovico; Acosta, Alicia T. R.; Cabido, Marcelo; Hoyos, Laura; Carranza, Maria Laura

2015-01-01

The context in which a forest exists strongly influences its function and sustainability. Unveiling the multi-scale nature of forest fragmentation context is crucial to understand how human activities affect the spatial patterns of forests across a range of scales. However, this issue remains almost unexplored in subtropical ecosystems. In this study, we analyzed temporal changes (1979–2010) in forest contexts in the Argentinean dry Chaco at multiple extents. We classified forests over the last three decades based on forest context amount (P f) and structural connectivity (P ff), which were measured using a moving window approach fixed at eight different extents (from local, ~ 6 ha, to regional, ~ 8300 ha). Specific multi-scale forest context profiles (for the years 1979 and 2010) were defined by projecting P f vs. P ff mean values and were compared across spatial extents. The distributions of P f across scales were described by scalograms and their shapes over time were compared. The amount of agricultural land and rangelands across the scales were also analyzed. The dry Chaco has undergone an intensive process of fragmentation, resulting in a shift from landscapes dominated by forests with gaps of rangelands to landscapes where small forest patches are embedded in agricultural lands. Multi-scale fragmentation analysis depicted landscapes in which local exploitation, which perforates forest cover, occurs alongside extensive forest clearings, reducing forests to small and isolated patches surrounded by agricultural lands. In addition, the temporal diminution of P f’s variability along with the increment of the mean slope of the P f ‘s scalograms, indicate a simplification of the spatial pattern of forest over time. The observed changes have most likely been the result of the interplay between human activities and environmental constraints, which have shaped the spatial patterns of forests across scales. Based on our results, strategies for the conservation

Regulation of Light Energy Utilization and Distribution of Photosynthesis in Five Subtropical Woody Plants

Institute of Scientific and Technical Information of China (English)

Nan Liu; Chang-Lian Peng; Zhi-Fang Lin; Gui-Zhu Lin; Xiao-Ping Pan

2007-01-01

The adaptations and responses of photosynthesis to long- and short-term growth light gradient treatments were investigated in five subtropical forest plants, namely Pinus massoniana Lamb., Schima superba Gardn. et Champ.,Castanopsis fissa (Champ. ex Benth.) Rehd. et Wils., Acmena acuminatissima (BI.) Merr et Perry, and Cryptocarya concinna Hance. With diurnal changes in sunlight and air temperature, the de-epoxidation state and lutein content in the five woody plants under three light intensifies first increased and then decreased during the day. However,maximal photochemical efficiency (Fv/Fm; where Fm is the maximum fluorescence yield and Fv is variable fluorescence) and the photochemical quantum yields of photosystem (PS) Ⅱ (ΦPSII) of the species examined changed in the opposite manner, with those in plants grown under 100% natural light changing the most. After long-term treatment (21 months), anti-oxidant capacity (1,1-diphenyl-2-picrylhydrazyl radical (DPPH·)-scavenging capacity) and utilization of excitation energy showed differences in modulation by different light intensities. It was shown that A.acuminatissima and C. concinna, as dominant species in the late succession stage of a subtropical forest in Dinghu mountain, South China, were better able to adapt to different light environments. However, P. massoniana, the pioneer species of this forest, exhibited less adaptation to Iow light intensity and was definitely eliminated by the forest successlon process.

Multi-scale forcing and the formation of subtropical desert and monsoon

Directory of Open Access Journals (Sweden)

G. X. Wu

2009-09-01

Full Text Available This study investigates three types of atmospheric forcing across the summertime subtropics that are shown to contribute in various ways to the occurrence of dry and wet climates in the subtropics. To explain the formation of desert over the western parts of continents and monsoon over the eastern parts, we propose a new mechanism of positive feedback between diabatic heating and vorticity generation that occurs via meridional advection of planetary vorticity and temperature. Monsoon and desert are demonstrated to coexist as twin features of multi-scale forcing, as follows. First, continent-scale heating over land and cooling over ocean induce the ascent of air over the eastern parts of continents and western parts of oceans, and descent over eastern parts of oceans and western parts of continents. Second, local-scale sea-breeze forcing along coastal regions enhances air descent over eastern parts of oceans and ascent over eastern parts of continents. This leads to the formation of the well-defined summertime subtropical LOSECOD quadruplet-heating pattern across each continent and adjacent oceans, with long-wave radiative cooling (LO over eastern parts of oceans, sensible heating (SE over western parts of continents, condensation heating (CO over eastern parts of continents, and double dominant heating (D: LO+CO over western parts of oceans. Such a quadruplet heating pattern corresponds to a dry climate over the western parts of continents and a wet climate over eastern parts. Third, regional-scale orographic-uplift-heating generates poleward ascending flow to the east of orography and equatorward descending flow to the west. The Tibetan Plateau (TP is located over the eastern Eurasian continent. The TP-forced circulation pattern is in phase with that produced by continental-scale forcing, and the strongest monsoon and largest deserts are formed over the Afro-Eurasian Continent. In contrast, the Rockies and the Andes are located over the western

Multi-scale forcing and the formation of subtropical desert and monsoon

Directory of Open Access Journals (Sweden)

G. X. Wu

2009-09-01

Full Text Available This study investigates three types of atmospheric forcing across the summertime subtropics that are shown to contribute in various ways to the occurrence of dry and wet climates in the subtropics. To explain the formation of desert over the western parts of continents and monsoon over the eastern parts, we propose a new mechanism of positive feedback between diabatic heating and vorticity generation that occurs via meridional advection of planetary vorticity and temperature. Monsoon and desert are demonstrated to coexist as twin features of multi-scale forcing, as follows.

First, continent-scale heating over land and cooling over ocean induce the ascent of air over the eastern parts of continents and western parts of oceans, and descent over eastern parts of oceans and western parts of continents. Second, local-scale sea-breeze forcing along coastal regions enhances air descent over eastern parts of oceans and ascent over eastern parts of continents. This leads to the formation of the well-defined summertime subtropical LOSECOD quadruplet-heating pattern across each continent and adjacent oceans, with long-wave radiative cooling (LO over eastern parts of oceans, sensible heating (SE over western parts of continents, condensation heating (CO over eastern parts of continents, and double dominant heating (D: LO+CO over western parts of oceans. Such a quadruplet heating pattern corresponds to a dry climate over the western parts of continents and a wet climate over eastern parts. Third, regional-scale orographic-uplift-heating generates poleward ascending flow to the east of orography and equatorward descending flow to the west.

The Tibetan Plateau (TP is located over the eastern Eurasian continent. The TP-forced circulation pattern is in phase with that produced by continental-scale forcing, and the strongest monsoon and largest deserts are formed over the Afro-Eurasian Continent. In contrast, the Rockies and the Andes are

Isolation with asymmetric gene flow during the nonsynchronous divergence of dry forest birds.

Science.gov (United States)

Oswald, Jessica A; Overcast, Isaac; Mauck, William M; Andersen, Michael J; Smith, Brian Tilston

2017-03-01

Dry forest bird communities in South America are often fragmented by intervening mountains and rainforests, generating high local endemism. The historical assembly of dry forest communities likely results from dynamic processes linked to numerous population histories among codistributed species. Nevertheless, species may diversify in the same way through time if landscape and environmental features, or species ecologies, similarly structure populations. Here we tested whether six co-distributed taxon pairs that occur in the dry forests of the Tumbes and Marañón Valley of northwestern South America show concordant patterns and modes of diversification. We employed a genome reduction technique, double-digest restriction site-associated DNA sequencing, and obtained 4407-7186 genomewide SNPs. We estimated demographic history in each taxon pair and inferred that all pairs had the same best-fit demographic model: isolation with asymmetric gene flow from the Tumbes into the Marañón Valley, suggesting a common diversification mode. Overall, we also observed congruence in effective population size (N e ) patterns where ancestral N e were 2.9-11.0× larger than present-day Marañón Valley populations and 0.3-2.0× larger than Tumbesian populations. Present-day Marañón Valley N e was smaller than Tumbes. In contrast, we found simultaneous population isolation due to a single event to be unlikely as taxon pairs diverged over an extended period of time (0.1-2.9 Ma) with multiple nonoverlapping divergence periods. Our results show that even when populations of codistributed species asynchronously diverge, the mode of their differentiation can remain conserved over millions of years. Divergence by allopatric isolation due to barrier formation does not explain the mode of differentiation between these two bird assemblages; rather, migration of individuals occurred before and after geographic isolation. © 2017 John Wiley & Sons Ltd.

Ammonia-Oxidizing Archaea Are More Resistant Than Denitrifiers to Seasonal Precipitation Changes in an Acidic Subtropical Forest Soil

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Jie Chen

2017-07-01

Full Text Available Seasonal precipitation changes are increasingly severe in subtropical areas. However, the responses of soil nitrogen (N cycle and its associated functional microorganisms to such precipitation changes remain unclear. In this study, two projected precipitation patterns were manipulated: intensifying the dry-season drought (DD and extending the dry-season duration (ED but increasing the wet-season storms following the DD and ED treatment period. The effects of these two contrasting precipitation patterns on soil net N transformation rates and functional gene abundances were quantitatively assessed through a resistance index. Results showed that the resistance index of functional microbial abundance (-0.03 ± 0.08 was much lower than that of the net N transformation rate (0.55 ± 0.02 throughout the experiment, indicating that microbial abundance was more responsive to precipitation changes compared with the N transformation rate. Spring drought under the ED treatment significantly increased the abundances of both nitrifying (amoA and denitrifying genes (nirK, nirS, and nosZ, while changes in these gene abundances overlapped largely with control treatment during droughts in the dry season. Interestingly, the resistance index of the ammonia-oxidizing archaea (AOA amoA abundance was significantly higher than that of the denitrifying gene abundances, suggesting that AOA were more resistant to the precipitation changes. This was attributed to the stronger environmental adaptability and higher resource utilization efficiency of the AOA community, as indicated by the lack of correlations between AOA gene abundance and environmental factors [i.e., soil water content, ammonium (NH4+ and dissolved organic carbon concentrations] during the experiment.

Effects of land use change on soil gross nitrogen transformation rates in subtropical acid soils of Southwest China.

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Xu, Yongbo; Xu, Zhihong

2015-07-01

Land use change affects soil gross nitrogen (N) transformations, but such information is particularly lacking under subtropical conditions. A study was carried out to investigate the potential gross N transformation rates in forest and agricultural (converted from the forest) soils in subtropical China. The simultaneously occurring gross N transformations in soil were quantified by a (15)N tracing study under aerobic conditions. The results showed that change of land use types substantially altered most gross N transformation rates. The gross ammonification and nitrification rates were significantly higher in the agricultural soils than in the forest soils, while the reverse was true for the gross N immobilization rates. The higher total carbon (C) concentrations and C / N ratio in the forest soils relative to the agricultural soils were related to the greater gross N immobilization rates in the forest soils. The lower gross ammonification combined with negligible gross nitrification rates, but much higher gross N immobilization rates in the forest soils than in the agricultural soils suggest that this may be a mechanism to effectively conserve available mineral N in the forest soils through increasing microbial biomass N, the relatively labile organic N. The greater gross nitrification rates and lower gross N immobilization rates in the agricultural soils suggest that conversion of forests to agricultural soils may exert more negative effects on the environment by N loss through NO3 (-) leaching or denitrification (when conditions for denitrification exist).

[Comparison of heavy metal elements between natural and plantation forests in a subtropical Montane forest].

Science.gov (United States)

Nie, Ming; Wan, Jia-Rong; Chen, Xiao-Feng; Wang, Li; Li, Bo; Chen, Jia-Kuan

2011-11-01

Heavy metals as one of major pollutants is harmful to the health of forest ecosystems. In the present paper, the concentrations of thirteen heavy metals (Fe, Al, Ti, Cr, Cu, Mn, V, Zn, Ni, Co, Pb, Se and Cd) were compared between natural and plantation forests in the Mt. Lushan by ICP-AES and atomic absorption spectroscopy. The results suggest that the soil of natural forest had higher concentrations of Fe, Al, Ti, Cu, Mn, V, Zn, Ni, Co, Pb, Se, and Cd than the plantation forest except for Cr. The soil of natural forest had a higher level of heavy metals than that of the plantation forest as a whole. This might be due to that the natural forest has longer age than the plantation forest, and fixed soil heavy metals take a longer period of time than the plantation forest.

Comparison of Ant Community Diversity and Functional Group Composition Associated to Land Use Change in a Seasonally Dry Oak Forest.

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Cuautle, M; Vergara, C H; Badano, E I

2016-04-01

Ants have been used to assess land use conversion, because they reflect environmental change, and their response to these changes have been useful in the identification of bioindicators. We evaluated ant diversity and composition associated to different land use change in a temperate forest (above 2000 m asl) in Mexico. The study was carried out in "Flor del Bosque" Park a vegetation mosaic of native Oak Forests and introduced Eucalyptus and grasslands. Species richness, dominance and diversity rarefaction curves, based on ant morphospecies and functional groups, were constructed and compared among the three vegetation types, for the rainy and the dry seasons of 2008-2009. Jaccard and Sorensen incidence-based indices were calculated to obtain similarity values among all the habitats. The Oak Forest was a rich dominant community, both in species and functional groups; the Eucalyptus plantation was diverse with low dominance. The most seasonality habitat was the grassland, with low species and high functional group diversity during the dry seasons, but the reverse pattern during the wet season. The Oak Forest was more similar to the Eucalyptus plantation than to the grassland, particularly during the dry season. Oak Forests are dominated by Cold Climate Specialists, specifically Prenolepis imparis (Say). The Eucalyptus and the grassland are characterized by generalized Myrmicinae, as Pheidole spp. and Monomorium ebenium (Forel). The conservation of the native Oak Forest is primordial for the maintenance of Cold Climate Specialist ant communities. The microclimatic conditions in this forest, probably, prevented the invasion by opportunistic species.

The impact of an invasive African bunchgrass (Pennisetum setaceum) on water availability and productivity of canopy trees within a tropical dry forest in Hawaii

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Susan Cordell; D. R. Sandquist

2008-01-01

Tropical dry forests are among the Earth's most threatened ecosystems. On the Island of Hawaii the African bunchgrass Pennisetum setaceum (fountain grass) dominates the understorey of the few remaining fragments of native dry forests and is contributing to the degradation of this once diverse ecosystem. In this study, we...

Resource partitioning by evergreen and deciduous species in a tropical dry forest.

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Álvarez-Yépiz, Juan C; Búrquez, Alberto; Martínez-Yrízar, Angelina; Teece, Mark; Yépez, Enrico A; Dovciak, Martin

2017-02-01

Niche differentiation can lead to coexistence of plant species by partitioning limiting resources. Light partitioning promotes niche differentiation in tropical humid forests, but it is unclear how niche partitioning occurs in tropical dry forests where both light and soil resources can be limiting. We studied the adult niche of four dominant evergreen (cycad, palm) and drought-deciduous (legume, oak) species co-occurring along environmental gradients. We analyzed light intensity and soil fertility effects on key functional traits related to plant carbon and water economy, how these traits determine species' functional strategies, and how these strategies relate to relative species abundance and spatial patterns. Light intensity was negatively associated with a key trait linked to plant water economy (leaf δ 13 C, a proxy for long-term water-use efficiency-WUE), while soil fertility was negatively associated with a key trait for plant carbon economy (LNC, leaf nitrogen content). Evergreens were highly sclerophyllous and displayed an efficient water economy but poor carbon economy, in agreement with a conservative resource-use strategy (i.e., high WUE but low LNC, photosynthetic rates and stature). Conversely, deciduous species, with an efficient carbon economy but poor water economy, exhibited an exploitative resource-use strategy (i.e., high LNC, photosynthetic rates and stature, but low WUE). Evergreen and deciduous species segregated spatially, particularly at fine-scales, as expected for species with different resource-use strategies. The efficient water economy of evergreens was related to their higher relative abundance, suggesting a functional advantage against drought-deciduous species in water-limited environments within seasonally dry tropical forests.

Dry coniferous forest restoration and understory plant diversity: The importance of community heterogeneity and the scale of observation

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Erich Kyle Dodson; David W. Peterson

2010-01-01

Maintaining understory plant species diversity is an important management goal as forest restoration and fuel reduction treatments are applied extensively to dry coniferous forests of western North America. However, understory diversity is a function of both local species richness (number of species in a sample unit) and community heterogeneity (beta diversity) at...

Successional position of dry Andean dwarf forest species as a basis for restoration trials

NARCIS (Netherlands)

Groenendijk, J.P.; Duivenvoorden, J.F.; Cleef, A.M.; Rietman, N.

2005-01-01

The successional affinity of nine woody species was inferred from the structure, diversity and disturbance history of the vegetation where these occurred. This was done in order to obtain a basis for a restoration experiment, currently in execution, in the dry Andean dwarf forest zone on the edge of

Mixed-Severity Fire Fosters Heterogeneous Spatial Patterns of Conifer Regeneration in a Dry Conifer Forest

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Sparkle L. Malone

2018-01-01

Full Text Available We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11–12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving trees, in three 4-ha plots following the 2002 Hayman Fire. Residual tree density ranged from 167 to 197 trees ha−1 (TPH, and these trees were clustered at distances up to 30 m. Post-fire regenerating conifers, which ranged in density from 241 to 1036 TPH, were also clustered at distances up to at least 30 m. Moreover, residual tree locations drove post-fire regenerating conifer locations, with the two showing a pattern of repulsion. Topography and post-fire sprouting tree species locations further drove post-fire conifer regeneration locations. These results provide a foundation for anticipating how the reintroduction of mixed-severity fire may affect long-term forest structure, and also yield insights into how historical mixed-severity fire may have regulated the spatially heterogeneous conditions commonly described for pre-settlement dry conifer forests of Colorado and elsewhere.

Late glacial and Holocene history of the dry forest area in south Colombian Cauca Valley from sites Quilichao and la Teta

International Nuclear Information System (INIS)

Berrio, Juan Carlos; Hooghiemstra, Henry; Marchant, Rob; Rangel Orlando

2002-01-01

Two sedimentary cores with records of pollen and charcoal content within a chronology provided by radiocarbon are presented from the southern Cauca Valley in Colombia (1020 m). These records document the late glacial and Holocene dry forest vegetation, fire and environment history. Specifically, core Quilichao -1 (640 cm; 3 degrade 6' N, 76 degrade 31' W) represents the periods of 13/150-7720 14 C yr BP and following a hiatus from 2880 14 C yr BP to recent. Core la Teta - 2 (250 cm; 3 degrade 5' N, 76 degrade 32' W) provides a record from 8700 14 C yr BP around 13/150 21 4 C yr BP Quilichao shown an active late glacial drainage system and presence of dry forest. From 11/465-10/520 14 C yr BP dry forest consists mainly of Crotalaria Moraceae Urticaceae, Melastomataceae, Piper and low stature trees, such as Acalypha, Alchornea, Cecropia and Celtis. At higher elevation on the slopes Andean forest with Quercus, Hedyosmum, Myrica and Alnus are common

Evaluate dry deposition velocity of the nitrogen oxides using Noah-MP physics ensemble simulations for the Dinghushan Forest, Southern China

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Zhang, Qi; Chang, Ming; Zhou, Shengzhen; Chen, Weihua; Wang, Xuemei; Liao, Wenhui; Dai, Jianing; Wu, ZhiYong

2017-11-01

There has been a rapid growth of reactive nitrogen (Nr) deposition over the world in the past decades. The Pearl River Delta region is one of the areas with high loading of nitrogen deposition. But there are still large uncertainties in the study of dry deposition because of its complex processes of physical chemistry and vegetation physiology. At present, the forest canopy parameterization scheme used in WRF-Chem model is a single-layer "big leaf" model, and the simulation of radiation transmission and energy balance in forest canopy is not detailed and accurate. Noah-MP land surface model (Noah-MP) is based on the Noah land surface model (Noah LSM) and has multiple parametric options to simulate the energy, momentum, and material interactions of the vegetation-soil-atmosphere system. Therefore, to investigate the improvement of the simulation results of WRF-Chem on the nitrogen deposition in forest area after coupled with Noah-MP model and to reduce the influence of meteorological simulation biases on the dry deposition velocity simulation, a dry deposition single-point model coupled by Noah- MP and the WRF-Chem dry deposition module (WDDM) was used to simulate the deposition velocity (Vd). The model was driven by the micro-meteorological observation of the Dinghushan Forest Ecosystem Location Station. And a series of numerical experiments were carried out to identify the key processes influencing the calculation of dry deposition velocity, and the effects of various surface physical and plant physiological processes on dry deposition were discussed. The model captured the observed Vd well, but still underestimated the Vd. The self-defect of Wesely scheme applied by WDDM, and the inaccuracy of built-in parameters in WDDM and input data for Noah-MP (e.g. LAI) were the key factors that cause the underestimation of Vd. Therefore, future work is needed to improve model mechanisms and parameterization.

Forecasting carbon budget under climate change and CO2 fertilization for subtropical region in China using integrated biosphere simulator (IBIS) model

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Zhu, Q.; Jiang, H.; Liu, J.; Peng, C.; Fang, X.; Yu, S.; Zhou, G.; Wei, X.; Ju, W.

2011-01-01

The regional carbon budget of the climatic transition zone may be very sensitive to climate change and increasing atmospheric CO2 concentrations. This study simulated the carbon cycles under these changes using process-based ecosystem models. The Integrated Biosphere Simulator (IBIS), a Dynamic Global Vegetation Model (DGVM), was used to evaluate the impacts of climate change and CO2 fertilization on net primary production (NPP), net ecosystem production (NEP), and the vegetation structure of terrestrial ecosystems in Zhejiang province (area 101,800 km2, mainly covered by subtropical evergreen forest and warm-temperate evergreen broadleaf forest) which is located in the subtropical climate area of China. Two general circulation models (HADCM3 and CGCM3) representing four IPCC climate change scenarios (HC3AA, HC3GG, CGCM-sresa2, and CGCM-sresb1) were used as climate inputs for IBIS. Results show that simulated historical biomass and NPP are consistent with field and other modelled data, which makes the analysis of future carbon budget reliable. The results indicate that NPP over the entire Zhejiang province was about 55 Mt C yr-1 during the last half of the 21st century. An NPP increase of about 24 Mt C by the end of the 21st century was estimated with the combined effects of increasing CO2 and climate change. A slight NPP increase of about 5 Mt C was estimated under the climate change alone scenario. Forests in Zhejiang are currently acting as a carbon sink with an average NEP of about 2.5 Mt C yr-1. NEP will increase to about 5 Mt C yr-1 by the end of the 21st century with the increasing atmospheric CO2 concentration and climate change. However, climate change alone will reduce the forest carbon sequestration of Zhejiang's forests. Future climate warming will substantially change the vegetation cover types; warm-temperate evergreen broadleaf forest will be gradually substituted by subtropical evergreen forest. An increasing CO2 concentration will have little

Structure and Composition of a Dry Mixed-Conifer Forest in Absence of Contemporary Treatments, Southwest, USA

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Douglas Cram

2017-09-01

Full Text Available Dry mixed-conifer forests in the Southwest occupy an important ecological and hydrological role in upper watersheds. In the absence of reoccurring fire and silvicultural treatments over the last 50 years, we quantified forest structure and composition on prevailing north and south aspects of a dry mixed-conifer forest in southcentral New Mexico using mixed models and ordination analysis in preparation for an experiment in ecological restoration. Results indicated overstory and midstory were dominated by Douglas-fir (Pseudotsuga menziesii and shade tolerant/fire intolerant white fir (Abies concolor with interspersed mature aspen on north aspects, and Douglas-fir and Southwestern white pine (Pinus strobiformis on south aspects. Ponderosa pine (Pinus ponderosa, which was historically co-dominant with Douglas-fir on north and south aspects, was subdominant on south aspects and almost entirely absent on north aspects. Regeneration was dominated by white fir saplings and seedlings on north aspects while ponderosa pine was completely absent. South aspect saplings and seedlings were characterized by Douglas-fir and Southwestern white pine, but almost no ponderosa pine. Ordination analysis characterized the effect of aspect on species composition. Understanding contemporary forest structure and composition is important when planning for desired future conditions that are to be achieved through ecological restoration using silvicultural techniques designed to foster resilience.

Floristic composition of the dry tropical forest in biological reserve (sanctuary "Los Besotes" and phenology of the dominant arboreal species (Valledupar, Cesar, Colombia

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Mary Lee Berdugo Lattke

2015-01-01

Full Text Available Based on the floristic composition and structural aspects, the formation tropical dry forest of the reserve "Los Besotes" (Valledupar, Cesar; 248 y 1046m of altitude was characterized. In 35 individuals from nine dominant tree species in two forest types, the phenological characteristics were assessed. Seven monitoring were performed along one year according to the scheme of distribution of rainfall. The leaf fall in the forests of Myrcianthes aff. fragrans and Brosimum alicastrum did not exceed 20% regardless of the climatic period (drought or rainy seasons. In others dominant understory species the leaf fall was less than 40%, thus species of the canopy are classified as evergreen while those of the understory as semideciduous. Blooming peaked during the dry season while fruit production peaked during the two rainy seasons. In the forest ofBursera simaruba and Pterocarpus acapulcensis the leaf fall exceeded 60% in the dry season, while in the rainy season was only 30%. The leaf fall increased to 60% in others dominant understory species. Both canopy as well as understory species are deciduous. Blooming was observed during the dry season (December to March, and July, but it is also likely to occur in October; fruit production was observed at the end of the rainy season. In the tropical dry forest formation evergreen plant communities with low values of leaf fall (40% and deciduous communities with values greater than 60% are recognized.

Ecological consequences of alternative fuel reduction treatments in seasonally dry forests: the national fire and fire surrogate study

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J.D. McIver; C.J. Fettig

2010-01-01

This special issue of Forest Science features the national Fire and Fire Surrogate study (FFS), a niultisite, multivariate research project that evaluates the ecological consequences of prescribed fire and its mechanical surrogates in seasonally dry forests of the United States. The need for a comprehensive national FFS study stemmed from concern that information on...

Factors affecting the abundance of leaf-litter arthropods in unburned and thrice-burned seasonally-dry Amazonian forests.

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Silveira, Juliana M; Barlow, Jos; Louzada, Julio; Moutinho, Paulo

2010-09-21

Fire is frequently used as a land management tool for cattle ranching and annual crops in the Amazon. However, these maintenance fires often escape into surrounding forests, with potentially severe impacts for forest biodiversity. We examined the effect of experimental fires on leaf-litter arthropod abundance in a seasonally-dry forest in the Brazilian Amazon. The study plots (50 ha each) included a thrice-burned forest and an unburned control forest. Pitfall-trap samples were collected at 160 randomly selected points in both plots, with sampling stratified across four intra-annual replicates across the dry and wet seasons, corresponding to 6, 8, 10 and 12 months after the most recent fire. Arthropods were identified to the level of order (separating Formicidae). In order to better understand the processes that determine arthropod abundance in thrice-burned forests, we measured canopy openness, understory density and litter depth. All arthropod taxa were significantly affected by fire and season. In addition, the interactions between burn treatment and season were highly significant for all taxa but Isoptera. The burned plot was characterized by a more open canopy, lower understory density and shallower litter depth. Hierarchical partitioning revealed that canopy openness was the most important factor explaining arthropod order abundances in the thrice-burned plot, whereas all three environmental variables were significant in the unburned control plot. These results reveal the marked impact of recurrent wildfires and seasonality on litter arthropods in this transitional forest, and demonstrate the overwhelming importance of canopy-openness in driving post-fire arthropod abundance.

Historical dominance of low-severity fire in dry and wet mixed-conifer forest habitats of the endangered terrestrial Jemez Mountains salamander (Plethodon neomexicanus)

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Margolis, Ellis; Malevich, Steven B.

2016-01-01

Anthropogenic alteration of ecosystem processes confounds forest management and conservation of rare, declining species. Restoration of forest structure and fire hazard reduction are central goals of forest management policy in the western United States, but restoration priorities and treatments have become increasingly contentious. Numerous studies have documented changes in fire regimes, forest stand structure and species composition following a century of fire exclusion in dry, frequent-fire forests of the western U.S. (e.g., ponderosa pine and dry mixed-conifer). In contrast, wet mixed-conifer forests are thought to have historically burned infrequently with mixed- or high-severity fire—resulting in reduced impacts from fire exclusion and low restoration need—but data are limited. In this study we quantified the current forest habitat of the federally endangered, terrestrial Jemez Mountains salamander (Plethodon neomexicanus) and compared it to dendroecological reconstructions of historical habitat (e.g., stand structure and composition), and fire regime parameters along a gradient from upper ponderosa pine to wet mixed-conifer forests. We found that current fire-free intervals in Jemez Mountains salamander habitat (116–165 years) are significantly longer than historical intervals, even in wet mixed-conifer forests. Historical mean fire intervals ranged from 10 to 42 years along the forest gradient. Low-severity fires were historically dominant across all forest types (92 of 102 fires). Although some mixed- or highseverity fire historically occurred at 67% of the plots over the last four centuries, complete mortality within 1.0 ha plots was rare, and asynchronous within and among sites. Climate was an important driver of temporal variability in fire severity, such that mixed- and high-severity fires were associated with more extreme drought than low-severity fires. Tree density in dry conifer forests historically ranged from open (90 trees/ha) to

Plant Trait Dataset for Tree-Like Growth Forms Species of the Subtropical Atlantic Rain Forest in Brazil

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Arthur Vinicius Rodrigues

2018-05-01

Full Text Available Plant functional traits have been incorporated in studies of vegetation ecology to better understand the mechanisms of ecological processes. For this reason, a global effort has been made to collect functional traits data for as many species as possible. In light of this, we identified the most common species of an area of 15,335 km2 inserted in the subtropical Atlantic Rain Forest in Southern Brazil. Then, we compiled functional trait information mostly from field samples, but also from herbarium and literature. The dataset presents traits of leaf, branch, maximum potential height, seed mass, and dispersion syndrome of 117 species, including trees, tree ferns, and palms. We also share images of anatomical features of branches used to measure wood traits. Data tables present mean trait values at individual and species level. Images of wood and stomatal features may be useful to assess other anatomical traits that were not covered in the data tables for the anatomical determination of species and/or for educational purposes.

Comparison of stream nutrient conditions in a subtropical lowland watershed to EPA suggested criteria

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April Mason; Y. Jun Xu; Johnny M. Grace

2007-01-01

Nutrients such as nitrogen, phosphorus and organic carbon are essential to the health and diversity of stream ecosystems. However, excess nutrients can cause eutrophication, resulting in overgrowth of aquatic plants and decline of the ecosystem diversity. A paired-watershed study was initiated in a subtropical forested watershed within the Ouachita River Basin in...

Age-dependent leaf physiology and consequences for crown-scale carbon uptake during the dry season in an Amazon evergreen forest.

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Albert, Loren P; Wu, Jin; Prohaska, Neill; de Camargo, Plinio Barbosa; Huxman, Travis E; Tribuzy, Edgard S; Ivanov, Valeriy Y; Oliveira, Rafael S; Garcia, Sabrina; Smith, Marielle N; Oliveira Junior, Raimundo Cosme; Restrepo-Coupe, Natalia; da Silva, Rodrigo; Stark, Scott C; Martins, Giordane A; Penha, Deliane V; Saleska, Scott R

2018-03-04

Satellite and tower-based metrics of forest-scale photosynthesis generally increase with dry season progression across central Amazônia, but the underlying mechanisms lack consensus. We conducted demographic surveys of leaf age composition, and measured the age dependence of leaf physiology in broadleaf canopy trees of abundant species at a central eastern Amazon site. Using a novel leaf-to-branch scaling approach, we used these data to independently test the much-debated hypothesis - arising from satellite and tower-based observations - that leaf phenology could explain the forest-scale pattern of dry season photosynthesis. Stomatal conductance and biochemical parameters of photosynthesis were higher for recently mature leaves than for old leaves. Most branches had multiple leaf age categories simultaneously present, and the number of recently mature leaves increased as the dry season progressed because old leaves were exchanged for new leaves. These findings provide the first direct field evidence that branch-scale photosynthetic capacity increases during the dry season, with a magnitude consistent with increases in ecosystem-scale photosynthetic capacity derived from flux towers. Interactions between leaf age-dependent physiology and shifting leaf age-demographic composition are sufficient to explain the dry season photosynthetic capacity pattern at this site, and should be considered in vegetation models of tropical evergreen forests. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Mega-fire Recovery in Dry Conifer Forests of the Interior West

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Malone, S. L.; Fornwalt, P.; Chambers, M. E.; Battaglia, M.

2015-12-01

Wildfire is a complex landscape process with great uncertainty in whether trends in size and severity are shifting trajectories for ecosystem recovery that are outside of the historical range of variability. Considering that wildfire size and severity is likely to increase into the future with a drier climate, it is important that we understand wildfire effects and ecosystem recovery. To evaluate how ecosystems recover from wildfire we measured spatial patterns in regeneration and mapped tree refugia within mega-fire perimeters (Hayman, Jasper, Bobcat, and Grizzly Gulch) in ponderosa pine (Pinus ponderosa) dominated forest. On average, high severity fire effects accounted for > 15% of burned area and increased with fire size. Areas with high severity fire effects contained 1 - 15% tree refugia cover, compared to 37 - 70% observed in low severity areas . Large high severity patches with low coverage of tree refugia, were more frequent in larger fires and regeneration distances required to initiate forest recovery far exceeded 1.5 canopy height or 200 m, distances where the vast majority of regeneration is likely to arise. Using a recovery model driven by distance, we estimate recovery times between 300 to > 1000 years for these mega-fires. In Western dry conifer forests, large patches of stand replacing fire are likely to lead to uneven aged forest and very long recovery times.

High density of tree-cavities and snags in tropical dry forest of western Mexico raises questions for a latitudinal gradient.

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Leopoldo Vázquez

Full Text Available It has been suggested that a latitudinal gradient exists of a low density of snags and high density of naturally-formed tree-cavities in tropical vs. temperate forests, though few cavities may have characteristics suitable for nesting by birds. We determined snag and cavity density, characteristics, and suitability for birds in a tropical dry forest biome of western Mexico, and evaluated whether our data fits the trend of snag and cavity density typically found in tropical moist and wet forests. We established five 0.25-ha transects to survey and measure tree-cavities and snags in each of three vegetation types of deciduous, semi-deciduous, and mono-dominant Piranhea mexicana forest, comprising a total of 3.75 ha. We found a high density of 77 cavities/ha, with 37 cavities suitable for birds/ha, where density, and characteristics of cavities varied significantly among vegetation types. Lowest abundance of cavities occurred in deciduous forest, and these were in smaller trees, at a lower height, and with a narrower entrance diameter. Only 8.6% of cavities were excavated by woodpeckers, and only 11% of cavities were occupied, mainly by arthropods, though 52% of all cavities were unsuitable for birds. We also found a high density of 56 snags/ha, with greatest density in deciduous forest (70 snags/ha, though these were of significantly smaller diameter, and snags of larger diameter were more likely to contain cavities. The Chamela-Cuixmala tropical dry forest had the highest density of snags recorded for any tropical or temperate forest, and while snag density was significantly correlated with mean snag dbh, neither latitude nor mean dbh predicted snag density in ten forest sites. The high spatial aggregation of snag and cavity resources in tropical dry forest may limit their availability, particularly for large-bodied cavity adopters, and highlights the importance of habitat heterogeneity in providing resources for primary and secondary cavity-nesters.

High density of tree-cavities and snags in tropical dry forest of western Mexico raises questions for a latitudinal gradient.

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Vázquez, Leopoldo; Renton, Katherine

2015-01-01

It has been suggested that a latitudinal gradient exists of a low density of snags and high density of naturally-formed tree-cavities in tropical vs. temperate forests, though few cavities may have characteristics suitable for nesting by birds. We determined snag and cavity density, characteristics, and suitability for birds in a tropical dry forest biome of western Mexico, and evaluated whether our data fits the trend of snag and cavity density typically found in tropical moist and wet forests. We established five 0.25-ha transects to survey and measure tree-cavities and snags in each of three vegetation types of deciduous, semi-deciduous, and mono-dominant Piranhea mexicana forest, comprising a total of 3.75 ha. We found a high density of 77 cavities/ha, with 37 cavities suitable for birds/ha, where density, and characteristics of cavities varied significantly among vegetation types. Lowest abundance of cavities occurred in deciduous forest, and these were in smaller trees, at a lower height, and with a narrower entrance diameter. Only 8.6% of cavities were excavated by woodpeckers, and only 11% of cavities were occupied, mainly by arthropods, though 52% of all cavities were unsuitable for birds. We also found a high density of 56 snags/ha, with greatest density in deciduous forest (70 snags/ha), though these were of significantly smaller diameter, and snags of larger diameter were more likely to contain cavities. The Chamela-Cuixmala tropical dry forest had the highest density of snags recorded for any tropical or temperate forest, and while snag density was significantly correlated with mean snag dbh, neither latitude nor mean dbh predicted snag density in ten forest sites. The high spatial aggregation of snag and cavity resources in tropical dry forest may limit their availability, particularly for large-bodied cavity adopters, and highlights the importance of habitat heterogeneity in providing resources for primary and secondary cavity-nesters.

Monitoring forest cover loss using multiple data streams, a case study of a tropical dry forest in Bolivia

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Dutrieux, Loïc Paul; Verbesselt, Jan; Kooistra, Lammert; Herold, Martin

2015-09-01

Automatically detecting forest disturbances as they occur can be extremely challenging for certain types of environments, particularly those presenting strong natural variations. Here, we use a generic structural break detection framework (BFAST) to improve the monitoring of forest cover loss by combining multiple data streams. Forest change monitoring is performed using Landsat data in combination with MODIS or rainfall data to further improve the modelling and monitoring. We tested the use of the Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) with varying spatial aggregation window sizes as well as a rainfall derived index as external regressors. The method was evaluated on a dry tropical forest area in lowland Bolivia where forest cover loss is known to occur, and we validated the results against a set of ground truth samples manually interpreted using the TimeSync environment. We found that the addition of an external regressor allows to take advantage of the difference in spatial extent between human induced and naturally induced variations and only detect the processes of interest. Of all configurations, we found the 13 by 13 km MODIS NDVI window to be the most successful, with an overall accuracy of 87%. Compared with a single pixel approach, the proposed method produced better time-series model fits resulting in increases of overall accuracy (from 82% to 87%), and decrease in omission and commission errors (from 33% to 24% and from 3% to 0% respectively). The presented approach seems particularly relevant for areas with high inter-annual natural variability, such as forests regularly experiencing exceptional drought events.

A framework for identifying carbon hotspots and forest management drivers

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Nilesh Timilsina; Francisco J. Escobedo; Wendell P. Cropper; Amr Abd-Elrahman; Thomas Brandeis; Sonia Delphin; Samuel Lambert

2013-01-01

Spatial analyses of ecosystem system services that are directly relevant to both forest management decision making and conservation in the subtropics are rare. Also, frameworks that identify and map carbon stocks and corresponding forest management drivers using available regional, national, and international-level forest inventory datasets could provide insights into...

Vegetation Response to Upper Pliocene Glacial/Interglacial Cyclicity in the Central Mediterranean

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Combourieu-Nebout, Nathalie

1993-09-01

New detailed pollen analysis of the lower part of the Upper Pliocene Semaforo section (Crotone, Italy) documents cyclic behavior of vegetation at the beginning of the Northern Hemisphere glaciations. The competition between four vegetation units (subtropical humid forest, deciduous temperate forest, altitudinal coniferous forest, and open xeric assemblage) probably reflects modifications of vegetation belts at this montane site. Several increases in herbaceous open vegetation regularly alternate with subtropical humid forest, which expresses rapid climatic oscillations. The complete temporal succession—deciduous forest (rich in Quercus), followed by subtropical humid forest (Taxodiaceae and Cathaya), then altitudinal coniferous forest ( Tsuga, Cedrus, Abies, and Picea), and finally herbaceous open vegetation (Graminae, Compositae, and Artemisia )—displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation. It also suggests an independent variation of temperature and humidity, the two main climatic parameters. The vegetation history of southern Calabria recorded in the Semaforo section have been correlated with the ∂ 18O signal established in the Atlantic Ocean.

Land surveys show regional variability of historical fire regimes and dry forest structure of the western United States.

Science.gov (United States)

Baker, William L; Williams, Mark A

2018-03-01

An understanding of how historical fire and structure in dry forests (ponderosa pine, dry mixed conifer) varied across the western United States remains incomplete. Yet, fire strongly affects ecosystem services, and forest restoration programs are underway. We used General Land Office survey reconstructions from the late 1800s across 11 landscapes covering ~1.9 million ha in four states to analyze spatial variation in fire regimes and forest structure. We first synthesized the state of validation of our methods using 20 modern validations, 53 historical cross-validations, and corroborating evidence. These show our method creates accurate reconstructions with low errors. One independent modern test reported high error, but did not replicate our method and made many calculation errors. Using reconstructed parameters of historical fire regimes and forest structure from our validated methods, forests were found to be non-uniform across the 11 landscapes, but grouped together in three geographical areas. Each had a mixture of fire severities, but dominated by low-severity fire and low median tree density in Arizona, mixed-severity fire and intermediate to high median tree density in Oregon-California, and high-severity fire and intermediate median tree density in Colorado. Programs to restore fire and forest structure could benefit from regional frameworks, rather than one size fits all. © 2018 by the Ecological Society of America.

Vegetation and Lepidoptera in Seasonally Dry Tropical Forests. Community structure along climate zones, forest succession and seasonality in the Southern Yucatán, Mexico

NARCIS (Netherlands)

Essens, T.; Leyequien, E.; Pozo, C.

2010-01-01

Seasonally dry tropical forests are worldwide recognized as important ecosystems for biodiversity conservation. Increasing agricultural activities (e.g., slash-and-burn agriculture) leads to a heterogeneous landscape matrix; and as ecological succession takes over in abandoned fields, plant and

Hydrologic ramifications of an increased role of wildland fire across the rangeland-dry forest continuum

Science.gov (United States)

The increased role of wildland fire across the rangeland-dry forest continuum in the western United States (US) presents landscape-scale consequences relative runoff and erosion. Much of the Intermountain West now exists in a state in which rangeland and woodland wildfires stimulated by invasive che...

Occurrence of termites (Isoptera on living and standing dead trees in a tropical dry forest in Mexico

Directory of Open Access Journals (Sweden)

Nancy Calderón-Cortés

2018-05-01

Full Text Available Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m2 than in riparian forests (0.022 and 0.027 trees/m2, even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m2 than in larger class sizes (0–0.02 trees/m2. Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.

Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico.

Science.gov (United States)

Calderón-Cortés, Nancy; Escalera-Vázquez, Luis H; Oyama, Ken

2018-01-01

Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60-98% of standing dead trees and 23-59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057-0.066 trees/m 2 ) than in riparian forests (0.022 and 0.027 trees/m 2 ), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01-0.09 trees/m 2 ) than in larger class sizes (0-0.02 trees/m 2 ). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.

Sensitivity Analysis of Biome-Bgc Model for Dry Tropical Forests of Vindhyan Highlands, India

Science.gov (United States)

Kumar, M.; Raghubanshi, A. S.

2011-08-01

A process-based model BIOME-BGC was run for sensitivity analysis to see the effect of ecophysiological parameters on net primary production (NPP) of dry tropical forest of India. The sensitivity test reveals that the forest NPP was highly sensitive to the following ecophysiological parameters: Canopy light extinction coefficient (k), Canopy average specific leaf area (SLA), New stem C : New leaf C (SC:LC), Maximum stomatal conductance (gs,max), C:N of fine roots (C:Nfr), All-sided to projected leaf area ratio and Canopy water interception coefficient (Wint). Therefore, these parameters need more precision and attention during estimation and observation in the field studies.

WET AND DRY SEASON ECOSYSTEM LEVEL FLUXES OF ISOPRENE AND MONOTERPENES FROM A SOUTHEAST ASIAN SECONDARY FOREST AND RUBBER TREE PLANTATION

Science.gov (United States)

Canopy scale fluxes of isoprene and monoterpenes were investigated in both wet and dry seasons above a rubber tree (Hevea brasiliensis)/secondary tropical forest in the Yunnan province of southwestern China. Drought conditions were unusually high during the dry season experiment....

Floristics and biogeography of vegetation in seasonally dry tropical regions

DEFF Research Database (Denmark)

Dexter, K.G.; Smart, B.; Baldauf, C.

2015-01-01

To provide an inter-continental overview of the floristics and biogeography of drought-adapted tropical vegetation formations, we compiled a dataset of inventory plots in South America (n=93), Africa (n=84), and Asia (n=92) from savannas (subject to fire), seasonally dry tropical forests (not...... similar vegetation formations (e.g. savannas) are floristically highly dissimilar. Neotropical moist forest, savanna and seasonally dry tropical forest are floristically distinct, but elsewhere there is no clear floristic division of savanna and seasonally dry tropical forest, though moist and dry...... of the ecology, biology and conservation of savannas and seasonally dry tropical forests may be difficult....

Geomorphology, disturbance, and the soil and vegetation of two subtropical wet steepland watersheds of Puerto Rico.

Science.gov (United States)

Ariel E. Lugo F.N. Scatena

1995-01-01

Relationships between landforms, soil nutrients, forest structure, and the relative importance of different disturbances were quantified in two subtropical wet steepland watersheds in Puerto Rico. Ridges had fewer landslides and treefall gaps, more above-ground biomass, older aged stands, and greater species richness than other landscape positions. Ridge soils had...

Estimating the terrestrial N processes in subtropical mountainous forestry catchment through INCA-N: A case study in FuShan catchment, Taiwan

Science.gov (United States)

Lu, Meng-Chang; Huang, -Chuan, Jr.; Chang, Chung-Te; Shih, Yu-Ting; Lin, Teng-Chiu

2016-04-01

The riverine DIN is a crucial indicator for eutrophication in river network. The riverine DIN export in Taiwan is featured by the extremely high yield, ~3800 kg-N km-2yr-1, nearly 20-fold than the global average, showing the interesting terrestrial N process yet rarely documented. In this study we collected the DIN samples in rainwater, soil water, and stream water in a mountainous forest watershed, FuShan experimental forest watershed 1 (WS1) which is a natural broadleaf forest without human activities. Based on the intensive observations, we applied the INCA-N to simulate the riverine DIN response and thus estimate the terrestrial N processes in a global synthesis. The result showed that both discharge and DIN yield were simulated well with the average Nash-Sutcliffe efficiency coefficient of 0.83 and 0.76 , respectively. Among all N processes, N uptake, mineralization, nitrification, denitrfication, and immobilization are significantly positive correlated with soil moisture (R2>0.99), which indicates that soil moisture greatly influences N cycle processes. The average rate of mineralization and nitrification in wet years are consistent with documented values, whereas the rates in dry years are lower than the observations. Despite the high nitrification rate, the secondary forest may uptake abundant N indicating the plant uptake, which responds for removing considerable nitrate, is a controlling factor in forest ecosystem. Our simulated denitrification rate falls between the documented rates of temperate forest and agricultural area, and that may be affected by the high N-deposition in Taiwan. Simulated in-stream denitrification rate is less than 10% of the rate in soil, and is a little lower than that in temperate forest. This preliminary simulation provides an insightful guide to establish the monitoring programme and improve the understanding of N cycle in subtropical.

Evaluation of forest structure, biomass and carbon sequestration in subtropical pristine forests of SW China.

Science.gov (United States)

Nizami, Syed Moazzam; Yiping, Zhang; Zheng, Zheng; Zhiyun, Lu; Guoping, Yang; Liqing, Sha

2017-03-01

Very old natural forests comprising the species of Fagaceae (Lithocarpus xylocarpus, Castanopsis wattii, Lithocarpus hancei) have been prevailing since years in the Ailaoshan Mountain Nature Reserve (AMNR) SW China. Within these forest trees, density is quite variable. We studied the forest structure, stand dynamics and carbon density at two different sites to know the main factors which drives carbon sequestration process in old forests by considering the following questions: How much is the carbon density in these forest trees of different DBH (diameter at breast height)? How much carbon potential possessed by dominant species of these forests? How vegetation carbon is distributed in these forests? Which species shows high carbon sequestration? What are the physiochemical properties of soil in these forests? Five-year (2005-2010) tree growth data from permanently established plots in the AMNR was analysed for species composition, density, stem diameter (DBH), height and carbon (C) density both in aboveground and belowground vegetation biomass. Our study indicated that among two comparative sites, overall 54 species of 16 different families were present. The stem density, height, C density and soil properties varied significantly with time among the sites showing uneven distribution across the forests. Among the dominant species, L. xylocarpus represents 30% of the total carbon on site 1 while C. wattii represents 50% of the total carbon on site 2. The average C density ranged from 176.35 to 243.97 t C ha -1 . The study emphasized that there is generous degree to expand the carbon stocking in this AMNR through scientific management gearing towards conservation of old trees and planting of potentially high carbon sequestering species on good site quality areas.

Land use history, environment, and tree composition in a tropical forest

Science.gov (United States)

Jill Thompson; Nicholas Brokaw; Jess K. Zimmerman; Robert B. Waide; Edwin M. III Everham; D. Jean Lodge; Charlotte M. Taylor; Diana Garcia-Montiel; Marcheterre Fluet

2002-01-01

The effects of historical land use on tropical forest must be examined to understand present forest characteristics and to plan conservation strategies. We compared the effects of past land use, topography, soil type, and other environmental variables on tree species composition in a subtropical wet forest in the Luquillo Mountains, Puerto Rico. The study involved...

Measuring species diversity in a subtropical forest across a tree size gradient: a comparison of diversity indices

International Nuclear Information System (INIS)

Ke, X.; Su, Z.; Hu, Y.; Zhou, Y.; Xu, M.

2017-01-01

Shannon-Wiener index and Simpson's diversity index together with other metrics, e.g., richness, number of stems per species or species-specific density (N: S ratio), and kurtosis, were applied to characterize the woody plant diversity patterns of a subtropical broadleaved forest in south China. The aims of our study were to compare the efficacy and sensitivity to community diversity measures between Shannon-Wiener index and Simpson's diversity index. Tree census data from a 5-ha sample plot was partitioned into 3 datasets by diameter class to represent 3 distinct woody plant communities for the characterization of diversity across communities. The 5-ha sample plot of the forest had a total abundance of 23,301 tree stems = 1 cm DBH and a richness of 139 species. The majority of tree stems were seedlings (41.1%) and saplings (38.8%), whereas canopy trees only accounted for 20.1% of the total tree stems. Both Shannon-Wiener index and Simpson's diversity index decreased significantly in response to a decrease in the N: S ratio across the datasets, but Shannon-Wiener index was more sensitive to plot-based richness changes and had a higher efficacy in predicting changes in species richness. Our findings are contrary to the general belief that Shannon-Wiener index is an insensitive measure of the character of the N: S relationship and have demonstrated that it remains a good measure for species diversity in plant community studies for its sensitivity and efficacy. We also suggest that the kurtosis statistic can be used as a new diversity measure due to its sensitivity to diversity change. (author)

Modeling seasonal surface temperature variations in secondary tropical dry forests

Science.gov (United States)

Cao, Sen; Sanchez-Azofeifa, Arturo

2017-10-01

Secondary tropical dry forests (TDFs) provide important ecosystem services such as carbon sequestration, biodiversity conservation, and nutrient cycle regulation. However, their biogeophysical processes at the canopy-atmosphere interface remain unknown, limiting our understanding of how this endangered ecosystem influences, and responds to the ongoing global warming. To facilitate future development of conservation policies, this study characterized the seasonal land surface temperature (LST) behavior of three successional stages (early, intermediate, and late) of a TDF, at the Santa Rosa National Park (SRNP), Costa Rica. A total of 38 Landsat-8 Thermal Infrared Sensor (TIRS) data and the Surface Reflectance (SR) product were utilized to model LST time series from July 2013 to July 2016 using a radiative transfer equation (RTE) algorithm. We further related the LST time series to seven vegetation indices which reflect different properties of TDFs, and soil moisture data obtained from a Wireless Sensor Network (WSN). Results showed that the LST in the dry season was 15-20 K higher than in the wet season at SRNP. We found that the early successional stages were about 6-8 K warmer than the intermediate successional stages and were 9-10 K warmer than the late successional stages in the middle of the dry season; meanwhile, a minimum LST difference (0-1 K) was observed at the end of the wet season. Leaf phenology and canopy architecture explained most LST variations in both dry and wet seasons. However, our analysis revealed that it is precipitation that ultimately determines the LST variations through both biogeochemical (leaf phenology) and biogeophysical processes (evapotranspiration) of the plants. Results of this study could help physiological modeling studies in secondary TDFs.

Impact of livestock on a mosquito community (Diptera: Culicidae) in a Brazilian tropical dry forest.

Science.gov (United States)

Santos, Cleandson Ferreira; Borges, Magno

2015-01-01

This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil. Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models. Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition. This is the first study to evaluate the impact of cattle removal on Culicidae community structure in Brazil and demonstrates the importance of assessing ecological parameters such as community species composition.

Assessing the Impact of Forest Change and Climate Variability on Dry Season Runoff by an Improved Single Watershed Approach: A Comparative Study in Two Large Watersheds, China

Directory of Open Access Journals (Sweden)

Yiping Hou

2018-01-01

Full Text Available Extensive studies on hydrological responses to forest change have been published for centuries, yet partitioning the hydrological effects of forest change, climate variability and other factors in a large watershed remains a challenge. In this study, we developed a single watershed approach combining the modified double mass curve (MDMC and the time series multivariate autoregressive integrated moving average model (ARIMAX to separate the impact of forest change, climate variability and other factors on dry season runoff variation in two large watersheds in China. The Zagunao watershed was examined for the deforestation effect, while the Meijiang watershed was examined to study the hydrological impact of reforestation. The key findings are: (1 both deforestation and reforestation led to significant reductions in dry season runoff, while climate variability yielded positive effects in the studied watersheds; (2 the hydrological response to forest change varied over time due to changes in soil infiltration and evapotranspiration after vegetation regeneration; (3 changes of subalpine natural forests produced greater impact on dry season runoff than alteration of planted forests. These findings are beneficial to water resource and forest management under climate change and highlight a better planning of forest operations and management incorporated trade-off between carbon and water in different forests.

Selective logging and fire as drivers of alien grass invasion in a Bolivian tropical dry forest

NARCIS (Netherlands)

Veldman, J.W.; Mostacedo, B.; Peña-Claros, M.; Putz, F.E.

2009-01-01

Logging is an integral component of most conceptual models that relate human land-use and climate change to tropical deforestation via positive-feedbacks involving fire. Given that grass invasions can substantially alter fire regimes, we studied grass distributions in a tropical dry forest 1-5 yr

Sub-tropical coastal lagoon salinization associated to shrimp ponds effluents

Science.gov (United States)

Cardoso-Mohedano, José-Gilberto; Lima-Rego, Joao; Sanchez-Cabeza, Joan-Albert; Ruiz-Fernández, Ana-Carolina; Canales-Delgadillo, Julio; Sánchez-Flores, Eric-Ivan; Páez-Osuna, Federico

2018-04-01

Anthropogenic salinization impacts the health of aquatic and terrestrial ecosystems worldwide. In tropical and subtropical areas, shrimp farm aquaculture uses water from adjacent ecosystems to fill the culture ponds, where enhanced evaporation cause salinization of discharged water. In this study, we studied water salinity before and after shrimp farm harvest and implemented a three-dimensional hydrodynamic model to assess the impact on a subtropical coastal lagoon that receives water releases from shrimp ponds. The shrimp pond discharge significantly increased the salinity of receiving waters, at least 3 psu over the local variation. In the worst-case salinization scenario, when harvest occurs after a long dry season, salinity could increase by up to 6 psu. The induced salinization due to shrimp pond effluents remained up to 2 tidal cycles after harvest, and could affect biota. The methodology and results of this study can be used to assess the impacts of shrimp aquaculture worldwide.

Water uptake and transport in lianas and co-occurring trees of a seasonally dry tropical forest.

Science.gov (United States)

José Luis Andrade; Frederick C. Meinzer; Guillermo Goldstein; Stefan A. Schnitzer

2005-01-01

Water uptake and transport were studied in eight liana species in a seasonally dry tropical forest on Barro Colorado Island, Panama. Stable hydrogen isotope composition (δD) of xylem and soil water, soil volumetric water content (θv), and basal sap flow were measured during the 1997 and...

Sources and sinks of diversification and conservation priorities for the Mexican tropical dry forest.

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Judith X Becerra

Full Text Available Elucidating the geographical history of diversification is critical for inferring where future diversification may occur and thus could be a valuable aid in determining conservation priorities. However, it has been difficult to recognize areas with a higher likelihood of promoting diversification. We reconstructed centres of origin of lineages and identified areas in the Mexican tropical dry forest that have been important centres of diversification (sources and areas where species are maintained but where diversification is less likely to occur (diversity sinks. We used a molecular phylogeny of the genus Bursera, a dominant member of the forest, along with information on current species distributions. Results indicate that vast areas of the forest have historically functioned as diversity sinks, generating few or no extant Bursera lineages. Only a few areas have functioned as major engines of diversification. Long-term preservation of biodiversity may be promoted by incorporation of such knowledge in decision-making.

Edge effects on foliar stable isotope values in a Madagascan tropical dry forest.

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Brooke E Crowley

Full Text Available Edge effects represent an inevitable and important consequence of habitat loss and fragmentation. These effects include changes in microclimate, solar radiation, or temperature. Such abiotic effects can, in turn, impact biotic factors. They can have a substantial impact on species, communities, and ecosystems. Here we examine clinal variations in stable carbon and nitrogen isotope values for trees along an edge-interior gradient in the dry deciduous forest at Ankarafantsika National Park. We predicted that soil respiration and differences in solar irradiance would result in stratified δ¹³C values where leaves collected close to the forest floor would have lower δ¹³C values than those growing higher up in the canopy. We also anticipated that plants growing at the savannah-forest boundary would have higher δ¹³C and δ¹⁵N values than plants growing in the forest interior. As expected, we detected a small but significant canopy effect. Leaves growing below 2 m from the forest floor exhibit δ¹³C values that are, on average, 1.1‰ lower than those growing above this threshold. We did not, however, find any relationship between foliar δ¹³C and distance from the edge. Unpredictably, we detected a striking positive relationship between foliar δ¹⁵N values and increasing distance into the forest interior. Variability in physiology among species, anthropogenic influence, organic input, and rooting depth cannot adequately explain this trend. Instead, this unexpected relationship most likely reflects decreasing nutrient or water availability, or a shift in N-sources with increasing distance from the savannah. Unlike most forest communities, the trees at Ampijoroa are growing in nutrient-limited sands. In addition to being nutrient poor, these well-drained soils likely decrease the amount of soil water available to forest vegetation. Continued research on plant responses to edge effects will improve our understanding of the conservation

Variations of net ecosystem production due to seasonal precipitation differences in a tropical dry forest of northwest Mexico

Science.gov (United States)

Verduzco, Vivian S.; Garatuza-Payán, Jaime; Yépez, Enrico A.; Watts, Christopher J.; Rodríguez, Julio C.; Robles-Morua, Agustin; Vivoni, Enrique R.

2015-10-01

Due to their large extent and high primary productivity, tropical dry forests (TDF) are important contributors to atmospheric carbon exchanges in subtropical and tropical regions. In northwest Mexico, a bimodal precipitation regime that includes winter precipitation derived from Pacific storms and summer precipitation from the North American monsoon (NAM) couples water availability with ecosystem processes. We investigated the net ecosystem production of a TDF ecosystem using a 4.5 year record of water and carbon fluxes obtained from the eddy covariance method complemented with remotely sensed data. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer that respiration is mainly due to decomposition of soil organic matter accumulated from the prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production but can be overwhelmed by the strength of the primary productivity during the NAM. Precipitation characteristics during NAM have significant controls on sustaining carbon fixation in the TDF into the fall season. We identified that a threshold of ~350 to 400 mm of monsoon precipitation leads to a switch in the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This monsoonal precipitation threshold is typically exceeded one out of every 2 years. The close coupling of winter and summer periods with respect to carbon fluxes suggests that the annual carbon balance is dependent on precipitation amounts in both seasons in TDF ecosystems.

Impact of livestock on a mosquito community (Diptera: Culicidae in a Brazilian tropical dry forest

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Cleandson Ferreira Santos

2015-08-01

Full Text Available AbstractINTRODUCTION: This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil.METHODS: Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models.RESULTS: Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition.CONCLUSIONS: This is the first study to evaluate the impact of cattle removal on Culicidae community structure in Brazil and demonstrates the importance of assessing ecological parameters such as community species composition.

germination of seeds from earlier fruits of bitter and sweet african

African Journals Online (AJOL)

ACSS

2014-11-18

Nov 18, 2014 ... Seed germination speed significantly depended on the drying level and the germination system (sunshine versus covered condition). .... the West African forest block) is characterised ..... tropical and subtropical America.

Variations in soil carbon sequestration and their determinants along a precipitation gradient in seasonally dry tropical forest ecosystems.

Science.gov (United States)

Campo, Julio; Merino, Agustín

2016-05-01

The effect of precipitation regime on the C cycle of tropical forests is poorly understood, despite the existence of models that suggest a drier climate may substantially alter the source-sink function of these ecosystems. Along a precipitation regime gradient containing 12 mature seasonally dry tropical forests growing under otherwise similar conditions (similar annual temperature, rainfall seasonality, and geological substrate), we analyzed the influence of variation in annual precipitation (1240 to 642 mm) and duration of seasonal drought on soil C. We investigated litterfall, decomposition in the forest floor, and C storage in the mineral soil, and analyzed the dependence of these processes and pools on precipitation. Litterfall decreased slightly - about 10% - from stands with 1240 mm yr(-1) to those with 642 mm yr(-1), while the decomposition decreased by 56%. Reduced precipitation strongly affected C storage and basal respiration in the mineral soil. Higher soil C storage at the drier sites was also related to the higher chemical recalcitrance of litter (fine roots and forest floor) and the presence of charcoal across sites, suggesting an important indirect influence of climate on C sequestration. Basal respiration was controlled by the amount of recalcitrant organic matter in the mineral soil. We conclude that in these forest ecosystems, the long-term consequences of decreased precipitation would be an increase in organic layer and mineral soil C storage, mainly due to lower decomposition and higher chemical recalcitrance of organic matter, resulting from changes in litter composition and, likely also, wildfire patterns. This could turn these seasonally dry tropical forests into significant soil C sinks under the predicted longer drought periods if primary productivity is maintained. © 2016 John Wiley & Sons Ltd.

Mixed-severity fire fosters heterogeneous spatial patterns of conifer regeneration in a dry conifer forest

Science.gov (United States)

Sparkle L. Malone; Paula J. Fornwalt; Mike A. Battaglia; Marin E. Chambers; Jose M. Iniguez; Carolyn H. Sieg

2018-01-01

We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11-12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving) trees, in three 4-ha plots following the 2002 Hayman Fire...

Acid deposition and assessment of its critical load for the environmental health of waterbodies in a subtropical watershed, China

Science.gov (United States)

Jia, Junjie; Gao, Yang

2017-12-01

Atmospheric acidic deposition in subtropical watersheds poses an environmental risk of causing acidification of aquatic ecosystems. In this study, we evaluated the frequency of acid deposition in a subtropical forest ecosystem and the associated critical loads of acidity for a sensitive aquatic ecosystem. We found that out of 132 rainfall events, 33(25%) were acidic rainfall occurrences. Estimated wet acid deposition (2282.78 eq·ha-1·yr-1), consistent with SO42- and NH4+ deposition, was high in spring and summer and low in autumn and winter. Waterbodies surrounded by mixed wood and citrus orchard experience severe acidification, mostly from S deposition because acidic deposition exceeds the corresponding critical loads of acidity. Modifications that take acid rain deposition into consideration are needed for land-use and agricultural management strategies to improve the environmental health of waterbodies in subtropical watersheds.

Patterns and correlates of plant diversity differ between common and rare species in a neotropical dry forest

NARCIS (Netherlands)

Tetetla-Rangel, Erika; Dupuy, Juan Manuel; Hernández-Stefanoni, José Luis; Hoekstra, Paul H.

2017-01-01

Determining which factors affect species richness is important for conservation theory and practice. However, richness of common and rare species may be affected by different factors. We use an extensive inventory of woody plants from a tropical dry forest landscape in Yucatan, Mexico to assess the

Predicting of biomass in Brazilian tropical dry forest: a statistical evaluation of generic equations

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ROBSON B. DE LIMA

2017-08-01

Full Text Available ABSTRACT Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005 generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005 is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

Predicting of biomass in Brazilian tropical dry forest: a statistical evaluation of generic equations.

Science.gov (United States)

Lima, Robson B DE; Alves, Francisco T; Oliveira, Cinthia P DE; Silva, José A A DA; Ferreira, Rinaldo L C

2017-01-01

Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005) generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005) is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

Effects of Habitat Structure, Plant Cover, and Successional Stage on the Bat Assemblage of a Tropical Dry Forest at Different Spatial Scales

Directory of Open Access Journals (Sweden)

Luiz A. D. Falcão

2018-05-01

Full Text Available Bats play a fundamental role in ecosystem functioning since they are responsible for several ecological services such as seed dispersal and pollination. Therefore, assessing the effects of habitat structure at different scales on the bat assemblage is extremely important for supporting conservation strategies. The objective of the present study was to investigate the effects of habitat structure at multiple spatial scales on the bat assemblages and their variation along a gradient of secondary succession in a Brazilian tropical dry forest. Our results suggest that bat abundance is higher in areas close to mature forests, which shows the important role of those habitats as refuges for the regional bat fauna (in a fragmented landscape and for the maintenance of ecosystem services provided by this group in tropical dry forests in a landscape context. In addition, bat abundance was lower in protected areas whose surroundings were better preserved (greater forest extension. This unexpected finding could result from an altered behavior in areas under a strong influence of a fruit crop matrix. Finally, we showed that the effects of the surroundings depend on the successional stage of the area under analysis. Late forests are more susceptible to variations in the forest cover in their surroundings, which show the higher fragility of these environments.

Does the edge effect influence plant community structure in a tropical dry forest?

Directory of Open Access Journals (Sweden)

Diogo Gallo Oliveira

2013-04-01

Full Text Available Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.

Holocene temperature variability revealed by brGDGTs in subtropical southwestern China

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Feng, X.; Zhao, C.

2017-12-01

Subtropical areas are important source region of moisture and heat in global climate system. Paleoclimate reconstructions from these regions, especially quantitative records, would not only help to better understand the nature of climate system through time, but also provide important constraining dataset for long-term ecosystem variations in these ecological important areas. To date, quantitative climate records with reliable chronological controls are still limited from terrestrial archives in subtropical areas. Here we present a 50-year-resolution quantitative temperature record throughout the Holocene based on branched GDGTs at a small alpine lake, Tiancai Lake (26°38'E, 99°43'N, 3898 m.a.s.l) in southwestern China. The record is based on a temporal calibration between instrumental mean annual air temperature (MAAT) and brGDGT compounds (GDGT-IIIa, GDGT-IIa', GDGT-IIb, GDGT-Ia and GDGT-Ic). The MAAT was relatively low -0.6 ° between 11 and 7.5 ka, then abruptly increased 1 ° to 4 °until 7 ka. The MAAT was relatively warm 2° between 7 and 1 ka, then decreased to 1° over the last 1 ka. The Middle to Late Holocene was 3 ° warmer than the Early Holocene. The MAAT variation at Lake Tiancai is supported by changes in evergreen oaks and Tsuga from the same sediment core, suggesting that the growth of cold-tolerant forest in place of subtropical evergreen broadleaved forest has been driven by the decrease in MAAT. The early Holocene cold interval revealed by our record and pollen data is different with the chironomid-based summer temperature reconstruction from the same lake, the latter has been driven by summer insolation. This difference suggests that a pronounced winter contribution to the mean annual temperature during the early Holocene, which was probably caused by a low winter insolation, and strengthened by a sparse vegetation cover and influences of winter ice/snow cover in tropical high latitude regions.

Long-term changes in above ground biomass after disturbance in a neotropical dry forest, Hellshire Hills, Jamaica

DEFF Research Database (Denmark)

Niño, Milena; McLaren, Kurt P.; Meilby, Henrik

2014-01-01

We used data from experimental plots (control, partially cut and clear-cut) established in 1998, in a tropical dry forest (TDF) in Jamaica, to assess changes in above ground biomass (AGB) 10 years after disturbance. The treatments reduced AGB significantly in 1999 (partially cut: 37.6 %, clear-cu...

Root depth and morphology in response to soil drought: comparing ecological groups along the secondary succession in a tropical dry forest.

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Paz, Horacio; Pineda-García, Fernando; Pinzón-Pérez, Luisa F

2015-10-01

Root growth and morphology may play a core role in species-niche partitioning in highly diverse communities, especially along gradients of drought risk, such as that created along the secondary succession of tropical dry forests. We experimentally tested whether root foraging capacity, especially at depth, decreases from early successional species to old-growth forest species. We also tested for a trade-off between two mechanisms for delaying desiccation, the capacity to forage deeper in the soil and the capacity to store water in tissues, and explored whether successional groups separate along such a trade-off. We examined the growth and morphology of roots in response to a controlled-vertical gradient of soil water, among seedlings of 23 woody species dominant along the secondary succession in a tropical dry forest of Mexico. As predicted, successional species developed deeper and longer root systems than old-growth forest species in response to soil drought. In addition, shallow root systems were associated with high plant water storage and high water content per unit of tissue in stems and roots, while deep roots exhibited the opposite traits, suggesting a trade-off between the capacities for vertical foraging and water storage. Our results suggest that an increased capacity of roots to forage deeper for water is a trait that enables successional species to establish under the warm-dry conditions of the secondary succession, while shallow roots, associated with a higher water storage capacity, are restricted to the old-growth forest. Overall, we found evidence that the root depth-water storage trade-off may constrain tree species distribution along secondary succession.

Fuels planning: science synthesis and integration; forest structure and fire hazard fact sheet 06: Guide to fuel treatments in dry forests of the Western United States: assessing forest structure and fire hazard

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Rocky Mountain Research Station USDA Forest Service

2005-01-01

The Guide to Fuel Treatments analyzes a range of potential silvicultural thinnings and surface fuel treatments for 25 representative dry-forest stands in the Western United States. The guide provides quantitative guidelines and visualization for treatment based on scientific principles identified for reducing potential crown fires. This fact sheet identifies the...

Identifying tropical dry forests extent and succession via the use of machine learning techniques

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Li, Wei; Cao, Sen; Campos-Vargas, Carlos; Sanchez-Azofeifa, Arturo

2017-12-01

Information on ecosystem services as a function of the successional stage for secondary tropical dry forests (TDFs) is scarce and limited. Secondary TDFs succession is defined as regrowth following a complete forest clearance for cattle growth or agriculture activities. In the context of large conservation initiatives, the identification of the extent, structure and composition of secondary TDFs can serve as key elements to estimate the effectiveness of such activities. As such, in this study we evaluate the use of a Hyperspectral MAPper (HyMap) dataset and a waveform LIDAR dataset for characterization of different levels of intra-secondary forests stages at the Santa Rosa National Park (SRNP) Environmental Monitoring Super Site located in Costa Rica. Specifically, a multi-task learning based machine learning classifier (MLC-MTL) is employed on the first shortwave infrared (SWIR1) of HyMap in order to identify the variability of aboveground biomass of secondary TDFs along a successional gradient. Our paper recognizes that the process of ecological succession is not deterministic but a combination of transitional forests types along a stochastic path that depends on ecological, edaphic, land use, and micro-meteorological conditions, and our results provide a new way to obtain the spatial distribution of three main types of TDFs successional stages.

Emerging deforestation trends in tropical dry forests ecoregions of Mexico and Central America

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Portillo, C. A.; Cao, G.; Smith, V.

2015-12-01

Neotropical dry forests (TDF) have experienced an unprecedented deforestation that is leading to the loss of tropical biodiversity at a rapid pace, but information on deforestation dynamics in TDF is scarce. In this study, we present a sub-continental and national level assessment of TDF loss patterns in Mexico and Central America at high spatial and temporal resolution using remote sensing and GIS technologies. We used the Global Forest Change (GFC) dataset published by Hansen et al. (2013) which shows results from time-series analysis of Landsat images in characterizing global forest extent and change from 2000 through 2013. We analyzed forest loss within and around mapped TDF cover mapped by Portillo-Quintero et al. 2010. In order to minimize errors in source data, we overlaid a 25 x 25 km grid on top of the regional dataset and conducted a cell by cell and country by country inspection at multiple scales using high resolution ancillary data. We identified trends in the clustering of space-time TDF deforestation data using ArcGIS, categorizing trends in: new, consecutive, intensifying, persistent, diminishing, sporadic, oscillating and historical hotspots (high frequency of deforestation events) and cold spots (low frequency of deforestation). In general, the region is experiencing less frequent deforestation events with a higher number of intensifying and new cold spots across TDF landscapes. However, an important number of intensifying and persistent hotspots exist so no general trend in forest loss was detected for the period 2001-2013, except for El Salvador which shows a significant decreasing trend in forest loss. Mexico, Nicaragua, Honduras and Guatemala are the major sources of intensifying, persistent and new deforestation hot spots. These were identified in the southern pacific coast and the Yucatan Peninsula in Mexico, northwestern Guatemala, both western and eastern Honduras and around Lake Nicaragua in Nicaragua.

Wetter subtropics in a warmer world: Contrasting past and future hydrological cycles

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Burls, Natalie J.; Fedorov, Alexey V.

2017-12-01

During the warm Miocene and Pliocene Epochs, vast subtropical regions had enough precipitation to support rich vegetation and fauna. Only with global cooling and the onset of glacial cycles some 3 Mya, toward the end of the Pliocene, did the broad patterns of arid and semiarid subtropical regions become fully developed. However, current projections of future global warming caused by CO2 rise generally suggest the intensification of dry conditions over these subtropical regions, rather than the return to a wetter state. What makes future projections different from these past warm climates? Here, we investigate this question by comparing a typical quadrupling-of-CO2 experiment with a simulation driven by sea-surface temperatures closely resembling available reconstructions for the early Pliocene. Based on these two experiments and a suite of other perturbed climate simulations, we argue that this puzzle is explained by weaker atmospheric circulation in response to the different ocean surface temperature patterns of the Pliocene, specifically reduced meridional and zonal temperature gradients. Thus, our results highlight that accurately predicting the response of the hydrological cycle to global warming requires predicting not only how global mean temperature responds to elevated CO2 forcing (climate sensitivity) but also accurately quantifying how meridional sea-surface temperature patterns will change (structural climate sensitivity).

Nitrogen, phosphorus, and cation use efficiency in stands of regenerating tropical dry forest.

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Waring, Bonnie G; Becknell, Justin M; Powers, Jennifer S

2015-07-01

Plants on infertile soils exhibit physiological and morphological traits that support conservative internal nutrient cycling. However, potential trade-offs among use efficiencies for N, P, and cations are not well explored in species-rich habitats where multiple elements may limit plant production. We examined uptake efficiency and use efficiency of N, P, K, Ca, Mg, Al, and Na in plots of regenerating tropical dry forests spanning a gradient of soil fertility. Our aim was to determine whether plant responses to multiple elements are correlated, or whether there are trade-offs among exploitation strategies across stands varying in community composition, soil quality, and successional stage. For all elements, both uptake efficiency and use efficiency decreased as availability of the corresponding element increased. Plant responses to N, Na, and Al were uncoupled from uptake and use efficiencies for P and essential base cations, which were tightly correlated. N and P use efficiencies were associated with shifts in plant species composition along the soil fertility gradient, and there was also a trend towards increasing N use efficiency with stand age. N uptake efficiency was positively correlated with the abundance of tree species that associate with ectomycorrhizal fungi. Taken together, our results suggest that successional processes and local species composition interact to regulate plant responses to availability of multiple resources. Successional tropical dry forests appear to employ different strategies to maximize response to N vs. P and K.

Fire, climate and vegetation linkages in the Bolivian Chiquitano seasonally dry tropical forest.

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Power, M J; Whitney, B S; Mayle, F E; Neves, D M; de Boer, E J; Maclean, K S

2016-06-05

South American seasonally dry tropical forests (SDTFs) are critically endangered, with only a small proportion of their original distribution remaining. This paper presents a 12 000 year reconstruction of climate change, fire and vegetation dynamics in the Bolivian Chiquitano SDTF, based upon pollen and charcoal analysis, to examine the resilience of this ecosystem to drought and fire. Our analysis demonstrates a complex relationship between climate, fire and floristic composition over multi-millennial time scales, and reveals that moisture variability is the dominant control upon community turnover in this ecosystem. Maximum drought during the Early Holocene, consistent with regional drought reconstructions, correlates with a period of significant fire activity between 8000 and 7000 cal yr BP which resulted in a decrease in SDTF diversity. As fire activity declined but severe regional droughts persisted through the Middle Holocene, SDTFs, including Anadenanthera and Astronium, became firmly established in the Bolivian lowlands. The trend of decreasing fire activity during the last two millennia promotes the idea among forest ecologists that SDTFs are threatened by fire. Our analysis shows that the Chiquitano seasonally dry biome has been more resilient to Holocene changes in climate and fire regime than previously assumed, but raises questions over whether this resilience will continue in the future under increased temperatures and drought coupled with a higher frequency anthropogenic fire regime.This article is part of the themed issue 'The interaction of fire and mankind'. © 2016 The Author(s).

Can small island mountains provide relief from the Subtropical Precipitation Decline? Simulating future precipitation regimes for small island nations using high resolution Regional Climate Models.

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Bowden, J.; Terando, A. J.; Misra, V.; Wootten, A.

2017-12-01

Small island nations are vulnerable to changes in the hydrologic cycle because of their limited water resources. This risk to water security is likely even higher in sub-tropical regions where anthropogenic forcing of the climate system is expected to lead to a drier future (the so-called `dry-get-drier' pattern). However, high-resolution numerical modeling experiments have also shown an enhancement of existing orographically-influenced precipitation patterns on islands with steep topography, potentially mitigating subtropical drying on windward mountain sides. Here we explore the robustness of the near-term (25-45 years) subtropical precipitation decline (SPD) across two island groupings in the Caribbean, Puerto Rico and the U.S. Virgin Islands. These islands, forming the boundary between the Greater and Lesser Antilles, significantly differ in size, topographic relief, and orientation to prevailing winds. Two 2-km horizontal resolution regional climate model simulations are used to downscale a total of three different GCMs under the RCP8.5 emissions scenario. Results indicate some possibility for modest increases in precipitation at the leading edge of the Luquillo Mountains in Puerto Rico, but consistent declines elsewhere. We conclude with a discussion of potential explanations for these patterns and the attendant risks to water security that subtropical small island nations could face as the climate warms.

Litter decomposition, N2-fixer abundance, and microbial dynamics govern tropical dry forest recovery to land use change

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Trierweiler, A.; Powers, J. S.; Xu, X.; Gei, M. G.; Medvigy, D.

2017-12-01

As one of the most threatened tropical biomes, Seasonal Dry Tropical Forests (TDF) have undergone extensive land-use change. However, some areas are undergoing recovery into secondary forests. Despite their broad distribution (42% of tropical forests), they are under-studied compared to wet tropical forests and our understanding of their biogeochemical cycling and belowground processes are limited. Here, we use models along with field measurements to improve our understanding of nutrient cycling and limitation in secondary TDFs. We ask (1) Is there modeling evidence that tropical dry forests can become nutrient limited? (2) What are the most important mechanisms employed to avoid nutrient limitation? (3) How might climate change alter biogeochemical cycling and nutrient limitation in recovering TDF? We use a new version of the Ecosystem Demography (ED2) model that has been recently parameterized for TDFs and incorporates a range of plant functional groups (including deciduousness and N2-fixation) and multiple resource constraints (carbon, nitrogen, phosphorus, and water). In the model, plants then can dynamically adjust their carbon allocation and nutrient acquisition strategies using N2-fixing bacteria and mycorrhizal fungi according to the nutrient limitation status. We ran the model for a nutrient gradient of field sites in Costa Rica and explored the sensitivity of nutrient limitation to key mechanisms including litter respiration, N resorption, N2-fixation, and overflow respiration. Future runs will evaluate how CO2 and climate change affect recovering TDFs. We found increasing nutrient limitation across the nutrient gradient of sites. Nitrogen limitation dominated the nutrient limitation signal. In the model, forest litter accumulation was negatively correlated with site fertility in Costa Rican forests. Our sensitivity analyses indicate that N2-fixer abundance, decomposition rates, and adding more explicit microbial dynamics are key factors in overcoming

Nitrogen distribution and cycling through water flows in a subtropical bamboo forest under high level of atmospheric deposition.

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Tu, Li-hua; Hu, Ting-xing; Zhang, Jian; Huang, Li-hua; Xiao, Yin-long; Chen, Gang; Hu, Hong-ling; Liu, Li; Zheng, Jiang-kun; Xu, Zhen-Feng; Chen, Liang-hua

2013-01-01

The hydrological cycle is an important way of transportation and reallocation of reactive nitrogen (N) in forest ecosystems. However, under a high level of atmospheric N deposition, the N distribution and cycling through water flows in forest ecosystems especially in bamboo ecosystems are not well understood. In order to investigate N fluxes through water flows in a Pleioblastus amarus bamboo forest, event rainfall/snowfall (precipitation, PP), throughfall (TF), stemflow (SF), surface runoff (SR), forest floor leachate (FFL), soil water at the depth of 40 cm (SW1) and 100 cm (SW2) were collected and measured through the whole year of 2009. Nitrogen distribution in different pools in this ecosystem was also measured. Mean N pools in vegetation and soil (0-1 m) were 351.7 and 7752.8 kg ha(-1). Open field nitrogen deposition at the study site was 113.8 kg N ha(-1) yr(-1), which was one of the highest in the world. N-NH4(+), N-NO3(-) and dissolved organic N (DON) accounted for 54%, 22% and 24% of total wet N deposition. Net canopy accumulated of N occurred with N-NO3(-) and DON but not N-NH4(+). The flux of total dissolved N (TDN) to the forest floor was greater than that in open field precipitation by 17.7 kg N ha(-1) yr(-1), due to capture of dry and cloudwater deposition net of canopy uptake. There were significant negative exponential relationships between monthly water flow depths and monthly mean TDN concentrations in PP, TF, SR, FFL and SW1. The open field nitrogen deposition through precipitation is very high over the world, which is the main way of reactive N input in this bamboo ecosystem. The water exchange and N consume mainly occurred in the litter floor layer and topsoil layer, where most of fine roots of bamboo distributed.

Effects of chronic anthropogenic disturbance and rainfall on the specialization of ant-plant mutualistic networks in the Caatinga, a Brazilian dry forest.

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Câmara, Talita; Leal, Inara R; Blüthgen, Nico; Oliveira, Fernanda M P; Queiroz, Rubens T de; Arnan, Xavier

2018-03-05

Anthropogenic disturbance and climate change might negatively affect the ecosystem services provided by mutualistic networks. However, the effects of such forces remain poorly characterized. They may be especially important in dry forests, which (1) experience chronic anthropogenic disturbances (CADs) as human populations exploit forest resources, and (2) are predicted to face a 22% decline in rainfall under climate change. In this study, we investigated the separate and combined effects of CADs and rainfall levels on the specialization of mutualistic networks in the Caatinga, a seasonally dry tropical forest typical of north-eastern Brazil. More specifically, we examined interactions between plants bearing extrafloral nectaries (EFNs) and ants. We analysed whether differences in network specialization could arise from environmentally mediated variation in the species composition, namely via the replacement of specialist by generalist species. We characterized these ant-plant networks in 15 plots (20 × 20 m) that varied in CAD intensity and mean annual rainfall. We quantified CAD intensity by calculating three indices related to the main sources of disturbance in the Caatinga: livestock grazing (LG), wood extraction (WE) and miscellaneous resource use (MU). We determined the degree of ant-plant network specialization using four metrics: generality, vulnerability, interaction evenness and H 2 '. Our results indicate that CADs differentially influenced network specialization: we observed positive, negative, and neutral responses along LG, MU and WE gradients, respectively. The pattern was most pronounced with LG. Rainfall also shaped network specialization, markedly increasing it. While LG and rainfall were associated with changes in network species composition, this trend was not related to the degree of species specialization. This result suggests that shifts in network specialization might be related to changes in species behaviour, not species composition

Emissions of Selected Semivolatile Organic Chemicals from Forest and Savannah Fires.

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Wang, Xianyu; Thai, Phong K; Mallet, Marc; Desservettaz, Maximilien; Hawker, Darryl W; Keywood, Melita; Miljevic, Branka; Paton-Walsh, Clare; Gallen, Michael; Mueller, Jochen F

2017-02-07

The emission factors (EFs) for a broad range of semivolatile organic chemicals (SVOCs) from subtropical eucalypt forest and tropical savannah fires were determined for the first time from in situ investigations. Significantly higher (t test, P fire (7,000 ± 170) compared to the tropical savannah fires (1,600 ± 110), due to the approximately 60-fold higher EFs for 3-ring PAHs from the former. EF data for many PAHs from the eucalypt forest fire were comparable with those previously reported from pine and fir forest combustion events. EFs for other SVOCs including polychlorinated biphenyl (PCB), polychlorinated naphthalene (PCN), and polybrominated diphenyl ether (PBDE) congeners as well as some pesticides (e.g., permethrin) were determined from the subtropical eucalypt forest fire. The highest concentrations of total suspended particles, PAHs, PCBs, PCNs, and PBDEs, were typically observed in the flaming phase of combustion. However, concentrations of levoglucosan and some pesticides such as permethrin peaked during the smoldering phase. Along a transect (10-150-350 m) from the forest fire, concentration decrease for PCBs during flaming was faster compared to PAHs, while levoglucosan concentrations increased.

Influence of matrix type on tree community assemblages along tropical dry forest edges.

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Benítez-Malvido, Julieta; Gallardo-Vásquez, Julio César; Alvarez-Añorve, Mariana Y; Avila-Cabadilla, Luis Daniel

2014-05-01

• Anthropogenic habitat edges have strong negative consequences for the functioning of tropical ecosystems. However, edge effects on tropical dry forest tree communities have been barely documented.• In Chamela, Mexico, we investigated the phylogenetic composition and structure of tree assemblages (≥5 cm dbh) along edges abutting different matrices: (1) disturbed vegetation with cattle, (2) pastures with cattle and, (3) pastures without cattle. Additionally, we sampled preserved forest interiors.• All edge types exhibited similar tree density, basal area and diversity to interior forests, but differed in species composition. A nonmetric multidimensional scaling ordination showed that the presence of cattle influenced species composition more strongly than the vegetation structure of the matrix; tree assemblages abutting matrices with cattle had lower scores in the ordination. The phylogenetic composition of tree assemblages followed the same pattern. The principal plant families and genera were associated according to disturbance regimes as follows: pastures and disturbed vegetation (1) with cattle and (2) without cattle, and (3) pastures without cattle and interior forests. All habitats showed random phylogenetic structures, suggesting that tree communities are assembled mainly by stochastic processes. Long-lived species persisting after edge creation could have important implications in the phylogenetic structure of tree assemblages.• Edge creation exerts a stronger influence on TDF vegetation pathways than previously documented, leading to new ecological communities. Phylogenetic analysis may, however, be needed to detect such changes. © 2014 Botanical Society of America, Inc.

Extremely low prevalence of Batrachochytrium dendrobatidis in frog populations from neotropical dry forest of Costa Rica supports the existence of a climatic refuge from disease.

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Zumbado-Ulate, Héctor; Bolaños, Federico; Gutiérrez-Espeleta, Gustavo; Puschendorf, Robert

2014-12-01

Population declines and extinctions of numerous species of amphibians, especially stream-breeding frogs, have been linked to the emerging infectious disease chytridiomycosis, caused by the chytrid fungus, Batrachochytrium dendrobatidis. In Central America, most of the 34 species of the Craugastor punctariolus species group have disappeared in recent years in high- and low-elevation rainforests. Distribution models for B. dendrobatidis and the continuous presence of the extirpated stream-dwelling species, Craugastor ranoides, in the driest site of Costa Rica (Santa Elena Peninsula), suggest that environmental conditions might restrict the growth and development of B. dendrobatidis, existing as a refuge from chytridiomycosis-driven extinction. We conducted field surveys to detect and quantify the pathogen using Real-time PCR in samples from 15 species of frogs in two locations of tropical dry forest. In Santa Elena Peninsula, we swabbed 310 frogs, and only one sample of the species, C. ranoides, tested positive for B. dendrobatidis (prevalence dry and hot environments of tropical dry forest. This study supports the existence of climatic refuges from chytridiomycosis and highlights the importance of tropical dry forest conservation for amphibians in the face of epidemic disease.

Environmental radioactivity investigations in the Georgian subtropical region

International Nuclear Information System (INIS)

Pagava, S.; Kakashvili, P.; Avtandilashvili, M.; Kharashvili, G.; Robakidze, Z.; Rusetski, V.; Togonidze, G.; Baratashvili, D.

2002-01-01

Environmental changes in the contamination of the Georgian subtropical region have been investigated by analysing anthropogenic and natural radionuclides in samples of soil and tea leaves for possible chromosome mutations. As the tea industry in Georgia is an important economic activity, such investigations are of great importance. The changes in the morphology of tea leaves, their colour, blossoming, growth inhibition or stimulation, prolongation of the germination period and levels of tanin-katechin complexes have been investigated. The results of radionuclide measurements in soil and tea leaves ( 40 K, 210 Pb and 137 Cs) are presented. Elevated concentrations of 137 Cs were observed in soil samples due to fallout from Chernobyl, however, no direct relationship between the concentration of 137 Cs in soil and tea leaves has been observed. Cyto-genetic analyses of tea primary roots will be presented and compared for different time periods. Further, ichtyofauna samples taken from the Georgian subtropical areas were analysed for anthropogenic ( 137 Cs) and natural ( 40 K) radionuclides. The observed concentrations of 137 Cs were low, close to the detection limit of the order of 0.4 Bq/kg dry weight. Some of the investigations were carried out in the framework of the IAEA Technical Co-operation project 'Marine Environmental Assessment of the Black Sea Region'

Effects of land use change and seasonality of precipitation on soil nitrogen in a dry tropical forest area in the Western Llanos of Venezuela.

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González-Pedraza, Ana Francisca; Dezzeo, Nelda

2014-01-01

We evaluated changes of different soil nitrogen forms (total N, available ammonium and nitrate, total N in microbial biomass, and soil N mineralization) after conversion of semideciduous dry tropical forest in 5- and 18-year-old pastures (YP and OP, resp.) in the western Llanos of Venezuela. This evaluation was made at early rainy season, at end rainy season, and during dry season. With few exceptions, no significant differences were detected in the total N in the three study sites. Compared to forest soils, YP showed ammonium losses from 4.2 to 62.9% and nitrate losses from 20.0 to 77.8%, depending on the season of the year. In OP, the ammonium content increased from 50.0 to 69.0% at the end of the rainy season and decreased during the dry season between 25.0 and 55.5%, whereas the nitrate content increased significantly at early rainy season. The net mineralization and the potentially mineralizable N were significantly higher (P forest and YP, which would indicate a better quality of the substrate in OP for mineralization. The mineralization rate constant was higher in YP than in forest and OP. This could be associated with a reduced capacity of these soils to preserve the available nitrogen.

Nitrogen dynamics in subtropical fringe and basin mangrove forests inferred from stable isotopes.

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Reis, Carla Roberta Gonçalves; Nardoto, Gabriela Bielefeld; Rochelle, André Luis Casarin; Vieira, Simone Aparecida; Oliveira, Rafael Silva

2017-03-01

Mangroves exhibit low species richness compared to other tropical forests, but great structural and functional diversity. Aiming to contribute to a better understanding of the functioning of mangrove forests, we investigated nitrogen (N) dynamics in two physiographic types of mangroves (fringe and basin forests) in southeastern Brazil. Because fringe forests are under great influence of tidal flushing we hypothesized that these forests would exhibit higher N cycling rates in sediment and higher N losses to the atmosphere compared to basin forests. We quantified net N mineralization and nitrification rates in sediment and natural abundance of N stable isotopes (δ 15 N) in the sediment-plant-litter system. The fringe forest exhibited higher net N mineralization rates and δ 15 N in the sediment-plant-litter system, but net nitrification rates were similar to those of the basin forest. The results of the present study suggest that fringe forests exhibit higher N availability and N cycling in sediment compared to basin forests.

Dry deposition of O_3 and SO_2 estimated from gradient measurements above a temperate mixed forest

International Nuclear Information System (INIS)

Wu, Zhiyong; Staebler, Ralf; Vet, Robert; Zhang, Leiming

2016-01-01

Vertical profiles of O_3 and SO_2 concentrations were monitored at the Borden Forest site in southern Ontario, Canada from May 2008 to April 2013. A modified gradient method (MGM) was applied to estimate O_3 and SO_2 dry deposition fluxes using concentration gradients between a level above and a level below the canopy top. The calculated five-year mean (median) dry deposition velocity (V_d) were 0.35 (0.27) and 0.59 (0.54) cm s"−"1, respectively, for O_3 and SO_2. V_d(O_3) exhibited large seasonal variations with the highest monthly mean of 0.68 cm s"−"1 in August and the lowest of 0.09 cm s"−"1 in February. In contrast, seasonal variations of V_d(SO_2) were smaller with monthly means ranging from 0.48 (May) to 0.81 cm s"−"1 (December). The different seasonal variations between O_3 and SO_2 were caused by the enhanced SO_2 uptake by snow surfaces in winter. Diurnal variations showed a peak value of V_d in early morning in summer months for both O_3 and SO_2. Canopy wetness increased the non-stomatal uptake of O_3 while decreasing the stomatal uptake. This also applied to SO_2, but additional factors such as surface acidity also played an important role on the overall uptake. - Highlights: • Application of a modified gradient-method for quantifying dry deposition is demonstrated. • A five-year dry deposition database is developed for O_3 and SO_2 over a mixed forest. • Canopy wetness enhances non-stomatal O_3 uptake while inhibits stomatal uptake. • High surface acidity reduces SO_2 dry deposition. - Capsule: A five-year dataset of O_3 and SO_2 dry deposition velocities was generated from concentration gradient measurement data using a modified gradient method.

Environmental, land cover and land use constraints on the distributional patterns of anurans: Leptodacylus species (Anura, Leptodactylidae from Dry Chaco

Directory of Open Access Journals (Sweden)

Regina Gabriela Medina

2016-11-01

Full Text Available Subtropical dry forests are among the most vulnerable biomes to land transformation at a global scale. Among them, the Dry Chaco suffers an accelerated change due to agriculture expansion and intensification. The Dry Chaco ecoregion is characterized by high levels of endemisms and species diversity, which are the result of a variety of climates and reliefs, allowing a wide variety of environments. The amphibian group exhibits a high richness in the Dry Chaco, which has been barely studied in relation to land cover changes. We used ecological niche models (ENMs to assess the potential geographic distribution of 10 Leptodactylus species (Anura, Leptodactylidae, which are mainly distributed within the Dry Chaco. We characterized these distributions environmentally, analyzed their overlap with land cover classes, and assessed their diversity of ecoregions. Also, we evaluated how these species potential distribution is affected by the transformation of land, and quantified the proportional area of the potential distribution in protected areas. We found that temperature seasonality is the main constraint to the occurrence of the species studied, whose main habitats are savannas, grasslands and croplands. The main threats to these species are the effects of climate change over spatial patterns of seasonality, which could affect their breeding and reproduction mode; the loss of their natural habitat; the exposure to contaminants used by intensive agriculture and their underrepresentation in protected areas.

Climate change impacts detection in dry forested ecosystem as indicated by vegetation cover change in -Laikipia, of Kenya.

Science.gov (United States)

M'mboroki, Kiambi Gilbert; Wandiga, Shem; Oriaso, Silas Odongo

2018-03-29

The objective of the study was to detect and identify land cover changes in Laikipia County of Kenya that have occurred during the last three decades. The land use types of study area are six, of which three are the main and the other three are the minor. The main three, forest, shrub or bush land and grassland, changed during the period, of which grasslands reduced by 5864 ha (40%), forest by 3071 ha (24%) and shrub and bush land increased by 8912 ha (43%). The other three minor land use types were bare land which had reduced by 238 ha (45%), river bed vegetation increased by 209 ha (72%) and agriculture increased by 52 ha (600%) over the period decades. Differences in spatiotemporal variations of vegetation could be largely attributed to the effects of climate factors, anthropogenic activities and their interactions. Precipitation and temperature have been demonstrated to be the key climate factors for plant growth and vegetation development where rainfall decreased by 200 mm and temperatures increased by 1.5 °C over the period. Also, the opinion of the community on the change of land use and management was attributed to climate change and also adaptation strategies applied by the community over time. For example unlike the common understanding that forest resources utilisation increases with increasing human population, Mukogodo dry forested ecosystem case is different in that the majority of the respondents (78.9%) reported that the forest resource use was more in that period than now and also a similar majority (74.2%) had the same opinion that forest resource utilisation was low compared to last 30 years. In Yaaku community, change impacts were evidenced and thus mitigation measures suggested to address the impacts which included the following: controlled bush management and indigenous grass reseeding programme were advocated to restore original grasslands, and agricultural (crop farming) activities are carried out in designated areas outside the

Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

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Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

2010-12-01

Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how

Linking Above- and Belowground Dynamics in Tropical Urban Forests

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Atkinson, E. E.; Marin-Spiotta, E.

2013-12-01

Secondary forests that emerge after a long history of agriculture can have altered plant community composition and relative abundances of different species. These forests can look and behave differently compared to pre-agricultural forests due changes in primary productivity, resource allocation, and phenology, which can significantly affect processes such as carbon accumulation and nutrient availability. Our research explores how alternative successional trajectories following intensive agricultural use affect linkages among the establishment of novel plant communities, soil nutrient availability and turnover, and soil microbial community composition and function. We hypothesize that different plant species composition due to differing land use legacies and successional trajectories would drive changes in soil microbial community structure and function, affecting soil C and N chemistry and turnover. We conducted this research in the subtropical dry forest life zone of St. Croix, U.S. Virgin Islands where island-wide abandonment of sugarcane resulted in a mosaic of sites in different stages of forest succession. We identified replicate sites with the following post-sugarcane trajectories: 1) natural forest regeneration, 2) low intensity pasture use, followed by reforestation with timber plantation, which are no longer being managed, 3) high intensity pasture use and recent natural forest regeneration, and 4) high intensity pasture use and current active grazing. During 2011-2013, we sampled soils seasonally (0-10 cm) and measured tree species composition. The successional trajectories showed distinct tree species composition. The first two trajectories yielded 40-year old mixed-species secondary forest, dominated by the dry forest tree species Melicoccus bijugatas, Guapira fragrans, Maniklara zapota, and Sideroxylon foetidissimum. The tree species Melicoccus bijugatas primarily drove differences between the first two trajectories (natural forest regeneration vs

Estimating forest carbon stocks in tropical dry forests of Zimbabwe ...

African Journals Online (AJOL)

Estimation and mapping of forest dendrometric characteristics such as carbon stocks using remote sensing techniques is fundamental for improved understanding of the role of forests in the carbon cycle and climate change. In this study, we tested whether and to what extent spectral transforms, i.e. vegetation indices ...

Radiation mutagenesis of subtropic plants

International Nuclear Information System (INIS)

Kerkadze, I.G.

1987-01-01

Possibilities of expansion of subtropic plant changeability and development of new gene bank for future selection-genetic studies are detected. New trends of radiation mutagenesis of subtropic plants are formulated as results of studies during many years. A lot of mutants is subjected to sufficient tests, and concrete results are obtained with the help of these tests for definite species. Summing genetic and selection estimations of the results, it is possible to make the conclusion that mutant selection represents one of the powerful methods of preparation of productive and qualitative species of subtropic plants, which are successfully introduced into practice

Standing crop dry matter accumulation and quality patterns of ...

African Journals Online (AJOL)

Nine-week production curves and quality values of eight subtropical pasture species were studied under supplemental spray irrigation to characterize their productive capacity, periodicity and quality.All species exhibited a slow dry matter regrowth rate for two to three weeks after defoliation to 7,5 or 10 cm height. Thereafter ...

Diversity and Phenology of Wild Bees in a Highly Disturbed Tropical Dry Forest "Desierto de la Tatacoa", Huila-Colombia.

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Poveda-Coronel, C A; Riaño-Jiménez, D; Cure, J R

2018-01-12

Colombian tropical dry forest is considered the most endangered tropical biome due to anthropic activities. Desierto de la Tatacoa (DsT) is an example of high disturbed tropical dry forest which still maintains a high biodiversity. The objective of the study was to record the diversity and phenology of wild bees in this place by monthly sampling between December 2014 and December 2016 in a 9-km 2 area. During the study, there was a prolonged El Niño-Southern Oscillation period. Bees were collected by entomological nets, malaise traps, eugenol scent trapping, and nest traps. Shannon index was calculated to estimate diversity and Simpson index to determine dominance of a species. The effect of environmental conditions (wet and dry season) in richness and abundance was analyzed by paired T tests. A total of 3004 bee specimens were collected, belonging to 80 species from Apidae, Megachilidae, Halictidae, and Colletidae. Apidae was the most diverse. Shannon index value was 2.973 (discarding Apis mellifera Linnaeus 1758 data); thus, DsT can be considered as a zone of high wild bee diversity. Dry and rainy season showed differences in diversity (p < 0.05). Rainy season showed larger blooming periods and higher bee diversity than dry season. In both seasons, social species were dominant (e.g., A. mellifera or Trigona fulviventris Guérin 1844). Although DsT is a highly disturbed ecosystem, this study found it has the second highest number of genera and the fourth highest number of species reported in Colombia.

The Forest Fire Problem of Degrading Tain II Forest Reserve in Ghana

African Journals Online (AJOL)

Agribotix GCS 068

2010-01-11

Jan 11, 2010 ... informal practice was done before the 1982/83 dry season when the country ..... Tain II Forest Reserve forms part of the Dry Semi-Deciduous Fire ...... 2003/08; Forest Resources Development Service Working Paper FFM/2. .... Environment, Resources and Development Thailand. web.idrc.ca/uploads/user-.

Chronic human disturbance affects plant trait distribution in a seasonally dry tropical forest

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Sfair, Julia C.; de Bello, Francesco; de França, Thaysa Q.; Baldauf, Cristina; Tabarelli, Marcelo

2018-02-01

The effects of human disturbance on biodiversity can be mediated by environmental conditions, such as water availability, climate and nutrients. In general, disturbed, dry or nutrient-depleted soils areas tend to have lower taxonomic diversity. However, little is known about how these environmental conditions affect functional composition and intraspecific variability in tropical dry forests. We studied a seasonally dry tropical forest (SDTF) under chronic anthropogenic disturbance (CAD) along rainfall and soil nutrient gradients to understand how these factors influence the taxonomic and functional composition. Specifically we evaluated two aspects of CAD, wood extraction and livestock pressure (goat and cattle grazing), along soil fertility and rainfall gradients on shrub and tree traits, considering species turnover and intraspecific variability. In addition, we also tested how the traits of eight populations of the most frequent species are affected by wood extraction, livestock pressure, rainfall and soil fertility. In general, although CAD and environmental gradients affected each trait of the most widespread species differently, the most abundant species also had a greater variation of traits. Considering species turnover, wood extraction is associated with species with a smaller leaf area and lower investment in leaf mass, probably due to the indirect effects of this disturbance type on the vegetation, i.e. the removal of branches and woody debris clears the vegetation, favouring species that minimize water loss. Livestock pressure, on the other hand, affected intraspecific variation: the herbivory caused by goats and cattle promoted individuals which invest more in wood density and leaf mass. In this case, the change of functional composition observed is a direct effect of the disturbance, such as the decrease of palatable plant abundance by goat and cattle herbivory. In synthesis, CAD, rainfall and soil fertility can affect trait distribution at community

Mangrove forest decline

DEFF Research Database (Denmark)

Malik, Abdul; Mertz, Ole; Fensholt, Rasmus

2017-01-01

Mangrove forests in the tropics and subtropics grow in saline sediments in coastal and estuarine environments. Preservation of mangrove forests is important for many reasons, including the prevention of coastal erosion and seawater intrusion; the provision of spawning, nursery, and feeding grounds...... of diverse marine biota; and for direct use (such as firewood, charcoal, and construction material)—all of which benefit the sustainability of local communities. However, for many mangrove areas of the world, unsustainable resource utilization and the profit orientation of communities have often led to rapid...... and severe mangrove loss with serious consequences. The mangrove forests of the Takalar District, South Sulawesi, are studied here as a case area that has suffered from degradation and declining spatial extent during recent decades. On the basis of a post-classification comparison of change detection from...

Functional strategies of tropical dry forest plants in relation to growth form and isotopic composition

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Santiago, L. S.; Silvera, K.; Andrade, J. L.; Dawson, T. E.

2017-11-01

Tropical dry forests (TDFs) undergo a substantial dry season in which plant species must endure several months of drought. Although TDFs support a diverse array of plant growth forms, it is not clear how they vary in mechanisms for coping with seasonal drought. We measured organic tissue stable isotopic composition of carbon (δ13C) and nitrogen (δ15N) across six plant growth forms including epiphytes, terrestrial succulents, trees, shrubs, herbs, and vines, and oxygen (δ18O) of four growth forms, to distinguish among patterns of resource acquisition and evaluate mechanisms for surviving annual drought in a lowland tropical dry forest in Yucatan, Mexico. Terrestrial succulent and epiphyte δ13C was around -14‰, indicating photosynthesis through the Crassulacean acid metabolism pathway, and along with one C4 herb were distinct from mean values of all other growth forms, which were between -26 and -29‰ indicating C3 photosynthesis. Mean tissue δ15N across epiphytes was -4.95‰ and was significantly lower than all other growth forms, which had values around +3‰. Tissue N concentration varied significantly among growth forms with epiphytes and terrestrial succulents having significantly lower values of about 1% compared to trees, shrubs, herbs and vines, which were around 3%. Tissue C concentration was highest in trees, shrubs and vines, intermediate in herbs and epiphytes and lowest in terrestrial succulents. δ18O did not vary among growth forms. Overall, our results suggest several water-saving aspects of resource acquisition, including the absolute occurrence of CAM photosynthesis in terrestrial succulents and epiphytes, high concentrations of leaf N in some species, which may facilitate CO2 drawdown by photosynthetic enzymes for a given stomatal conductance, and potentially diverse N sources ranging from atmospheric N in epiphytes with extremely depleted δ15N values, and a large range of δ15N values among trees, many of which are legumes and dry season

Future drying of the southern Amazon and central Brazil

Science.gov (United States)

Yoon, J.; Zeng, N.; Cook, B.

2008-12-01

Recent climate modeling suggests that the Amazon rainforest could exhibit considerable dieback under future climate change, a prediction that has raised considerable interest as well as controversy. To determine the likelihood and causes of such changes, we analyzed the output of 15 models from the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC/AR4) and a dynamic vegetation model VEGAS driven by these climate output. Our results suggest that the core of the Amazon rainforest should remain largely stable. However, the periphery, notably the southern edge, is in danger of drying out, driven by two main processes. First, a decline in precipitation of 24% in the southern Amazon lengthens the dry season and reduces soil moisture, despite of an increase in precipitation during the wet season, due to the nonlinear response in hydrology and ecosystem dynamics. Two dynamical mechanisms may explain the lower dry season precipitation: (1) a stronger north-south tropical Atlantic sea surface temperature gradient; (2) a general subtropical drying under global warming when the dry season southern Amazon is under the control of the subtropical high pressure. Secondly, evaporation will increase due to the general warming, thus also reducing soil moisture. As a consequence, the median of the models projects a reduction of vegetation by 20%, and enhanced fire carbon flux by 10-15% in the southern Amazon, central Brazil, and parts of the Andean Mountains. Because the southern Amazon is also under intense human influence, the double pressure of deforestation and climate change may subject the region to dramatic changes in the 21st century.

Climate change versus deforestation: Implications for tree species distribution in the dry forests of southern Ecuador

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Hildebrandt, Patrick; Cueva, Jorge; Espinosa, Carlos Iván; Stimm, Bernd; Günter, Sven

2017-01-01

Seasonally dry forests in the neotropics are heavily threatened by a combination of human disturbances and climate change; however, the severity of these threats is seldom contrasted. This study aims to quantify and compare the effects of deforestation and climate change on the natural spatial ranges of 17 characteristic tree species of southern Ecuador dry deciduous forests, which are heavily fragmented and support high levels of endemism as part of the Tumbesian ecoregion. We used 660 plant records to generate species distribution models and land-cover data to project species ranges for two time frames: a simulated deforestation scenario from 2008 to 2014 with native forest to anthropogenic land-use conversion, and an extreme climate change scenario (CCSM4.0, RCP 8.5) for 2050, which assumed zero change from human activities. To assess both potential threats, we compared the estimated annual rates of species loss (i.e., range shifts) affecting each species. Deforestation loss for all species averaged approximately 71 km2/year, while potential climate-attributed loss was almost 21 km2/year. Moreover, annual area loss rates due to deforestation were significantly higher than those attributed to climate-change (P < 0.01). However, projections into the future scenario show evidence of diverging displacement patterns, indicating the potential formation of novel ecosystems, which is consistent with other species assemblage predictions as result of climate change. Furthermore, we provide recommendations for management and conservation, prioritizing the most threatened species such as Albizia multiflora, Ceiba trichistandra, and Cochlospermum vitifolium. PMID:29267357

Climate change versus deforestation: Implications for tree species distribution in the dry forests of southern Ecuador.

Science.gov (United States)

Manchego, Carlos E; Hildebrandt, Patrick; Cueva, Jorge; Espinosa, Carlos Iván; Stimm, Bernd; Günter, Sven

2017-01-01

Seasonally dry forests in the neotropics are heavily threatened by a combination of human disturbances and climate change; however, the severity of these threats is seldom contrasted. This study aims to quantify and compare the effects of deforestation and climate change on the natural spatial ranges of 17 characteristic tree species of southern Ecuador dry deciduous forests, which are heavily fragmented and support high levels of endemism as part of the Tumbesian ecoregion. We used 660 plant records to generate species distribution models and land-cover data to project species ranges for two time frames: a simulated deforestation scenario from 2008 to 2014 with native forest to anthropogenic land-use conversion, and an extreme climate change scenario (CCSM4.0, RCP 8.5) for 2050, which assumed zero change from human activities. To assess both potential threats, we compared the estimated annual rates of species loss (i.e., range shifts) affecting each species. Deforestation loss for all species averaged approximately 71 km2/year, while potential climate-attributed loss was almost 21 km2/year. Moreover, annual area loss rates due to deforestation were significantly higher than those attributed to climate-change (P < 0.01). However, projections into the future scenario show evidence of diverging displacement patterns, indicating the potential formation of novel ecosystems, which is consistent with other species assemblage predictions as result of climate change. Furthermore, we provide recommendations for management and conservation, prioritizing the most threatened species such as Albizia multiflora, Ceiba trichistandra, and Cochlospermum vitifolium.

Macroecology of Australian Tall Eucalypt Forests: Baseline Data from a Continental-Scale Permanent Plot Network

Science.gov (United States)

Wood, Sam W.; Prior, Lynda D.; Stephens, Helen C.; Bowman, David M. J. S.

2015-01-01

Tracking the response of forest ecosystems to climate change demands large (≥1 ha) monitoring plots that are repeatedly measured over long time frames and arranged across macro-ecological gradients. Continental scale networks of permanent forest plots have identified links between climate and carbon fluxes by monitoring trends in tree growth, mortality and recruitment. The relationship between tree growth and climate in Australia has been recently articulated through analysis of data from smaller forest plots, but conclusions were limited by (a) absence of data on recruitment and mortality, (b) exclusion of non-eucalypt species, and (c) lack of knowledge of stand age or disturbance histories. To remedy these gaps we established the Ausplots Forest Monitoring Network: a continental scale network of 48 1 ha permanent plots in highly productive tall eucalypt forests in the mature growth stage. These plots are distributed across cool temperate, Mediterranean, subtropical and tropical climates (mean annual precipitation 850 to 1900 mm per year; mean annual temperature 6 to 21°C). Aboveground carbon stocks (AGC) in these forests are dominated by eucalypts (90% of AGC) whilst non-eucalypts in the understorey dominated species diversity and tree abundance (84% of species; 60% of stems). Aboveground carbon stocks were negatively related to mean annual temperature, with forests at the warm end of the temperature range storing approximately half the amount of carbon as forests at the cool end of the temperature range. This may reflect thermal constraints on tree growth detected through other plot networks and physiological studies. Through common protocols and careful sampling design, the Ausplots Forest Monitoring Network will facilitate the integration of tall eucalypt forests into established global forest monitoring initiatives. In the context of projections of rapidly warming and drying climates in Australia, this plot network will enable detection of links between

Unsupported inferences of high-severity fire in historical dry forests of the western United States: Response to Williams and Baker

Science.gov (United States)

Fulé, Peter Z.; Swetnam, Thomas W.; Brown, Peter M.; Falk, Donald A.; Peterson, David L.; Allen, Craig D.; Aplet, Gregory H.; Battaglia, Mike A.; Binkley, Dan; Farris, Calvin; Keane, Robert E.; Margolis, Ellis Q.; Grissino-Mayer, Henri; Miller, Carol; Sieg, Carolyn Hull; Skinner, Carl; Stephens, Scott L.; Taylor, Alan

2014-01-01

Reconstructions of dry western US forests in the late 19th century in Arizona, Colorado and Oregon based on General Land Office records were used by Williams & Baker (2012; Global Ecology and Biogeography, 21, 1042–1052; hereafter W&B) to infer past fire regimes with substantial moderate and high-severity burning. The authors concluded that present-day large, high-severity fires are not distinguishable from historical patterns. We present evidence of important errors in their study. First, the use of tree size distributions to reconstruct past fire severity and extent is not supported by empirical age–size relationships nor by studies that directly quantified disturbance history in these forests. Second, the fire severity classification of W&B is qualitatively different from most modern classification schemes, and is based on different types of data, leading to an inappropriate comparison. Third, we note that while W&B asserted ‘surprising’ heterogeneity in their reconstructions of stand density and species composition, their data are not substantially different from many previous studies which reached very different conclusions about subsequent forest and fire behaviour changes. Contrary to the conclusions of W&B, the preponderance of scientific evidence indicates that conservation of dry forest ecosystems in the western United States and their ecological, social and economic value is not consistent with a present-day disturbance regime of large, high-severity fires, especially under changing climate

Climate Drives Episodic Conifer Establishment after Fire in Dry Ponderosa Pine Forests of the Colorado Front Range, USA

Directory of Open Access Journals (Sweden)

Monica T. Rother

2017-05-01

Full Text Available In recent years, warming climate and increased fire activity have raised concern about post-fire recovery of western U.S. forests. We assessed relationships between climate variability and tree establishment after fire in dry ponderosa pine forests of the Colorado Front Range. We harvested and aged over 400 post-fire juvenile ponderosa pine (Pinus ponderosa and Douglas-fir (Pseudotsuga menziesii trees using an improved tree-ring based approach that yielded annually-resolved dates and then assessed relationships between climate variability and pulses of tree establishment. We found that tree establishment was largely concentrated in years of above-average moisture availability in the growing season, including higher amounts of precipitation and more positive values of the Palmer Drought Severity Index. Under continued climate change, drier conditions associated with warming temperatures may limit forest recovery after fire, which could result in lower stand densities or shifts to non-forested vegetation in some areas.

Organismal responses to habitat change: herbivore performance, climate and leaf traits in regenerating tropical dry forests.

Science.gov (United States)

Agosta, Salvatore J; Hulshof, Catherine M; Staats, Ethan G

2017-05-01

The ecological effects of large-scale climate change have received much attention, but the effects of the more acute form of climate change that results from local habitat alteration have been less explored. When forest is fragmented, cut, thinned, cleared or otherwise altered in structure, local climates and microclimates change. Such changes can affect herbivores both directly (e.g. through changes in body temperature) and indirectly (e.g. through changes in host plant traits). We advance an eco-physiological framework to understand the effects of changing forests on herbivorous insects. We hypothesize that if tropical forest caterpillars are climate and resource specialists, then they should have reduced performance outside of mature forest conditions. We tested this hypothesis with a field experiment contrasting the performance of Rothschildia lebeau (Saturniidae) caterpillars feeding on the host plant Casearia nitida (Salicaceae) in two different aged and structured tropical dry forests in Area de Conservación Guanacaste, Costa Rica. Compared to more mature closed-canopy forest, in younger secondary forest we found that: (1) ambient conditions were hotter, drier and more variable; (2) caterpillar growth and development were reduced; and (3) leaves were tougher, thicker and drier. Furthermore, caterpillar growth and survival were negatively correlated with these leaf traits, suggesting indirect host-mediated effects of climate on herbivores. Based on the available evidence, and relative to mature forest, we conclude that reduced herbivore performance in young secondary forest could have been driven by changes in climate, leaf traits (which were likely climate induced) or both. However, additional studies will be needed to provide more direct evidence of cause-and-effect and to disentangle the relative influence of these factors on herbivore performance in this system. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Diptera of Medico-Legal Importance Associated With Pig Carrion in a Tropical Dry Forest.

Science.gov (United States)

Vasconcelos, S D; Salgado, R L; Barbosa, T M; Souza, J R B

2016-06-20

The diversity of necrophagous Diptera is largely unknown in seasonally dry tropical forests, despite their medical, veterinary, and forensic relevance. We performed a study in the dry Caatinga forest exclusive to Brazil in order to assess the diversity and temporal pattern of Diptera species using pig carcasses as substrates. Adults were collected daily until complete skeletonization. We collected 17,142 adults from 18 families, 10 of which comprise species with known necrophagous habits. The most abundant families were Calliphoridae (47.3% of specimens), Sarcophagidae (20.8%), and Muscidae (15.5%), whereas Sarcophagidae stood out in terms of richness with 21 species. The native Cochliomyia macellaria (F.) (Diptera: Calliphoridae) and the invasive Chrysomya albiceps (Wiedmann) (Calliphoridae) were the dominant species. A total of 18 species reached the carcass during the first 48 h postdeath. The bloated and active decay stages had the highest richness and abundance of dipterans. From a forensic standpoint, C. macellaria and C. albiceps are likely to aid in establishing postmortem interval due to their early arrival and high abundance on the carcass. Despite harsh environmental conditions, the Caatinga harbors a rich assemblage of dipterans that play a key role in carrion decomposition. Their medico-veterinary importance is strengthened by the poor local sanitary conditions. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Aerosol dynamics within and above forest in relation to turbulent transport and dry deposition

DEFF Research Database (Denmark)

Rannik, Üllar; Zhou, Luxi; Zhou, Putian

2016-01-01

of 10 days in May 2013 to a pine forest site in southern Finland. The period was characterized by frequent new particle formation events and simultaneous intensive aerosol transformation. The aim of the study was to analyze and quantify the role of aerosol and ABL dynamics in the vertical transport...... of aerosols. It was of particular interest to what extent the fluxes above the canopy deviate from the particle dry deposition on the canopy foliage due to the above-mentioned processes. The model simulations revealed that the particle concentration change due to aerosol dynamics frequently exceeded...... the effect of particle deposition by even an order of magnitude or more. The impact was, however, strongly dependent on particle size and time. In spite of the fact that the timescale of turbulent transfer inside the canopy is much smaller than the timescales of aerosol dynamics and dry deposition, leading...

Climate change effects on the geographic distribution of specialist tree species of the Brazilian tropical dry forests.

Science.gov (United States)

Rodrigues, P M S; Silva, J O; Eisenlohr, P V; Schaefer, C E G R

2015-08-01

The aim of this study was to evaluate the ecological niche models (ENMs) for three specialist trees (Anadenanthera colubrina, Aspidosperma pyrifolium and Myracrodruon urundeuva) in seasonally dry tropical forests (SDTFs) in Brazil, considering present and future pessimist scenarios (2080) of climate change. These three species exhibit typical deciduousness and are widely distributed by SDTF in South America, being important in studies of the historical and evolutionary processes experienced by this ecosystem. The modeling of the potential geographic distribution of species was done by the method of maximum entropy (Maxent).We verified a general expansion of suitable areas for occurrence of the three species in future (c.a., 18%), although there was reduction of areas with high environmental suitability in Caatinga region. Precipitation of wettest quarter and temperature seasonality were the predictor variables that most contributed to our models. Climatic changes can provide more severe and longer dry season with increasing temperature and tree mortality in tropics. On this scenario, areas currently occupied by rainforest and savannas could become more suitable for occurrence of the SDTF specialist trees, whereas regions occupied by Caatinga could not support the future level of unsustainable (e.g., aridity). Long-term multidisciplinary studies are necessary to make reliable predictions of the plant's adaptation strategies and responses to climate changes in dry forest at community level. Based on the high deforestation rate, endemism and threat, public policies to minimize the effects of climate change on the biodiversity found within SDTFs must be undertaken rapidly.

impact of re-forestation of a re-growth secondary forest with

African Journals Online (AJOL)

BIG TIMMY

In general, the forest stand had more density of trees in each dbh class with a peak in .... Awolowo University Estate, Ile-Ife, Osun state, ... forest sub-type is dry deciduous forest (Onochie, ..... eastern Cascades, USA. .... Agriculture, Washington.

Nitrogen distribution and cycling through water flows in a subtropical bamboo forest under high level of atmospheric deposition.

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Li-hua Tu

Full Text Available BACKGROUND: The hydrological cycle is an important way of transportation and reallocation of reactive nitrogen (N in forest ecosystems. However, under a high level of atmospheric N deposition, the N distribution and cycling through water flows in forest ecosystems especially in bamboo ecosystems are not well understood. METHODOLOGY/PRINCIPAL FINDINGS: In order to investigate N fluxes through water flows in a Pleioblastus amarus bamboo forest, event rainfall/snowfall (precipitation, PP, throughfall (TF, stemflow (SF, surface runoff (SR, forest floor leachate (FFL, soil water at the depth of 40 cm (SW1 and 100 cm (SW2 were collected and measured through the whole year of 2009. Nitrogen distribution in different pools in this ecosystem was also measured. Mean N pools in vegetation and soil (0-1 m were 351.7 and 7752.8 kg ha(-1. Open field nitrogen deposition at the study site was 113.8 kg N ha(-1 yr(-1, which was one of the highest in the world. N-NH4(+, N-NO3(- and dissolved organic N (DON accounted for 54%, 22% and 24% of total wet N deposition. Net canopy accumulated of N occurred with N-NO3(- and DON but not N-NH4(+. The flux of total dissolved N (TDN to the forest floor was greater than that in open field precipitation by 17.7 kg N ha(-1 yr(-1, due to capture of dry and cloudwater deposition net of canopy uptake. There were significant negative exponential relationships between monthly water flow depths and monthly mean TDN concentrations in PP, TF, SR, FFL and SW1. CONCLUSIONS/SIGNIFICANCE: The open field nitrogen deposition through precipitation is very high over the world, which is the main way of reactive N input in this bamboo ecosystem. The water exchange and N consume mainly occurred in the litter floor layer and topsoil layer, where most of fine roots of bamboo distributed.

Soil fauna as an indicator of soil quality in forest stands, pasture and secondary forest

Directory of Open Access Journals (Sweden)

Felipe Vieira da Cunha Neto

2012-11-01

Full Text Available The interactions between soil invertebrates and environmental variations are relatively unknown in the assessment of soil quality. The objective of this study was to evaluate soil quality in areas with different soil management systems, based on soil fauna as indicator, in Além Paraíba, Minas Gerais, Brazil. The soil invertebrate community was sampled using pitfall traps, in the dry and rainy seasons, from areas with five vegetation types (acacia, mimosa, eucalyptus, pasture, and secondary forest. The abundance of organisms and the total and average richness, Shannon's diversity index, the Pielou uniformity index, and change index V were determined. The fauna was most abundant in the areas of secondary forest and mimosa plantations in the dry season (111.3 and 31.7 individuals per trap per day, respectively. In the rainy season, the abundance of organisms in the three vegetation types did not differ. The highest values of average and total richness were recorded in the secondary forest in the dry season and in the mimosa stand in the rainy season. Shannon's index ranged from 1.57 in areas with acacia and eucalyptus in the rainy season to 3.19 in the eucalyptus area in the dry season. The uniformity index was highest in forest stands (eucalyptus, acacia and mimosa in the dry season, but higher in the rainy season in the pasture and secondary forest than in the forest stands. The change index V indicated that the percentage of extremely inhibited groups was lowest in the area with mimosa, both in the dry and rainy season (36 and 23 %, respectively. Of all forest stands, the mimosa area had the most abundant soil fauna.

Litterfall mercury dry deposition in the eastern USA

International Nuclear Information System (INIS)

Risch, Martin R.; DeWild, John F.; Krabbenhoft, David P.; Kolka, Randall K.; Zhang, Leiming

2012-01-01

Mercury (Hg) in autumn litterfall from predominately deciduous forests was measured in 3 years of samples from 23 Mercury Deposition Network sites in 15 states across the eastern USA. Annual litterfall Hg dry deposition was significantly higher (median 12.3 micrograms per square meter (μg/m 2 ), range 3.5–23.4 μg/m 2 ) than annual Hg wet deposition (median 9.6 μg/m 2 , range 4.4–19.7 μg/m 2 ). The mean ratio of dry to wet Hg deposition was 1.3–1. The sum of dry and wet Hg deposition averaged 21 μg/m 2 per year and 55% was litterfall dry deposition. Methylmercury was a median 0.8% of Hg in litterfall and ranged from 0.6 to 1.5%. Annual litterfall Hg and wet Hg deposition rates differed significantly and were weakly correlated. Litterfall Hg dry deposition differed among forest-cover types. This study demonstrated how annual litterfall Hg dry deposition rates approximate the lower bound of annual Hg dry fluxes. - Highlights: ► Annual litterfall mercury dry deposition was significantly higher than wet deposition. ► The mean ratio of dry to wet mercury deposition was 1.3–1. ► The sum of dry and wet mercury deposition averaged 55% litterfall dry deposition. ► Litterfall mercury deposition was highest in the oak-hickory forest-cover type. ► Methylmercury was a median 0.8% of mercury in litterfall and ranged to 1.5%. - A multi-year study of Mercury Deposition Network sites found that annual mercury dry deposition from litterfall in predominately deciduous forests exceeded annual mercury wet deposition in the eastern USA.

Dependence of Soil Respiration on Soil Temperature and Soil Moisture in Successional Forests in Southern China

Institute of Scientific and Technical Information of China (English)

Xu-Li Tang; Guo-Yi Zhou; Shu-Guang Liu; De-Qiang Zhang; Shi-Zhong Liu; Jiong Li; Cun-Yu Zhou

2006-01-01

The spatial and temporal variations in soil respiration and its relationship with biophysical factors in forests near the Tropic of Cancer remain highly uncertain. To contribute towards an improvement of actual estimates, soil respiration rates, soil temperature, and soil moisture were measured in three successional subtropical forests at the Dinghushan Nature Reserve (DNR) in southern China from March 2003 to February 2005. The overall objective of the present study was to analyze the temporal variations of soil respiration and its biophysical dependence in these forests. The relationships between biophysical factors and soil respiration rates were compared in successional forests to test the hypothesis that these forests responded similarly to biophysical factors. The seasonality of soil respiration coincided with the seasonal climate pattern, with high respiration rates in the hot humid season (April-September) and with low rates in the cool dry season (October-March). Soil respiration measured at these forests showed a clear increasing trend with the progressive succession. Annual mean (± SD) soil respiration rate in the DNR forests was (9.0±4.6) Mg CO2-C/hm2 per year, ranging from (6.1±3.2) Mg CO2-C/hm2 per year in early successional forests to (10.7±4.9) Mg CO2-C/hm2 per year in advanced successional forests. Soil respiration was correlated with both soil temperature and moisture. The T/M model, where the two biophysical variables are driving factors, accounted for 74%-82% of soil respiration variation in DNR forests. Temperature sensitivity decreased along progressive succession stages, suggesting that advanced-successional forests have a good ability to adjust to temperature. In contrast, moisture increased with progressive succession processes. This increase is caused, in part, by abundant respirators in advanced-successional forest, where more soil moisture is needed to maintain their activities.

Dependence of soil respiration on soil temperature and soil moisture in successional forests in Southern China

Science.gov (United States)

Tang, X.-L.; Zhou, G.-Y.; Liu, S.-G.; Zhang, D.-Q.; Liu, S.-Z.; Li, Ji; Zhou, C.-Y.

2006-01-01

The spatial and temporal variations in soil respiration and its relationship with biophysical factors in forests near the Tropic of Cancer remain highly uncertain. To contribute towards an improvement of actual estimates, soil respiration rates, soil temperature, and soil moisture were measured in three successional subtropical forests at the Dinghushan Nature Reserve (DNR) in southern China from March 2003 to February 2005. The overall objective of the present study was to analyze the temporal variations of soil respiration and its biophysical dependence in these forests. The relationships between biophysical factors and soil respiration rates were compared in successional forests to test the hypothesis that these forests responded similarly to biophysical factors. The seasonality of soil respiration coincided with the seasonal climate pattern, with high respiration rates in the hot humid season (April-September) and with low rates in the cool dry season (October-March). Soil respiration measured at these forests showed a clear increasing trend with the progressive succession. Annual mean (±SD) soil respiration rate in the DNR forests was (9.0 ± 4.6) Mg CO2-C/hm2per year, ranging from (6.1 ± 3.2) Mg CO2-C/hm2per year in early successional forests to (10.7 ± 4.9) Mg CO2-C/hm2 per year in advanced successional forests. Soil respiration was correlated with both soil temperature and moisture. The T/M model, where the two biophysical variables are driving factors, accounted for 74%-82% of soil respiration variation in DNR forests. Temperature sensitivity decreased along progressive succession stages, suggesting that advanced-successional forests have a good ability to adjust to temperature. In contrast, moisture increased with progressive succession processes. This increase is caused, in part, by abundant respirators in advanced-successional forest, where more soil moisture is needed to maintain their activities.

Hurricane recovery at Cabezas de San Juan, Puerto Rico, and research opportunities at Conservation Trust Reserves

Science.gov (United States)

Peter L. Weaver; Elizabeth Padilla Rodriguez

2009-01-01

The Cabezas de San Juan Natural Reserve (El Faro), an exposed peninsular area located in the Subtropical dry forest of northeastern Puerto Rico, was impacted by hurricanes Hugo (1989) and Georges (1998). From 1998 to 2008, a 0.10 ha plot was used to assess forest structure, species composition, and stem growth. During post-hurricane recovery, stem density, tree height...

CLIMATE-TREE GROWTH RELATIONSHIPS OF Mimosa tenuiflora IN SEASONALLY DRY TROPICAL FOREST, BRAZIL

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Patrícia Póvoa Mattos

2015-03-01

Full Text Available Mimosa tenuiflora is a native pioneer tree from the Caatinga used commercially as firewood due to its high calorific value. It is deciduous, its trunk does not reach large diameters and it has good regrowth capacity. This study intended to determine the annual increment in diameter of M. tenuiflora and its correlation with rainfall, as basis for fuel wood management. Disks from the stem base of M. tenuiflora trees were collected in 2008 in Sertânia and Serra Talhada, Pernambuco State, from regrowth of trees coppiced in 2003 and in Limoeiro do Norte, Ceará State, from a plantation established in 2002. The trees have well-defined annual growth rings, highly correlated with annual precipitation and are well-suited for dendrochronological investigations. Forest managers must consider the influence of previous drier years in the wood production when predicting fuel wood harvesting. The high growth correlation with the previous year’s rainfall in regions where the rains start after photoperiodic stimulation indicate the necessity of understanding the growth dynamics of the species under dry forest conditions through additional ecophysiology studies.

Tropical dry forest status and relative importance of woody flora, islands of Old Providence and Santa Catalina, Colombia, Southwestern Caribbean

International Nuclear Information System (INIS)

Linares, Jorge Ruiz; Fandino Orozco, Maria Claudia

2009-01-01

The purpose of this paper is to present evidence on the condition of the Dry Tropical Forest (DtF) in Old Providence. A chronological study was carried out in order to assess the land cover change in DtF between 1944 and 2005. Additionally, we established 109 plots 2 x 50 m, following the protocol by Gentry (1982); and species abundance models were fitted to the data. It is concluded that up to 2000 the forest recovered, yet, in 2005 it retreated to 1990 levels. The lognormal distribution suggests that the forest is indeed in good condition. Anacardiaceae is the family with the highest Importance Value Index (IVI) while Acacia collinsii is the species with the highest IVI.

Successional and seasonal variations in soil and litter microbial community structure and function during tropical postagricultural forest regeneration: a multiyear study.

Science.gov (United States)

Smith, A Peyton; Marín-Spiotta, Erika; Balser, Teri

2015-09-01

Soil microorganisms regulate fundamental biochemical processes in plant litter decomposition and soil organic matter (SOM) transformations. Understanding how microbial communities respond to changes in vegetation is critical for improving predictions of how land-cover change affects belowground carbon storage and nutrient availability. We measured intra- and interannual variability in soil and forest litter microbial community composition and activity via phospholipid fatty acid analysis (PLFA) and extracellular enzyme activity across a well-replicated, long-term chronosequence of secondary forests growing on abandoned pastures in the wet subtropical forest life zone of Puerto Rico. Microbial community PLFA structure differed between young secondary forests and older secondary and primary forests, following successional shifts in tree species composition. These successional patterns held across seasons, but the microbial groups driving these patterns differed over time. Microbial community composition from the forest litter differed greatly from those in the soil, but did not show the same successional trends. Extracellular enzyme activity did not differ with forest succession, but varied by season with greater rates of potential activity in the dry seasons. We found few robust significant relationships among microbial community parameters and soil pH, moisture, carbon, and nitrogen concentrations. Observed inter- and intrannual variability in microbial community structure and activity reveal the importance of a multiple, temporal sampling strategy when investigating microbial community dynamics with land-use change. Successional control over microbial composition with forest recovery suggests strong links between above and belowground communities. © 2015 John Wiley & Sons Ltd.

Long-term understory vegetation dynamics and responses to ungulate exclusion in the dry forest of Mona Island

Science.gov (United States)

J. Rojas-Sandoval; E.J. Melendez-Ackerman; J. Fumero-Caban; M. Garcia-Bermudez; J. Sustache; S. Aragon; M. Morales-Vargas; G. Olivieri; D.S. Fernandez

2016-01-01

Mona Island protects one of the most important remnants of Caribbean dry forests and hosts a high diversity of rare and endangered plant and animal species. Feral ungulates (goats and pigs) were introduced to the island ~500 y ago, and their populations may be threatening the conservation of Mona Island’s native biodiversity. In this study, we used permanent fenced and...

Intra- and interspecific trait variations reveal functional relationships between specific leaf area and soil niche within a subtropical forest.

Science.gov (United States)

He, Dong; Chen, Yongfa; Zhao, Kangning; Cornelissen, J H C; Chu, Chengjin

2018-02-03

How functional traits vary with environmental conditions is of fundamental importance in trait-based community ecology. However, how intraspecific variability in functional traits is connected to species distribution is not well understood. This study investigated inter- and intraspecific variation of a key functional trait, i.e. specific leaf area (leaf area per unit dry mass; SLA), in relation to soil factors and tested if trait variation is more closely associated with specific environmental regimes for low-variability species than for high-variability species. In a subtropical evergreen forest plot (50 ha, southern China), 106 700 leaves from 5335 individuals of 207 woody species were intensively collected, with 30 individuals sampled for most species to ensure a sufficient sample size representative of intraspecific variability. Soil conditions for each plant were estimated by kriging from more than 1700 observational soil locations across the plot. Intra- and interspecific variation in SLA were separately related to environmental factors. Based on the species-specific variation of SLA, species were categorized into three groups: low-, intermediate- and high-intraspecific variability. Intraspecific habitat ranges and the strength of SLA-habitat relationships were compared among these three groups. Interspecific variation in SLA overrides the intraspecific variation (77 % vs. 8 %). Total soil nitrogen (TN, positively) and total organic carbon (TOC, negatively) are the most important explanatory factors for SLA variation at both intra- and interspecific levels. SLA, both within and between species, decreases with decreasing soil nitrogen availability. As predicted, species with low intraspecific variability in SLA have narrower habitat ranges with respect to soil TOC and TN and show a stronger SLA-habitat association than high-variability species. For woody plants low SLA is a phenotypic and probably adaptive response to nitrogen stress, which drives the

Carbon dioxide and water vapour exchange in a tropical dry forest as influenced by the North American Monsoon System (NAMS)

Science.gov (United States)

To better understand the effects and relationship between precipitation, net ecosystem carbon dioxide (NEE) and water vapor exchange (ET), we report a study conducted in the tropical dry forest (TDF) in the northwest of Mexico. Ecosystem gas exchange was measured using the eddy correlation technique...

Solar drying of uruguayan red gum

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Andrés Ono

2011-04-01

Full Text Available he use of solar energy as an alternative to non-renewable energy sources has been widely researched in the last decades. Compared to air drying, solar drying kilns can better control the drying process, resulting in a higher quality of the dry wood and lower final wood moisture content values. Investment and running costs for a solar drying kiln are lower than those of a conventional kiln. Moreover, the solar drying process can be advantageous for drying hardwoods which are traditionally considered difficult to dry such as eucalyptus wood of medium and high density (Red gums, known in Spanish as “Eucaliptos colorados”. The solar drying kiln naturally incorporates a daily high relative humidity period that can be similar to a conditioning or steaming step, although at a lower temperature.This results in fewer defects due to the drying process.A pilot scale 2.5 m3 semi-greenhouse type solar wood drying kiln was constructed at LATU (Uruguay Technological Laboratory in Montevideo, Uruguay. The operating conditions and the results from two drying runs are presented. Two species of red gum (Eucalyptus tereticornis Sm., ADD 870 kg/m3, and Eucalyptus camaldulensis Dehnh., ADD 800 kg/m3 were dried from initial average moisture contents (WMC of around 60% down to 10.0% and 12.7% in 108 days and 76 days, respectively. Boards were provided by the Grupo Forestal San Gregorio from trees harvested at Tacuarembo and Paysandu Departments from cattle shelter forests 60 and 70 years old.Mean volume shrinkage was 18% for E. tereticornis, and 16% for E. camaldulensis, and the level of defects was moderate. Residual stresses and moisture content gradients were observed for both species. Final moisture content values were similar compared to those obtained in conventional drying kilns but with longer drying periods and lower operating costs. This would make the solar drying process attractive to small and medium sized forest products industries in a small country

Phytogeographical patterns of dry forests sensu stricto in northern Minas Gerais State, Brazil.

Science.gov (United States)

Arruda, Daniel M; Ferreira-Júnior, Walnir G; Duque-Brasil, Reinaldo; Schaefer, Carlos E R

2013-01-01

The Deciduous Complex that occurs in northern Minas Gerais State, Brazil, raises questions about the floristic affinities of these formations in relation to neighboring phytogeographical domains. Little is known about the identity of the seasonal forest formations that comprise this complex, or about its relationships to abiotic components, such as soils, topography and climate. This study aimed to recognize the patterns of floristic similarity of all studied fragments of dry forest of northern Minas Gerais with soil and climate attributes, based on the available database. Cluster analysis indicated the existence of two floristic groups that had clear associations with either the Koppen's BSh (semi-arid) or Aw (seasonal tropical) climates. Likewise, the subdivisions of these groups showed clear associations with the dominant soil classes in the region. The Red-Yellow Latosol is the dominant soil classes in the BSh climatic domain, seconded by alluvial areas associated with Fluvic Neosols. The Aw domain comprised a much varied set of soils: Nitosols, Argisols, Cambisols and Litholic Neosols, most derived from the Bambuí limestone/slate formation. The ecotonal nature of northern Minas Gerais State provides a complex interaction between the flora of neighboring phytogeographical domains. This, allied to pedogeomorphological factors, allowed a better understanding of the effects of late Quaternary climate changes for the Deciduous Complex evolution. We conclude that the Latosols under present-day semi-arid climates (BSh) are relicts of former wetter climates, during which humid forest (semideciduous) expansion took place. Later, these semideciduous forests were subjected to a much drier climate, when selection for deciduousness led to the present-days Deciduous Complex scenario.

Aerosol dynamics within and above forest in relation to turbulent transport and dry deposition

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Ü. Rannik

2016-03-01

Full Text Available A 1-D atmospheric boundary layer (ABL model coupled with a detailed atmospheric chemistry and aerosol dynamical model, the model SOSAA, was used to predict the ABL and detailed aerosol population (characterized by the number size distribution time evolution. The model was applied over a period of 10 days in May 2013 to a pine forest site in southern Finland. The period was characterized by frequent new particle formation events and simultaneous intensive aerosol transformation. The aim of the study was to analyze and quantify the role of aerosol and ABL dynamics in the vertical transport of aerosols. It was of particular interest to what extent the fluxes above the canopy deviate from the particle dry deposition on the canopy foliage due to the above-mentioned processes. The model simulations revealed that the particle concentration change due to aerosol dynamics frequently exceeded the effect of particle deposition by even an order of magnitude or more. The impact was, however, strongly dependent on particle size and time. In spite of the fact that the timescale of turbulent transfer inside the canopy is much smaller than the timescales of aerosol dynamics and dry deposition, leading us to assume well-mixed properties of air, the fluxes at the canopy top frequently deviated from deposition inside the forest. This was due to transformation of aerosol concentration throughout the ABL and resulting complicated pattern of vertical transport. Therefore we argue that the comparison of timescales of aerosol dynamics and deposition defined for the processes below the flux measurement level do not unambiguously describe the importance of aerosol dynamics for vertical transport above the canopy. We conclude that under dynamical conditions reported in the current study the micrometeorological particle flux measurements can significantly deviate from the dry deposition into the canopy. The deviation can be systematic for certain size ranges so that the

Dung beetles in a Caatinga Natural Reserve: a threatened Brazilian dry-forest with high biological value

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Letícia Vieira

2017-12-01

Full Text Available ABSTRACT The Caatinga is an endemic and threatened dry-forest biome distributed across northern Brazil. We evaluated the conservation value of a Caatinga Natural Reserve (NR - Floresta Nacional (FLONA Contendas do Sincorá - using Scarabaeinae dung beetles as a biodiversity indicator. Specifically, we contrasted two zones impacted by two distinct intensity of selective logging that happened inside the NR until 1997. Dung beetles were collected 14 years after logging, using baited pitfall traps within three main habitats (riparian forest, regenerating Caatinga or arboreal Caatinga found in two zones (Preservation and Management Zones. A total of 1,214 individuals from 21 species were sampled. The two zones presented distinct species composition, although the habitats did not exhibit such differences. Our results indicated that the secondary areas are in a conservation status similar to arboreal Caatinga and riparian forest, 14 y after logging. Furthermore, we identified seven habitat-indicator species, two of them typical to Caatinga biome, highlighting the importance of updates in NR management plan considering the Scarabaeinae regional diversity management.

Tree species effects on pathogen-suppressive capacities of soil bacteria across two tropical dry forests in Costa Rica.

Science.gov (United States)

Becklund, Kristen; Powers, Jennifer; Kinkel, Linda

2016-11-01

Antibiotic-producing bacteria in the genus Streptomyces can inhibit soil-borne plant pathogens, and have the potential to mediate the impacts of disease on plant communities. Little is known about how antibiotic production varies among soil communities in tropical forests, despite a long history of interest in the role of soil-borne pathogens in these ecosystems. Our objective was to determine how tree species and soils influence variation in antibiotic-mediated pathogen suppression among Streptomyces communities in two tropical dry forest sites (Santa Rosa and Palo Verde). We targeted tree species that co-occur in both sites and used a culture-based functional assay to quantify pathogen-suppressive capacities of Streptomyces communities beneath 50 focal trees. We also measured host-associated litter and soil element concentrations as potential mechanisms by which trees may influence soil microbes. Pathogen-suppressive capacities of Streptomyces communities varied within and among tree species, and inhibitory phenotypes were significantly related to soil and litter element concentrations. Average proportions of inhibitory Streptomyces in soils from the same tree species varied between 1.6 and 3.3-fold between sites. Densities and proportions of pathogen-suppressive bacteria were always higher in Santa Rosa than Palo Verde. Our results suggest that spatial heterogeneity in the potential for antibiotic-mediated disease suppression is shaped by tree species, site, and soil characteristics, which could have significant implications for understanding plant community composition and diversity in tropical dry forests.