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ABSTRACT: Where large disturbances do not cause landscape-wide mortality and successional change, forested ecosystems should exhibit
landscape metastability (landscape equilibrium) at a scale equal to the dominant patch size of disturbance and recovery within
the landscape. We investigated this in a 16-ha contiguous plot of subtropical wet forest in Puerto Rico, the Luquillo Forest
Dynamics Plot (LFDP), which experienced two major hurricanes during the 15-year study and has a land use history (logging
and agriculture 40 or more years hence) that differs in intensity between two areas of the plot. Using he LFDP as our “landscape,”
we studied the spatial pattern of community change through time (3–5year intervals) by calculating community dissimilarity
between tree censuses for two size classes of trees (1 to <10cm DBH and ≥10cm DBH) in quadrats ranging in size from 0.010–1ha
and for the entire landscape, i.e., plot or land use type. The point at which the decline in community dissimilarity with
quadrat size showed maximum curvature identified the dominant patch size (i.e., point of metastability). For canopy trees
≥10cm dbh, there was no evidence that the community experienced landscape-wide successional changes in either land use type,
and we found a consistent patch size of community change around 0.1ha (range 0.091–0.107). For the understory tree and shrub
community (1 to <10cm dbh) there was some evidence of landscape-wide community changes over time in response to hurricane
damage, apparently driven by interactions with the dominant canopy species, whose composition varied with land use intensity,
and their species-specific susceptibility to hurricane damage.
KeywordsHurricane-Landscape dynamics-Luquillo Experimental Forest-Puerto Rico-Succession-Tropical forest
Landscape Ecology 04/2012; 25(7):1099-1111. · 3.06 Impact Factor
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Nathan G Swenson,
James C Stegen,
Stuart J Davies,
David L Erickson,
Jimena Forero-Montaña,
Allen H Hurlbert,
W John Kress,
Jill Thompson,
María Uriarte,
S Joseph Wright, Jess K Zimmerman
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ABSTRACT: The degree to which turnover in biological communities is structured by deterministic or stochastic factors and the identities of influential deterministic factors are fundamental, yet unresolved, questions in ecology. Answers to these questions are particularly important for projecting the fate of forests with diverse disturbance histories worldwide. To uncover the processes governing turnover we use species-level molecular phylogenies and functional trait data sets for two long-term tropical forest plots with contrasting disturbance histories: one forest is older-growth, and one was recently disturbed. Having both phylogenetic and functional information further allows us to parse out the deterministic influences of different ecological filters. With the use of null models we find that compositional turnover was random with respect to phylogeny on average, but highly nonrandom with respect to measured functional traits. Furthermore, as predicted by a deterministic assembly process, the older-growth and disturbed forests were characterized by less than and greater than expected functional turnover, respectively. These results suggest that the abiotic environment, which changes due to succession in the disturbed forest, strongly governs the temporal dynamics of disturbed and undisturbed tropical forests. Predicting future changes in the composition of disturbed and undisturbed forests may therefore be tractable when using a functional-trait-based approach.
Ecology 03/2012; 93(3):490-9. · 4.85 Impact Factor
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ABSTRACT: Species employ diverse strategies to cope with natural disturbance, but the importance of these strategies for maintaining tree species diversity in forests has been debated. Mechanisms that have the potential to promote tree species coexistence in the context of repeated disturbance include life history trade-offs in colonization and competitive ability or in species' ability to survive at low resource conditions and exploit the temporary resource-rich conditions often generated in the wake of disturbance (successional niche). Quantifying these trade-offs requires long-term forest monitoring and modeling. We developed a hierarchical Bayes model to investigate the strategies tree species employ to withstand and recover from hurricane disturbance and the life history trade-offs that may facilitate species coexistence in forests subject to repeated hurricane disturbance. Unlike previous approaches, our model accommodates temporal variation in process error and observations from multiple sources. We parameterized the model using growth and mortality data from four censuses of a 16-ha plot taken every five years (1990-2005), together with damage data collected after two hurricanes and annual seed production data (1992-2005). Species' susceptibilities to hurricane damage as reflected by changes in diameter growth and fecundity immediately following a storm were weak, highly variable, and unpredictable using traditional life history groupings. The lower crowding conditions (e.g., high light) generated in the wake of storms, however, led to greater gains in growth and fecundity for pioneer and secondary-forest species than for shade-tolerant species, in accordance with expectation of life history. We found moderate trade-offs between survival in high crowding conditions, a metric of competitive ability, and long-distance colonization. We also uncovered a strong trade-off between mean species fecundity in low crowding conditions, a metric of recovery potential, and competitive ability. Trade-offs in competitive and colonization ability, in addition to successional niche processes, are likely to contribute to species persistence in these hurricane-impacted forests. The strategies species employ to cope with hurricane damage depend on the degree to which species rely on sprouting, repair of adult damage, changes in demographic rates in response to enhanced resource availability after storms, or long-distance dispersal as recovery mechanisms.
Ecology 01/2012; 93(1):191-205. · 4.85 Impact Factor
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ABSTRACT: Ecology Letters (2010) 13: 1503-1514 ABSTRACT: The phylogenetic structure and distribution of functional traits in a community can provide insights into community assembly processes. However, these insights are sensitive to the spatial scale of analysis. Here, we use spatially explicit, neighbourhood models of tree growth and survival for 19 tree species, a highly resolved molecular phylogeny and information on eight functional traits to quantify the relative efficacy of functional similarity and shared ancestry in describing the effects of spatial interactions between tree species on demographic rates. We also assess the congruence of these results with observed phylogenetic and functional structure in the neighbourhoods of live and dead trees. We found strong support for models in which the effects of spatial neighbourhood interactions on tree growth and survival were scaled to species-specific mean functional trait values (e.g., wood specific gravity, leaf succulence and maximum height) but not to phylogenetic distance. The weak phylogenetic signal in functional trait data allowed us to independently interpret the static neighbourhood functional and phylogenetic patterns. We observed greater functional trait similarity in the neighbourhoods of live trees relative to those of dead trees suggesting that environmental filtering is the major force structuring this tree community at this scale while competitive interactions play a lesser role.
Ecology Letters 11/2010; 13(12):1503-14. · 17.56 Impact Factor
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ABSTRACT: Human-impacted forests are increasing in extent due to widespread regrowth of secondary forests on abandoned lands. The degree and speed of recovery from human disturbance in these forests will determine their value in terms of biodiversity conservation and ecosystem function. In areas subject to periodic, severe natural disturbances, such as hurricanes, it has been hypothesized that human and natural disturbance may interact to either erase or preserve land use legacies. To increase understanding of how interactions between human and natural disturbance influence forest regeneration and recovery, we monitored seedlings in a human- and hurricane-impacted forest in northeastern Puerto Rico over a approximately 10-yr period and compared seedling composition and dynamics in areas that had experienced high- and low-intensity human disturbance during the first half of the 20th century. We found that land use history significantly affected the composition and diversity of the seedling layer and altered patterns of canopy openness and seedling dynamics following hurricane disturbance. The area that had been subject to high-intensity land use supported a higher density, but lower diversity, of species. In both land use history categories, the seedling layer was dominated by the same two species, Prestoea acuminata var. montana and Guarea guidonia. However, seedlings of secondary-successional species tended to be more abundant in the high-intensity land use area, while late-successional species were more abundant in the low-intensity area, consistent with patterns of adult tree distributions. Seedlings of secondary-forest species showed greater increases in growth and survival following hurricane disturbance compared to late-successional species, providing support for the hypothesis that hurricanes help preserve the signature of land use history. However, the increased performance of secondary-forest species occurred predominantly in the low-intensity land use area, suggesting that hurricanes act to homogenize differences in species composition between areas with differing land use histories by increasing secondary-forest species regeneration in areas that experienced little direct human disturbance. Our results suggest that, through effects on seedling dynamics, hurricanes may extend the signature of land use history beyond the average recovery time of forests not subject to intense natural disturbance events.
Ecological Applications 07/2010; 20(5):1270-84. · 5.10 Impact Factor
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ABSTRACT: p1 Current address: Centre for Ecology and Hydrology (Edinburgh) Bush Estate, Penicuik, Midlothian, EH26 0QB, UK.
Journal of Tropical Ecology 06/2010; 26(04):433 - 443. · 1.40 Impact Factor
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ABSTRACT: Summary1. We simulated two key components of severe hurricane disturbance, canopy openness and detritus deposition, to determine the independent and interactive effects of these components on woody plant recruitment and forest structure.2. We increased canopy openness by trimming branches and added or subtracted canopy detritus in a factorial design. Plant responses were measured during the 4-year study, which followed at least 1 year of pre-manipulation monitoring.3. The physical conditions of canopy openness and detritus deposition in our experiment resembled the responses to Hurricane Hugo, a severe category 4 hurricane that struck this forest in 1989.4. Canopy detritus deposition killed existing woody seedlings and provided a mechanical barrier that suppressed seedling recruitment. The increase in understorey light caused by canopy trimming stimulated germination from the seed bank and increased seedling recruitment and density of pioneer species several hundred-fold when hurricane debris was absent. Many significant interactions between trimming and detritus deposition were evident from the manner in which seedling density, recruitment and mortality changed over time, and subsequently influenced the composition of woody stems (individuals ≥ 1 cm d.b.h.).5. When the canopy was trimmed, stem densities increased > 2-fold and rates of recruitment into the stem size class increased > 25-fold. Trimming had no significant effect on stem mortality. The two dominant species that flourished following canopy trimming were the pioneer species Cecropia schreberiana and Psychotria berteriana. Deposition of canopy detritus had little effect on stems, although basal area increased slightly when detritus was added. There were no evident effects of the interactions between canopy trimming and detritus deposition on stems.6. Synthesis. The separate and interactive effects of canopy openness and detritus deposition result in variable short-term trajectories of forest recovery. However, the short interval of increased canopy openness due to hurricane impacts and its influence on the recruitment of pioneer trees is the dominant factor that drives short-term recovery and may alter long-term structure and composition of the forest.
Journal of Ecology 04/2010; 98(3):659 - 673. · 4.69 Impact Factor
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ABSTRACT: Species number, functional traits, and phylogenetic history all contribute to characterizing the biological diversity in plant communities. The phylogenetic component of diversity has been particularly difficult to quantify in species-rich tropical tree assemblages. The compilation of previously published (and often incomplete) data on evolutionary relationships of species into a composite phylogeny of the taxa in a forest, through such programs as Phylomatic, has proven useful in building community phylogenies although often of limited resolution. Recently, DNA barcodes have been used to construct a robust community phylogeny for nearly 300 tree species in a forest dynamics plot in Panama using a supermatrix method. In that study sequence data from three barcode loci were used to generate a well-resolved species-level phylogeny.
Here we expand upon this earlier investigation and present results on the use of a phylogenetic constraint tree to generate a community phylogeny for a diverse, tropical forest dynamics plot in Puerto Rico. This enhanced method of phylogenetic reconstruction insures the congruence of the barcode phylogeny with broadly accepted hypotheses on the phylogeny of flowering plants (i.e., APG III) regardless of the number and taxonomic breadth of the taxa sampled. We also compare maximum parsimony versus maximum likelihood estimates of community phylogenetic relationships as well as evaluate the effectiveness of one- versus two- versus three-gene barcodes in resolving community evolutionary history.
As first demonstrated in the Panamanian forest dynamics plot, the results for the Puerto Rican plot illustrate that highly resolved phylogenies derived from DNA barcode sequence data combined with a constraint tree based on APG III are particularly useful in comparative analysis of phylogenetic diversity and will enhance research on the interface between community ecology and evolution.
PLoS ONE 01/2010; 5(11):e15409. · 4.09 Impact Factor
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ABSTRACT: One of the most significant challenges in developing a predictive understanding of the long-term effects of hurricanes on tropical forests is the development of quantitative models of the relationships between variation in storm intensity and the resulting severity of tree damage and mortality. There have been many comparative studies of interspecific variation in resistance of trees to wind damage based on aggregate responses to individual storms. We use a new approach, based on ordinal logistic regression, to fit quantitative models of the susceptibility of a tree species to different levels of damage across an explicit range of hurricane intensity. Our approach simultaneously estimates both the local intensity of the storm within a plot and the susceptibility to storm damage of different tree species within plots. Using the spatial variation of storm intensity embedded in two hurricanes (Hugo in 1989 and Georges in 1998) that struck the 16 ha Luquillo Forest Dynamics Plot in eastern Puerto Rico, we show that variation in susceptibility to storm damage is an important aspect of life history differentiation. Pioneers such as Cecropia schreberiana are highly susceptible to stem damage, while the late successional species Dacryodes excelsa suffered very little stem damage but significant crown damage. There was a surprisingly weak relationship between tree diameter and the susceptibility to damage for most of the 12 species examined. This may be due to the effects of repeated storms and trade winds on the architecture of trees and forest stands in this Puerto Rican subtropical wet forest.RESUMENEl desarrollo de modelos que puedan caracterizar la relación cuantitativa entre la intensidad de los huracanes y su efecto sobre los árboles es uno de los retos mas importantes en nuestro entendimiento de la influencia de los huracanes sobre los bosques tropicales. Usando respuestas agregadas, varios studios han comparado la variación interespecífica en la resistencia de los árboles al viento. En este artículo, usamos un nuevo enfoque, basado en la regresión logística ordinal, para parametrizar modelos de susceptibilidad a un rango de intensidades de huracanes para 12 especies de árboles. Nuestro enfoque estima simultaneamente la intensidad local de la tormenta dentro de una parcela y la susceptibilidad de cada especie en varias parcelas. Usando la variación espacial de intensidad de dos huracanes (Hugo en 1989 y Georges en 1998) que azotaron la parcela de 16-ha en el Luquillo Forest Dynamics Plot en el este de Puerto Rico, demonstramos que la variación en susceptibilidad es un aspect importante de diferenciación en historias de vida. Especies pioneras como Cecropia schreberiana, son muy susceptibles a la quiebra del tronco durante los huracanes mientras que la especie sucesional tardía, Dacryodes excelsa, sufre solamente daño al dosel. La relación entre el diámetro de los árboles y su susceptibilidad es sorprendentemente debil para la mayoría de las 12 especies analizadas. Este resultado se puede deber al efecto de repetidos huracanes y tormentas tropicales sobre la arquitectura de los árboles y la estructura de los bosques en Puerto Rico.
Biotropica 12/2009; 42(1):87 - 94. · 2.23 Impact Factor
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ABSTRACT: Summary1. Many forests experience periodic, large-scale disturbances, such as hurricanes and cyclones, which open the forest canopy, causing dramatic changes in understorey light conditions and seedling densities. Thus, in hurricane-impacted forests, large variations in abiotic and biotic conditions likely shape seedling dynamics, which in turn will contribute to patterns of forest recovery.2. We monitored 13 836 seedlings of 82 tree and shrub species over 10 years following Hurricane Georges in 1998 in a subtropical, montane forest in Puerto Rico. We quantified changes in the biotic and abiotic environment of the understorey and linked seedling dynamics to changes in canopy openness and seedling density, and to spatial variation in soil type, topography and tree density.3. Canopy openness was highest when first measured after Hurricane Georges and dropped significantly within c. 3 years, while seedling densities remained high for c. 5 years post-hurricane. When all species and census intervals were analysed together, generalized linear mixed effects models revealed that canopy openness, seedling and adult tree densities were significant drivers of seedling survival.4. The relative importance of abiotic and biotic factors changed over time. Separate analyses for each census interval revealed that canopy openness was a significant predictor of survival only for the first census interval, with lower survival at the highest levels of canopy openness. The effect of conspecific seedling density was significant in all intervals except the first, and soil type only in the final census interval.5. When grouping species into life-history guilds based on adult tree susceptibility to hurricane damage, we found clear differences among guilds in the effects of biotic and abiotic factors on seedling survival. Seedlings of hurricane-susceptible and intermediate guilds were more strongly influenced by canopy openness, while seedlings of the hurricane-resistant group were less affected by conspecific seedling density. Individual species-level analyses for 12 common species, however, showed considerable variation among species within guilds.6. Synthesis. Our results suggest that hurricanes shape species composition by altering understorey conditions that differentially influence the success of seedlings. Thus, predicted increases in the intensity and frequency of hurricanes in the Caribbean will likely alter seedling dynamics and ultimately the species composition in hurricane-impacted forests.
Journal of Ecology 10/2009; 97(6):1346 - 1359. · 4.69 Impact Factor
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Jérôme Chave,
Richard Condit,
Helene C Muller-Landau,
Sean C Thomas,
Peter S Ashton,
Sarayudh Bunyavejchewin,
Leonardo L Co,
Handanakere S Dattaraja,
Stuart J Davies,
Shameema Esufali, [......],
Hebbalalu S Suresh,
Sylvester Tan,
Jill Thompson,
Ma Dolores C Tongco,
Renato Valencia,
Martha Vallejo,
Gorky Villa,
Takuo Yamakura, Jess K Zimmerman,
Elizabeth C Losos
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ABSTRACT: In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration of mature tropical forests was attributed to global environmental change, such as an increase in atmospheric CO2 concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2 million trees in ten large (16-52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests. Aboveground biomass increased at seven of our ten plots, significantly so at four plots, and showed a large decrease at a single plot. Carbon accumulation pooled across sites was significant (+0.24 MgC ha(-1) y(-1), 95% confidence intervals [0.07, 0.39] MgC ha(-1) y(-1)), but lower than reported previously for Amazonia. At three sites for which we had data for multiple census intervals, we found no concerted increase in biomass gain, in conflict with the increased productivity hypothesis. Over all ten plots, the fastest-growing quartile of species gained biomass (+0.33 [0.09, 0.55] % y(-1)) compared with the tree community as a whole (+0.15 % y(-1)); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantly when calculated over all plots (+0.21 [0.02, 0.37] % y(-1)), and in half of our plots when calculated individually. Our results do not support the hypothesis that fast-growing species are consistently increasing in dominance in tropical tree communities. Instead, they suggest that our plots may be simultaneously recovering from past disturbances and affected by changes in resource availability. More long-term studies are necessary to clarify the contribution of global change to the functioning of tropical forests.
PLoS Biology 04/2008; 6(3):e45. · 11.45 Impact Factor
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ABSTRACT: The relative importance of biotic, abiotic, and stochastic processes in structuring ecological communities continues to be a central focus in community ecology. In order to assess the role of phylogenetic relatedness on the nature of biodiversity we first quantified the degree of phylogenetic niche conservatism of several plant traits linked to plant form and function. Next we quantified the degree of phylogenetic relatedness across two fundamental scaling dimensions: plant size and neighborhood size. The results show that phylogenetic niche conservatism is likely widespread, indicating that closely related species are more functionally similar than distantly related species. Utilizing this information we show that three of five tropical forest dynamics plots (FDPs) exhibit similar scale-dependent patterns of phylogenetic structuring using only a spatial scaling axis. When spatial- and size-scaling axes were analyzed in concert, phylogenetic overdispersion of co-occurring species was most important at small spatial scales and in four of five FDPs for the largest size class. These results suggest that phylogenetic relatedness is increasingly important: (1) at small spatial scales, where phylogenetic overdispersion is more common, and (2) in large size classes, where phylogenetic overdispersion becomes more common throughout ontogeny. Collectively, our results highlight the critical spatial and size scales at which the degree of phylogenetic relatedness between constituent species influences the structuring of tropical forest diversity.
Ecology 08/2007; 88(7):1770-80. · 4.85 Impact Factor
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ABSTRACT: The problem of scale dependency is widespread in investigations of ecological communities. Null model investigations of community assembly exemplify the challenges involved because they typically include subjectively defined "regional species pools." The burgeoning field of community phylogenetics appears poised to face similar challenges. Our objective is to quantify the scope of the problem of scale dependency by comparing the phylogenetic structure of assemblages across contrasting geographic and taxonomic scales. We conduct phylogenetic analyses on communities within three tropical forests, and perform a sensitivity analysis with respect to two scaleable inputs: taxonomy and species pool size. We show that (1) estimates of phylogenetic overdispersion within local assemblages depend strongly on the taxonomic makeup of the local assemblage and (2) comparing the phylogenetic structure of a local assemblage to a species pool drawn from increasingly larger geographic scales results in an increased signal of phylogenetic clustering. We argue that, rather than posing a problem, "scale sensitivities" are likely to reveal general patterns of diversity that could help identify critical scales at which local or regional influences gain primacy for the structuring of communities. In this way, community phylogenetics promises to fill an important gap in community ecology and biogeography research.
Ecology 11/2006; 87(10):2418-24. · 4.85 Impact Factor
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Helene C Muller-Landau,
Richard S Condit,
Kyle E Harms,
Christian O Marks,
Sean C Thomas,
Sarayudh Bunyavejchewin,
George Chuyong,
Leonardo Co,
Stuart Davies,
Robin Foster, [......], Jess K Zimmerman,
Handanakere Shavaramaiah Dattaraja,
Shameema Esufali,
Pamela Hall,
Fangliang He,
Consuelo Hernandez,
Somboon Kiratiprayoon,
Hebbalalu S Suresh,
Christopher Wills,
Peter Ashton
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ABSTRACT: Tropical forests vary substantially in the densities of trees of different sizes and thus in above-ground biomass and carbon stores. However, these tree size distributions show fundamental similarities suggestive of underlying general principles. The theory of metabolic ecology predicts that tree abundances will scale as the -2 power of diameter. Demographic equilibrium theory explains tree abundances in terms of the scaling of growth and mortality. We use demographic equilibrium theory to derive analytic predictions for tree size distributions corresponding to different growth and mortality functions. We test both sets of predictions using data from 14 large-scale tropical forest plots encompassing censuses of 473 ha and > 2 million trees. The data are uniformly inconsistent with the predictions of metabolic ecology. In most forests, size distributions are much closer to the predictions of demographic equilibrium, and thus, intersite variation in size distributions is explained partly by intersite variation in growth and mortality.
Ecology Letters 06/2006; 9(5):589-602. · 17.56 Impact Factor
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ABSTRACT: 1 We used inverse modelling to parameterize spatially-explicit seedling recruitment functions for nine canopy tree species in the Luquillo Forest Dynamics Plot (LFDP), Puerto Rico. We modelled the observed spatial variation in seedling recruitment following Hurricane Georges as a function of the potential number of seedlings at a given location (based on local source trees and the potential contribution of parents from outside of the mapped area) and of light levels and density-dependent mortality during establishment. We adopted the model comparison paradigm and compared the performance of increasingly complex models against a null model that assumes uniform seedling distribution across the plot. 2 Our data supported a model in which parents must reach a threshold size before any seedling production will occur. Once parents attain that size, the relationship between tree diameter and the number of seedlings produced is fairly flat for the majority of species. These results contradict previous analyses that simply assumed a linear relationship between biomass and seedling production and a uniform size threshold for seedling production across species. 3 The majority of species tested supported models that included at least one of a bath term (contribution from non-local trees), conspecific density dependence and light availability after the hurricane. Density dependence shifted the mode of the effective dispersal kernel away from potential parent trees and significantly reduced the number of seedlings established near parent trees. Recruitment from non-local sources accounted for 6-81% of observed seedling recruitment depending upon the tree species. Light availability appeared to divide species into three groups that showed more successful seedling establishment at low (< 5% of full sun), intermediate or high light levels (> 30% full sun). 4 Differences between individual species in the importance of local vs. bath recruitment and the intensity of density dependence suggest the existence of distinct recruitment syndromes that go beyond the traditional focus of tropical tree life histories. Understanding these syndromes will provide valuable insights into the spatial distribution of tropical tree species and the maintenance of tropical forest diversity.
Journal of Ecology 03/2005; 93(2):291 - 304. · 4.69 Impact Factor
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Jerome Chave,
Richard Condit,
Helene C Muller-Landau,
Sean C. Thomas,
Peter S. Ashton,
Sarayudh Bunyavejchewin,
Leonardo L Co,
Handanakere S Dattaraja,
Stuart J Davies,
Shameema Esufali, [......],
Hebbalalu S Suresh,
Sylvester Tan,
Jill Thompson,
Ma. Dolores C Tongco,
Renato Valencia,
Martha Vallejo,
Gorky Villa,
Takuo Yamakura, Jess K Zimmerman,
Elizabeth C Losos
[show abstract]
[hide abstract]
ABSTRACT: In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration of mature tropical forestswas attributed to global environmental change, such as an increase in atmospheric $CO_2$ concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2 million trees in ten large (16–52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests. Above ground biomass increased at seven of our ten plots, significantly so at four plots, and showed a large decrease at a single plot. Carbon accumulation pooled across sites was significant (+0.24 MgC $ha^{-1} y^{-1}$, 95% confidence intervals [0.07, 0.39] MgC $ha^{-1} y^{-1}$, but lower than reported previously for Amazonia. At three sites for which we had data for multiple census intervals, we found no concerted increase in biomass gain, in conflict with the increased productivity hypothesis. Over all ten plots, the fastest-growing quartile of species gained biomass (+0.33 [0.09, 0.55]%$y^{-1}$) compared with the tree community as a whole (+0.15%$y^{-1}$) however, this significant trend was due to single plot. Biomass of slow-growing species increased ignificantly when calculated over all plots (+0.21 [0.02, 0.37]%$y^{-1}$) and in half of our plots when calculated individually. Our results do not support the hypothesis that fast-growing species are consistently increasing in dominance in tropical tree communities. Instead, they suggest that our plots may be simultaneously recovering from past disturbances and affected by changes in resource availability. More long-termstudies are necessary to clarify the contribution of global change to the functioning of tropical forests.
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Jerome Chave,
Richard S. Condit,
Helene Muller-Landau,
Sean C. Thomas,
Peter S. Ashton,
Sarayudh Bunyavejchewin,
Leonardo L Co,
Handanakere S Dattaraja,
Stuart J Davies,
Shameema Esufali, [......],
Hebbalalu S. Sureh,
Sylvester Tan,
Jill Thompson,
Maria Dolores C. Tongco,
Renato Valencia,
Martha Isabel Vallejo,
Gorky Villa,
Takuo Yamakura, Jess K Zimmerman,
Elizabeth C Losos
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Christopher Wills,
Kyle E Harms,
Richard S. Condit,
David A. King,
Jill Thompson,
Fangliang He,
Helene C Muller-Landau,
Peter Ashton,
Elizabeth Losos,
Liza Comita, [......],
Marie Massa,
Cheryl Nath,
Md Nur Supardi Noor,
Abdul Rahman Kassim,
Raman Sukumar,
Hebbalalu Satyanarayana Suresh,
I-Fang Sun,
Sylvester Tan,
Takuo Yamakura, Jess K Zimmerman
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Helene C Muller-Landau,
Richard S. Condit,
Kyle E Harms,
Christian O. Marks,
Sean C. Thomas,
Sarayudh Bunyavejchewin,
George Chuyong,
Leonardo Co,
Stuart Davies,
Robin B. Foster, [......],
M N Nur Supardi,
Sylvester Tan,
Duncan Thomas,
Jill Thompson,
Renato Valencia,
Martha Isabel Vallejo,
Gorky Villa Munoz,
Takuo Yamakura, Jess K Zimmerman,
Handanakere Shavaramaiah Dattaraja
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Richard S. Condit,
Mark S. Ashton,
Henrik Balslev,
Nicholas V. L. Brokaw,
Sarayudh Bunyavejchewin,
George B. Chuyong,
Leonardo Co,
Handanakere Shivaramaiah Dattaraja,
Stuart James Davies,
Shameema Esufali, [......],
Raman Sukumar,
Jens-Christian Svenning,
Sylvester Tan,
Duncan W. Thomas,
James D. Thompson,
Martha Isabel Vallejo,
Gorky Villa Munoz,
Renato Valencia,
Takuo Yamakura, Jess K Zimmerman
