Papers by Nimal Gunatilleke
PLOS Biology, Mar 4, 2008
In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and ... more 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 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. 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 (þ0.24 MgC ha À1 y À1 , 95% confidence intervals [0.07, 0.39] MgC ha À1 y À1), 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 (þ0.33 [0.09, 0.55] % y À1) compared with the tree community as a whole (þ0.15 % y À1); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantly when calculated over all plots (þ0.21 [0.02, 0.37] % y À1), 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.
Forestry, Aug 14, 2023
Conserving plant diversity is integral to sustainable forest management. This study aims at diver... more Conserving plant diversity is integral to sustainable forest management. This study aims at diversifying tools to map spatial distribution of species richness. We develop a sampling strategy of using rapid assessments by local communities to gather prior information on species richness distribution to drive census cell selection by sampling with covariate designs. An artificial neural network model is built to predict the spatial patterns. Accuracy and consistency of rapid assessment factors, sample selection methods, and sampling intensity of census cells were tested in a simulation study with seven 25–50-ha census plots in the tropics and subtropics. Results showed that identifying more plant individuals in a rapid assessment improved accuracy and consistency, while transect was comparable to or slightly better than nearest-neighbor assessment, but knowing more species had little effects. Results of sampling with covariate designs depended on covariates. The covariate Ifreq, inverse of the frequency of the rapidly assessed species richness strata, was the best choice. List sampling and local pivotal method with Ifreq increased accuracy by 0.7%–1.6% and consistency by 7.6%–12.0% for 5% to 20% sampling intensity. This study recommends a rapid assessment method of selecting 20 individuals at every 20-m interval along a transect. Knowing at least half of the species in a forest that are abundant is sufficient. Local pivotal method is recommended at 5% sampling intensity or less. This study presents a methodology to directly involve local communities in probability-based forest resource assessment to support decision-making in forest management.
The Sinharaja World Heritage Site is the largest remnant of Sri Lanka's forests and contains ... more The Sinharaja World Heritage Site is the largest remnant of Sri Lanka's forests and contains the Sinharaja Forest Dynamics Plot. The Sinharaja Forest Dynamics Plot was founded in 1993 by the University of Peradeniya in Sri Lanka, the Sri Lankan Department of Forestry, and CTFS/Harvard University. The forests of Sri Lanka display relatively low diversity but very high endemism. For example, in the Sinharaja World Heritage Site, 70% of its 190 tree species are endemic. The Sinharaja Forest Dynamics Plot contains one-half of the species in the World Heritage Site's lowland rain forests and one-quarter of all of Sri Lanka's tree species. The forest demographic work at the plot complements ongoing silvicultural and economic studies of the University of Peradeniya, Sri Lanka Forest Department, Yale School of Forestry and the Environment, CTFS/Harvard University. Research issues at Sinharaja include silvicultural management for diverse forest products including hardwoods, fores...
APN Science Bulletin, 2013
Preface The aPN's activities continue to grow and this has warranted a supplement to Issue 3 of o... more Preface The aPN's activities continue to grow and this has warranted a supplement to Issue 3 of our Science Bulletin. The supplement showcases 12 activities that were conducted in 2012 and early 2013 that sit outside the aPN's core programmes of activities, the arcP and caPaBLe Programmes. Showcasing articles from two focused activities that began in 2010 with funding from the Ministry of the environment, Japan, the supplement reports two featured projects from the Ecosystems, Biodiversity and Land Use (EBLU) scientific focus; and two from Resources Utilisation and Pathways for Sustainable Development (RUSD). The articles highlight issues such as solid waste management, emerging work on biochar development and the UNfccc-driven reDD+ and MrV system and their importance for sustaining healthy forest ecosystems in Southeast asia.
... used in paper "Xiangcheng Mi, Nathan G. Swenson, Renato Valencia, John Kress, David L. E... more ... used in paper "Xiangcheng Mi, Nathan G. Swenson, Renato Valencia, John Kress, David L. Erickson, álvaro J. Pérez, Haibao Ren ... 2002, The 52-hectrare forest research plot at Lambir Hills, Sarawak, Malaysia: Tree distribution maps, diameter table and species documentation. ...
PLOS Computational Biology, 2021
When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands’ physica... more When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands’ physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees’ distributions, growth, recruitment, and mortality. These interactions decline smoothly ...
Oecologia, 2016
III phylogeny to examine how phylogenetic beta diversity (indicating the degree of phylogenetic s... more III phylogeny to examine how phylogenetic beta diversity (indicating the degree of phylogenetic similarity of two communities) was related to environmental gradients within tropical tree communities. Using distance-based redundancy analysis we found that phylogenetic beta diversity, expressed as either nearest neighbor distance or mean pairwise distance, was significantly related to both soil and topographic variation in all study sites. In general, more phylogenetic beta diversity within a forest plot was explained by environmental variables this was expressed as nearest neighbor distance versus mean pairwise distance (3.0-10.3 % and 0.4-8.8 % of variation explained among plots, respectively), and more variation was explained by soil resource variables
Qualitative reconstruction of the 34 large-scale clusters of the double-cluster component pattern... more Qualitative reconstruction of the 34 large-scale clusters of the double-cluster component pattern and cluster occupancy for recruits and adults.
All species must balance their allocation to growth, survival and recruitment. Among trees, evolu... more All species must balance their allocation to growth, survival and recruitment. Among trees, evolution has resulted in different strategies of partitioning resources to these key demographic processes, i.e. demographic trade-offs. It is unclear whether the same demographic trade-offs structure tropical forests worldwide. Here, we used data from 13 large-scale and long-term tropical forest plots to estimate the principal trade-offs in growth, survival, recruitment, and tree stature at each site. For ten sites, two trade-offs appeared repeatedly. One trade-off showed a negative relationship between growth and survival, i.e. the well-known fast−slow continuum. The second trade-off distinguished between tall-statured species and species with high recruitment rates, i.e. a stature−recruitment trade-off. Thus, the fast-slow continuum and tree stature are two independent dimensions structuring most tropical tree communities. Our discovery of the consistency of demographic trade-offs and str...
Bryce, and several anonymous reviewers for valuable reviews and discussions, and J. Selverstone a... more Bryce, and several anonymous reviewers for valuable reviews and discussions, and J. Selverstone and T. Wawrzyniec for assisting in field site selection. Supported by NSF grant EAR-9805218 (D.J.D.) and a Berkeley Geochronology Center Fellowship (E.F.B.).
PLoS Biology, 2008
In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and ... more 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 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. 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 (þ0.24 MgC ha À1 y À1 , 95% confidence intervals [0.07, 0.39] MgC ha À1 y À1), 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 (þ0.33 [0.09, 0.55] % y À1) compared with the tree community as a whole (þ0.15 % y À1); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantly when calculated over all plots (þ0.21 [0.02, 0.37] % y À1), 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.
Oecologia, Jul 2, 2013
forest dynamics plots. niche overlap values, indicating the similarity of two species' distributi... more forest dynamics plots. niche overlap values, indicating the similarity of two species' distributions along soil or topographic axes, were calculated for all pairwise combinations of co-occurring tree species at each study site. Congeneric species pairs often showed greater niche overlap (i.e., more similar niches) than non-congeneric pairs along both soil and topographic axes, though significant effects were found for only five sites based on mantel tests. no evidence for taxonomic effects was found at the family level. Our results indicate that local habitat niches of trees exhibit varying degrees of phylogenetic signal at different sites, which may have important ramifications for the phylogenetic structure of these communities. Abstract the integration of ecology and evolutionary biology requires an understanding of the evolutionary lability in species' ecological niches. For tropical trees, specialization for particular soil resource and topographic conditions is an important part of the habitat niche, influencing the distributions of individual species and overall tree community structure at the local scale. however, little is known about how these habitat niches are related to the evolutionary history of species. We assessed the relationship between taxonomic rank and tree species' soil resource and topographic niches in eight large (24-50 ha) tropical Communicated by Walt Carson.
... successional site generalists in this forest type are usually dependent upon medium to large-... more ... successional site generalists in this forest type are usually dependent upon medium to large-sized animals (bat, bird, civet ... 13.2 (continued) 45 years; 3understory initiation stage at about 80 years).(d) Dynamic canopy stratification depicted in the vertical photographic profile ...
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Papers by Nimal Gunatilleke