Publication Search Results

ID: 159181
Type: article
Authors: Arellano, Gabriel; Zuleta, Daniel; Davies, Stuart J.
Abstract: Tree mortality drives changes in forest structure and dynamics, community composition, and carbon and nutrient cycles. Since tropical forests store a large fraction of terrestrial biomass and tree diversity, improved understanding of changing tree mortality and biomass loss rates is critical. Tropical tree mortality rates have been challenging to estimate due to low background rates of tree death, and high spatial and temporal heterogeneity. Furthermore, the causes of mortality remain unclear because many factors may be involved in individual tree death, and the rapid decomposition of wood in the tropics obscures evidence of possible causes of tree mortality. We present a field protocol to assess tree mortality in tropical forests. The protocol focuses on the rapid, repeatable and inexpensive assessment of individual tree death and damage. The protocol has been successfully tested with annual assessments of >62,000 stems in total in several ForestGEO plots in Asia and the Neotropics. Standardized methods for the assessment of tree death and biomass loss will advance understanding of the underlying causes and consequences of tree mortality.

ID: 158553
Type: article
Authors: Davies, Stuart J.; Abiem, Iveren; Abu Salim, Kamariah; Aguilar, Salomon; Allen, David; Alonso, Alfonso; Anderson-Teixeira, Kristina; Andrade, Ana; Arellano, Gabriel; Ashton, Peter S.; Baker, Patrick J.; Baker, Matthew E.; Baltzer, Jennifer L.; Basset, Yves; Bissiengou, Pulcherie; Bohlman, Stephanie; Bourg, Norman A.; Brockelman, Warren Y.; Bunyavejchewin, Sarayudh; Burslem, David F. R. P.; Cao, Min; Cardenas, Dairon; Chang, Li-Wan; Chang-Yang, Chia-Hao; Chao, Kuo-Jung; Chao, Wei-Chun; Chapman, Hazel; Chen, Yu-Yun; Chisholm, Ryan A.; Chu, Chengjin; Chuyong, George; Clay, Keith; Comita, Liza S.; Condit, Richard; Cordell, Susan; Dattaraja, Handanakere S.; de Oliveira, Alexandre Adalardo; den Ouden, Jan; Detto, Matteo; Dick, Christopher; Du, Xiaojun; Duque, Alvaro; Ediriweera, Sisira; Ellis, Erle C.; Obiang, Nestor Laurier Engone; Esufali, Shameema; Ewango, Corneille E. N.; Fernando, Edwino S.; Filip, Jonah; Fischer, Gunter A.; Foster, Robin; Giambelluca, Thomas; Giardina, Christian; Gilbert, Gregory S.; Gonzalez-Akre, Erika; Gunatilleke, I. A. U. N.; Gunatilleke, C. V. S.; Hao, Zhanqing; Hau, Billy C. H.; He, Fangliang; Ni, Hongwei; Howe, Robert W.; Hubbell, Stephen P.; Huth, Andreas; Inman-Narahari, Faith; Itoh, Akira; Janik, David; Jansen, Patrick A.; Jiang, Mingxi; Johnson, Daniel J.; Jones, F. Andrew; Kanzaki, Mamoru; Kenfack, David; Kiratiprayoon, Somboon; Kral, Kamil; Krizel, Lauren; Lao, Suzanne; Larson, Andrew J.; Li, Yide; Li, Xiankun; Litton, Creighton M.; Liu, Yu; Liu, Shirong; Lum, Shawn K. Y.; Luskin, Matthew S.; Lutz, James A.; Hong Truong Luu; Ma, Keping; Makana, Jean-Remy; Malhi, Yadvinder; Martin, Adam; McCarthy, Caly; McMahon, Sean M.; McShea, William J.; Memiaghe, Herve; Mi, Xiangcheng; Mitre, David; Mohamad, Mohizah; Monks, Logan; Muller-Landau, Helene C.; Musili, Paul M.; Myers, Jonathan A.; Nathalang, Anuttara; Ngo, Kang Min; Norden, Natalia; Novotny, Vojtech; O'Brien, Michael J.; Orwig, David; Ostertag, Rebecca; Papathanassiou, Konstantinos; Parker, Geoffrey G.; Perez, Rolando; Perfecto, Ivette; Phillips, Richard P.; Pongpattananurak, Nantachai; Pretzsch, Hans; Ren, Haibo; Reynolds, Glen; Rodriguez, Lillian J.; Russo, Sabrina E.; Sack, Lawren; Sang, Weiguo; Shue, Jessica; Singh, Anudeep; Song, Guo-Zhang M.; Sukumar, Raman; Sun, I-Fang; Suresh, Hebbalalu S.; Swenson, Nathan G.; Tan, Sylvester; Thomas, Sean C.; Thomas, Duncan; Thompson, Jill; Turner, Benjamin L.; Uowolo, Amanda; Uriarte, Maria; Valencia, Renato; Vandermeer, John; Vicentini, Alberto; Visser, Marco; Vrska, Tomas; Wang, Xugao; Wang, Xihua; Weiblen, George D.; Whitfeld, Timothy J. S.; Wolf, Y.; Wright, S. Joseph; Xu, Han; Yao, Tze Leong; Yap, Sandra L.; Ye, Wanhui; Yu, Mingjian; Zhang, Minhua; Zhu, Daoguang; Zhu, Li; Zimmerman, Jess K.; Zuleta, Daniel
Abstract: ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems >= 1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.

ID: 158537
Type: article
Authors: Kunert, Norbert; Zailaa, Joseph; Herrmann, Valentine; Muller-Landau, Helene C.; Wright, S. Joseph; Perez, Rolando; McMahon, Sean M.; Condit, Richard C.; Hubbell, Steven P.; Sack, Lawren; Davies, Stuart J.; Anderson-Teixeira, Kristina J.
Abstract: The effects of climate change on tropical forests will depend on how diverse tropical tree species respond to drought. Current distributions of evergreen and deciduous tree species across local and regional moisture gradients reflect their ability to tolerate drought stress, and might be explained by functional traits. We measured leaf water potential at turgor loss (i.e. 'wilting point'; pi(tlp)), wood density (WD) and leaf mass per area (LMA) on 50 of the most abundant tree species in central Panama. We then tested their ability to explain distributions of evergreen and deciduous species within a 50 ha plot on Barro Colorado Island and across a 70 km rainfall gradient spanning the Isthmus of Panama. Among evergreen trees, species with lower pi(tlp) were associated with drier habitats, with pi(tlp) explaining 28% and 32% of habitat association on local and regional scales, respectively, greatly exceeding the predictive power of WD and LMA. In contrast, pi(tlp) did not predict habitat associations among deciduous species. Across spatial scales, pi(tlp) is a useful indicator of habitat preference for tropical tree species that retain their leaves during periods of water stress, and holds the potential to predict vegetation responses to climate change.

ID: 159052
Type: article
Authors: Luskin, Matthew Scott; Johnson, Daniel J.; Ickes, Kalan; Yao, Tze Leong; Davies, Stuart J.
Abstract: Large vertebrates are rarely considered important drivers of conspecific negative density-dependent mortality (CNDD) in plants because they are generalist consumers. However, disturbances like trampling and nesting also cause plant mortality, and their impact on plant diversity depends on the spatial overlap between wildlife habitat preferences and plant species composition. We studied the impact of native wildlife on a hyperdiverse tree community in Malaysia. Pigs (Sus scrofa) are abnormally abundant at the site due to food subsidies in nearby farmland and they construct birthing nests using hundreds of tree saplings. We tagged 34 950 tree saplings in a 25 ha plot during an initial census and assessed the source mortality by recovering tree tags from pig nests (n = 1672 pig-induced deaths). At the stand scale, pigs nested in flat dry habitats, and at the local neighbourhood scale, they nested within clumps of saplings, both of which are intuitive for safe and efficient nest building. At the stand scale, flat dry habitats contained higher sapling densities and higher proportions of common species, so pig nesting increased the weighted average species evenness across habitats. At the neighbourhood scale, pig-induced sapling mortality was associated with higher heterospecific and especially conspecific sapling densities. Tree species have clumped distributions due to dispersal limitation and habitat filtering, so pig disturbances in sapling clumps indirectly caused CNDD. As a result, Pielou species evenness in 400 m(2) quadrats increased 105% more in areas with pig-induced deaths than areas without disturbances. Wildlife induced CNDD and this supported tree species evenness, but they also drove a 62% decline in sapling densities from 1996 to 2010, which is unsustainable. We suspect pig nesting is an important feature shaping tree composition throughout the region.

ID: 159522
Type: article
Authors: Wiegand, Thorsten; Wang, Xugao; Anderson-Teixeira, Kristina J.; Bourg, Norman A.; Cao, Min; Ci, Xiuqin; Davies, Stuart J.; Hao, Zhanqing; Howe, Robert W.; Kress, W. John; Lian, Juyu; Li, Jie; Lin, Luxiang; Lin, Yiching; Ma, Keping; McShea, William; Mi, Xiangcheng; Su, Sheng-Hsin; Sun, I-Fang; Wolf, Amy; Ye, Wanhui; Huth, Andreas
Abstract: Ecology cannot yet fully explain why so many tree species coexist in natural communities such as tropical forests. A major difficulty is linking individual-level processes to community dynamics. We propose a combination of tree spatial data, spatial statistics and dynamical theory to reveal the relationship between spatial patterns and population-level interaction coefficients and their consequences for multispecies dynamics and coexistence. Here we show that the emerging population-level interaction coefficients have, for a broad range of circumstances, a simpler structure than their individual-level counterparts, which allows for an analytical treatment of equilibrium and stability conditions. Mechanisms such as animal seed dispersal, which result in clustering of recruits that is decoupled from parent locations, lead to a rare-species advantage and coexistence of otherwise neutral competitors. Linking spatial statistics with theories of community dynamics offers new avenues for explaining species coexistence and calls for rethinking community ecology through a spatial lens. Tree spatial data, spatial statistics and dynamical theory reveal the relationship between spatial patterns and population-level interaction coefficients and their consequences for multispecies dynamics and coexistence.

ID: 159498
Type: article
Authors: Wills, Christopher; Wang, Bin; Fang, Shuai; Wang, Yunquan; Jin, Yi; Lutz, James; Thompson, Jill; Harms, Kyle E.; Pulla, Sandeep; Pasion, Bonifacio; Germain, Sara; Liu, Heming; Smokey, Joseph; Su, Sheng-Hsin; Butt, Nathalie; Chu, Chengjin; Chuyong, George; Chang-Yang, Chia-Hao; Dattaraja, H. S.; Davies, Stuart; Ediriweera, Sisira; Esufali, Shameema; Fletcher, Christine Dawn; Gunatilleke, Nimal; Gunatilleke, Savi; Hsieh, Chang-Fu; He, Fangliang; Hubbell, Stephen; Hao, Zhanqing; Itoh, Akira; Kenfack, David; Li, Buhang; Li, Xiankun; Ma, Keping; Morecroft, Michael; Mi, Xiangcheng; Malhi, Yadvinder; Ong, Perry; Rodriguez, Lillian Jennifer; Suresh, H. S.; Sun, I. Fang; Sukumar, Raman; Tan, Sylvester; Thomas, Duncan; Uriarte, Maria; Wang, Xihua; Wang, Xugao; Yao, T. L.; Zimmermann, Jess
Abstract: Author summary Worldwide, ecosystems are collapsing or in danger of collapse, but the precise causes of these collapses are often unknown. Observational and experimental evidence shows that all ecosystems are characterized by strong interactions between and among species, and that these webs of interactions can be important contributors to the preservation of ecosystem diversity. But many of the interactions-such as those involving pathogenic microorganisms and the chemical defenses that are mounted by their prey-are not easily identified and analyzed in ecosystems that may have hundreds or thousands of species. Here we use our equal-area-annulus analytical method to examine census data from over three million trees in forest plots from around the world. We show how the method can be used to flag pairs and groups of species that exhibit unusual levels of interaction and that are likely on further investigation to yield information about their causative mechanisms. We give a detailed example showing how some of these interactions can be traced to defense mechanisms that are possessed by one of the tree species. We explore how our method can be used to identify the between-species interactions that play the largest roles in the maintenance of ecosystems and their diversity. 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 in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions.

ID: 153274
Type: article
Authors: Fung, Tak; Chisholm, Ryan A.; Anderson-Teixeira, Kristina J.; Bourg, Norm; Brockelman, Warren Y.; Bunyavejchewin, Sarayudh; Chang‐Yang, Chia-Hao; Chitra‐Tarak, Rutuja; Chuyong, George; Condit, Richard; Dattaraja, Handanakere S.; Davies, Stuart J.; Ewango, Corneille E. N.; Fewless, Gary; Fletcher, Christine; Gunatilleke, C. V. S.; Gunatilleke, I. A. U. N.; Hao, Zhanqing; Hogan, J. A.; Howe, Robert; Hsieh, Chang-Fu; Kenfack, David; Lin, Yiching; Ma, Keping; Makana, Jean-Remy; McMahon, Sean; McShea, William J.; Mi, Xiangcheng; Nathalang, Anuttara; Ong, Perry S.; Parker, Geoffrey; Rau, E. -P; Shue, Jessica; Su, Sheng-Hsin; Sukumar, Raman; Sun, I. -F; Suresh, Hebbalalu S.; Tan, Sylvester; Thomas, Duncan; Thompson, Jill; Valencia, Renato; Vallejo, Martha I.; Wang, Xugao; Wang, Yunquan; Wijekoon, Pushpa; Wolf, Amy; Yap, Sandra; Zimmerman, Jess
Abstract: Among the local processes that determine species diversity in ecological communities, fluctuation-dependent mechanisms that are mediated by temporal variability in the abundances of species populations have received significant attention. Higher temporal variability in the abundances of species populations can increase the strength of temporal niche partitioning but can also increase the risk of species extinctions, such that the net effect on species coexistence is not clear. We quantified this temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species. A fitted mechanistic model showed that among the forest plots, the net effect of temporal population variability on tree species coexistence was usually negative, but sometimes positive or negligible. Therefore, our results suggest that temporal variability in the abundances of species populations has no clear negative or positive contribution to the latitudinal gradient in tree species richness.

ID: 156584
Type: article
Authors: Kohyama, Takashi S.; Potts, Matthew D.; Kohyama, Tetsuo I.; Niiyama, Kaoru; Leong, Yao Tze; Davies, Stuart J.; Sheil, Douglas

ID: 155905
Type: article
Authors: Koven, Charles D.; Knox, Ryan G.; Fisher, Rosie A.; Chambers, Jeffrey Q.; Christoffersen, Bradley O.; Davies, Stuart J.; Detto, Matteo; Dietze, Michael C.; Faybishenko, Boris; Holm, Jennifer; Huang, Maoyi; Kovenock, Marlies; Kueppers, Lara M.; Lemieux, Gregory; Massoud, Elias; McDowell, Nathan G.; Muller-Landau, Helene C.; Needham, Jessica F.; Norby, Richard J.; Powell, Thomas; Rogers, Alistair; Serbin, Shawn P.; Shuman, Jacquelyn K.; Swann, Abigail L. S.; Varadharajan, Charuleka; Walker, Anthony P.; Wright, S. Joseph; Xu, Chonggang
Abstract: Plant functional traits determine vegetation responses to environmental variation, but variation in trait values is large, even within a single site. Likewise, uncertainty in how these traits map to Earth system feedbacks is large. We use a vegetation demographic model (VDM), the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), to explore parameter sensitivity of model predictions, and comparison to observations, at a tropical forest site: Barro Colorado Island in Panama. We define a single 12-dimensional distribution of plant trait variation, derived primarily from observations in Panama, and define plant functional types (PFTs) as random draws from this distribution. We compare several model ensembles, where individual ensemble members vary only in the plant traits that define PFTs, and separate ensembles differ from each other based on either model structural assumptions or non-trait, ecosystem-level parameters, which include (a) the number of competing PFTs present in any simulation and (b) parameters that govern disturbance and height-based light competition. While single-PFT simulations are roughly consistent with observations of productivity at Barro Colorado Island, increasing the number of competing PFTs strongly shifts model predictions towards higher productivity and biomass forests. Different ecosystem variables show greater sensitivity than others to the number of competing PFTs, with the predictions that are most dominated by large trees, such as biomass, being the most sensitive. Changing disturbance and height-sorting parameters, i.e., the rules of competitive trait filtering, shifts regimes of dominance or coexistence between early- and late-successional PFTs in the model. Increases to the extent or severity of disturbance, or to the degree of determinism in height-based light competition, all act to shift the community towards early-successional PFTs. In turn, these shifts in competitive outcomes alter predictions of ecosystem states and fluxes, with more early-successional-dominated forests having lower biomass. It is thus crucial to differentiate between plant traits, which are under competitive pressure in VDMs, from those model parameters that are not and to better understand the relationships between these two types of model parameters to quantify sources of uncertainty in VDMs.

ID: 157553
Type: article
Authors: Russo, Sabrina E.; McMahon, Sean M.; Detto, Matteo; Ledder, Glenn; Wright, S. Joseph; Condit, Richard S.; Davies, Stuart J.; Ashton, Peter S.; Bunyavejchewin, Sarayudh; Chang-Yang, Chia-Hao; Ediriweera, Sisira; Ewango, Corneille E. N.; Fletcher, Christine; Foster, Robin B.; Gunatilleke, C. V. Savi; Gunatilleke, I. A. U. Nimal; Hart, Terese; Hsieh, Chang-Fu; Hubbell, Stephen P.; Itoh, Akira; Kassim, Abdul Rahman; Leong, Yao Tze; Lin, Yi Ching; Makana, Jean-Remy; Mohamad, Mohizah Bt; Ong, Perry; Sugiyama, Anna; Sun, I-Fang; Tan, Sylvester; Thompson, Jill; Yamakura, Takuo; Yap, Sandra L.; Zimmerman, Jess K.
Abstract: Using demographic data for 1,111 tree species across ten tropical forests, the authors test the generality of the growth-mortality trade-off, finding that it holds in undisturbed but not disturbed forests. Resource allocation within trees is a zero-sum game. Unavoidable trade-offs dictate that allocation to growth-promoting functions curtails other functions, generating a gradient of investment in growth versus survival along which tree species align, known as the interspecific growth-mortality trade-off. This paradigm is widely accepted but not well established. Using demographic data for 1,111 tree species across ten tropical forests, we tested the generality of the growth-mortality trade-off and evaluated its underlying drivers using two species-specific parameters describing resource allocation strategies: tolerance of resource limitation and responsiveness of allocation to resource access. Globally, a canonical growth-mortality trade-off emerged, but the trade-off was strongly observed only in less disturbance-prone forests, which contained diverse resource allocation strategies. Only half of disturbance-prone forests, which lacked tolerant species, exhibited the trade-off. Supported by a theoretical model, our findings raise questions about whether the growth-mortality trade-off is a universally applicable organizing framework for understanding tropical forest community structure.

ID: 152409
Type: article
Authors: Rutishauser, Ervan; Wright, S. Joseph; Condit, Richard; Hubbell, Stephen P.; Davies, Stuart J.; Muller-Landau, Helene C.
Abstract: Tropical forest responses to climate and atmospheric change are critical to the future of the global carbon budget. Recent studies have reported increases in estimated above-ground biomass (EAGB) stocks, productivity, and mortality in old-growth tropical forests. These increases could reflect a shift in forest functioning due to global change and/or long-lasting recovery from past disturbance. We introduce a novel approach to disentangle the relative contributions of these mechanisms by decomposing changes in whole-plot biomass fluxes into contributions from changes in the distribution of gap-successional stages and changes in fluxes for a given stage. Using 30 years of forest dynamic data at Barro Colorado Island (BCI), Panama, we investigated temporal variation in EAGB fluxes as a function of initial EAGB in 10x10m quadrats. Productivity and mortality fluxes both increased strongly with initial quadrat EAGB. The distribution of EAGB (and thus initial EAGB) across quadrats hardly varied over 30 years (and 7 censuses). EAGB fluxes as a function of initial EAGB varied strongly and significantly among census intervals, with notably higher productivity in 1985-1990 associated with recovery from the 1982-83 El Niño event. Variation in whole-plot fluxes among census intervals was explained overwhelmingly by variation in fluxes as a function of initial EAGB, with essentially no contribution from changes in initial EAGB distributions. The high observed temporal variation in productivity and mortality suggests that this forest is very sensitive to climate variability. There was no consistent long-term trend in productivity, mortality, or biomass in this forest over 30 years, although the temporal variability in productivity and mortality was so strong that it could well mask a substantial trend. Accurate prediction of future tropical forest carbon budgets will require accounting for disturbance-recovery dynamics and understanding temporal variability in productivity and mortality.

ID: 155713
Type: article
Authors: Segnitz, R. Max; Russo, Sabrina E.; Davies, Stuart J.; Peay, Kabir G.
Abstract: While work in temperate forests suggests that there are consistent differences in plant–soil feedback (PSF) between plants with arbuscular and ectomycorrhizal associations, it is unclear whether these differences exist in tropical rainforests. We tested the effects of mycorrhizal type, phylogenetic relationships to overstory species, and soil fertility on the growth of tree seedlings in a tropical Bornean rainforest with a high diversity of both ectomycorrhizal and arbuscular mycorrhizal trees. We found that ectomycorrhizal tree seedlings had higher growth in soils conditioned by close relatives, and that this was associated with higher mycorrhizal colonization. By contrast, arbuscular mycorrhizal tree seedlings generally grew more poorly in soils conditioned by close relatives. For ectomycorrhizal species, the phylogenetic trend was insensitive to soil fertility. For arbuscular mycorrhizal seedlings, however, the effect of growing in soils conditioned by close relatives became increasingly negative as soil fertility increased. Our results demonstrate consistent effects of mycorrhizal type on plant–soil feedbacks across forest biomes. The positive effects of ectomycorrhizal symbiosis may help explain biogeographic variation across tropical forests, such as familial dominance of the Dipterocarpaceae in SE Asia. However, positive feedbacks also raise questions about the role of PSFs in maintaining tropical diversity.

ID: 155762
Type: article
Authors: Sullivan, Martin J. P.; Lewis, Simon L.; Affum-Baffoe, Kofi; Castilho, Carolina; Costa, Flavia; Sanchez, Aida Cuni; Ewango, Corneille E. N.; Hubau, Wannes; Marimon, Beatriz; Monteagudo-Mendoza, Abel; Qie, Lan; SonkE, Bonaventure; Vasquez Martinez, Rodolfo; Baker, Timothy R.; Brienen, Roel J. W.; Feldpausch, Ted R.; Galbraith, David; Gloor, Manuel; Malhi, Yadvinder; Aiba, Shin-ichiro; Alexiades, Miguel N.; Almeida, Everton C.; de Oliveira, Edmar Almeida; Alvarez Davila, Esteban; Loayza, Patricia Alvarez; Andrade, Ana; Vieira, Simone Aparecida; Aragao, Luiz E. O. C.; Araujo-Murakami, Alejandro; Arets, Eric J. M. M.; Arroyo, Luzmila; Ashton, Peter; Aymard, Gerardo C.; Baccaro, Fabricio B.; Banin, Lindsay F.; Baraloto, Christopher; Camargo, Plinio Barbosa; Barlow, Jos; Barroso, Jorcely; Bastin, Jean-Francois; Batterman, Sarah A.; Beeckman, Hans; Begne, Serge K.; Bennett, Amy C.; Berenguer, Erika; Berry, Nicholas; Blanc, Lilian; Boeckx, Pascal; Bogaert, Jan; Bonal, Damien; Bongers, Frans; Bradford, Matt; Brearley, Francis Q.; Brncic, Terry; Brown, Foster; Burban, Benoit; Camargo, Jose Luis; Castro, Wendeson; Ceron, Carlos; Ribeiro, Sabina Cerruto; Moscoso, Victor Chama; Chave, Jerome; Chezeaux, Eric; Clark, Connie J.; de Souza, Fernanda Coelho; Collins, Murray; Comiskey, James A.; Cornejo Valverde, Fernando; Corrales Medina, Massiel; Da Costa, Lola; Dancak, Martin; Dargie, Greta C.; Davies, Stuart; Davila Cardozo, Nallaret; de Haulleville, Thales; de Medeiros, Marcelo Brilhante; del Aguila Pasquel, Jhon; Derroire, Geraldine; Di Fiore, Anthony; Doucet, Jean-Louis; Dourdain, Aurelie; Droissart, Vincent; Fernanda Duque, Luisa; Ekoungoulou, Romeo; Elias, Fernando; Erwin, Terry; Esquivel-Muelbert, Adriane; Fauset, Sophie; Ferreira, Joice; Flores Llampazo, Gerardo; Foli, Ernest; Ford, Andrew; Gilpin, Martin; Hall, Jefferson S.; Hamer, Keith C.; Hamilton, Alan C.; Harris, David J.; Hart, Terese B.; Hedl, Radim; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Hladik, Annette; Honorio Coronado, Euridice; Huamantupa-Chuquimaco, Isau; Huaraca Huasco, Walter; Jeffery, Kathryn J.; Jimenez-Rojas, Eliana; Kalamandeen, Michelle; Djuikouo, Marie Noel Kamdem; Kearsley, Elizabeth; Umetsu, Ricardo Keichi; Kho, Lip Khoon; Killeen, Timothy; Kitayama, Kanehiro; Klitgaard, Bente; Koch, Alexander; Labriere, Nicolas; Laurance, William; Laurance, Susan; Leal, Miguel E.; Levesley, Aurora; Lima, Adriano J. N.; Lisingo, Janvier; Lopes, Aline P.; Lopez-Gonzalez, Gabriela; Lovejoy, Tom; Lovett, Jon C.; Lowe, Richard; Magnusson, William E.; Malumbres-Olarte, Jagoba; Manzatto, Angelo Gilberto; Marimon, Ben Hur, Jr.; Marshall, Andrew R.; Marthews, Toby; de Almeida Reis, Simone Matias; Maycock, Colin; Melgaco, Karina; Mendoza, Casimiro; Metali, Faizah; Mihindou, Vianet; Milliken, William; Mitchard, Edward T. A.; Morandi, Paulo S.; Mossman, Hannah L.; Nagy, Laszlo; Nascimento, Henrique; Neill, David; Nilus, Reuben; Nunez Vargas, Percy; Palacios, Walter; Camacho, Nadir Pallqui; Peacock, Julie; Pendry, Colin; Penuela Mora, Maria Cristina; Pickavance, Georgia C.; Pipoly, John; Pitman, Nigel; Playfair, Maureen; Poorter, Lourens; Poulsen, John R.; Poulsen, Axel Dalberg; Preziosi, Richard; Prieto, Adriana; Primack, Richard B.; Ramirez-Angulo, Hirma; Reitsma, Jan; Rejou-Mechain, Maxime; Restrepo Correa, Zorayda; de Sousa, Thaiane Rodrigues; Rodriguez Bayona, Lily; Roopsind, Anand; Rudas, Agustin; Rutishauser, Ervan; Abu Salim, Kamariah; Salomao, Rafael P.; Schietti, Juliana; Sheil, Douglas; Silva, Richarlly C.; Silva Espejo, Javier; Valeria, Camila Silva; Silveira, Marcos; Simo-Droissart, Murielle; Simon, Marcelo Fragomeni; Singh, James; Soto Shareva, Yahn Carlos; Stahl, Clement; Stropp, Juliana; Sukri, Rahayu; Sunderland, Terry; Svatek, Martin; Swaine, Michael D.; Swamy, Varun; Taedoumg, Hermann; Talbot, Joey; Taplin, James; Taylor, David; ter Steege, Hans; Terborgh, John; Thomas, Raquel; Thomas, Sean C.; Torres-Lezama, Armando; Umunay, Peter; Valenzuela Gamarra, Luis; van der Heijden, Geertje; van der Hout, Peter; van der Meer, Peter; van Nieuwstadt, Mark; Verbeeck, Hans; Vernimmen, Ronald; Vicentini, Alberto; Guimaraes Vieira, Ima Celia; Torre, Emilio Vilanova; Vleminckx, Jason; Vos, Vincent; Wang, Ophelia; White, Lee J. T.; Willcock, Simon; Woods, John T.; Wortel, Verginia; Young, Kenneth; Zagt, Roderick; Zemagho, Lise; Zuidema, Pieter A.; Zwerts, Joeri A.; Phillips, Oliver L.
Abstract: The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (-9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per degrees C in the hottest forests (>32.2 degrees C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth's climate.

ID: 155714
Type: article
Authors: Weemstra, Monique; Peay, Kabir G.; Davies, Stuart J.; Mohamad, Mohizah; Itoh, Akira; Tan, Sylvester; Russo, Sabrina E.
Abstract: Arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) produce contrasting plant-soil feedbacks, but how these feedbacks are constrained by lithology is poorly understood. -We investigated the hypothesis that lithological drivers of soil fertility filter plant resource economic strategies in ways that influence the relative fitness of trees with AMF or EMF symbioses in a Bornean rain forest containing species with both mycorrhizal strategies. -Using forest inventory data on 1245 tree species, we found that although AMF-hosting trees had greater relative dominance on all soil types, with declining lithological soil fertility, EMF-hosting trees became more dominant. Data on 13 leaf traits and wood density for a total of 150 species showed that variation was almost always associated with soil type, whereas for six leaf traits (structural properties; carbon, nitrogen, phosphorus ratios; nitrogen isotopes), variation was also associated with mycorrhizal strategy. EMF-hosting species had slower leaf economics than AMF-hosts, demonstrating the central role of mycorrhizal symbiosis in plant resource economies. -At the global scale, climate has been shown to shape forest mycorrhizal composition, but here we show that, in communities, it depends on soil lithology, suggesting scale-dependent abiotic factors influence feedbacks underlying the relative fitness of different mycorrhizal strategies.

ID: 155909
Type: article
Authors: Xu, Han; Detto, Matteo; Fang, Suqin; Chazdon, Robin L.; Li, Yide; Hau, Billy C. H.; Fischer, Gunter A.; Weiblen, George D.; Hogan, J. A.; Zimmerman, Jess K.; Uriarte, Maria; Thompson, Jill; Lian, Juyu; Cao, Ke; Kenfack, David; Alonso, Alfonso; Bissiengou, Pulchérie; Memiaghe, Hervé Roland; Valencia, Renato; Yap, Sandra L.; Davies, Stuart J.; Mi, Xiangcheng; Yao, Tze Leong

ID: 148506
Type: article
Authors: Arellano, Gabriel; Medina, Nagore G.; Tan, Sylvester; Mohamad, Mohizah; Davies, Stuart J.
Abstract: What causes individual tree death in tropical forests remains a major gap in our understanding of the biology of tropical trees and leads to significant uncertainty in predicting global carbon cycle dynamics. We measured individual characteristics (diameter at breast height, wood density, growth rate, crown illumination and crown form) and environmental conditions (soil fertility and habitat suitability) for 26 425 trees ≥ 10 cm diameter at breast height belonging to 416 species in a 52-ha plot in Lambir Hills National Park, Malaysia. We used structural equation models to investigate the relationships among the different factors and tree mortality. Crown form (a proxy for mechanical damage and other stresses) and prior growth were the two most important factors related to mortality. The effect of all variables on mortality (except habitat suitability) was substantially greater than expected by chance. Tree death is the result of interactions between factors, including direct and indirect effects. Crown form/damage and prior growth mediated most of the effect of tree size, wood density, fertility and habitat suitability on mortality. Large-scale assessment of crown form or status may result in improved prediction of individual tree death at the landscape scale.

ID: 151530
Type: article
Authors: Bunyavejchewin, Sarayudh; Sinbumroong, Aroon; Turner, Benjamin L.; Davies, Stuart J.
Abstract: In 2000, we established a 24-ha plot in Peninsular Thailand to investigate how forest composition, structure and dynamics vary with spatial heterogeneity in resource availability. Detailed soil and topographic surveys were used to describe four edaphic habitats in the plot. Disturbance history was inferred from historical records and floristic analysis. The plot included >119 000 trees ≥1 cm dbh in 578 species, and was recensused in 2010. Species distributions, floristic turnover, stand structure, demographic rates and biomass dynamics were strongly influenced by heterogeneity in soils, topography and disturbance history. Over 75% of species were aggregated on specific edaphic habitats leading to strong compositional turnover across the plot. Soil chemistry more strongly affected species turnover than topography. Forest with high biomass and slow dynamics occurred on well-drained, low fertility ridges. The distribution and size structure of pioneer species reflected habitat-specific differences in disturbance history. Overall, above-ground biomass (AGB) increased by 0.64 Mg ha−1 y−1, from 385 to 392 Mg ha−1, an increase that was entirely attributable to recovery after natural disturbance. Forest composition and stand structure, by reflecting local disturbance history, provide insights into the likely drivers of AGB change in forests. Predicting future changes in tropical forests requires improved understanding of how soils and disturbance regulate forest dynamics.

ID: 151369
Type: article
Authors: Chave, Jérôme; Davies, Stuart J.; Phillips, Oliver L.; Lewis, Simon L.; Sist, Plinio; Schepaschenko, Dmitry; Armston, John; Baker, Tim R.; Coomes, David; Disney, Mathias; Duncanson, Laura; Hérault, Bruno; Labrière, Nicolas; Meyer, Victoria; Réjou-Méchain, Maxime; Scipal, Klaus; Saatchi, Sassan
Abstract: Several remote sensing missions will soon produce detailed carbon maps over all terrestrial ecosystems. These missions are dependent on accurate and representative in situ datasets for the training of their algorithms and product validation. However, long-term ground-based forest-monitoring systems are limited, especially in the tropics, and to be useful for validation, such ground-based observation systems need to be regularly revisited and maintained at least over the lifetime of the planned missions. Here we propose a strategy for a coordinated and global network of in situ data that would benefit biomass remote sensing missions. We propose to build upon existing networks of long-term tropical forest monitoring. To produce accurate ground-based biomass estimates, strict data quality must be guaranteed to users. It is more rewarding to invest ground resources at sites where there currently is assurance of a long-term commitment locally and where a core set of data is already available. We call these ‘supersites’. Long-term funding for such an inter-agency endeavour remains an important challenge, and we here provide costing estimates to facilitate dialogue among stakeholders. One critical requirement is to ensure in situ data availability over the lifetime of remote sensing missions. To this end, consistent guidelines for supersite selection and management are proposed within the Forest Observation System, long-term funding should be assured, and principal investigators of the sites should be actively involved.

ID: 151753
Type: article
Authors: Dahl, Chris; Ctvrtecka, Richard; Gripenberg, Sofia; Lewis, Owen T.; Segar, Simon T.; Klimes, Petr; Sam, Katerina; Rinan, Dominic; Filip, Jonah; Lilip, Roll; Kongnoo, Pitoon; Panmeng, Montarika; Putnaul, Sutipun; Reungaew, Manat; Rivera, Marleny; Barrios, Hector; Davies, Stuart J.; Bunyavejchewin, Sarayudh; Wright, S. Joseph; Weiblen, George D.; Novotny, Vojtech; Basset, Yves

ID: 151668
Type: article
Authors: Luskin, Matthew Scott; Ickes, Kalan; Yao, Tze Leong; Davies, Stuart J.