Publication Search Results

ID: 159180
Type: article
Authors: Abiem, Iveren; Dickie, Ian; Kenfack, David; Chapman, Hazel
Abstract: Questions A leading hypothesis for species coexistence in species-rich, lowland tropical forests is conspecific negative density dependence (CNDD), driven by host-specific pests and pathogens and competition for available resources. The extent to which this applies to Afromontane forests with relatively low diversity, a high frequency of single-species stands, relatively few pests and pathogens and larger edge:core ratios, is unknown. We hoped that the results of our investigation would either confirm the generality of CNDD across these different tropical forest types or offer novel insights into alternative mechanisms leading to the maintenance of Afromontane tree species diversity. Location Ngel Nyaki Forest Reserve, southeastern Nigeria. Methods We monitored the survival of 10,741 seedlings of 93 species over two years in a long-term Forest Global Earth Observatory (ForestGEO) study plot in a montane forest in Nigeria. We assessed the effect of conspecific and heterospecific seedling and adult neighbours on the survival of every seedling and seedling guild (shade vs light-demanding; canopy vs understorey; edge specialists vs generalists; small vs large seedlings). Results We found strong evidence for non-species-specific positive and negative density dependence. CNDD was stronger in canopy species and light-demanding species than in the other growth form and shade tolerance guilds. Conclusions Our study offers some clear predictions about drivers of community coexistence in this environment, which will require further testing using field-based experiments.

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: 159518
Type: article
Authors: Kenfack, David; Arellano, Gabriel; Kibet, Staline; Kimuyu, Duncan; Musili, Paul
Abstract: Key message The high mortality and low recruitment of the myrmecophytic Acacia drepanolobium are not consistent with the demographic rates of monodominant species. The positive conspecific density dependence observed from the spatial analysis is consistent with the defensive benefits conferred by symbiotic ants to trees when they grow close to each other. Patches of savanna dominated by Acacia drepanolobium occur throughout East Africa on nutrient-rich vertisols, also known as black cotton soils. We assessed the survival and recruitment for all freestanding trees with diameter at knee height (dkh) >= 10 mm in one of such mono-dominated patches (47 ha) at the Mpala Research Centre, Kenya, with the aim of identifying demographic traits that might explain the dominance of this species. Over a mean 6-year interval, mortality and recruitment rates in the habitat were 4.55%/year and 1.42%/year respectively, resulting in a net loss of 17.8% of the initial individuals. Of the 30 species recorded from the first census, 11 decreased in abundance, nine increased, and the remainder 10 did not change in abundance. The monodominant A. drepanolobium had a high mortality (4.69%/year), a low recruitment (1.31%/year), and a 19% population decline. There was no evidence of conspecific negative density dependence for this species. Rather, we found a statistically significant positive correlation between the number of conspecific neighbors and individual-level probability of survival, consistent with the "shared defense" benefits that symbiotic ant colonies occupying multiple trees can confer to these latter in a small neighborhood. Thus, mortality of A. drepanolobium was higher in areas where it occurred in lower densities, which resulted in an increase in the spatial aggregation of conspecifics. Mortality increased with dkh size classes and was mostly caused by elephants and stem-boring beetles. The demographic rates during the study period in theory are inconsistent with those of monodominant species. The protection against herbivory conferred by mutualistic ants associated with this species remains the most probable explanation of its dominance in this habitat.

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: 154309
Type: article
Authors: Abiem, Iveren; Arellano, Gabriel; Kenfack, David; Chapman, Hazel
Abstract: Local factors can play an important role in defining tree species distributions in species rich tropical forests. To what extent the same applies to relatively small, species poor West African montane forests is unknown. Here, forests survive in a grassland matrix and fire has played a key role in their spatial and temporal dynamics since the Miocene. To what extent these dynamics influence local species distributions, as compared with other environmental variables such as altitude and moisture remain unknown. Here, we use data from the 20.28 ha montane forest plot in Ngel Nyaki Forest Reserve, South-East Nigeria to explore these questions. The plot features a gradient from grassland to core forest, with significant edges. Within the plot, we determined tree stand structure and species diversity and identified all trees ≥1 cm in diameter. We recorded species guild (pioneer vs. shade tolerant), seed size, and dispersal mode. We analyzed and identified to what extent species showed a preference for forest edges/grasslands or core forest. Similarly, we looked for associations with elevation, distance to streams and forest versus grassland. We recorded 41,031 individuals belonging to 105 morphospecies in 87 genera and 47 families. Around 40% of all tree species, and 50% of the abundant species, showed a clear preference for either the edge/grassland habitat or the forest core. However, we found no obvious association between species guild, seed size or dispersal mode, and distance to edge, so what leads to this sorting remains unclear. Few species distributions were influenced by distance to streams or altitude.

ID: 157713
Type: article
Authors: Fischer, Fabian Jorg; Labriere, Nicolas; Vincent, Gregoire; Herault, Bruno; Alonso, Alfonso; Memiaghe, Herve; Bissiengou, Pulcherie; Kenfack, David; Saatchi, Sassan; Chave, Jerome
Abstract: Tropical forests are characterized by large carbon stocks and high biodiversity, but they are increasingly threatened by human activities. Since structure strongly influences the functioning and resilience of forest communities and ecosystems, it is important to quantify it at fine spatial scales. Here, we propose a new simulation-based approach, the "Canopy Constructor", with which we quantified forest structure and biomass at two tropical forest sites, one in French Guiana, the other in Gabon. In a first step, the Canopy Constructor combines field inventories and airborne lidar scans to create virtual 3D representations of forest canopies that best fit the data. From those, it infers the forests' structure, including crown packing densities and allometric scaling relationships between tree dimensions. In a second step, the results of the first step are extrapolated to create virtual tree inventories over the whole lidar-scanned area. Across the French Guiana and Gabon plots, we reconstructed empirical canopies with a mean absolute error of 3.98 m [95% credibility interval: 3.02, 4.98], or 14.4%, and a small upwards bias of 0.66 m [-0.41, 1.8], or 2.7%. Height-stem diameter allometries were inferred with more precision than crown-stem diameter allometries, with generally larger heights at the Amazonian than the African site, but similar crown-stem diameter allometries. Plot-based aboveground biomass was inferred to be larger in French Guiana with 400.8 t ha(-1) [366.2-437.9], compared to 302.2 t ha(-1) in Gabon [267.8-336.8] and decreased to 299.8 t ha(-1) [275.9-333.9] and 251.8 t ha(-1) [206.7-291.7] at the landscape scale, respectively. Predictive accuracy of the extrapolation procedure had an RMSE of 53.7 t ha(-1) (14.9%) at the 1 ha scale and 87.6 t ha(-1) (24.2%) at the 0.25 ha scale, with a bias of -17.1 t ha(-1) (-4.7%). This accuracy was similar to regression-based approaches, but the Canopy Constructor improved the representation of natural heterogeneity considerably, with its range of biomass estimates larger by 54% than regression-based estimates. The Canopy Constructor is a comprehensive inference procedure that provides fine-scale and individual-based reconstructions even in dense tropical forests. It may thus prove vital in the assessment and monitoring of those forests, and has the potential for a wider applicability, for example in the exploration of ecological and physiological relationships in space or the initialisation and calibration of forest growth models.

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: 154770
Type: article
Authors: Hubau, Wannes; Lewis, Simon L.; Phillips, Oliver L.; Affum-Baffoe, Kofi; Beeckman, Hans; Cuní-Sanchez, Aida; Daniels, Armandu K.; Ewango, Corneille E. N.; Fauset, Sophie; Mukinzi, Jacques M.; Sheil, Douglas; Sonké, Bonaventure; Sullivan, Martin J. P.; Sunderland, Terry C. H.; Taedoumg, Hermann; Thomas, Sean C.; White, Lee J. T.; Abernethy, Katharine A.; Adu-Bredu, Stephen; Amani, Christian A.; Baker, Timothy R.; Banin, Lindsay F.; Baya, Fidèle; Begne, Serge K.; Bennett, Amy C.; Benedet, Fabrice; Bitariho, Robert; Bocko, Yannick E.; Boeckx, Pascal; Boundja, Patrick; Brienen, Roel J. W.; Brncic, Terry; Chezeaux, Eric; Chuyong, George B.; Clark, Connie J.; Collins, Murray; Comiskey, James A.; Coomes, David A.; Dargie, Greta C.; de Haulleville, Thales; Kamdem, Marie Noel Djuikouo; Doucet, Jean-Louis; Esquivel-Muelbert, Adriane; Feldpausch, Ted R.; Fofanah, Alusine; Foli, Ernest G.; Gilpin, Martin; Gloor, Emanuel; Gonmadje, Christelle; Gourlet-Fleury, Sylvie; Hall, Jefferson S.; Hamilton, Alan C.; Harris, David J.; Hart, Terese B.; Hockemba, Mireille B. N.; Hladik, Annette; Ifo, Suspense A.; Jeffery, Kathryn J.; Jucker, Tommaso; Yakusu, Emmanuel Kasongo; Kearsley, Elizabeth; Kenfack, David; Koch, Alexander; Leal, Miguel E.; Levesley, Aurora; Lindsell, Jeremy A.; Lisingo, Janvier; Lopez-Gonzalez, Gabriela; Lovett, Jon C.; Makana, Jean-Remy; Malhi, Yadvinder; Marshall, Andrew R.; Martin, Jim; Martin, Emanuel H.; Mbayu, Faustin M.; Medjibe, Vincent P.; Mihindou, Vianet; Mitchard, Edward T. A.; Moore, Sam; Munishi, Pantaleo K. T.; Bengone, Natacha Nssi; Ojo, Lucas; Ondo, Fidèle Evouna; Peh, Kelvin S. -H; Pickavance, Georgia C.; Poulsen, Axel Dalberg; Poulsen, John R.; Qie, Lan; Reitsma, Jan; Rovero, Francesco; Swaine, Michael D.; Talbot, Joey; Taplin, James; Taylor, David M.; Thomas, Duncan W.; Toirambe, Benjamin; Mukendi, John Tshibamba; Tuagben, Darlington; Umunay, Peter M.; van der Heijden, Geertje M. F.; Verbeeck, Hans; Vleminckx, Jason; Willcock, Simon; Wöll, Hannsjörg; Woods, John T.; Zemagho, Lise
Abstract: Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions1-3. Climate-driven vegetation models typically predict that this tropical forest 'carbon sink' will continue for decades4,5. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53-0.79), in contrast to the long-term decline in Amazonian forests6. Therefore the carbon sink responses of Earth's two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature7-9. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth's intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth's climate.

ID: 157188
Type: article
Authors: Kimuyu, Duncan M.; Kenfack, David; Musili, Paul M.; Ang'ila, Robert O.

ID: 156517
Type: article
Authors: Marselis, Suzanne M.; Abernethy, Katharine; Alonso, Alfonso; Armston, John; Baker, Timothy R.; Bastin, Jean-Francois; Bogaert, Jan; Boyd, Doreen S.; Boeckx, Pascal; Burslem, David F. R. P.; Chazdon, Robin; Clark, David B.; Coomes, David; Duncanson, Laura; Hancock, Steven; Hill, Ross; Hopkinson, Chris; Kearsley, Elizabeth; Kellner, James R.; Kenfack, David; Labriere, Nicolas; Lewis, Simon L.; Minor, David; Memiaghe, Herve; Monteagudo, Abel; Nilus, Reuben; O'Brien, Michael; Phillips, Oliver L.; Poulsen, John; Tang, Hao; Verbeeck, Hans; Dubayah, Ralph
Abstract: Aim Mapping tree species richness across the tropics is of great interest for effective conservation and biodiversity management. In this study, we evaluated the potential of full-waveform lidar data for mapping tree species richness across the tropics by relating measurements of vertical canopy structure, as a proxy for the occupation of vertical niche space, to tree species richness. Location Tropics. Time period Present. Major taxa studied Trees. Methods First, we evaluated the characteristics of vertical canopy structure across 15 study sites using (simulated) large-footprint full-waveform lidar data (22 m diameter) and related these findings to in-situ tree species information. Then, we developed structure-richness models at the local (within 25-50 ha plots), regional (biogeographical regions) and pan-tropical scale at three spatial resolutions (1.0, 0.25 and 0.0625 ha) using Poisson regression. Results The results showed a weak structure-richness relationship at the local scale. At the regional scale (within a biogeographical region) a stronger relationship between canopy structure and tree species richness across different tropical forest types was found, for example across Central Africa and in South America [R(2)ranging from .44-.56, root mean squared difference as a percentage of the mean (RMSD%) ranging between 23-61%]. Modelling the relationship pan-tropically, across four continents, 39% of the variation in tree species richness could be explained with canopy structure alone (R-2 = .39 and RMSD% = 43%, 0.25-ha resolution). Main conclusions Our results may serve as a basis for the future development of a set of structure-richness models to map high resolution tree species richness using vertical canopy structure information from the Global Ecosystem Dynamics Investigation (GEDI). The value of this effort would be enhanced by access to a larger set of field reference data for all tropical regions. Future research could also support the use of GEDI data in frameworks using environmental and spectral information for modelling tree species richness across the tropics.

ID: 156520
Type: article
Authors: Ploton, Pierre; Mortier, Frederic; Barbier, Nicolas; Cornu, Guillaume; Rejou-Mechain, Maxime; Rossi, Vivien; Alonso, Alfonso; Bastin, Jean-Francois; Bayol, Nicolas; Benedet, Fabrice; Bissiengou, Pulcherie; Chuyong, Georges; Demarquez, Benoit; Doucet, Jean-Louis; Droissart, Vincent; Kamdem, Narcisse Guy; Kenfack, David; Memiaghe, Herve; Moses, Libalah; SonkE, Bonaventure; Texier, Nicolas; Thomas, Duncan; Zebaze, Donatien; Pelissier, Raphael; Gourlet-Fleury, Sylvie
Abstract: Forest biomass is key in Earth carbon cycle and climate system, and thus under intense scrutiny in the context of international climate change mitigation initiatives (e.g. REDD+). In tropical forests, the spatial distribution of aboveground biomass (AGB) remains, however, highly uncertain. There is increasing recognition that progress is strongly limited by the lack of field observations over large and remote areas. Here, we introduce the Congo basin Forests AGB (CoFor-AGB) dataset that contains AGB estimations and associated uncertainty for 59,857 1-km pixels aggregated from nearly 100,000 ha ofin situforest management inventories for the 2000 - early 2010s period in five central African countries. A comprehensive error propagation scheme suggests that the uncertainty on AGB estimations derived from c. 0.5-ha inventory plots (8.6-15.0%) is only moderately higher than the error obtained from scientific sampling plots (8.3%). CoFor-AGB provides the first large scale view of forest AGB spatial variation from field data in central Africa, the second largest continuous tropical forest domain of the world.

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: 149947
Type: article
Authors: Chu, Chengjin; Lutz, James A.; Kral, Kamil; Vrska, Tomas; Yin, Xue; Myers, Jonathan A.; Abiem, Iveren; Alonso, Alfonso; Bourg, Norm; Burslem, David F. R. P.; Cao, Min; Chapman, Hazel; Condit, Richard S.; Fang, Suqin; Fischer, Gunter A.; Gao, Lianming; Hao, Zhanqin; Hau, Billy C. H.; He, Qing; Hector, Andrew; Hubbell, Stephen P.; Jiang, Mingxi; Jin, Guangze; Kenfack, David; Lai, Jiangshan; Li, Buhang; Li, Xiankun; Li, Yide; Lian, Juyu; Lin, Luxiang; Liu, Yankun; Liu, Yu; Luo, Yahuang; Ma, Keping; McShea, William; Memiaghe, Herve; Mi, Xiangcheng; Ni, Ming; O'Brien, Michael J.; de Oliveira, Alexandre A.; Orwig, David A.; Parker, Geoffrey G.; Qiao, Xiujuan; Ren, Haibao; Reynolds, Glen; Sang, Weiguo; Shen, Guochun; Su, Zhiyao; Sui, Xinghua; Sun, I-Fang; Tian, Songyan; Wang, Bin; Wang, Xihua; Wang, Xugao; Wang, Youshi; Weiblen, George D.; Wen, Shujun; Xi, Nianxun; Xiang, Wusheng; Xu, Han; Xu, Kun; Ye, Wanhui; Zhang, Bingwei; Zhang, Jiaxin; Zhang, Xiaotong; Zhang, Yingming; Zhu, Kai; Zimmerman, Jess; Storch, David; Baltzer, Jennifer L.; Anderson-Teixeira, Kristina J.; Mittelbach, Gary G.; He, Fangliang
Abstract: Climate is widely recognised as an important determinant of the latitudinal diversity gradient. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Using data from 35 large forest plots, we test hypothesised relationships amongst climate, topography, forest structural attributes (stem abundance, tree size variation and stand basal area) and tree species richness to better understand drivers of latitudinal tree diversity patterns. Climate influences tree richness both directly, with more species in warm, moist, aseasonal climates and indirectly, with more species at higher stem abundance. These results imply direct limitation of species diversity by climatic stress and more rapid (co-)evolution and narrower niche partitioning in warm climates. They also support the idea that increased numbers of individuals associated with high primary productivity are partitioned to support a greater number of species.

ID: 152052
Type: article
Authors: Kenfack, David; Nguema, Diosdado Ekomo

ID: 152059
Type: article
Authors: Marselis, Suzanne Mariëlle; Tang, Hao; Armston, John; Abernethy, Katharine; Alonso, Alfonso; Barbier, Nicolas; Bissiengou, Pulchérie; Jeffery, Kathryn; Kenfack, David; Labrière, Nicolas; Lee, Seung Kuk; Lewis, Simon; Memiaghe, Hervé; Poulsen, John R.; White, Lee; Dubayah, Ralph
Abstract: Mapping tree species diversity is increasingly important in the face of environmental change and biodiversity conservation. We explore a potential way of mapping this diversity by relating forest structure to tree species diversity in Gabon. First, we test the relation between canopy height, as a proxy for niche volume, and tree species diversity. Then, we test the relation between vertical canopy structure, as a proxy for vertical niche occupation, and tree species diversity. We use large footprint full-waveform airborne lidar data collected across four study sites in Gabon (Lopé, Mabounié, Mondah, and Rabi) in combination with in-situ estimates of species richness (S) and Shannon diversity (H’). Linear models using canopy height explained 44 and 43% of the variation in S and H’ at the 0.25 ha resolution. Linear models using canopy height and the Plant Area Volume Density (PAVD) profile explained 71% of this variation. We demonstrate applications of these models by mapping S and H’ in Mondah using a simulated GEDI-TanDEM-X fusion height product, across the four sites using wall-to-wall airborne lidar data products, and across and between the study sites using ICESat lidar waveforms. The modeling results are encouraging in the context of developing pan-tropical structure-diversity models applicable to data from current and upcoming spaceborne remote sensing missions.

ID: 151674
Type: article
Authors: Mutuku, Paul Musili; Kenfack, David

ID: 151762
Type: article
Authors: Obiang, Nestor Laurier Engone; Kenfack, David; Picard, Nicolas; Lutz, James A.; Bissiengou, Pulchérie; Memiaghe, Hervé R.; Alonso, Alfonso

ID: 151772
Type: article
Authors: Ren, Haibao; Keil, Petr; Mi, Xiangcheng; Ma, Keping; Hao, Zhanqing; Ye, Wanhui; Lin, Luxiang; Valencia, Renato; Fletcher, Christine Dawn; Thomas, Duncan W.; Howe, Robert W.; Lutz, James; Bourg, Norman A.; Su, Sheng-Hsin; Sun, I. F.; Zhu, Li; Chang, Li-Wan; Wang, Xihua; Du, Xiaojun; Kenfack, David; Chuyong, George B.; Jetz, Walter

ID: 152060
Type: article
Authors: Sainge, Moses N.; Lyonga, Ngoh M.; Mbatchou, Gildas P. T.; Kenfack, David; Nchu, Felix; Peterson, Andrew T.

ID: 150307
Type: article
Authors: Bastin, Jean-François; Rutishauser, Ervan; Kellner, James R.; Saatchi, Sassan; Pélissier, Raphael; Hérault, Bruno; Slik, Ferry; Bogaert, Jan; Cannière, Charles De; Marshall, Andrew R.; Poulsen, John; Alvarez‐Loyayza, Patricia; Andrade, Ana; Angbonga‐Basia, Albert; Araujo‐Murakami, Alejandro; Arroyo, Luzmila; Ayyappan, Narayanan; Azevedo, Celso Paulo de; Banki, Olaf; Barbier, Nicolas; Barroso, Jorcely G.; Beeckman, Hans; Bitariho, Robert; Boeckx, Pascal; Boehning‐Gaese, Katrin; Brandão, Hilandia; Brearley, Francis Q.; Hockemba, Mireille Breuer Ndoundou; Brienen, Roel; Camargo, Jose Luis C.; Campos‐Arceiz, Ahimsa; Cassart, Benoit; Chave, Jé; Chazdon, Robin; Chuyong, Georges; Clark, David B.; Clark, Connie J.; Condit, Richard S.; Coronado, Euridice N. Honorio; Davidar, Priya; Haulleville, Thalès de; Descroix, Laurent; Doucet, Jean-Louis; Dourdain, Aurelie; Droissart, Vincent; Duncan, Thomas; Espejo, Javier Silva; Espinosa, Santiago; Farwig, Nina; Fayolle, Adeline; Feldpausch, Ted R.; Ferraz, Antonio; Fletcher, Christine; Gajapersad, Krisna; Gillet, Jean-François; Amaral, Iê; Gonmadje, Christelle; Grogan, James; Harris, David; Herzog, Sebastian K.; Homeier, Jü; Hubau, Wannes; Hubbell, Stephen P.; Hufkens, Koen; Hurtado, Johanna; Kamdem, Narcisse G.; Kearsley, Elizabeth; Kenfack, David; Kessler, Michael; Labrière, Nicolas; Laumonier, Yves; Laurance, Susan; Laurance, William F.; Lewis, Simon L.; Libalah, Moses B.; Ligot, Gauthier; Lloyd, Jon; Lovejoy, Thomas E.; Malhi, Yadvinder; Marimon, Beatriz S.; Junior, Ben Hur Marimon; Martin, Emmanuel H.; Matius, Paulus; Meyer, Victoria; Bautista, Casimero Mendoza; Monteagudo‐Mendoza, Abel; Mtui, Arafat; Neill, David; Gutierrez, Germaine Alexander Parada; Pardo, Guido; Parren, Marc; Parthasarathy, N.; Phillips, Oliver L.; Pitman, Nigel C. A.; Ploton, Pierre; Ponette, Quentin; Ramesh, B. R.; Razafimahaimodison, Jean-Claude; Réjou‐Méchain, Maxime; Rolim, Samir Gonçalves; Saltos, Hugo Romero; Rossi, Luiz Marcelo Brum; Spironello, Wilson Roberto; Rovero, Francesco; Saner, Philippe; Sasaki, Denise; Schulze, Mark; Silveira, Marcos; Singh, James; Sist, Plinio; SonkE, Bonaventure; Soto, J. D.; Souza, Cintia Rodrigues de; Stropp, Juliana; Sullivan, Martin J. P.; Swanepoel, Ben; Steege, Hans ter; Terborgh, John; Texier, Nicolas; Toma, Takeshi; Valencia, Renato; Valenzuela, Luis; Ferreira, Leandro Valle; Valverde, Fernando Cornejo; Andel, Tinde R. van; Vasque, Rodolfo; Verbeeck, Hans; Vivek, Pandi; Vleminckx, Jason; Vos, Vincent A.; Wagner, Fabien H.; Warsudi, Papi Puspa; Wortel, Verginia; Zagt, Roderick J.; Zebaze, Donatien
Abstract: Aim Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and field inventories. To close this gap, we propose a new pan-tropical model to predict plot-level forest structure properties and biomass from only the largest trees. Location Pan-tropical. Time period Early 21st century. Major taxa studied Woody plants. Methods Using a dataset of 867 plots distributed among 118 sites across the tropics, we tested the prediction of the quadratic mean diameter, basal area, Lorey's height, community wood density and aboveground biomass (AGB) from the ith largest trees. Results Measuring the largest trees in tropical forests enables unbiased predictions of plot- and site-level forest structure. The 20 largest trees per hectare predicted quadratic mean diameter, basal area, Lorey's height, community wood density and AGB with 12, 16, 4, 4 and 17.7% of relative error, respectively. Most of the remaining error in biomass prediction is driven by differences in the proportion of total biomass held in medium-sized trees (50–70 cm diameter at breast height), which shows some continental dependency, with American tropical forests presenting the highest proportion of total biomass in these intermediate-diameter classes relative to other continents. Main conclusions Our approach provides new information on tropical forest structure and can be used to generate accurate field estimates of tropical forest carbon stocks to support the calibration and validation of current and forthcoming space missions. It will reduce the cost of field inventories and contribute to scientific understanding of tropical forest ecosystems and response to climate change.