Browsing by Author "White, Lee JT"
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Item Open Access Above-ground biomass and structure of 260 African tropical forests.(Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 2013-01) Lewis, Simon L; Sonké, Bonaventure; Sunderland, Terry; Begne, Serge K; Lopez-Gonzalez, Gabriela; van der Heijden, Geertje MF; Phillips, Oliver L; Affum-Baffoe, Kofi; Baker, Timothy R; Banin, Lindsay; Bastin, Jean-François; Beeckman, Hans; Boeckx, Pascal; Bogaert, Jan; De Cannière, Charles; Chezeaux, Eric; Clark, Connie J; Collins, Murray; Djagbletey, Gloria; Djuikouo, Marie Noël K; Droissart, Vincent; Doucet, Jean-Louis; Ewango, Cornielle EN; Fauset, Sophie; Feldpausch, Ted R; Foli, Ernest G; Gillet, Jean-François; Hamilton, Alan C; Harris, David J; Hart, Terese B; de Haulleville, Thales; Hladik, Annette; Hufkens, Koen; Huygens, Dries; Jeanmart, Philippe; Jeffery, Kathryn J; Kearsley, Elizabeth; Leal, Miguel E; Lloyd, Jon; Lovett, Jon C; Makana, Jean-Remy; Malhi, Yadvinder; Marshall, Andrew R; Ojo, Lucas; Peh, Kelvin S-H; Pickavance, Georgia; Poulsen, John R; Reitsma, Jan M; Sheil, Douglas; Simo, Murielle; Steppe, Kathy; Taedoumg, Hermann E; Talbot, Joey; Taplin, James RD; Taylor, David; Thomas, Sean C; Toirambe, Benjamin; Verbeeck, Hans; Vleminckx, Jason; White, Lee JT; Willcock, Simon; Woell, Hannsjorg; Zemagho, LiseWe report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha⁻¹ (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha⁻¹) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha⁻¹ greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationships with C : N ratio (suggesting a positive soil phosphorus-AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes.Item Open Access African forest elephant movements depend on time scale and individual behavior.(Scientific reports, 2021-06-16) Beirne, Christopher; Houslay, Thomas M; Morkel, Peter; Clark, Connie J; Fay, Mike; Okouyi, Joseph; White, Lee JT; Poulsen, John RThe critically endangered African forest elephant (Loxodonta cyclotis) plays a vital role in maintaining the structure and composition of Afrotropical forests, but basic information is lacking regarding the drivers of elephant movement and behavior at landscape scales. We use GPS location data from 96 individuals throughout Gabon to determine how five movement behaviors vary at different scales, how they are influenced by anthropogenic and environmental covariates, and to assess evidence for behavioral syndromes-elephants which share suites of similar movement traits. Elephants show some evidence of behavioral syndromes along an 'idler' to 'explorer' axis-individuals that move more have larger home ranges and engage in more 'exploratory' movements. However, within these groups, forest elephants express remarkable inter-individual variation in movement behaviours. This variation highlights that no two elephants are the same and creates challenges for practitioners aiming to design conservation initiatives.Item Open Access Deadwood stocks increase with selective logging and large tree frequency in Gabon.(Glob Chang Biol, 2017-04) Carlson, Ben S; Koerner, Sally E; Medjibe, Vincent P; White, Lee JT; Poulsen, John RDeadwood is a major component of aboveground biomass (AGB) in tropical forests and is important as habitat and for nutrient cycling and carbon storage. With deforestation and degradation taking place throughout the tropics, improved understanding of the magnitude and spatial variation in deadwood is vital for the development of regional and global carbon budgets. However, this potentially important carbon pool is poorly quantified in Afrotropical forests and the regional drivers of deadwood stocks are unknown. In the first large-scale study of deadwood in Central Africa, we quantified stocks in 47 forest sites across Gabon and evaluated the effects of disturbance (logging), forest structure variables (live AGB, wood density, abundance of large trees), and abiotic variables (temperature, precipitation, seasonality). Average deadwood stocks (measured as necromass, the biomass of deadwood) were 65 Mg ha-1 or 23% of live AGB. Deadwood stocks varied spatially with disturbance and forest structure, but not abiotic variables. Deadwood stocks increased significantly with logging (+38 Mg ha-1 ) and the abundance of large trees (+2.4 Mg ha-1 for every tree >60 cm dbh). Gabon holds 0.74 Pg C, or 21% of total aboveground carbon in deadwood, a threefold increase over previous estimates. Importantly, deadwood densities in Gabon are comparable to those in the Neotropics and respond similarly to logging, but represent a lower proportion of live AGB (median of 18% in Gabon compared to 26% in the Neotropics). In forest carbon accounting, necromass is often assumed to be a constant proportion (9%) of biomass, but in humid tropical forests this ratio varies from 2% in undisturbed forest to 300% in logged forest. Because logging significantly increases the deadwood carbon pool, estimates of tropical forest carbon should at a minimum use different ratios for logged (mean of 30%) and unlogged forests (mean of 18%).Item Open Access Diversity and carbon storage across the tropical forest biome.(Sci Rep, 2017-01-17) Sullivan, Martin JP; Talbot, Joey; Lewis, Simon L; Phillips, Oliver L; Qie, Lan; Begne, Serge K; Chave, Jerôme; Cuni-Sanchez, Aida; Hubau, Wannes; Lopez-Gonzalez, Gabriela; Miles, Lera; Monteagudo-Mendoza, Abel; Sonké, Bonaventure; Sunderland, Terry; Ter Steege, Hans; White, Lee JT; Affum-Baffoe, Kofi; Aiba, Shin-Ichiro; de Almeida, Everton Cristo; de Oliveira, Edmar Almeida; Alvarez-Loayza, Patricia; Dávila, Esteban Álvarez; Andrade, Ana; Aragão, Luiz EOC; Ashton, Peter; Aymard C, Gerardo A; Baker, Timothy R; Balinga, Michael; Banin, Lindsay F; Baraloto, Christopher; Bastin, Jean-Francois; Berry, Nicholas; Bogaert, Jan; Bonal, Damien; Bongers, Frans; Brienen, Roel; Camargo, José Luís C; Cerón, Carlos; Moscoso, Victor Chama; Chezeaux, Eric; Clark, Connie J; Pacheco, Álvaro Cogollo; Comiskey, James A; Valverde, Fernando Cornejo; Coronado, Eurídice N Honorio; Dargie, Greta; Davies, Stuart J; De Canniere, Charles; Djuikouo K, Marie Noel; Doucet, Jean-Louis; Erwin, Terry L; Espejo, Javier Silva; Ewango, Corneille EN; Fauset, Sophie; Feldpausch, Ted R; Herrera, Rafael; Gilpin, Martin; Gloor, Emanuel; Hall, Jefferson S; Harris, David J; Hart, Terese B; Kartawinata, Kuswata; Kho, Lip Khoon; Kitayama, Kanehiro; Laurance, Susan GW; Laurance, William F; Leal, Miguel E; Lovejoy, Thomas; Lovett, Jon C; Lukasu, Faustin Mpanya; Makana, Jean-Remy; Malhi, Yadvinder; Maracahipes, Leandro; Marimon, Beatriz S; Junior, Ben Hur Marimon; Marshall, Andrew R; Morandi, Paulo S; Mukendi, John Tshibamba; Mukinzi, Jaques; Nilus, Reuben; Vargas, Percy Núñez; Camacho, Nadir C Pallqui; Pardo, Guido; Peña-Claros, Marielos; Pétronelli, Pascal; Pickavance, Georgia C; Poulsen, Axel Dalberg; Poulsen, John R; Primack, Richard B; Priyadi, Hari; Quesada, Carlos A; Reitsma, Jan; Réjou-Méchain, Maxime; Restrepo, Zorayda; Rutishauser, Ervan; Salim, Kamariah Abu; Salomão, Rafael P; Samsoedin, Ismayadi; Sheil, Douglas; Sierra, Rodrigo; Silveira, Marcos; Slik, JW Ferry; Steel, Lisa; Taedoumg, Hermann; Tan, Sylvester; Terborgh, John W; Thomas, Sean C; Toledo, Marisol; Umunay, Peter M; Gamarra, Luis Valenzuela; Vieira, Ima Célia Guimarães; Vos, Vincent A; Wang, Ophelia; Willcock, Simon; Zemagho, LiseTropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1 ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1 ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity.Item Open Access Forest elephant movement and habitat use in a tropical forest-grassland mosaic in Gabon.(PloS one, 2018-01) Mills, Emily C; Poulsen, John R; Fay, J Michael; Morkel, Peter; Clark, Connie J; Meier, Amelia; Beirne, Christopher; White, Lee JTPoaching of forest elephants (Loxodonta cyclotis) for ivory has decimated their populations in Central Africa. Studying elephant movement can provide insight into habitat and resource use to reveal where, when, and why they move and guide conservation efforts. We fitted 17 forest elephants with global positioning system (GPS) collars in 2015 and 2016 in the tropical forest-grassland mosaic of the Wonga Wongué Presidential Reserve (WW), Gabon. Using the location data, we quantified movement distances, home ranges, and habitat use to examine the environmental drivers of elephant movements and predict where elephants occur spatially and temporally. Forest elephants, on average, traveled 2,840 km annually and had home ranges of 713 km2, with males covering significantly larger home ranges than females. Forest elephants demonstrated both daily and seasonal movement patterns. Daily, they moved between forest and grassland at dawn and dusk. Seasonally, they spent proportionally more time in grassland than forest during the short-wet season when grasses recruit. Forest elephants also traveled faster during the short-wet season when fruit availability was greatest, likely reflecting long, direct movements to preferred fruiting tree species. Forest elephants tended to select areas with high tree and shrub density that afford cover and browse. When villages occurred in their home ranges elephants spent a disproportionate amount of time near them, particularly in the dry season, probably for access to agricultural crops and preferred habitat. Given the importance of the grassland habitat for elephants, maintenance of the forest-grassland matrix is a conservation priority in WW. Law enforcement, outreach, and education should focus on areas of potential human-elephant conflict near villages along the borders of the reserve. GPS-tracking should be extended into multi-use areas in the peripheries of protected areas to evaluate the effects of human disturbance on elephant movements and to maintain connectivity among elephant populations in Gabon.Item Open Access Long-term thermal sensitivity of Earth's tropical forests.(Science (New York, N.Y.), 2020-05-21) Sullivan, Martin JP; Lewis, Simon L; Affum-Baffoe, Kofi; Castilho, Carolina; Costa, Flávia; Sanchez, Aida Cuni; Ewango, Corneille EN; Hubau, Wannes; Marimon, Beatriz; Monteagudo-Mendoza, Abel; Qie, Lan; Sonké, Bonaventure; Martinez, Rodolfo Vasquez; Baker, Timothy R; Brienen, Roel JW; Feldpausch, Ted R; Galbraith, David; Gloor, Manuel; Malhi, Yadvinder; Aiba, Shin-Ichiro; Alexiades, Miguel N; Almeida, Everton C; de Oliveira, Edmar Almeida; Dávila, Esteban Álvarez; Loayza, Patricia Alvarez; Andrade, Ana; Vieira, Simone Aparecida; Aragão, Luiz EOC; Araujo-Murakami, Alejandro; Arets, Eric JMM; Arroyo, Luzmila; Ashton, Peter; Aymard C, Gerardo; Baccaro, Fabrício B; Banin, Lindsay F; Baraloto, Christopher; Camargo, Plínio Barbosa; Barlow, Jos; Barroso, Jorcely; Bastin, Jean-François; 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, José Luís; Castro, Wendeson; Céron, Carlos; Ribeiro, Sabina Cerruto; Moscoso, Victor Chama; Chave, Jerôme; Chezeaux, Eric; Clark, Connie J; de Souza, Fernanda Coelho; Collins, Murray; Comiskey, James A; Valverde, Fernando Cornejo; Medina, Massiel Corrales; da Costa, Lola; Dančák, Martin; Dargie, Greta C; Davies, Stuart; Cardozo, Nallaret Davila; de Haulleville, Thales; de Medeiros, Marcelo Brilhante; Del Aguila Pasquel, Jhon; Derroire, Géraldine; Di Fiore, Anthony; Doucet, Jean-Louis; Dourdain, Aurélie; Droissart, Vincent; Duque, Luisa Fernanda; Ekoungoulou, Romeo; Elias, Fernando; Erwin, Terry; Esquivel-Muelbert, Adriane; Fauset, Sophie; Ferreira, Joice; Llampazo, Gerardo Flores; Foli, Ernest; Ford, Andrew; Gilpin, Martin; Hall, Jefferson S; Hamer, Keith C; Hamilton, Alan C; Harris, David J; Hart, Terese B; Hédl, Radim; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Hladik, Annette; Coronado, Eurídice Honorio; Huamantupa-Chuquimaco, Isau; Huasco, Walter Huaraca; Jeffery, Kathryn J; Jimenez-Rojas, Eliana; Kalamandeen, Michelle; Djuikouo, Marie Noël Kamdem; Kearsley, Elizabeth; Umetsu, Ricardo Keichi; Kho, Lip Khoon; Killeen, Timothy; Kitayama, Kanehiro; Klitgaard, Bente; Koch, Alexander; Labrière, Nicolas; Laurance, William; Laurance, Susan; Leal, Miguel E; Levesley, Aurora; Lima, Adriano JN; Lisingo, Janvier; Lopes, Aline P; Lopez-Gonzalez, Gabriela; Lovejoy, Tom; Lovett, Jon C; Lowe, Richard; Magnusson, William E; Malumbres-Olarte, Jagoba; Manzatto, Ângelo Gilberto; Marimon, Ben Hur; Marshall, Andrew R; Marthews, Toby; de Almeida Reis, Simone Matias; Maycock, Colin; Melgaço, Karina; Mendoza, Casimiro; Metali, Faizah; Mihindou, Vianet; Milliken, William; Mitchard, Edward TA; Morandi, Paulo S; Mossman, Hannah L; Nagy, Laszlo; Nascimento, Henrique; Neill, David; Nilus, Reuben; Vargas, Percy Núñez; Palacios, Walter; Camacho, Nadir Pallqui; Peacock, Julie; Pendry, Colin; Peñuela 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; Ramírez-Angulo, Hirma; Reitsma, Jan; Réjou-Méchain, Maxime; Correa, Zorayda Restrepo; de Sousa, Thaiane Rodrigues; Bayona, Lily Rodriguez; Roopsind, Anand; Rudas, Agustín; Rutishauser, Ervan; Abu Salim, Kamariah; Salomão, Rafael P; Schietti, Juliana; Sheil, Douglas; Silva, Richarlly C; Espejo, Javier Silva; 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; Svátek, 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; Gamarra, Luis Valenzuela; van der Heijden, Geertje; van der Hout, Peter; van der Meer, Peter; van Nieuwstadt, Mark; Verbeeck, Hans; Vernimmen, Ronald; Vicentini, Alberto; Vieira, Ima Célia Guimarães; Torre, Emilio Vilanova; Vleminckx, Jason; Vos, Vincent; Wang, Ophelia; White, Lee JT; Willcock, Simon; Woods, John T; Wortel, Verginia; Young, Kenneth; Zagt, Roderick; Zemagho, Lise; Zuidema, Pieter A; Zwerts, Joeri A; Phillips, Oliver LThe 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 °C in the hottest forests (>32.2°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.Item Open Access Poaching empties critical Central African wilderness of forest elephants.(Curr Biol, 2017-02-20) Poulsen, John R; Koerner, Sally E; Moore, Sarah; Medjibe, Vincent P; Blake, Stephen; Clark, Connie J; Akou, Mark Ella; Fay, Michael; Meier, Amelia; Okouyi, Joseph; Rosin, Cooper; White, Lee JTElephant populations are in peril everywhere, but forest elephants in Central Africa have sustained alarming losses in the last decade [1]. Large, remote protected areas are thought to best safeguard forest elephants by supporting large populations buffered from habitat fragmentation, edge effects and human pressures. One such area, the Minkébé National Park (MNP), Gabon, was created chiefly for its reputation of harboring a large elephant population. MNP held the highest densities of elephants in Central Africa at the turn of the century, and was considered a critical sanctuary for forest elephants because of its relatively large size and isolation. We assessed population change in the park and its surroundings between 2004 and 2014. Using two independent modeling approaches, we estimated a 78-81% decline in elephant numbers over ten years - a loss of more than 25,000 elephants. While poaching occurs from within Gabon, cross-border poaching largely drove the precipitous drop in elephant numbers. With nearly 50% of forest elephants in Central Africa thought to reside in Gabon [1], their loss from the park is a considerable setback for the preservation of the species.Item Open Access Resistance of African tropical forests to an extreme climate anomaly.(Proceedings of the National Academy of Sciences of the United States of America, 2021-05) Bennett, Amy C; Dargie, Greta C; Cuni-Sanchez, Aida; Tshibamba Mukendi, John; Hubau, Wannes; Mukinzi, Jacques M; Phillips, Oliver L; Malhi, Yadvinder; Sullivan, Martin JP; Cooper, Declan LM; Adu-Bredu, Stephen; Affum-Baffoe, Kofi; Amani, Christian A; Banin, Lindsay F; Beeckman, Hans; Begne, Serge K; Bocko, Yannick E; Boeckx, Pascal; Bogaert, Jan; Brncic, Terry; Chezeaux, Eric; Clark, Connie J; Daniels, Armandu K; de Haulleville, Thales; Djuikouo Kamdem, Marie-Noël; Doucet, Jean-Louis; Evouna Ondo, Fidèle; Ewango, Corneille EN; Feldpausch, Ted R; Foli, Ernest G; Gonmadje, Christelle; Hall, Jefferson S; Hardy, Olivier J; Harris, David J; Ifo, Suspense A; Jeffery, Kathryn J; Kearsley, Elizabeth; Leal, Miguel; Levesley, Aurora; Makana, Jean-Remy; Mbayu Lukasu, Faustin; Medjibe, Vincent P; Mihindu, Vianet; Moore, Sam; Nssi Begone, Natacha; Pickavance, Georgia C; Poulsen, John R; Reitsma, Jan; Sonké, Bonaventure; Sunderland, Terry CH; Taedoumg, Hermann; Talbot, Joey; Tuagben, Darlington S; Umunay, Peter M; Verbeeck, Hans; Vleminckx, Jason; White, Lee JT; Woell, Hannsjoerg; Woods, John T; Zemagho, Lise; Lewis, Simon LThe responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015-2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species. Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015-2016 El Niño event. These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha-1 y-1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.