I compared the efficacy of terrestrial, arboreal, carnivore, and pitfall trapping methods for censusing small (200 animals per 1000 trap-nights), whereas carnivore (83.7 animals per 1000 trap-nights) and pitfall (9.1 animals per 1000 trap-nights) traps were less effective. However, each method was particularly effective for 1-4 species, with factors such as diet, vertical microhabitat use, body size and trap avoidance strongly influencing trappability of different species. Strategies for censusing small mammals in tropical rainforest are discussed.
Automatic cameras triggered by infrared beams were used to identify animals visiting artificial groundnests in north Queensland rainforest. In 1992-93 six cameras and nests were established at four sites ranging from 340 to 840m in elevation, and a total of 279 identifiable photographs of nest visitors were recorded. White-tailed rats (Uromys caudimaculatus) comprised 74% of all photographs and were the most frequent visitor at five of six nests. Bush rats (Rattus fuscipes) were second in frequency (17%), with other small mammals (Rattus leucopus, Melomys cervinipes, Perameles nasuta), birds (Ailuroedus melanotis, Pitta versicolor) and reptiles (Varanus varius) each accounting for less than 2% of nest visits. Omnivorous rodents comprised the large majority (96%) of visits and may be significant predators on nests of some ground-nesting birds in Australian tropical rainforest.
Predation on artificial avian ground-nests was assessed from March to December 1991 in rainforest and nearby modified habitats in tropical Queensland. Data from 610 experimental nests were used to determine relative predation intensity in five types of habitat or microhabitat. Nest predators were identified with live-traps, with baited grease-plates and by regular observations of 380 additional nests. Predation intensity was patchy but often heavy in forested habitats (rainforest interiors, secondary forest, rainforest-pasture edges, and a rainforest-secondary forest edge) and negligible in adjoining cattle pastures. Forest edges exhibited no obvious edge-interior gradients in predation intensity. Most predation occurred at night in rainforest (88%) and secondary forest (61%), and patterns of egg damage suggested that mammals were responsible for most (>71%) nest predation. A combined nest-predation and live-trapping experiment on six study plots revealed that the abundance of white-tailed rats (Uromys caudimaculatus) was a highly effective predictor of local predation intensity (F=30.15, r*2=0.85, P=0.004). One of Australia's largest rodents, the white-tailed rat may be a key opportunistic predator of some bird nests in north Queensland rainforest.
The Cross River State Government in Nigeria is proposing to construct a ''Cross River Superhighway'' that would bisect critical remaining areas of tropical rainforest in south eastern Nigeria. We offer and evaluate two alternative routes to the superhighway that would be less damaging to forests, protected areas, and biological diversity. The first alternative we identified avoids intact forests entirely while seeking to benefit agriculture and existing settlements. The second alternative also avoids intact forests while incorporating existing paved and unpaved roads to limit construction costs. As currently proposed, the superhighway would be 260 km long, would intersect 115 km of intact forests or protected areas, and would cost an estimated ~US$2.5 billion to construct. Alternative Routes 1 and 2 are only slightly longer (~290 and ~353 km, respectively) and have markedly lower estimated construction costs (~US$0.92 billion). Furthermore, the alternative routes would have negligible impacts on forests and protected areas and would be better aligned to benefit local communities and agriculture. We argue that alternative routings such as those we examined here could markedly reduce the economic and environmental costs, and potentially increase the socioeconomic benefits, for the proposed Cross River Superhighway.
This is the final version. Available on open access from Wiley via the DOI in this record ; Competition among trees is an important driver of community structure and dynamics in tropical forests. Neighboring trees may impact an individual tree's growth rate and probability of mortality, but large-scale geographic and environmental variation in these competitive effects has yet to be evaluated across the tropical forest biome. We quantified effects of competition on tree-level basal area growth and mortality for trees ≥ 10 cm diameter across 151 ~1-ha plots in mature tropical forests in Amazonia and tropical Africa by developing non-linear models that accounted for wood density, tree size and neighborhood crowding. Using these models, we assessed how water availability (i.e., climatic water deficit) and soil fertility influenced the predicted plot-level strength of competition (i.e., the extent to which growth is reduced, or mortality is increased, by competition across all individual trees). On both continents, tree basal area growth decreased with wood density, and increased with tree size. Growth decreased with neighborhood crowding, which suggests that competition is important. Tree mortality decreased with wood density and generally increased with tree size, but was apparently unaffected by neighborhood crowding. Across plots, variation in the plot-level strength of competition was most strongly related to plot basal area (i.e., the sum of the basal area of all trees in a plot), with greater reductions in growth occurring in forests with high basal area, but in Amazonia the strength of competition also varied with plot-level wood density. In Amazonia, the strength of competition increased with water availability because of the greater basal area of wetter forests, but was only weakly related to soil fertility. In Africa, competition was weakly related to soil fertility, and invariant across the shorter water availability gradient. Overall, our results suggest that competition influences the structure and dynamics of tropical forests primarily through effects on individual tree growth rather than mortality, and that the strength of competition largely depends on environment-mediated variation in basal area. ; Gordon and Betty Moore Foundation ; European Union FP7 ; European Research Council (ERC) ; Natural Environment Research Council (NERC) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil (CNPq) ; Microsoft Research ; University of Regina ; Royal Society
This is the final version of the article. Available from Wiley via the DOI in this record. ; Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs. ; This paper is a product of the European Union's Seventh Framework Programme AMAZALERT project (282664). The field data used in this study have been generated by the RAINFOR network, which has been supported by a Gordon and Betty Moore Foundation grant, the European Union's Seventh Framework Programme projects 283080, 'GEOCARBON'; and 282664, 'AMAZALERT'; ERC grant 'Tropical Forests in the Changing Earth System'), and Natural Environment Research Council (NERC) Urgency, Consortium and Standard Grants 'AMAZONICA' (NE/F005806/1), 'TROBIT' (NE/D005590/1) and 'Niche Evolution of South American Trees' (NE/I028122/1). Additional data were included from the Tropical Ecology Assessment and Monitoring (TEAM) Network – a collaboration between Conservation International, the Missouri Botanical Garden, the Smithsonian Institution and the Wildlife Conservation Society, and partly funded by these institutions, the Gordon and Betty Moore Foundation, and other donors. Fieldwork was also partially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil (CNPq), project Programa de Pesquisas Ecológicas de Longa Duração (PELD-403725/2012-7). A.R. acknowledges funding from the Helmholtz Alliance 'Remote Sensing and Earth System Dynamics'; L.P., M.P.C. E.A. and M.T. are partially funded by the EU FP7 project 'ROBIN' (283093), with co-funding for E.A. from the Dutch Ministry of Economic Affairs (KB-14-003-030); B.C. [was supported in part by the US DOE (BER) NGEE-Tropics project (subcontract to LANL). O.L.P. is supported by an ERC Advanced Grant and is a Royal Society-Wolfson Research Merit Award holder. P.M. acknowledges support from ARC grant FT110100457 and NERC grants NE/J011002/1, and T.R.B. acknowledges support from a Leverhulme Trust Research Fellowship.
Aim: The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset. Location: Tropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: http://dx.doi.org/10.5521/FORESTPLOTS.NET/2014_1 Methods: Two recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons. Results: The two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by >???25%, whereas regional uncertainties for the maps were reported to be ??5%. Main conclusions: Pantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space.
Tropical 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. ; This paper is a product of the RAINFOR, AfriTRON and T-FORCES networks, for which we are hugely indebted to hundreds of institutions, field assistants and local communities across many countries that have hosted fieldwork. The three networks have been supported by a European Research Council (ERC) grant ("T-FORCES" - Tropical Forests in the Changing Earth System), the Gordon and Betty Moore Foundation, the David and Lucile Packard Foundation, the European Union's Seventh Framework Programme (283080, 'GEOCARBON'; 282664, 'AMAZALERT'), and Natural Environment Research Council (NERC) Urgency Grants and NERC Consortium Grants 'AMAZONICA' (NE/F005806/1) and 'TROBIT' (NE/D005590/1), 'BIO-RED' (NE/N012542/1) and a NERC New Investigators Grant, the Royal Society, the Centre for International Forestry (CIFOR) and Gabon's National Parks Agency (ANPN). Additional data were included from the Tropical Ecology Assessment and Monitoring (TEAM) Network, a collaboration between Conservation International, the Missouri Botanical Garden, the Smithsonian Institution and the Wildlife Conservation Society, and partly funded by these institutions, the Gordon and Betty Moore Foundation, and other donors. J.T. was supported by a NERC PhD Studentship with CASE sponsorship from UNEP-WCMC. R.J.W.B. is funded by a NERC research fellowship (grant ref: NE/I021160/1). S.L.L. was supported by a Royal Society University Research Fellowship, ERC Advanced Grant (T-FORCES) and a Phillip Leverhulme Prize. O.L.P. is supported by an ERC Advanced Grant (T-FORCES) and a Royal Society Wolfson Research Merit Award. L.F.B. was supported by a NERC studentship and RGS-IBG Henrietta Hutton Grant. We thank the National Council for Science and Technology Development of Brazil (CNPq) for support to Project Cerrado/Amazonia Transition (PELD/403725/2012-7), Project Phytogeography of Amazonia/Cerrado Transition (CNPq/PPBio/457602/2012-0) and Productivity Grant to B.S.M and B.H.M-J. Funding for plots in the Udzungwa Mountains (Tanzania) was obtained from the Leverhulme Trust under the Valuing the Arc project. We thank the ANPN (Gabon), WCS-Congo and WCS-DR Congo, Marien Ngouabi University and the University of Kisangani for logistical support in Africa, and the Tropenbos Kalimantan project (ITCI plots) and WWF (KUB plots) for providing data from Asia. This study is contribution number 706 to the Technical Series (TS) of the BDFFP – (INPA-STRI). For assistance with access to datasets we thank Adriana Prieto, Agustín Rudas, Alejandro Araujo-Murakami, Alexander G. Parada Gutierrez, Anand Roopsind, Atila Alves de Oliveira, Claudinei Oliveira dos Santos, C. E. Timothy Paine, David Neill, Eliana Jimenez-Rojas, Freddy Ramirez Arevalo, Hannsjoerg Woell, Iêda Leão do Amaral, Irina Mendoza Polo, Isau Huamantupa-Chuquimaco, Julien Engel, Kathryn Jeffery, Luzmila Arroyo, Michael D. Swaine, Nallaret Davila Cardozo, Natalino Silva, Nigel C. A. Pitman, Niro Higuchi, Raquel Thomas, Renske van Ek, Richard Condit, Rodolfo Vasquez Martinez, Timothy J. Killeen, Walter A. Palacios, Wendeson Castro. We thank Georgina Mace and Jon Lloyd for comments on the manuscript. We thank our deceased colleagues, Samuel Almeida, Kwaku Duah, Alwyn Gentry, and Sandra Patiño, for their invaluable contributions to this work and our wider understanding of tropical forest ecology.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1714977115/-/DCSupplemental. ; Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests. ; European Union's Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie Grant Agreement 660020, Instituto Bem Ambiental (IBAM), Myr Projetos Sustentáveis, IEF, and CNPq, CAPES FAPEMIG, German Research Foundation (DFG; Grants CRC 552, CU127/3-1, HO 3296/2-2, HO3296/4-1, and RU 816), UNAM-PAPIIT IN218416 and Semarnat-CONACYT 128136, Conselho Nacional de Desenvolvimento Científico e Tecnoloógico (CNPq, Brazil), Fundação Grupo Boticário de Proteção à Natureza/Brazil, PAPIIT-DGAPA-UNAM (Project IN-204215), National Geographic Society, National Foundation for Scientific and Technology Development Vietnam (Grant 106.11-2010.68), Operation Wallacea, and core funding for Crown Research Institutes from the New Zealand Ministry of Business, Innovation and Employment's Science and Innovation Group. ; Peer-reviewed ; Publisher Version