Philip M. Fearnside
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Featured researches published by Philip M. Fearnside.
Global Change Biology | 2014
Jérôme Chave; Maxime Réjou-Méchain; Alberto Búrquez; Emmanuel Chidumayo; Matthew S. Colgan; Welington Braz Carvalho Delitti; Alvaro Duque; Tron Eid; Philip M. Fearnside; Rosa C. Goodman; Matieu Henry; Wilson A Mugasha; Helene C. Muller-Landau; Maurizio Mencuccini; Bruce Walker Nelson; Alfred Ngomanda; Euler Melo Nogueira; Edgar Ortiz-Malavassi; Raphaël Pélissier; Pierre Ploton; Casey M. Ryan; Juan Saldarriaga; Ghislain Vieilledent
Terrestrial carbon stock mapping is important for the successful implementation of climate change mitigation policies. Its accuracy depends on the availability of reliable allometric models to infer oven-dry aboveground biomass of trees from census data. The degree of uncertainty associated with previously published pantropical aboveground biomass allometries is large. We analyzed a global database of directly harvested trees at 58 sites, spanning a wide range of climatic conditions and vegetation types (4004 trees ≥ 5 cm trunk diameter). When trunk diameter, total tree height, and wood specific gravity were included in the aboveground biomass model as covariates, a single model was found to hold across tropical vegetation types, with no detectable effect of region or environmental factors. The mean percent bias and variance of this model was only slightly higher than that of locally fitted models. Wood specific gravity was an important predictor of aboveground biomass, especially when including a much broader range of vegetation types than previous studies. The generic tree diameter-height relationship depended linearly on a bioclimatic stress variable E, which compounds indices of temperature variability, precipitation variability, and drought intensity. For cases in which total tree height is unavailable for aboveground biomass estimation, a pantropical model incorporating wood density, trunk diameter, and the variable E outperformed previously published models without height. However, to minimize bias, the development of locally derived diameter-height relationships is advised whenever possible. Both new allometric models should contribute to improve the accuracy of biomass assessment protocols in tropical vegetation types, and to advancing our understanding of architectural and evolutionary constraints on woody plant development.
Environmental Conservation | 2001
Philip M. Fearnside
Summary Soybeans represent a recent and powerful threat to tropical biodiversity in Brazil. Developing effective strategies to contain and minimize the environmental impact of soybean cultivation requires understanding of both the forces that drive the soybean advance and the many ways that soybeans and their associated infrastructure catalyse destructive processes. The present paper presents an up-to-date review of the advance of soybeans in Brazil, its environmental and social costs and implications for development policy. Soybeans are driven by global market forces, making them different from many of the land-use changes that have dominated the scene in Brazil so far, particularly in Amazonia. Soybeans are much more damaging than other crops because they justify massive transportation infrastructure projects that unleash a chain of events leading to destruction of natural habitats over wide areas in addition to what is directly cultivated for soybeans. The capacity of global markets to absorb additional production represents the most likely limit to the spread of soybeans, although Brazil may someday come to see the need for discouraging rather than subsidizing this crop because many of its effects are unfavourable to national interests, including severe concentration of land tenure and income, expulsion of population to Amazonian frontier, and gold-mining, as well as urban areas, and the opportunity cost of substantial drains on government resources. The multiple impacts of soybean expansion on biodiversity and other development considerations have several implications for policy: (1) protected areas need to be created in advance of soybean frontiers, (2) elimination of the many subsidies that speed soybean expansion beyond what would occur otherwise from market forces is to be encouraged, (3) studies to assess the costs of social and environmental impacts associated with soybean expansion are urgently required, and (4) the environmental-impact regulatory system requires strengthening, including mechanisms for commitments not to implant specific infrastructure projects that are judged to have excessive impacts.
Science | 2008
G. Philip Robertson; Virginia H. Dale; Otto C. Doering; Steven P. Hamburg; Jerry M. Melillo; Michele M. Wander; William J. Parton; Paul R. Adler; Jacob N. Barney; Richard M. Cruse; Clifford S. Duke; Philip M. Fearnside; R. F. Follett; Holly K. Gibbs; José Goldemberg; David J. Mladenoff; Dennis Ojima; Michael W. Palmer; Andrew N. Sharpley; Linda L. Wallace; Kathleen C. Weathers; John A. Wiens; Wallace Wilhelm
Science-based policy is essential for guiding an environmentally sustainable approach to cellulosic biofuels.
Ecology | 2001
William F. Laurance; Diego R. Pérez-Salicrup; Patricia Delamônica; Philip M. Fearnside; Sammya D'Angelo; Adriano Jerozolinski; Luciano Pohl; Thomas E. Lovejoy
In tropical forests, lianas (woody vines) are important structural parasites of trees. We assessed the effects of forest fragmentation, treefall disturbance, soils, and stand attributes on liana communities in central Amazonian rain forests. Over 27 500 liana stems (≥2 cm diameter at breast height [dbh]) were recorded in 27 1-ha plots in continuous forest and 42 plots in 10 forest fragments ranging from 1 to 100 ha in area. For each plot, an index of forest disturbance was determined from a 20-yr study of tree-community dynamics, and 19 soil-texture and chemistry parameters were derived from soil surface samples (top 20 cm). Liana abundance was 187–701 stems/ha, and liana aboveground dry biomass varied from 3.7 to 12.3 Mg/ha. Liana abundance increased significantly near forest edges and was significantly positively associated with forest disturbance and significantly negatively associated with tree biomass. Liana biomass was similarly associated with disturbance and tree biomass but also increased signifi...
Forest Ecology and Management | 1999
William F. Laurance; Philip M. Fearnside; Susan G. Laurance; Patricia Delamônica; Thomas E. Lovejoy; Judy M. Rankin-de Merona; Jeffrey Q. Chambers; Claude Gascon
Above-ground dry biomass of living trees including palms was estimated in 65 1 ha plots spanning a 1000 km 2 landscape in central Amazonia. The study area was located on heavily weathered, nutrient-poor soils that are widespread in the Amazon region. Biomass values were derived by measuring the diameter-at-breast-height (DBH) of all10 cm trees in each plot, then using an allometric equation and correction factor for small trees to estimate total tree biomass. Detailed information on soil texture, organic carbon, available water capacity, pH, macro- and micro-nutrients, and trace elements was collected from soil surface samples (0‐20 cm) in each plot, while slope was measured with a clinometer. Biomass estimates varied more than two-fold, from 231 to 492 metric tons ha ˇ1 , with a mean of 356 47 tons ha ˇ1 . Simple correlations with stringent (p < 0.006) Bonferroni corrections suggested that biomass was positively associated with total N, total exchangeable bases, K a ,M g 2a , clay, and organic C in soils, and negatively associated with Zn a , aluminum saturation, and sand. An ordination analysis revealed one major and several minor soil gradients in the study area, with the main gradient discriminating sites with varying proportions of clay (with clayey soils having higher concentrations of total N, organic C, most cations, and lower aluminum saturation and less sand). A multiple regression analysis revealed that the major clay-nutrient gradient was the only significant predictor, with the model explaining 32.3% of the total variation in biomass. Results of the analysis suggest that soil-fertility parameters can account for a third or more of the variation in above-ground biomass in Amazonian terra-firme forests. We suggest that, because the conversion of forest to pasture tends to reduce the nitrogen, clay, organic carbon, and nutrient contents of soils, forests that regenerate on formerly cleared lands may have lower biomass than the original forest, especially in areas with low soil fertility. # 1999 Elsevier Science B.V. All rights reserved.
Ecology | 2006
William F. Laurance; Henrique E. M. Nascimento; Susan G. Laurance; Ana Andrade; Philip M. Fearnside; Jose E. L. S. Ribeiro; Robson L. Capretz
The effects of habitat fragmentation on diverse tropical tree communities are poorly understood. Over a 20-year period we monitored the density of 52 tree species in nine predominantly successional genera (Annona, Bellucia, Cecropia, Croton, Goupia, Jacaranda, Miconia, Pourouma, Vismia) in fragmented and continuous Amazonian forests. We also evaluated the relative importance of soil, topographic, forest dynamic, and landscape variables in explaining the abundance and species composition of successional trees. Data were collected within 66 permanent 1-ha plots within a large (approximately 1000 km2) experimental landscape, with forest fragments ranging from 1 to 100 ha in area. Prior to forest fragmentation, successional trees were uncommon, typically comprising 2-3% of all trees (> or =10 cm diameter at breast height [1.3 m above the ground surface]) in each plot. Following fragmentation, the density and basal area of successional trees increased rapidly. By 13-17 years after fragmentation, successional trees had tripled in abundance in fragment and edge plots and constituted more than a quarter of all trees in some plots. Fragment age had strong, positive effects on the density and basal area of successional trees, with no indication of a plateau in these variables, suggesting that successional species could become even more abundant in fragments over time. Nonetheless, the 52 species differed greatly in their responses to fragmentation and forest edges. Some disturbance-favoring pioneers (e.g., Cecropia sciadophylla, Vismia guianensis, V. amazonica, V. bemerguii, Miconia cf. crassinervia) increased by >1000% in density on edge plots, whereas over a third (19 of 52) of all species remained constant or declined in numbers. Species responses to fragmentation were effectively predicted by their median growth rate in nearby intact forest, suggesting that faster-growing species have a strong advantage in forest fragments. An ordination analysis revealed three main gradients in successional-species composition across our study area. Species gradients were most strongly influenced by the standlevel rate of tree mortality on each plot and by the number of nearby forest edges. Species-composition also varied significantly among different cattle ranches, which differed in their surrounding matrices and disturbance histories. These same variables were also the best predictors of total successional-tree abundance and species richness. Successional-tree assemblages in fragment interior plots (>150 m from edge), which are subjected to fragment area effects but not edge effects, did not differ significantly from those in intact forest, indicating that area effects per se had little influence on successional trees. Soils and topography also had little discernable effect on these species. Collectively, our results indicate that successional-tree species proliferate rapidly in fragmented Amazonian forests, largely as a result of chronically elevated tree mortality near forest edges and possibly an increased seed rain from successional plants growing in nearby degraded habitats. The proliferation of fast-growing successional trees and correlated decline of old-growth trees will have important effects on species composition, forest dynamics, carbon storage, and nutrient cycling in fragmented forests.
Climatic Change | 1997
Philip M. Fearnside
Deforestation in Brazilian Amazonia is a significant source of greenhouse gases today and, with almost 90% of the originally forested area still uncleared, is a very large potential source of future emissions. The 1990 rate of loss of forest (13.8 × 103 km2/year) and cerrado savanna (approximately 5 × 103 km2/year) was responsible for releasing approximately 261 × 106 metric tons of carbon (106 t C) in the form of CO2, or 274–285 × 106 t of CO2-equivalent C considering IPCC 1994 global warming potentials for trace gases over a 100-year horizon. These calculations consider conversion to a landscape of agriculture, productive pasture, degraded pasture, secondary forest, and regenerated forest in the proportions corresponding to the equilibrium condition implied by current land-use patterns. Emissions are expressed as ‘net committed emissions’, or the gases released over a period of years as the carbon stock in each hectare deforested approaches a new equilibrium in the landscape that replaces the original forest. For low and high trace gas scenarios, respectively, 1990 clearing produced net committed emissions (in 106 t of gas) of 957–958 for CO2, 1.10–1.42 for CH4, 28–35 for CO, 0.06–0.16 for N2O, 0.74–0.74 for NOx and 0.58–1.16 for non-methane hydrocarbons.
Forest Ecology and Management | 1997
Philip M. Fearnside
Abstract Reliable estimates of the biomass of Amazonian forests are needed for calculations of greenhouse gas emissions from deforestation. Interpretation of forest volume data for the region is the most practical means of obtaining representative biomass estimates. The density of the wood used in converting volume data to biomass is a key factor affecting estimates of biomass and of emissions. Interpreting density data for biomass purposes, which is different from the normal use of these data for commercial timber uses, is complicated by a variety of factors. There is variability among individuals of a given species, among geographic locations, and within the vertical and radial dimensions of individual trees. Considerable confusion has resulted from the variety of ways that densities are reported with respect to humidity at time of the weight and volume measurements used in calculating the density value. The most appropriate measure for biomass is basic density, or oven-dry weight divided by wet volume. Corrections for hollow trees and the position of samples within trunks are also needed. Here, available data are brought together for 268 species of trees, with an unweighted mean basic density of 0.65 (range 0.14–1.21). Weighting the mean by the volume of wood of each species in a sample of vegetation types, and weighting the means of the vegetation types by the extent of each in the region, yields a mean density of 0.69. Although the weighted mean density calculated here has a much firmer empirical basis than previously available estimates for this parameter, uncertainty is still considerable, particularly as a result of doubt concerning taxonomic identifications in the forestry surveys. Were the wood density of a small but botanically well-studied plot near Manaus to apply to the region as a whole, Brazils 1990 emissions of greenhouse gases would be higher by an amount equivalent to two-thirds of the countrys annual emission from fossil fuels.
World Development | 2001
Philip M. Fearnside
Abstract Land-tenure issues have been prominent forces driving deforestation and the spread of extensive ranching as the dominant land use in Brazilian Amazonia. Southern Para is the part of Amazonia where these issues are most explosive, and an examination of this region in terms of its land-tenure issues, their environmental consequences and measures needed provides potentially valuable information for formulating policies that promote more socially and environmentally sound development. The problems of southern Para are likely to spread to increasingly broader sections of Amazonia. The present paper reviews the current land-tenure situation in southern Para and attempts to identify policy changes that would reduce its environmental impact.
Forest Ecology and Management | 1996
Philip M. Fearnside; Walba Malheiros Guimarães
Abstract Estimating the contribution of deforestation to greenhouse gas emissions requires calculations of the uptake of carbon by the vegetation that replaces the forest, as well as the emissions from burning and decay of forest biomass and from altered emissions and uptakes by the soil. The role of regeneration in offsetting emissions from deforestation in the Brazilian Legal Amazon has sometimes been exaggerated. Unlike many other tropical areas, cattle pasture (rather than shifting cultivation) usually replaces forest in Brazilian Amazonia. Degraded cattle pastures regenerate secondary forests more slowly than do fallows in shifting cultivation systems, leading to lower uptake of carbon. The calculations presented here indicate that in 1990 the 410 x 103 km2 deforested landscape was taking up 29 x 106 t of carbon (C) annually (0.7 t C ha-1 year-1). This does not include the emissions from clearing of secondary forests, which in 1990 released an estimated 27 x 106 t C, almost completely offsetting the uptake from the landscape. Were the present land-use change processes to continue, carbon uptake would rise to 365 x 106 t annually (0.9 t C ha-1 year-1) in 2090 in the 3.9 x 106 km6 area that would have been deforested by that year. The 1990 rate of emissions from deforestation in the region greatly exceeded the uptake from regrowth of replacement vegetation.