Relationship between soils and Amazon forest biomass: a landscape-scale study

Laurance, William F.; Fearnside, Philip M.; Laurance, Susan G.; Delamônica, Patricia; Lovejoy, Thomas Ε.; Merona, Judy M. Rankin-de; Chambers, Jeffrey Q.; Gascon, Claude

doi:10.1016/s0378-1127(98)00494-0

Cited by 384 publications

(343 citation statements)

References 45 publications

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“…With regard to soil nutrients, at the basin scale, analyses indicate that forest composition, structure, biomass, and dynamics also vary across a gradient in soil fertility (16,17), with the younger, more fertile soils of western Amazonia supporting forests with lower AGB and higher rates of biomass productivity and stem turnover relative to the forests of the central Amazon and Guianan Shield, which are located on older, more nutrient-poor soils. Meanwhile, landscape-scale studies in central (29) and northwestern (30) Amazonia have found that more fertile clay soils have higher AGB than nutrient-poor sandy soils. Further discussion of the impact of soil nutrients can be found in SI Appendix, section S2).…”

Section: Significancementioning

confidence: 99%

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

Levine

Zhang

Longo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

188

179

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Amazon forests, which store ∼50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale dieback of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size-and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem's resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest's response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions.Amazon forests | biomass | ecological resilience | climate change | ecosystem heterogeneity A mazonia consists of 815 million ha of rainforest, transitional forest, and tropical savannahs; stores approximately half of tropical forest carbon (1); and plays a vital role in global water, energy, and carbon cycling (2). Although uncertainties in climate predictions for the region remain large (3), recent analyses imply that significant portions of the basin will experience both longer and more intense dry seasons by the end of the 21st century (3-6). There is particular concern about southern Amazonian forests that experience longer dry seasons than forests in central and western Amazonia (3) and where a trend of increasing dry season length (DSL) and intensity has already been observed (7). Despite the importance of this region for regional and global climate, the climate sensitivity of the Amazon forests remains uncertain: model predictions range from a large-scale die-back of the Amazon (8, 9) to predictions that the biome will remain largely intact, and may even increase in biomass (10-12). Although some of these differences can be attributed to differences in the predicted future climate forcing of the region (13, 14), accurate predictions of how changes in climate will affect Amazonian forests also rely on an accurate characterization of how the ecosystem is affected by a given change in climate forcing. In this study, we examine the climate sensitivity of the Amazon ecosystem, focusing on the mechanisms underpinning changes in forest dynamics and their implications for the timing and nature of...

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Section: Significancementioning

confidence: 99%

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

Levine

Zhang

Longo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

188

179

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“…As they are spatially very heterogeneous, the variability within a single soil type is usually high and can equal the variability of the whole region (Rasmussen, 2006). Their characterization by a mean value and a defined uncertainty is much more difficult, and it requires a higher number of observations (Laurance et al, 1999;Galbraith et al, 2003;Amichev and Galbraith, 2004;Maia et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Landscape and soil regionalization in southern Brazilian Amazon and contiguous areas: methodology and relevance for ecological studies

Volkoff

Mello²,

Maia

et al. 2012

Sci. agric. (Piracicaba, Braz.)

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Soils of a large tropical area with differentiated landscapes cannot be treated uniformly for ecological applications. We intend to develop a framework based on physiography that can be used in regional applications. The study region occupies more than 1.1 million km 2 and is located at the junction of the savanna region of Central Brazil and the Amazon forest.It includes a portion of the high sedimentary Central Brazil plateau and large areas of mostly peneplained crystalline shield on the border of the wide inner-Amazon low sedimentary plain.A first broad subdivision was made into landscape regions followed by a more detailed subdivision into soil regions. Mapping information was extracted from soil survey maps at scales of 1:250000-1:500000. Soil units were integrated within a homogenized legend using a set of selected attributes such as taxonomic term, the texture of the B horizon and the associated vegetation. For each region, a detailed inventory of the soil units with their area distribution was elaborated. Ten landscape regions and twenty-four soil regions were recognized and delineated.Soil cover of a region is normally characterized by a cluster composed of many soil units. Soil diversity is comparable in the landscape and the soil regions. Composition of the soil cover is quantitatively expressed in terms of area extension of the soil units. Such geographic divisions characterized by grouping soil units and their spatial estimates must be used for regional ecological applications.

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“…In this case, the coefficient of variation (CV) was 13.2 %, with mean aboveground live biomass of 356 ± 47 Mg ha -1 for all trees, based on measurements for trees C10 cm DBH (diameter at breast height: diameter at 1.3 m above the ground or above any buttresses) with a 12 % correction for small trees (Laurance et al 1999). In 72 1-ha plots in the Ducke Reserve, also near Manaus, the CV was 12.8 %, with mean aboveground live biomass for trees C1 cm DBH, which allows as few as three 1-ha plots to provide an estimate with a mean value within 10 % of the true mean (considering a 95 % confidence interval), indicating the priority for surveys at widely spaced locations, each with only a small numbers of plots (Nascimento and Laurance 2002).…”

Section: Improving Ground-based Measurementsmentioning

confidence: 99%

Brazil’s Amazonian forest carbon: the key to Southern Amazonia’s significance for global climate

Fearnside

2016

Reg Environ Change

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Southern Amazonia is the first region of Brazil's Amazon area to be exposed to intensive conversion to agriculture and ranching. This conversion emits greenhouse gases from the carbon stock in the biomass and soils of the previous vegetation. Quantifying these carbon stocks is the first step in quantifying the impact on global warming from this conversion. This review is limited to information on Brazilian Amazonia's carbon stocks. It indicates large amounts of carbon at risk of emission in both biomass and soils, as well as considerable uncertainty in estimates. Reducing uncertainty is a priority for research but the existence of uncertainty must not be used as an excuse for delaying measures to contain deforestation. The magnitude of carbon stocks is proportional to greenhouse gas emissions per hectare of deforestation and consequently to impact on global climate.

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Relationship between soils and Amazon forest biomass: a landscape-scale study

Cited by 384 publications

References 45 publications

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

Landscape and soil regionalization in southern Brazilian Amazon and contiguous areas: methodology and relevance for ecological studies

Brazil’s Amazonian forest carbon: the key to Southern Amazonia’s significance for global climate

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