Pervasive alteration of tree communities in undisturbed Amazonian forests

Laurance, William F.; Oliveira, Alexandre Adalardo de; Laurance, Susan G.; Condit, Richard; Nascimento, Henrique E. M.; Sanchez-Thorin, Ana C.; Lovejoy, Thomas Ε.; Andrade, Ana; D’Angelo, Sammya; Ribeiro, José E. L. S.; Dick, Christopher W.

doi:10.1038/nature02383

Cited by 257 publications

(289 citation statements)

References 29 publications

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“…Lowland tropical climates are also changing in ways that are likely to affect forest organisms (Box 2). However, to my knowledge, there are no studies The changing structure and dynamics of lowland tropical forests The evidence for change in old-growth tropical forests comes mainly from censuses of the woody stems of trees and lianas that are larger than a threshold size in fully enumerated plots [29][30][31][32][33]. The threshold stem size is usually 10 cm in diameter at breast height (dbh), and median plot area is w1 ha.…”

Section: Global Anthropogenic Effects On Lowland Tropical Forestsmentioning

confidence: 99%

Tropical forests in a changing environment

Wright

2005

Trends in Ecology & Evolution

639

502

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Section: Global Anthropogenic Effects On Lowland Tropical Forestsmentioning

confidence: 99%

Tropical forests in a changing environment

Wright

2005

Trends in Ecology & Evolution

639

502

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“…There have been few studies of trends in functional composition in old-growth tropical forests, although Phillips et al (2002) have shown that large lianas in intact western Amazon forests have recently increased in relative dominance, a pattern that may extend across the Neotropics Schnitzer and Bongers 2011) and Laurance et al (2004) found increasing rates of growth in most relatively abundant tree genera in a central Amazonian landscape, and a general increase in rates of tree mortality and recruitment. The results suggested that numbers of faster-growing old-growth genera (primarily canopy trees) increased, while slower-growing understory genera decreased.…”

Section: Introductionmentioning

confidence: 99%

Shifting dynamics of climate-functional groups in old-growth Amazonian forests

Butt

Malhi

New

et al. 2012

Plant Ecology & Diversity

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Background: Climate change is driving ecosystem shifts, which has implications for tropical forest system function and productivity. Aim: To investigate Amazon forest dynamics and test for compositional changes between 1985 and 2005 across different plant groups. Methods: Tree census data from 46 long-term RAINFOR forest plots in Amazonia for three climate-functional groups were used: dry-affiliate, climate-generalist and wet affiliate. Membership of each group was ascribed at genus level from the distribution of individuals across a wet-dry gradient in Amazonia, and then used to determine whether the proportions of these functional groups have changed over time, and the direction of any change. Results: In total, 91 genera, representing 59% of the stems and 18% of genera in the plots, were analysed. Wet-affiliates tended to move from a state of net basal area gain towards dynamic equilibrium, defined as where gain ≈ loss, governed by an increase in loss rather than a decrease in growth and mainly driven by plots in north-west Amazonia, the wettest part of the region. Dry-affiliates remained in a state of strong net basal area gain across western Amazonia and showed a strong increase in stem recruitment. Wet-affiliates and climate-generalists showed increases in stem mortality, and climate-generalists showed increased stem recruitment, resulting in overall equilibrium of stem numbers. Conclusions: While there were no significant shifts in most genera, the results suggest an overall shift in climate-functional forest composition in western Amazonia away from wet-affiliates, and potential for increased forest persistence under projected drier conditions in the future.

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“…Thus, plot-based studies in old-growth tropical forests that observe changing tree species composition (2), increased liana abundance (3), faster turnover rates (4), and forest biomass accumulation (5,6), are viewed as surprising departures from an expected steady-state condition. However, disturbance events can create a landscape with patches of varying successional age, and the extent to which forest plots representatively sample this mosaic remains an open question.…”

mentioning

confidence: 99%

The steady-state mosaic of disturbance and succession across an old-growth Central Amazon forest landscape

Chambers

Negrón‐Juárez

Marra

et al. 2013

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

213

238

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Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. The size distribution and return frequency of disturbance events, and subsequent recovery processes, determine to a large extent the spatial scale over which this old-growth steady state develops. Here, we characterize this mosaic for a Central Amazon forest by integrating field plot data, remote sensing disturbance probability distribution functions, and individual-based simulation modeling. Results demonstrate that a steady state of patches of varying successional age occurs over a relatively large spatial scale, with important implications for detecting temporal trends on plots that sample a small fraction of the landscape. Long highly significant stochastic runs averaging 1.0 Mg biomass·ha −1 ·y −1 were often punctuated by episodic disturbance events, resulting in a sawtooth time series of hectare-scale tree biomass. To maximize the detection of temporal trends for this Central Amazon site (e.g., driven by CO 2 fertilization), plots larger than 10 ha would provide the greatest sensitivity. A model-based analysis of fractional mortality across all gap sizes demonstrated that 9.1-16.9% of tree mortality was missing from plot-based approaches, underscoring the need to combine plot and remote-sensing methods for estimating net landscape carbon balance. Old-growth tropical forests can exhibit complex large-scale structure driven by disturbance and recovery cycles, with ecosystem and community attributes of hectare-scale plots exhibiting continuous dynamic departures from a steady-state condition.biodiversity | community composition | gap dynamics | NEP NEE NBP A common assumption in old-growth forest studies is that, in the absence of a directional forcing, ecosystem characteristics and tree species composition should exhibit some type of steady-state behavior (1). Thus, plot-based studies in old-growth tropical forests that observe changing tree species composition (2), increased liana abundance (3), faster turnover rates (4), and forest biomass accumulation (5, 6), are viewed as surprising departures from an expected steady-state condition. However, disturbance events can create a landscape with patches of varying successional age, and the extent to which forest plots representatively sample this mosaic remains an open question. An important issue is how to distinguish directional trends driven by a warming climate, or rising atmospheric CO 2 concentration, from smaller-scale stochastic patterns driven by disturbance and recovery cycles (7,8).Over long time periods, the disturbance regime of a forested region creates a shifting steady-state mosaic, represented by patches of different successional ages, with the fraction of the landscape in any particular state remaining relatively constant over time (9,10). In many tropical forests, gaps created by the windthrow of canopy trees is a major mode of disturb...

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Pervasive alteration of tree communities in undisturbed Amazonian forests

Cited by 257 publications

References 29 publications

Tropical forests in a changing environment

Tropical forests in a changing environment

Shifting dynamics of climate-functional groups in old-growth Amazonian forests

The steady-state mosaic of disturbance and succession across an old-growth Central Amazon forest landscape

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