Ecosystem decay of Amazonian forest fragments: implications for conservation

Laurance, William F.

doi:10.1007/978-3-540-30290-2_2

Cited by 27 publications

(36 citation statements)

References 118 publications

(159 reference statements)

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“…The null hypothesis our sampling was explicitly designed to test was that characteristics of understory woody plant assemblages do not vary among edge distance categories in fragments, and the interior plots were our control. Tests of forest ecosystem response to edges in the absence of comparable continuous forest require the assumption that conditions similar to those of continuous forest can be found in fragments beyond some minimum distance to edges (Laurance et al 2002). We made this assumption, selecting 300 m as the minimum distance from edges to forest interior on the basis of findings of the BDFFP (Laurance et al 2002).…”

Section: Discussionmentioning

confidence: 99%

“…T he type and degree of edge effects on neotropical forest woody vegetation vary in relation to geographical location, to size class sampled, and to landscape configuration and time elapsed following edge formation. A large proportion of the published information on this subject comes from a strongly seasonal Amazonian environment on nutrient poor soils, during the first 20 yr following the experimental creation of fragments in the 1–100 ha size range (the BDFFP project; Laurance et al 2002). In these forests of relatively high wood densities (Chave et al 2006) and low stem turnover rates (Laurance et al 2006a), tree mortality increases near edges, especially among individuals ≥60 cm diameter at breast height (dbh), with a concomitant loss of aboveground biomass, and species composition shifts toward disturbance‐adapted species (D'Angelo et al 2004, Laurance et al 2006a, b).…”

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Tree Regeneration and Understory Woody Plants Show Diverse Responses to Forest-Pasture Edges in Costa Rica

Bouroncle

Finegan

2011

Biotropica

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Edge effects along tropical forest-pasture margins are thought to cause a shift toward early successional characteristics of the understory forest vegetation. We tested this idea by sampling vegetation at five forest sites in northeast Costa Rica each of which had edges that were established over 20 yr earlier. Four of these sites had been selectively logged. We sampled woody plants 4 0.2 and 1.3 m height in 54 m 2 within 0.2 ha plots at edges (N = 14), and at 150 m (N = 11) and 300 m from edges (N = 9). Composition and diversity did not vary with edge distance. Abundance of tree regeneration, mainly of canopy and emergent species, increased at edges. Abundance of lianas and slow-growing tree species did not differ significantly across the sampling locations. Weighted mean wood density varied little, with a reduction at edges for canopy species. Palms were less abundant at edges, but not less species rich. At edges, these plant assemblages maintain many of the characteristics of forest interior vegetation, though the changes observed may indicate ongoing functional change. Degradation of forest-pasture edges is not a universal feature of tropical forest fragmentation, and forests with high rates of natural turnover might have a high capacity to maintain themselves within forest edges alongside pasture.Foreign language abstract is available in the online version of this article.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Tree Regeneration and Understory Woody Plants Show Diverse Responses to Forest-Pasture Edges in Costa Rica

Bouroncle

Finegan

2011

Biotropica

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“…habitat fragmentation and the resulting creation of forest edges is one of the most pervasive consequences of present‐day human land use (Whitmore 1997, Broadbent et al 2008). Many of the ecological alterations in fragmented forests ( e.g ., species loss, biomass collapse) can be attributed to edge effects (Laurance et al 2002, Tabarelli & Gascon 2005) and understanding edge‐mediated alterations of species interactions is of fundamental importance when analyzing the impacts of habitat fragmentation (Fagan et al 1999, Hunter 2002).…”

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Persisting Hyper‐abundance of Leaf‐cutting Ants (Atta spp.) at the Edge of an Old Atlantic Forest Fragment

2009

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Leaf-cutting ants (LCAs) profoundly benefit from edge creation in Neotropical forests, where they act as a keystone species and disturbance agent. In view of their poorly explored population dynamics, the question arises whether high densities of LCAs are a transitional or a persisting phenomenon. We studied the temporal variation of LCA colony densities at the edge of the Brazilian Atlantic forest. At physically stable edges of an old forest fragment, densities of Atta cephalotes and Atta sexdens (11 and five times higher in a 50 m edge zone in comparison with the forest interior) persisted over a 4-yr interval (2001)(2002)(2003)(2004)(2005) with no significant difference in densities between years. Species-specific per colony growth rates ranged from 12 to À5 percent/yr, suggesting that populations were approximately at equilibrium. High rates of colony turnover (little less than 50% in 4 yr) indicated an average colony life span of about 7 yr-a life expectancy considerably lower than previous estimates for Atta colonies. Stable, hyper-abundant populations of LCAs accord with the constantly high availability of palatable pioneer vegetation (the preferred food source of LCAs) at forest edges and are expected to persist in time as long as forests are characterized by high edge to interior ratios, with potentially long-lasting consequences for the ecosystem.Abstract in Portuguese is available at

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“…Offspring with higher inbreeding coefficients might have higher chances of expressing negative effects of inbreeding ( i.e ., inbreeding depression), which may negatively affect one or some of their fitness parameters. Moreover, early offspring fitness traits in particular ( i.e ., seed mass or seed germination) might also be negatively affected as a consequence of adverse abiotic conditions that often prevail in forest fragments ( e.g ., lower relative humidity, higher temperatures, lower nutrient cycling rates; Didham 1998, Didham & Lawton 1999, Laurance et al . 2002, Vergeer et al .…”

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Forest Fragmentation and Seed Germination of Native Species from the Chaco Serrano Forest

Ashworth

Marti

2010

Biotropica

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Habitat fragmentation is a widespread phenomenon that alters pollination and plant reproductive processes. These effects have demographic and genetic implications that determine offspring fitness and the long-term viability of plant populations in fragmented systems. We evaluated fragmentation effects on early plant offspring fitness traits, individual seed mass, and percentage of seed germination in five native plant species (Acacia caven, Celtis ehrenbergiana, Croton lachnostachyus, Rivina humilis, Schinus fasciculatus) from the Chaco Serrano forest, a subtropical highly fragmented ecosystem. We found evidence of strong negative fragmentation effects on germination in the shrub C. lachnostachyus and the perennial herb R. humilis, after 30 d of controlled tests. No fragmentation effects were found in the studied traits on the remaining three tree species. We found significant maternal effects in offspring fitness traits in all five species. We discuss the relative magnitude of maternal vs. fragmentation effects taking into account both plant species' lifespan and the time elapsed in fragmentation conditions. We emphasize the need to increase the study of early and late plant offspring fitness produced in fragmented habitats coupled with analyses of genetic parameters and the pollination process in order to evaluate the conservation value of remnant forest fragments.

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Ecosystem decay of Amazonian forest fragments: implications for conservation

Cited by 27 publications

References 118 publications

Tree Regeneration and Understory Woody Plants Show Diverse Responses to Forest-Pasture Edges in Costa Rica

Tree Regeneration and Understory Woody Plants Show Diverse Responses to Forest-Pasture Edges in Costa Rica

Persisting Hyper‐abundance of Leaf‐cutting Ants (Atta spp.) at the Edge of an Old Atlantic Forest Fragment

Forest Fragmentation and Seed Germination of Native Species from the Chaco Serrano Forest

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