Abstract
The Atlantic forest has historically been severely deforested, and only fragments currently remain that are subject to a wide variety of anthropogenic impacts, including edge effects that can cause structural and functional degradation. The Tingua Biological Reserve-RJ comprises approximately 26,000 hectares of well-preserved Atlantic Forest, but it is subject to impacts caused by two canopy openings along oil pipelines. Comparisons were made between pipeline edges and forest interiors to evaluate edge effects on the structure and dynamics of those tree communities. Tree densities were higher along forest edges, apparently increasing over time. Tree basal areas, on the other hand, have decreased along edges due to higher mortality rates. Linear canopy opening edges showed higher densities of small trees, while the interior had more very large trees, indicating changes in successional processes and community structural patterns due to edge effects.
Highlights
Fragmentation of tropical forests can promote edge effects that lead to accelerated increases in plant recruitment and mortality [1] [2]
The local vegetation is relatively well-preserved, mainly because of the difficult access to the reserve, and its rivers supply water for part of Rio de Janeiro. Human impacts such as hunting and selective extraction are commonly observed, and two oil pipelines run through the area creating linear canopy openings [25], designated here as the Old Pipeline (OldP) and New Pipeline (NewP)
Trees densities per plot were higher along the disturbance edges, with a significant difference mainly between the New Pipeline and the Interior in the years 2004 and 2005 (F = 4.25; p < 0.02 and F = 5.05; p < 0.01 respectively) (Figure 1)
Summary
Fragmentation of tropical forests can promote edge effects that lead to accelerated increases in plant recruitment and mortality [1] [2]. The ecological relationships between species have been severely altered in many tropical forests and their biological communities are at risk of extinction [15] due to deforestation, selective cutting, highway construction, and urban expansion [16], all leading to habitat loss and fragmentation [14] [17] [18] These anthropogenic processes create mosaics of small forest remnants within urban or agricultural matrices [19], and increases in forest edges are followed by structural and functional changes in communities that arise from alterations of abiotic and biotic conditions [20] [21]. These changes invariably lead to negative biotic responses, including increased mortality, recruitment, damage, and tree falls [7] [8] [22]
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