Forest fragmentation in central Amazonia and its effects on litter-dwelling ants

Influence of habitat, litter type, and soil invertebrates on leaf-litter decomposition in a fragmented Amazonian landscape

“…These organisms play a vital role in leaf-litter decomposition, by consuming litter and, by physically breaking up organic material, facilitating the activity of microbes (Petersen and Luxton 1982;Bradford et al 2002). Variations in the abundance, species richness, and composition of many groups of soil invertebrates are known to occur in response to edge effects or changes in vegetation cover (Lasebikan 1976;Belshaw and Bolton 1993;Eggleton et al 1995;Didham 1997;Carvalho and Vasconcelos 1999;Vasconcelos 1999). Similarly, deforestation and forest fragmentation may affect litter quality by favoring the recruitment of successional-tree species at the expense of old-growth species (Laurance et al 1998), as these two groups can differ strongly in nutrient, carbon, lignin, and phenolic contents (Coley 1983;Newberry and de Foresta 1985;Mesquita et al 1998;Xuluc-Tolosa et al 2003).…”

Ecosystem decay of Amazonian forest fragments: implications for conservation

“…Microclimatic changes near edges, such as reduced humidity, increased light, and greater temperature variability, penetrate up to 60 m into fragment interiors (Kapos 1989) and can negatively affect species adapted for humid, dark forest interiors (Lovejoy et al 1986, Benitez-Malvido 1998. Leaf litter accumulates near edges (Carvalho and Vasconcelos 1999 Edge penetration distance (m) Didham and Lawton 1999) because drought-stressed trees shed leaves and possibly because drier edge conditions slow litter decomposition (Kapos et al 1993, Didham 1998, Vasconcelos and Laurance 2005. Accumulating litter may negatively affect seed germination (Bruna 1999) and seedling survival (Scariot 2001) and makes forest edges vulnerable to surface fires during droughts (Cochrane et al 1999).…”

“…Numerous flies, bees, wasps , beetles (Didham et al 1998a(Didham et al , 1998b, ants (Carvalho and Vasconcelos 1999), and butterflies (Brown and Hutchings 1997) decline in abundance near edges. A number of insectivorous understory birds avoid edges (Quintela 1985), particularly solitary species, obligatory ant followers, and those that forage in mixed-species flocks (S.G. Laurance 2004).…”

“…The most striking edge effects in the BDFFP study area occur within 100 m of forest edges (Figure 3). However, wind damage to forests can penetrate up to 300-400 m from edges (Laurance et al 1998b, Lewis 1998, and changes in beetle, ant, and butterfly communities can be detected as far as 200-400 m from edges (Figure 4, Brown and Hutchings 1997, Didham 1997b, Carvalho and Vasconcelos 1999. Notably, some edge effects occur over even larger spatial scales in more-seasonal areas of the Amazon: ground fires in two fragmented landscapes of eastern Amazonia were sharply elevated in frequency within at least 2400 m of forest edges (Cochrane and Laurance 2002).…”

Rapid land-use change and its impacts on tropical biodiversity

“…Many species that decline in fragments are sensitive to edge effects, including numerous flies, bees, wasps [Fowler et al, 1993], beetles [Didham, 1997], ants [Carvalho and Vasconcelos, 1999], and butterflies [Brown and Hutchings, 1997]. A number of insectivorous understory birds avoid edges, particularly solitary species, obligatory ant followers, and those that forage in mixed-species flocks [S. G. Laurance, in press, 2004;.…”