Impacts of rain forest fragmentation on butterflies in northern Borneo: species richness, turnover and the value of small fragments

Abstract

Summary 1.Widespread and rapid losses of tropical rain forests have made understanding the responses of species to rain forest fragmentation an area of major concern. In this study we examined the impacts of habitat fragmentation on the species richness and faunal composition of butterflies in tropical rain forests in Sabah, Borneo. We analysed patterns of both α -and β -diversity to assess the relative importance of differences in patch size, isolation and vegetation structure on the diversity and similarity of species assemblages. We used additive partitioning to assess the relative contributions of intact forest and forest remnants to overall species richness at a landscape scale and we examined which traits of species best predicted their responses to fragmentation. 2. Species richness and diversity in rain forest remnants was significantly positively related to remnant size and significantly negatively related to isolation, in keeping with theories of island biogeography. Species assemblages at different sites were significantly nested, with those species most adversely affected by forest fragmentation having a narrow range of larval host-plants and, to a lesser extent, being large-bodied. No species endemic to Borneo was recorded in forest remnants smaller than 4000 ha, but even the smallest remnant (120 ha) supported species with geographical distributions confined within Sundaland (West Malaysia and the islands of the Sunda Shelf). 3. Although assemblages were significantly nested, they departed substantially from perfect nestedness, with some species recorded only or predominantly in small, relatively depauperate remnants. As a result there was substantial β -diversity among sites, which was related to variation in both fragment size and vegetation structure. At the landscape scale, diversity within sites was less than that between sites, and the majority of the diversity between sites was related to variation in fragment size. 4. Synthesis and applications . Substantial diversity was added to the assemblage of butterflies in Bornean rain forests by virtue of species differences among fragments, which were related mainly to differences in patch size and vegetation structure. The data reported indicate that, despite having lower species richness, relatively small and isolated remnants of rain forest make a substantial contribution to regional diversity. Small isolated forest remnants are generally accorded low conservation status and given little protection, with the result that they often disappear over time because of continued anthropogenic disturbance. The results of this study indicate that the conservation value of small remnants of forest, in particular their contribution to environmental heterogeneity, should not be overlooked.

Ecological impacts of tropical forest fragmentation: how consistent are patterns in species richness and nestedness?

“…Small fragments often experience increased habitat disturbance (this study; [27]) and altered micro-climates, and whether or not changes in trophic organization Figure 6. Maximally ordered species presence-absence matrix for (a) fruit-feeding moths and (b) fruit-feeding butterflies in rainforest fragments in Sabah, Borneo.…”

“…As an index of vagility, we measured butterfly forewing length in the field (+1 mm using vernier calipers), and obtained data on moth forewing length from published sources [66 -71]. To assess the vulnerability of species to local extinction, butterflies and moths were assigned to four geographical range size groups ( [27]; endemic to Borneo, restricted to Sundaland, restricted to the Oriental region, occurring beyond the Oriental region (using data from [66][67][68][69][70][71]85])).…”

Species diversity and community structure of fruit-feeding butterflies (Lepidoptera: Nymphalidae) in an eastern amazonian forest

“…Additionally, butterfly richness has been suggested as being positively correlated with habitat area, following the classic species-area relationship (Ricklefs & Lovette, 1999;Benedick et al, 2006). An empirical example is provided by Uehara-Prado et al (2007), where a positive relationship was found between fragment area and species richness of fruit-feeding butterflies in the Atlantic forest.…”

“…Considering that SAG is a small Amazon forest remnant inserted in a matrix of villages and crops, it is possible that sensitive butterfly species have already become locally extinct due the reduced size and habitat heterogeneity of this forest patch, impacting the observed species richness. Interestingly, despite presenting low species richness, small forest fragments can still contribute substantially to regional diversity (Benedick et al, 2006), since these areas can maintain species that are no longer present in disturbed habitats nearby.…”

Conservation of the Ethiopian church forests: Threats, opportunities and implications for their management

“…Traditionally, conservation efforts have focused either on large and relatively undisturbed habitats because large areas conserve relatively more species (Laurance 2005), or on biodiversity hotspots with exceptional concentrations of endemic species under relatively high levels of threat (Myers et al 2000). However, conserving a number of small habitat patches such as sacred groves can have additional value for conserving biodiversity, for instance by covering a wider variety of habitats than would be achieved by protecting a few large patches of an equivalent total area (Bhagwat and Rutte 2006;Hokkanen et al 2009) and thus contributing to higher total biodiversity covered (Benedick et al 2006). Another important benefit is that a habitat network enabling dispersal amongst sacred groves and other protected areas (Laita et al 2010;Chiarucci et al 2012) may make an important contribution to genetic connectivity (Lander et al 2010) and the survival of species as metapopulations (sensu Hanski 1998).…”