Landscape modification and habitat fragmentation are key drivers of global species loss. Their effects may be understood by focusing on: (1) individual species and the processes threatening them, and (2) human-perceived landscape patterns and their correlation with species and assemblages. Individual species may decline as a result of interacting exogenous and endogenous threats, including habitat loss, habitat degradation, habitat isolation, changes in the biology, behaviour, and interactions of species, as well as additional, stochastic threats. Human-perceived landscape patterns that are frequently correlated with species assemblages include the amount and structure of native vegetation, the prevalence of anthropogenic edges, the degree of landscape connectivity, and the structure and heterogeneity of modified areas. Extinction cascades are particularly likely to occur in landscapes with low native vegetation cover, low landscape connectivity, degraded native vegetation and intensive land use in modified areas, especially if keystone species or entire functional groups of species are lost. This review (1) demonstrates that species-oriented and pattern-oriented approaches to understanding the ecology of modified landscapes are highly complementary, (2) clarifies the links between a wide range of interconnected themes, and (3) provides clear and consistent terminology. Tangible research and management priorities are outlined that are likely to benefit the conservation of native species in modified landscapes around the world.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1466-8238.2007.00287.x

Landscape modification and habitat fragmentation: a synthesis

A review of the literature shows that in nearly all cases tropical rain forest fragmentation has led to a local loss of species. Isolated fragments suffer reductions in species richness with time after excision from continuous forest, and small fragments often have fewer species recorded for the same effort of observation than large fragments or areas of continuous forest. Birds have been the most frequently studied taxonomic group with respect to the effects of tropical forest fragmentation. The mechanisms of fragmentation-related extinction include the deleterious effects of human disturbance during and after deforestation, the reduction of population sizes, the reduction of immigration rates, forest edge effects, changes in community structure (second- and higher-order effects) and the immigration of exotic species. The relative importance of these mechanisms remains obscure. Animals that are large, sparsely or patchily distributed, or very specialized and intolerant of the vegetation surrounding fragments, are particularly prone to local extinction. The large number of indigenous species that are very sparsely distributed and intolerant of conditions outside the forest make evergreen tropical rain forest particularly susceptible to species loss through fragmentation. Much more research is needed to study what is probably the major threat to global biodiversity.

Species loss in fragments of tropical rain forest: a review of the evidence.

The 1990s may be the last decade during which constructive and creative decisions, activities, and investments can be made to ensure that many of the world's species and ecosystems are maintained, examined for their material and ecological value, and promoted for sustainable use to support new and innovative approaches to development. The combination of maintaining the maximum possible biological and cultural diversity, and the greatest possible scientific endeavor seems the most sensible approach toward dealing with the dynamic future facing humanity. The elements now exist that will reverse the trend toward the biotic impoverishment of the world. New partners in conservation need to be found, involving all ministries, departments, and private institutions that are directly dependent on biological resources. For example, national parks departments should be joined in habitat management by a wide range of other institutions to represent all interests. Furthermore, other line agencies need to develop the capacity to manage biodiversity of particular relevance to their respective missions. Actions taken in the next few years will determine whether we take a road toward a chaotic future characterized by overexploitation and abuse of our biological resources, or take the road toward maintaining greater biological diversity and resource sustainability.

Conserving the World's Biological Diversity

The consumption of figs (the fruit of Ficus spp.; Moraceae) by vertebrates is reviewed using data from the literature, unpublished accounts and new field data from Borneo and Hong Kong. Records of frugivory from over 75 countries are presented for 260 Ficus species (approximately 30% of described species). Explanations are presented for geographical and taxonomic gaps in the otherwise extensive literature. In addition to a small number of reptiles and fishes, 1274 bird and mammal species in 523 genera and 92 families are known to eat figs. In terms of the number of species and genera of fig-eaters and the number of fig species eaten we identify the avian families interacting most with Ficus to be Columbidae, Psittacidae, Pycnonotidae, Bucerotidae, Sturnidae and Lybiidae. Among mammals, the major fig-eating families are Pteropodidae, Cercopithecidae, Sciuridae, Phyllostomidae and Cebidae. We assess the role these and other frugivores play in Ficus seed dispersal and identify fig-specialists. In most, but not all, cases fig specialists provide effective seed dispersal services to the Ficus species on which they feed. The diversity of fig-eaters is explained with respect to fig design and nutrient content, phenology of fig ripening and the diversity of fig presentation. Whilst at a gross level there exists considerable overlap between birds, arboreal mammals and fruit bats with regard to the fig species they consume, closer analysis, based on evidence from across the tropics, suggests that discrete guilds of Ficus species differentially attract subsets of sympatric frugivore communities. This dispersal guild structure is determined by interspecific differences in fig design and presentation. Throughout our examination of the fig-frugivore interaction we consider phylogenetic factors and make comparisons between large-scale biogeographical regions. Our dataset supports previous claims that Ficus is the most important plant genus for tropical frugivores. We explore the concept of figs as keystone resources and suggest criteria for future investigations of their dietary importance. Finally, fully referenced lists of frugivores recorded at each Ficus species and of Ficus species in the diet of each frugivore are presented as online appendices. In situations where ecological information is incomplete or its retrieval is impractical, this valuable resource will assist conservationists in evaluating the role of figs or their frugivores in tropical forest sites.

Fig-eating by vertebrate frugivores: a global review.

The survival of primates in moderately disturbed forests is determined by a complex of variables. Correlation analyses suggest that ecological features of a species may confer a basal survival ability but that details of the form of disturbance may be crucially important. Correlation analyses reveal that body size alone is a poor predictor of primate response to moderate forest disturbance. However, when the effects of diet variables are held constant, body size more strongly correlates with survival ability (smaller species surviving better). Degree of frugivory shows a significant negative correlation with survival ability at both univariate and multivariate levels of analysis. In contrast, dietetic diversity is not correlated with survival ability at either level of analysis. Together, body size and percentage frugivory explain 44% of the variation in species’ responses to moderate habitat disturbance. Idiosyncratic responses of species can usually be traced to specific features of the changing environment, such as selective elimination of important food sources and, conversely, the presence of increased densities of particular food sources arising from the disturbance.

Responses of rain-forest primates to habitat disturbance: A review

Selective logging and wildlife conservation in tropical rain-forest: Problems and recommendations

The use of primary and selectively logged rainforest by Malaysian hornbills (bucerotidae) and implications for their conservation

Diversity and abundance of selected animal species in undisturbed forest, selectively logged forest and plantations in East Kalimantan, Indonesia

Until two decades ago, the only reference to the white uacari of the upper Amazon, known locally as the ‘English monkey’, had been provided by the British naturalist Henry Walter Bates, who saw captured animals during his sojourn in Amazonia in the 1850s. A major Brazilian initiative led us to the first intensive field study of the species, which was carried out in 1983 and 1984 by one of the authors, J. M. Ayres, with the participation of a large number of Brazilian scientists and a few from overseas. The study illustrated the uniqueness of the varzea habitat in which the animals live and the threats it currently faces. It also captured the attention of both the Brazilian scientific community and the public. Possibilities for the creation of a reserve area within the varzea are now being implemented.

Andrew D. Johns

Papers

Responses of rain-forest primates to habitat disturbance: A review

Selective logging and wildlife conservation in tropical rain-forest: Problems and recommendations

The use of primary and selectively logged rainforest by Malaysian hornbills (bucerotidae) and implications for their conservation

Diversity and abundance of selected animal species in undisturbed forest, selectively logged forest and plantations in East Kalimantan, Indonesia

Conservation of white uacaries in Amazonian várzea