Factors determining mammal species richness on habitat islands and isolates: habitat diversity, disturbance, species interactions and guild assembly rules

Abstract

For over three decades the equilibrium theory of island biogeography has galvanized studies in ecological biogeography. Studies of oceanic islands and of natural habitat islands share some similarities to continental studies, particularly in developed regions where habitat fragmentation results from many land uses. Increasingly, remnant habitat is in the form of isolates created by the clearing and destruction of natural areas. Future evolution of a theory to predict patterns of species abundance may well come from the application of island biogeography to habitat fragments or isolates. In this paper we consider four factors other than area and isolation that influence the number and type of mammal species coexisting in one place: habitat diversity, habitat disturbance, species interactions and guild assembly rules. In all examples our data derive from mainland habitat, fragmented to differing degrees, with different levels of isolation. Habitat diversity is seen to be a good predictor of species richness. Increased levels of disturbance produce a relatively greater decrease in species richness on smaller than on larger isolates. Species interactions in the recolonization of highly disturbed sites, such as regenerating mined sites, is analogous to island colonization. Species replacement sequences in secondary successions indicate not just how many, but which species are included. Lastly, the complement of species established on islands, or in insular habitats, may be governed by guild assembly rules. These contributions may assist in taking a renewed theory into the new millennium.

Managing Landscapes for Conservation Under Uncertainty

“…Indices of spatial pattern are uncertain because habitat quality is heterogeneous within patches, and gradients vary with different stages of an organism's life history, with ecological succession and following disturbance (Whittaker et al 1973, Austin 1999, Fox and Fox 2000. Different species use landscapes differently and at different scales, making it difficult to abstract landscape properties in a way that makes sense for all, or even for most, species (Wiens 1994, Manning et al 2004).…”

Area and habitat relationships in island land snail faunas: an Aegean case study exploring the choros model

“…Although there have been many attempts to establish the superiority of one hypothesis over the other, it is generally acknowledged that habitat diversity and area per se are not mutually exclusive mechanisms but supplementary and may operate individually or in combination (Connor and McCoy, 1979;2000;Kohn and Walsh, 1994;Rosenzweig, 1995;Ricklefs and Lovette, 1999). Hence, at least four models have been developed combining the effects of area and habitat diversity on species richness (for a review see Triantis et aI., 2003).…”

Bryophytes in a changing landscape: The hierarchical effects of habitat fragmentation on ecological and evolutionary processes

“…Their simplified dispersal system contrasts with the complex system of most mammals and vascular plants. Recent reviews have highlighted the importance of considering species interactions for mammals and vascular plants in order to understand the causal mechanisms which control species richness in habitat fragments (Fox and Fox, 2000;Murphy and Lovett-Doust, 2004). Since much of the empirical evidence has been based on vascular plant and vertebrate data, increased focus on experimental research utilising bryophytes should provide novel insights into how local (i.e., habitat quality) and regional (i.e., spatial) factors influence plant distributions in a fragmented landscape.…”