PARENT SESSION
Organized Oral Session 2: Measuring landscape connectivity - tool for species conservation
Organizer(s): P Kindlmann, F Burel, and J Baudry
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 510b, Level 5, Palais des congrès de Montréal
Effects of habitat loss and fragmentation on population dynamics.
Wiegand, Thorsten*,1, Wiegand, Kerstin2, 1 Department of Ecological Modelling, Leipzig, Germany2 Institute of Ecology, Jena, Germany
ABSTRACT- Although ecologists have studied the effects of habitat loss and fragmentation on biodiversity and extinction extensively, our understanding of these effects is still limited. In part this is due to problems to describe habitat loss and fragmentation (there are as yet no common measures of landscape structure and composition). A second important reason is that population level variables (e.g., risk of extinction, population size, connectivity between habitat patches) often critically depend on species-specific processes acting on local scales (e.g., dispersal) and that several processes of population dynamics may interact with landscape structure and composition. Therefore, we cannot safely abstract from species specific details. One approach to nevertheless obtain a more general understanding is to generalize species-specific models to ecological profiles (i.e., a spectrum of species which share important ecological characteristics). We present results of population models for ecological profiles of long-lived species with stable home ranges and natal dispersal (e.g., brown bears Ursus arctos) and ground beetles in agricultural landscapes (Coleoptera, Carabidae) which are sensitive to land-use change. Our general approach involves first simulating population dynamics for all ecological profiles within landscapes with largely different structure and composition. For each concrete landscape we calculate several scale-dependent landscape measures which are hypothesized to describe fragmentation effects for specific processes of population dynamics. To find the link between landscape structure and species abundance, we use general linear models (GLM) to determine those landscape measures which account for the variation in population size introduced by altering landscape structure. The general linear models explain population size generally well. We reveal the circumstances under which fragmentation matters by comparing the landscape measures which enter into the models for the different ecological profiles. Our findings suggest that predicting fragmentation effects requires a good understanding of the biology and habitat use of the species in question and that the uniqueness of species and the landscapes in which they live confound simple analyses.
Key words: ecological profiles, individual-based spatially explicit population model, landscape metrics, landscape structure