Continuous versus binary representations of landscape heterogeneity in spatially-explicit models of mobile populations

Authored by Steven T Stoddard

Date Published: 2010

DOI: 10.1016/j.ecolmodel.2010.06.024

Sponsors: United States Army Corps of Engineers

Platforms: NetLogo

Model Documentation: AORML Other Narrative Mathematical description

Model Code URLs: https://ars-els-cdn-com.ezproxy1.lib.asu.edu/content/image/1-s2.0-S0304380010003121-mmc1.doc

Abstract

How a landscape is represented is an important structural assumption in spatially-explicit simulation models. Simple models tend to specify just habitat and non-habitat (binary), while more complex models may use multiple levels or a continuum of habitat quality (continuous). How these different representations influence model projections is unclear. To assess the influence of landscape representation on population models, I developed a general, individual-based model with local dispersal and examined population persistence across binary and continuous landscapes varying in the amount and fragmentation of habitat. In binary and continuous landscapes habitat and non-habitat were assigned a unique mean suitability. In continuous landscapes, suitability of each individual site was then drawn from a normal distribution with fixed variance. Populations went extinct less often and abundances were higher in continuous landscapes. Production in habitat and non-habitat was higher in continuous landscapes, because the range of habitat suitability sampled by randomly dispersing individuals was higher than the overall mean habitat suitability. Increasing mortality, dispersal distance, and spatial heterogeneity all increased the discrepancy between continuous and binary landscapes. The effect of spatial structure on the probability of extinction was greater in binary landscapes. These results show that, under certain circumstances, model projections are influenced by how variation in suitability within a landscape is represented. Care should be taken to assess how a given species actually perceives the landscape when conducting population viability analyses or empirical validation of theory. (C) 2010 Elsevier B.V. All rights reserved.

Tags

connectivity Management Dynamics movement Habitat fragmentation Dispersal birds perspective Biodiversity conservation Extinction thresholds