Simple process-based simulators for generating spatial patterns of habitat loss and fragmentation: a review and introduction to the G-RaFFe model

PLoS One. 2013 May 28;8(5):e64968. doi: 10.1371/journal.pone.0064968. Print 2013.

Abstract

Landscape simulators are widely applied in landscape ecology for generating landscape patterns. These models can be divided into two categories: pattern-based models that generate spatial patterns irrespective of the processes that shape them, and process-based models that attempt to generate patterns based on the processes that shape them. The latter often tend toward complexity in an attempt to obtain high predictive precision, but are rarely used for generic or theoretical purposes. Here we show that a simple process-based simulator can generate a variety of spatial patterns including realistic ones, typifying landscapes fragmented by anthropogenic activities. The model "G-RaFFe" generates roads and fields to reproduce the processes in which forests are converted into arable lands. For a selected level of habitat cover, three factors dominate its outcomes: the number of roads (accessibility), maximum field size (accounting for land ownership patterns), and maximum field disconnection (which enables field to be detached from roads). We compared the performance of G-RaFFe to three other models: Simmap (neutral model), Qrule (fractal-based) and Dinamica EGO (with 4 model versions differing in complexity). A PCA-based analysis indicated G-RaFFe and Dinamica version 4 (most complex) to perform best in matching realistic spatial patterns, but an alternative analysis which considers model variability identified G-RaFFe and Qrule as performing best. We also found model performance to be affected by habitat cover and the actual land-uses, the latter reflecting on land ownership patterns. We suggest that simple process-based generators such as G-RaFFe can be used to generate spatial patterns as templates for theoretical analyses, as well as for gaining better understanding of the relation between spatial processes and patterns. We suggest caution in applying neutral or fractal-based approaches, since spatial patterns that typify anthropogenic landscapes are often non-fractal in nature.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Computer Simulation*
  • Conservation of Natural Resources*
  • Ecosystem*
  • Human Activities
  • Humans
  • Models, Theoretical*
  • Regression Analysis
  • Software
  • Spatial Analysis*

Grants and funding

The model was developed within the scope of GP's postdoctoral position at the Dept. of Ecological Modelling as part of the BioCAPSP project “Biodiversity conservation in fragmented landscapes at the Atlantic Plateau of São Paulo” (funded by the German Federal Ministry of Education and Research (BMBF), project number 01 LB 0202 A1). The study was further supported by a Visiting Researcher grant to GZ from the Dept. of Ecological Modelling at the Helmholtz Centre for Environmental Research – UFZ, and was completed within the scope of a post-doc fellowship of GP within the EU FP7 large-scale integrated project SCALES (grant number 226 852). Field work of GZ was funded by CONICET, the ANPCyT and the University of Buenos Aires. SP was funded by the Helmholtz Association of German Research Centres within the project “Biomass and Bioenergy Systems”. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.