Thesis abstract: Assessing the effect of land-cover changes on species distributions: application of habitat models to conservation of Mediterranean bird communities

Sara Vallecillo

doi:10.21425/f5fbg12277

Abstract

ISSN 1948-6596 news and update thesis abstract Assessing the effect of land-cover changes on species distribu- tions: application of habitat models to conservation of Mediter- ranean bird communities Sara Vallecillo PhD, Biodiversity and Landscape Ecology Lab, Centre Tecnologic Forestal de Catalunya, Solsona, Lleida, and Universitat de Lleida, Spain E-mail: sara.vallecillo.r@gmail.com; http://biodiversitylandscapeecologylab.blogspot.com/ Land-cover changes since the last decades of 20th century are leading to important declines in habi- tat quality, which are responsible for negative im- pacts on global biodiversity and shifts in species distributions (Steffen et al. 2004). Species distribu- tion models (SDM), which map probabilities of a species’ presence based on the correlation be- tween occurrences and several environmental predictors, are thus becoming of prime impor- tance for assessing the response of species to en- vironmental changes (Guisan & Thuiller 2005). SDM-derived maps are also being applied in the selection of priority areas for conservation, an approach that has been encouraged under a global conservation perspective (Rodriguez et al. Land-cover changes are geographically vari- able depending on the ecological and socio- economical context where they occur (Foley et al. 2005). More concretely, in Mediterranean Euro- pean countries, recent socio-economical transfor- mations have altered traditional agricultural prac- tices and caused the abandonment of less fertile and/or remote rural areas. In these landscapes, the abandonment of human activities leads to shrubland and forest encroachment (Preiss et al. 1997). As a result, fire is becoming the main cause of large-scale habitat disturbance and a major agent in maintaining open habitats and landscape heterogeneity (Lloret et al. 2002). Habitat changes induced by these opposing driving forces (i.e. land abandonment and fire) are expected to be critical in determining future biodiversity patterns (Herrando et al. 2003, Moreira & Russo 2007). This is particularly important for birds, because several open-habitat species have declined alarm- ingly and many of them have been designated as species of conservation concern in Europe (BirdLife International 2004). Nevertheless, little is known about how land-cover changes affect pat- terns of species distribution, and further studies at a landscape scale are needed to assess changes in species occurrence in dynamic landscapes. Aims and methods The general aim of my thesis was to identify the ecological processes explaining the distribution of open-habitat bird species in response to the land- cover changes at the landscape scale, emphasizing the role of variations in environmental conditions in space and time. The main processes considered as determinants of land-cover changes in the study area (Catalonia, NE Spain) have been land abandonment and wildfires. In spite of the great impact of fire (130,000 ha of forest burned during the last 20 years of 20th century; Diaz-Delgado et al. 2004), forest extent has not decreased . This is because of the succession that follows land aban- donment, leading to forest expansion in aban- doned areas. Furthermore, fire has been shown to play a critical role, favouring open-habitat bird species at both local and large spatial scales in the study area (Brotons et al. 2004, 2008). To evaluate the response of bird species over space and time, SDMs were built using bird occurrence data from the Catalan Breeding Bird Atlas (Estrada et al. 2004) and environmental data (e.g. land use, topography and climate). We first analysed how the role of habitat conditions varied throughout the species’ range when building global habitat models. Then we evaluated the ca- pability of habitat models to predict changes over time using bird data from two different time peri- frontiers of biogeography 2.1, 2010 — © 2010 the authors; journal compilation © 2010 The International Biogeography Society

Highlights

Land-cover changes since the last decades of 20th century are leading to important declines in habitat quality, which are responsible for negative impacts on global biodiversity and shifts in species distributions (Steffen et al 2004)
As a first approach to assessing the ecological processes determining changes in species distributions, we evaluated the response curves described by the variation in the occurrence patterns of eight open-habitat bird species along habitat gradients (Vallecillo et al 2008)
We defined a gradient of decreasing farmland proportion for three different landscape settings: a semi-permanent farmland–forest landscape and two landscape settings that mimic those favoured by land abandonment and fire: a farmland–shrubland landscape and a mosaic landscape

Summary

Introduction

Assessing the effect of land-cover changes on species distributions: application of habitat models to conservation of Mediterranean bird communities Land-cover changes since the last decades of 20th century are leading to important declines in habitat quality, which are responsible for negative impacts on global biodiversity and shifts in species distributions (Steffen et al 2004).

Results

Conclusion