Assessing the response of open-habitat bird species to landscape changes in Mediterranean mosaics

Abstract

In Mediterranean landscapes, wildfires and land abandonment lead to major landscape modifications primarily by favouring the presence of open, shrub-like habitats. At present, we know very little of how these changes affect patterns of species occurrence at the landscape scale. In this work, we analyse the impact of these landscape changes on the occurrence patterns of eight open-habitat species by using presence/absence data collected in the Catalan Breeding Bird Atlas (NE Spain). We compared the species occurrence patterns along habitat gradients for three different landscape settings: a semi-permanent farmland-forest landscape (i.e. with variable proportions of farmland and forests) and two landscape settings which mimic those favoured by land abandonment and fire: farmland-shrubland landscapes and mosaic landscapes (i.e. variable proportions of farmland and forest coexisting with a shrubby matrix). In the forest-farmland landscape, we found a dominant negative effect of adjacent forest on species occurrence rates. This overall effect mostly disappeared in farmland-shrubland landscapes composed by two habitats with more similar vegetation structure. In mosaic landscapes, the general negative effect of forest habitats also appeared to be partially compensated by the presence of a shrubby matrix. Our results suggest that landscape gradients induced by fire and to some degree also land abandonment, mainly favouring availability of shrublands may potentially enhance the resilience of threatened open-habitat species at the landscape scale by increasing the range of potential habitats used. The analysis of species-occurrence patterns along predefined habitat gradients appears as a useful tool to predict potential species responses to land use change.

WoodlarksLullula arboreaand landscape heterogeneity created by land abandonment

“…a given individual will need different types of habitat patches within the landscape to meet its vital needs (Delettre et al 1992). The process of complementation found in the present study is also likely to explain the previously reported preference of Woodlarks for regions with a mix of farmland and shrubland in Spain (Vallecillo et al 2008). …”

Relating landscape structure, environment and management to biodiversity indicators estimated from forest inventory data in Catalonia (NE Spain)

“…This is consistent with the intermediate disturbance hypothesis applied also at the landscape scale, which postulates that maximum diversity is provided by intermediate disturbance size, frequency and intensity (Roberts and Gilliam, 1995). Indeed, the rural land abandonment processes and the reduction in forestry activities due to the low profitability of traditional forest products and the introduction of new fuel sources have favoured forest maturation, increased biomass (Poyatos et al, 2003;Roura-Pascual et al, 2005;GilTena et al, 2009) and a potentially excessive landscape homogenization and densification that may induce the dominance of a few adapted species and may have a negative effect on some forest generalists or open habitat species (Vallecillo et al, 2008). For example, many forest bird species in the Mediterranean seem to be adapted to landscape heterogeneity derived from anthropogenic practices (Tellería andSantos, 1999), andLasanta-Martínez et al (2005) also observed a negative impact of abandoned rural landscapes and homogenization on biodiversity.…”

Rural abandoned landscapes and bird assemblages: winners and losers in the rewilding of a marginal mountain area (NW Spain)

“…Forest bird species appear to benefit from forest maturation and spread, which has offset the potentially negative effects of fires on forest birds in Mediterranean regions (Preiss et al 1997;Moreira et al 2001;Suarez-Seoane et al 2002;Laiolo et al 2004;Sirami et al 2007;Gil-Tena et al 2009). Furthermore, once succession from shrubland to forest dominates over the creation of new low-vegetation areas derived from wildfire, open-habitat species might be the group most affected by losses of suitable habitat (Vallecillo et al 2007;De Cáceres et al 2013).…”