Abstract

Land use and cover changes have been identified as a major factor contributing to shape landscape struc-ture and biodiversity patterns, particulary in areas with a long history of human occupation and habitatfragmentation, such as the Mediterranean landscapes. However, the existing studies on landscape changeindicators for Mediterranean areas have mostly focused in Europe, while for other Mediterranean zones,and especially for South America, there is a serious lack of knowledge concerning the impact of landscapedynamics on ecological processes. Further research on this topic is urgently needed, given the high bio-diversity levels and the rapidly increasing rates of human modification in the Mediterranean landscapesof South America. For this purpose, we investigated the dynamics of a landscape in the semiarid region ofthe Mediterranean zone of Chile, and measured the effect of those dynamics on functional connectivity,during a period of about four decades (1975–2011). Landscape connectivity indicators were extractedfrom a series of Landsat images. The Equivalent Connnected Area index (ECA) was used as indicator ofconnectivity trends, and was evaluated for three representative distances of seed dispersal in the studyarea (150 m, 500 m and 1000 m). In addition, the patches that most contribute to maintain the presentconnectivity, and their roles as connectivity providers, were identified through a set of commensurableindicators: betweenness centrality and the fractions (intra, flux connector) of the Integral Index of Con-nectivity. We found that these indicators were useful to detect and summarize a number of previouslyunreported trends in these Mediterranean landscapes. First, population growth and economic develop-ment were compatible with an increase in functional connectivity for forest habitats, mainly because theabandonment of marginal agricultural lands and their subsequent conversion to espinals (Acacia caven)triggered vegetation succession towards secondary forests. Second, increased forest connectivity was notassociated to a decrease in the characteristic heterogeneity of Mediterranean landscapes. Third, manypatches of espinal, despite being commonly regarded as of poor conservation value, were crucial to pro-mote connectivity by acting as stepping stones among other patches with higher habitat quality. Theapproach here presented provides a combined assessment of landscape structure, function and changethat should be valuable and applicable to deliver operational indicators in dynamic landscapes in SouthAmerica and other Mediterranean regions.