Satellite remote sensing of land cover change in a mixed agro-silvo-pastoral landscape in the Alentejo, Portugal

ABSTRACT

Mixed agro-silvo-pastoral landscapes are typically of significant natural, economic and cultural value. The montado (wood pasture) dominated systems of southern Portugal are a prime example, and experience high rates of land cover change. Tracking these changes is of importance for landscape level conservation and management. Whilst satellite remote sensing is the most realistic approach at large spatial scales, heterogeneous landscapes can present challenges to the accurate classification of land cover and its change. In this investigation we demonstrate a novel approach to the investigation of land cover change over a 25 year period (1984–2009) in an area of importance for the conservation of the Iberian lynx, Black vulture, and other threatened biodiversity in south-east Alentejo, Portugal. We apply a Tasselled Cap Transformation (TCT) to Landsat imagery from these two years, and then Change Vector Analysis (CVA) on the transformed data to highlight areas of vegetation gain and loss during the intervening period. Using a 2009 land cover classification, and a set of rules based on these vegetation changes, we then predict the land change over the 25 year period focussing on predominant classes of vegetation physiognomy. The results are discussed in terms of probable drivers, as well as implications for biodiversity and other landscape values.

Acknowledgments

The authors are grateful for the support provided by funding from the Cambridge Conservation Initiative, and to the Portuguese land owners who gave us access to their farms during the fieldwork for this project. In addition we thank representatives from the Portuguese nature conservation sector (government and NGOs), farmers’ and foresters’ federations, and hunting and landowning interests in our study area who provided us with their expertise at two project workshops, and in particular to Nuno Pedroso (LPN), Dr Miguel Bugalho (Centre for Applied Ecology, School of Agriculture, University of Lisbon), Dr Jorge Palmeirim (Centre of Environmental Biology, Faculty of Sciences of Lisbon University) and Antonio Claudio Heitor (CONFRAGI, the National Federation of Agricultural Cooperatives) for their expert advice. Last, but not least, we thank Zuzanna Swirad for her GIS expertise.

Disclosure statement

The project’s UK-Portuguese partners were the University of Cambridge (William Simonson, Department of Plant Sciences, and Harriet Allen, Department of Geography), Fauna and Flora International (Paul Hotham, Erin Parham and Philine von Guretzky) and Liga para a Protecção de Natureza (Eduardo Santos, Nuno Curado and Filipa Loureiro). There is no financial interest or benefit for the authors arising from the direct applications of this research.

Additional information

Funding

This paper derives from a collaborative project Mediterranean Wood Pastures for Biodiversity – Making the Lynx, funded by the Cambridge Conservation Initiative Collaborative Fund which is sponsored by Arcadia (Project grant CCI 05-13-008). The aim of the project was to develop new tools to help conserve the emblematic wood pasture landscapes of southern Portugal.