Application of the state-and-transition approach to conservation management of a grazed Mediterranean landscape in Greece

Traditionally, management of rangelands is based on the successional theory for vegetation developed by Clements. This approach, which came to be known as “the range succession model”, assumes a progressive change of vegetation towards the final (climax) stage and considers grazing as a primary driver of its dynamics. This model cannot be applied in Mediterranean rangelands, however, because they are largely modified plant communities and their final stage is usually a forest or dense woodland. Such “climax-type” vegetation is not necessarily best for conservation, nor does it serve the best management objective. In addition, rangelands are fragmented areas within Mediterranean landscapes requiring an integrated approach to their conservation and management. The “state-and-transition model” developed over the last 15 years seems to be more appropriate for Mediterranean rangelands, because it accommodates a broader spectrum of vegetation changes compared to the range succession model since, besides successional factors, several management factors are also considered. In this paper, a site-specific state-and-transition model is developed for a representative Mediterranean area of northern Greece after analyzing the socio-economic and land cover/use changes for a 33-year period. The model includes four states (arable lands, grasslands, evergreen shrublands, and deciduous oak forests) and seven transitions, all of them management-related. These transitions provide an adequate explanation of the vegetation changes that occurred in the study area and can serve as measures to confront the re-dominance of woody vegetation in the region. It is concluded that the state-and-transition approach provides an effective framework for conservation management of Mediterranean rangelands and landscapes.