The socio-ecological system dominated by pastureland in the Asteroussia Mountains (Crete, Greece) was analyzed over a long time interval (1945–2010) to identify the most relevant system’s characteristics and changes. Vegetation cover and land-uses have been quantified by analyzing aerial photographs exploring the whole study period. Soil characteristics have been assessed by carrying out an extensive field survey for the last reference year (2010) and by estimating the average soil loss for the past period using the PESERA soil erosion model validated by field measurements. Based on environmental, social and economic attributes, three major periods characterizing the socio-ecological system of Asteroussia Mountains have been distinguished. During the first and second period, the land was satisfactorily managed with moderate–low soil erosion rates despite the adverse (prevailing) soil, topographic and climate conditions for vegetation growth. The third time interval featured a rapid growth in the livestock density causing increased soil erosion rates, loss in plant productivity, and a generalized over-exploitation of natural resources. As a consequence, the desertification process has significantly increased in the last period. The analysis of the long-term evolution of socio-ecological system provided evidence to understand the main drivers of land degradation and to recommend mitigation policies specifically addressing Mediterranean pastureland.
The impact of simulated future climate change on land degradation was assessed in three representative study sites of Thessaly, Greece, one of the country’s most important agronomic zones. Two possible scenarios were used for estimation of future climatic conditions, which were based on greenhouse gas emissions (RCP4.5 and RCP8.5). Three time periods were selected: the reference past period 1981–2000 for comparison, and the future periods 2041–2060 and 2081–2100. Based on soil characteristics, past and future climate conditions, type of land uses, and land management prevailing in the study area, the Environmentally Sensitive to desertification Areas (ESAs) were assessed for each period using the MEDALUS-ESAI index. Soil losses derived by water and tillage erosion were also assessed for the future periods using existing empirical equations. Furthermore, primary soil salinization risk was assessed using an algorithm of individual indicators related to the natural environment or socio-economic characteristics. The obtained data by both climatic scenarios predicted increases in mean maximum and mean minimum air temperature. Concerning annual precipitation, reductions are generally expected for the three study sites. Desertification risk in the future is expected to increase in comparison to the reference period. Soil losses are estimated to be more important in sloping areas, due especially to tillage erosion in at least one study site. Primary salinization risk is expected to be higher in one study site and in soils under poorly drainage conditions.
The degradation of natural resources at an intense rate creates serious problems in the environmental systems particularly with the compounding effects of climatic vagaries and changes. On the one hand, desertification is a crucial universal, mostly an anthropogenic environmental issue affecting soils all over the world. On the other hand, drought is a natural phenomenon in direct association with reduced rainfall in various spatial and temporal frames. Vulnerabilities to drought and desertification are complex processes caused by environmental, ecological, social, economic and anthropogenic factors. Particularly for the Mediterranean semi-arid conditions, where the physical and structural systems are more vulnerable, the abuse and overuse of the natural resources lead to their degradation and ultimately, if the current trends continue, to their marginalization. The scope of the current effort is trying to find any common drivers for the pressures of both processes. Thus, the vulnerabilities to drought and desertification are comparing by using the Standardized Drought Vulnerability Index (SDVI) and the Environmentally Sensitive Areas Index (ESAI). The indices are calculated from October 1983 to September 1996 in Greece. Greece is prone to desertification and it is often experiencing intense droughts, thus it presents an almost ideal case study area. The results may indicate that the most important factor for such procedures is the deficits in water resources, either due to lower than usually expected rainfall or to higher societal water demand.