Dryness is accelerating degradation of vulnerable shrublands in semiarid Mediterranean environments

Semiarid Mediterranean regions are highly susceptible to desertification processes. This study investigated the influence of increasing climate aridity in explaining the decline in vegetation cover in highly vulnerable gypsum semiarid shrublands of the Mediterranean region. For this purpose, we have used time series of the percentage of vegetation coverage obtained from remote sensing imagery (Landsat satellites). We found a dominant trend toward decreased vegetation cover, mainly in summer and in areas affected by the most severe water stress conditions (low precipitation, higher evapotranspiration rates and sun-exposed slopes). We show that past human management and current climate trends interact with local environmental conditions to determine the occurrence of vegetation degradation processes. The results suggest that degradation could be a consequence of the past overexploitation that has characterized this area (and many others in the Mediterranean region), but increased aridity,...半干旱地中海地区极易发生荒漠化过程。本研究针对地中海地区高度脆弱的石膏质半干旱灌丛，探究了气候干旱化加剧对其植被覆盖度下降的解释作用。为此，本研究采用了基于陆地卫星（Landsat）遥感影像获取的植被覆盖度百分比时序数据。研究发现，植被覆盖度呈显著下降趋势，该趋势主要出现在夏季以及受最严重水分胁迫的区域（低降水、高蒸散速率且向阳的坡地）。本研究表明，既往人类活动管理模式与当前气候趋势，会同局地环境条件共同作用，决定了植被退化过程的发生。研究结果显示，该区域（以及地中海地区诸多其他区域）的植被退化或源于过往以过度开发为特征的人类活动，但干旱化加剧……