21世纪地中海群山区的气候变化

由于气候的变化直接或间接地影响了诸如生物多样性、雪盖、冰川、径流过程、水的可利用性等各种不同的关键要素,人们认为地中海群山区的生物群落正在遭受威胁。本文中,基于不同排放情景(排放情景特别报告)和大气-海洋耦合总体循环模型(AOGCMs,Atmosphere-Ocean-Coupled General CirculationModels),我们对两个时期即2055(2040～2069年间)和2085(2070～2099年间)期间地中海群山区的温度、降水量、春季降水量的变化进行了评价。最后,将地中海群山区和欧洲地区非地中海群山区的未来气候变化趋势的预测结果进行了对比。预计到2055期间,温度将增高1.4～5.1℃,而到2085期间将增温1.6～8.3℃。气候模型也预测地中海群山区的降水量将减少,且主要集中于春季(2085期间,排放情景Alfi下减少17%,B1下减少4.8%)。而与之相反,欧洲非地中海群山的年降水量和春季降水量并不会减少。将预期的气候变化对自然和人文特性的意义结合到一个综合框架中,以得到一个关于未来趋势及其后果的更广阔的视角。

Effects of cropland abandonment and afforestation on soil redistribution in a small Mediterranean mountain catchment

In slopes of Mediterranean mid-mountain areas,land use and land cover changes linked to the aban-donment of cropland activity affect soil quality and degradation and soil redistribution;however,limited attention has been paid to this issue at catchment scale.This paper evaluates the effects of cropland abandonment and post-land abandonment management(through natural revegetation and afforesta-tion)on soil redistribution rates using fallout ^(137)Cs measurements in the Araguás catchment(0.45 km^(2),Central Spanish Pyrenees).A total of 52 soil core samples,distributed in a regular grid,from the first 30-40 cm and 9 sectioned reference samples were collected across the catchment and soil properties were analysed.Fallout ^(137)Cs was measured in a 5 cm sectioned references samples and in bulk grid samples.^(137)Cs inventories were used to estimate soil erosion and deposition rates across the catchment.Results show that the highest erosion rates were recorded under sparsely vegetated sites in the badland area,while the lowest rates were found in the afforested area,but no significant differences were observed between the different uses and covers in soil redistribution rates likely due to a long history of human intervention through cultivation in steep slopes and afforestation practices.However,the recovery of the soil organic matter in afforested areas suggest that afforestation can reduce soil degradation at long-term scale.The information gained achieve a better understanding of soil redistribution dynamics and provide knowledge for effective land management after cropland abandonment of agroecosystems in Mediter-ranean mountain areas.