Instituto Pirenaico de Ecología, Procesos Geoambientales y Cambio Global, IPE-CSIC, Zaragoza, Spain.
Instituto Pirenaico de Ecología, Procesos Geoambientales y Cambio Global, IPE-CSIC, Zaragoza, Spain.
Sci Total Environ. 2020 May 15;717:137160. doi: 10.1016/j.scitotenv.2020.137160. Epub 2020 Feb 7.
The Mediterranean mountains have been subject to significant land abandonment process during the second half of the 20th century. The subsequent natural revegetation following abandonment in rural areas has been widely documented to have substantial implications on the hydrological cycle and the vegetation. The Spanish Pyrenees are one of the most affected areas by these land transformations which could threaten their importance for water supply and agricultural activities in the downstream lowland areas. Land managers as well as scientists around the world have taken different positions on how to deal with these land use changes. Some are in favor of active management (AM) (i.e. density reduction) while others are supporting passive management (PM) (letting the process of revegetation continue). This study aims to investigate the implication of AM and PM on hydrological and vegetation dynamics under different climate trajectories in a representative abandoned cropland catchment in the Central Spanish Pyrenees. A coupled ecohydrologic model is used to estimate the post management response of streamflow (STR), evapotranspiration (ET), soil saturation deficit (SD) and plant carbon (PC) following shrub clearing. Clearing increased annual STR by 16%, while ET and SD decreased by around -9% and -6% respectively during the first year after management with changes to monthly flows. These changes to water regimes may be even higher in wetter years. Over a 10-years period of vegetation recovery annual STR increased between 7.1% and 24.2%, while annual ET and SD decreased between -2.6% to -8.7% and -2.7% to -6% respectively due to shrub clearing, with the highest changes occurring in the first three years of AM. On the effect of climate change, our results show that a 2 °C increase in temperature could reduce AM effects on water regimes and accelerate the recovery of PC given averaged rainfall conditions.
地中海山区在 20 世纪下半叶经历了大规模的土地弃置过程。在农村地区废弃后，随后的自然植被恢复已被广泛记录，对水文循环和植被有重大影响。西班牙比利牛斯山脉是受这些土地转化影响最严重的地区之一，这可能威胁到下游低地地区的供水和农业活动的重要性。世界各地的土地管理者和科学家对如何应对这些土地利用变化持不同立场。一些人赞成主动管理（AM）（即降低密度），而另一些人则支持被动管理（PM）（让植被恢复过程继续）。本研究旨在调查在中央西班牙比利牛斯山脉一个代表性的废弃耕地流域中，不同气候轨迹下 AM 和 PM 对水文和植被动态的影响。耦合的生态水文模型用于估算管理后溪流流量（STR）、蒸散（ET）、土壤饱和度亏缺（SD）和植物碳（PC）对灌丛清除的响应。清除灌木增加了 16%的年 STR，而 ET 和 SD 在管理后的第一年分别减少了约 9%和 6%，同时改变了月流量。在较湿润的年份，这些水流变化可能更高。在植被恢复的 10 年期间，由于灌木清除，年 STR 增加了 7.1%至 24.2%，年 ET 和 SD 减少了 2.6%至 8.7%和 2.7%至 6%，AM 的前三年变化最大。关于气候变化的影响，我们的结果表明，在平均降雨条件下，温度升高 2°C 可能会减少 AM 对水情的影响，并加速 PC 的恢复。
