Cropland abandonment is a global problem that has affected countries worldwide since the 19th century. Abandoned lands usually undergo a process of plant succession. This process has been widely shown to have implications for ecosystem services, including water provision. Mediterranean mountains are currently in the middle of these land transformations: for example, in the Pyrenees, 80% of the agricultural lands have been abandoned. During the last decades, the management of these areas have become a target of environmental policy makers to ensure the sustainability of ecosystem services. Targeting available resources for land management, however, requires estimates of the effectiveness of different treatment options. This study address this need by relating the management of the abandoned lands to plant succession and hydrological dynamics. We used the Regional Hydro-Ecological Simulation System (RHESSys) to predict the changes to land cover and hydrological dynamics following land abandonment in the Estarrún watershed in the Central Spanish Pyrenees. Projections from passive management allowing vegetation succession, and active management via shrub clearing were defined and their effects on annual streamflow (STR) and annual evapotranspiration (ET) are compared. Results show a high increase in forest cover due to the conversion of all the currently existing shrubs to forest during the upcoming three decades. This conversion to forest cover, would decrease STR by 19%, increase ET by 34%, and reduce the target area for shrub clearing by 72% within 30 years of plant succession. However, shrub clearing would similarly increase STR and decrease ET by 6%, if 7.5% of the study area is cleared. For both STR and ET changes decline rapidly if the management is delayed and the vegetation succession process continues. This study confirms the need to take into account succession following land abandonment in designing land management strategies to preserve water resources in Mediterranean mountain areas.

自19世纪以来，遗弃农田是一个全球性问题，已影响到世界各地的国家。被遗弃的土地通常会经历植物演替的过程。业已广泛表明，这一过程对包括水供应在内的生态系统服务具有影响。目前，地中海山区正处于这些土地转换的中间：例如，在比利牛斯山脉，80％的农田被废弃了。在过去的几十年中，这些区域的管理已成为环境政策制定者的目标，以确保生态系统服务的可持续性。但是，针对土地管理的可用资源，需要估算不同处理方案的有效性。这项研究通过将荒地的管理与植物演替和水文动力学联系起来，满足了这一需求。我们使用区域水生态模拟系统（RHESSys）来预测西班牙比利牛斯中部埃斯塔伦流域的土地遗弃后土地覆盖和水文动态的变化。定义了允许植被演替的被动管理和通过灌木清除的主动管理的投影，并比较了它们对年流量（STR）和年蒸散量（ET）的影响。结果表明，由于在接下来的三十年内所有当前存在的灌木都已转变为森林，因此森林覆盖率大大增加。转换为森林覆盖后，在植物演替的30年内，其STR降低19％，ET升高34％，灌木清理的目标面积减少72％。但是，如果清除灌木丛，则如果增加7，则同样会增加STR，使ET降低6％。清理了研究区域的5％。对于STR和ET而言，如果管理被延迟并且植被演替过程继续进行，则变化会迅速下降。这项研究证实了在设计土地管理策略以保护地中海山区水资源时需要考虑土地遗弃后的继承。