Instituto Biósfera, Universidad San Francisco de Quito USFQ, Diego de Robles y Vía Interoceánica, Quito 170901, Ecuador.
Departamento de Recursos Hídricos y Ciencias Ambientales & Facultad de Ingeniería, Universidad de Cuenca, Av. 12 de abril, Cuenca 010203, Ecuador; Facultad de Ciencias Agropecuarias, Carrera de Ingeniería Agronómica, Universidad de Cuenca, Av. 12 de octubre, Cuenca, Ecuador.
Sci Total Environ. 2022 Jan 15;804:150112. doi: 10.1016/j.scitotenv.2021.150112. Epub 2021 Sep 4.
High-elevation grasslands worldwide provide essential hydrological services including water provision, flow regulation, and erosion control. Despite their importance, hydrological research of grasslands in montane regions is usually scarce and disperse, limiting the capacity to improve water resource management. We present a systematic literature review of the hydrological function of high Andean grasslands under conserved, degraded, and restored conditions in ecosystems situated above the tree line in the tropical Andes (páramos, punas, and jalcas). Most hydrological research on these grasslands has been developed in páramos (92%), especially in Ecuador, while research in punas is scarce (6%) despite being the largest grassland extent in the region. For páramos, published literature highlights the importance of conserving grasslands to facilitate water infiltration to soils, which in turn reduces erosive processes. Water-vegetation relations for conserved páramos are well understood, indicating that about 50% of water inputs return to the atmosphere via evapotranspiration, but knowledge about hydrological functions of conserved punas and jalcas is virtually non-existent. Under changing land use, afforestation of grassland ecosystems with exotic tree species, especially pines, reduces soil water storage as well as water yield and flow regulation capacity. Impacts of grazing and agriculture on the hydrological function of páramo grasslands strongly depend on historical land management and current land use practices and are not generalizable. Short-term restoration studies indicate that more than two years are necessary to recover the hydrological function of degraded grasslands, therefore medium and long-term studies are required to determine efficient restoration periods. These knowledge gaps limit the ability to extrapolate and regionalize findings. Future directions aimed to fill them are proposed, and methods successfully used to investigate the hydrology of high Andean grasslands are highlighted. This research not only enlightens what is known about the hydrology of high Andean grasslands, but also seeks to guide future hydrological evaluations to fill identified geographical and topical knowledge gaps precluding improved management of water resources in the tropical Andes.
高海拔草原在全球范围内提供了重要的水文服务，包括供水、流量调节和侵蚀控制。尽管它们很重要，但山地地区草原的水文研究通常很少且分散，限制了改善水资源管理的能力。我们对热带安第斯山脉（帕拉莫、潘纳和哈拉卡）林线以上生态系统中保护、退化和恢复条件下的高安第斯草原的水文功能进行了系统的文献综述。这些草原的大部分水文研究都是在帕拉莫（92%）进行的，尤其是在厄瓜多尔，而在潘纳的研究很少（6%），尽管潘纳是该地区最大的草原面积。对于帕拉莫，已发表的文献强调了保护草原的重要性，以促进水渗透到土壤中，从而减少侵蚀过程。保护帕拉莫的水-植被关系得到了很好的理解，表明大约 50%的水输入通过蒸散返回大气，但关于保护潘纳和哈拉卡的水文功能的知识几乎不存在。在土地利用变化的情况下，外来树种，特别是松树，对草原生态系统的造林减少了土壤水分储存以及产水量和流量调节能力。放牧和农业对帕拉莫草原水文功能的影响强烈取决于历史土地管理和当前土地利用实践，并且不具有普遍性。短期恢复研究表明，退化草原的水文功能需要两年以上的时间才能恢复，因此需要进行中长期研究以确定有效的恢复期。这些知识差距限制了外推和区域化研究的能力。提出了填补这些差距的未来方向，并强调了成功用于研究高海拔安第斯草原水文的方法。这项研究不仅阐明了我们对高海拔安第斯草原水文的了解，而且旨在指导未来的水文评估，以填补确定的地理和专题知识差距，从而改善热带安第斯山脉的水资源管理。
