Polylepis树生长在整个安第斯山脉的连续树线(3000-5000ma.s.l.)上方。他们容忍极端的环境条件,使它们成为全球气候变化的敏感生物指标。因此,调查它们的生态水文作用是了解安第斯源头水循环如何受到环境条件预测变化影响的关键,以及该地区正在进行的Polylepis重新造林计划。我们估计,第一次,位于厄瓜多尔南部的成熟Polylepis森林(Polylepisreticulata)流域(3780ma.s.l.)的年度水平衡,使用一组独特的野外生态水文测量,包括总降雨量,穿透,水流,和木质部汁液流结合森林和土壤特征的表征。我们还将森林水平衡与草丛(中间的Calamagrostis)流域的水平衡进行了比较,主要的páramo植被。研究期间(2019年4月至2020年3月)的年总降雨量为1290.6mmyr-1。Polylepis森林的穿透量占年总降雨量的61.2%。溪流是林地水量平衡的主要组成部分(59.6%),而其土壤储水量的变化可忽略不计(<1%)。森林蒸散量为54.0%,冠层截留蒸发(38.8%)是蒸腾作用(15.1%)的两倍多。Polylepis流域年水平衡误差较小(<15%),对用于估计其组成部分的测量和假设提供信心。相比之下,草地上的流量和蒸散量分别占水平衡的63.7%和36.0%,分别。尽管森林流域的蒸散量较大,相对于草地流域,其产水量仅略有减少(<4%)。与草地地区(31.8%)相比,森林地区(47.6%)的土壤有机质含量高得多,这表明即使Polylepis森林不会损害高安第斯流域的水文功能,它们的存在有助于森林凋落物层和底层土壤中的碳储存。这些发现为安第斯高生态系统中的植被-水碳关系提供了关键见解,考虑到土地利用和全球气候的变化,这可以作为未来生态水文研究和改善páramo自然资源管理的基础。
Polylepis trees grow at elevations above the continuous tree line (3000-5000 m a.s.l.) across the Andes. They tolerate extreme environmental conditions, making them sensitive bioindicators of global climate change. Therefore, investigating their ecohydrological role is key to understanding how the water cycle of Andean headwaters could be affected by predicted changes in environmental conditions, as well as ongoing Polylepis reforestation initiatives in the region. We estimate, for the first time, the annual water balance of a mature Polylepis
forest (Polylepis reticulata) catchment (3780 m a.s.l.) located in the south Ecuadorian páramo using a unique set of field ecohydrological measurements including gross rainfall, throughfall, streamflow, and xylem sap flow in combination with the characterization of forest and soil features. We also compare the
forest water balance with that of a tussock grass (Calamagrostis intermedia) catchment, the dominant páramo vegetation. Annual gross rainfall during the study period (April 2019-March 2020) was 1290.6 mm yr-1. Throughfall in the Polylepis
forest represented 61.2 % of annual gross rainfall. Streamflow was the main component of the water balance of the forested site (59.6 %), while its change in soil water storage was negligible (<1 %).
Forest evapotranspiration was 54.0 %, with evaporation from canopy interception (38.8 %) more than twice as high as transpiration (15.1 %). The error in the annual water balance of the Polylepis catchment was small (<15 %), providing confidence in the measurements and assumptions used to estimate its components. In comparison, streamflow and evapotranspiration at the grassland site accounted for 63.7 and 36.0 % of the water balance, respectively. Although evapotranspiration was larger in the forest catchment, its water yield was only marginally reduced (<4 %) in relation to the grassland catchment. The substantially higher soil organic matter content in the
forest site (47.6 %) compared to the grassland site (31.8 %) suggests that even though Polylepis forests do not impair the hydrological function of high-Andean catchments, their presence contributes to carbon storage in the litter layer of the forest and the underlying soil. These findings provide key insights into the vegetation-water‑carbon nexus in high Andean ecosystems, which can serve as a basis for future ecohydrological studies and improved management of páramo natural resources considering changes in land use and global climate.