Intensified slash‐and‐burn cultivation and forest clearing have caused severe land degradation in the Khasi Hills (Meghalaya plateau, NE India). Despite very high annual rainfall, the region faces severe water scarcity during the dry season. Local initiatives aim to restore forests through assisted natural regeneration (ANR) in this hydrologically poorly known area. As a first step towards assessing the potential hydrological impact of forest regrowth and ANR, we measured infiltrability at sites representing Imperata‐dominated grassland (n = 2, degraded baseline); < 20‐year‐old fallows with ANR (n = 3); semi‐mature to old‐growth forests (n = 4, near‐natural baseline); and a bench‐terraced Cryptomeria plantation. Group‐median infiltrability was highest in forests (425 mm h−1), followed by young fallows with ANR, and grasslands (145 and 68 mm h−1, respectively), and the terraced plantation (50 mm h−1). Infiltrability increased with regrowth age at an average rate of 3.0 mm h−1 y−1. Dye infiltration experiments were used to identify dominant percolation pathways per main land‐cover type. Infiltration in the least‐disturbed forest was dominated by flow along roots, stones and other preferential pathways, while matrix flow dominated in the grassland; the ANR site showed intermediate behaviour (macropore flow with high matrix interaction). Comparing median infiltrabilities with (maximum) hourly rainfall intensities suggested infiltration‐excess overland flow may occur occasionally in the grasslands. Despite improved infiltrability during regrowth (with or without ANR), the extreme monsoon rainfall and often shallow and stony soils pose serious limitations to rebuilding soil water storage capacity and favour frequent saturation‐excess overland flow.

中文翻译：

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（辅助）自然再生对卡西山（印度东北部梅加拉亚邦）渗透性和优先流动途径的影响


集约化的刀耕火种和森林砍伐导致卡西山（印度东北部梅加拉亚高原）的土地严重退化。尽管年降雨量非常高，但该地区在旱季面临严重的缺水问题。地方倡议旨在通过辅助自然再生 （ANR） 在这个水文鲜为人知的地区恢复森林。作为评估森林再生和 ANR 潜在水文影响的第一步，我们测量了代表 Imperata 主导草原的地点的渗透性（n = 2，退化基线）;< 20 岁休耕期伴 ANR （n = 3）;半成熟至老龄森林（n = 4，接近自然基线）;和一个长凳梯田的柳杉种植园。森林 （425 mm h-1） 的群体中位渗透率最高，其次是具有 ANR 的幼苗休耕地、草原（分别为 145 和 68 mm h-1）和梯田种植园 （50 mm h-1）。渗透性随着再生年龄的增加而增加，平均速率为 3.0 mm h-1 y-1。染料渗透实验用于确定每种主要土地覆盖类型的主要渗流途径。在受干扰最少的森林中，沿根、石和其他优先途径的流以渗透为主，而基质流在草原中占主导地位;ANR 位点表现出中等行为 （具有高基质相互作用的大孔流）。将中位渗透率与（最大）小时降雨强度进行比较表明，草原偶尔会出现过量的陆上渗透。尽管再生过程中的渗透性有所提高（有或没有 ANR），但极端的季风降雨和通常的浅层和石质土壤对重建土壤储水能力构成了严重限制，并有利于频繁的饱和过剩的陆上水流。