Forest thinning is often used as a strategy to augment water supply by decreasing stand evapotranspiration. To study the influence of such thinning on the water balance of a Larch (Larix principis-upprechtii Mayr.) plantation in the water-limited Loess Plateau of Northwest China, this study analyzed the components of the stand water balance after thinning during an extremely wet and dry year using the water balance approach. Tree transpiration (Et) was measured by tree sap flow, which was scaled to the plot level. The canopy interception loss (E_c) was estimated by subtracting the throughfall and stemflow from the gross precipitation. Unerstory evapotranspiration (E_u) was measured by weighing micro-lysimeters in each plot. Changes in the soil moisture were manually measured by the drying method. The results showed that thinning enhanced the stand-level soil water moisture due to the increased throughfall in the Larch plantation. Thinning induced decreases in E_t and E_c, while increasing E_u and water yield during the observation periods. With regard to the components of evapotranspiration (ET), thinning increased the contribution of E_u to ET, and decreased the contribution of E_t and E_c to ET. The decrease in LAI due to thinning also led to an increase in water yield and a decrease in both E_t and E_c. Only high-intensity thinning can maintain the water yield function under the extreme drought. Under the current conditions, thinning to less than 844 stems/hm² may be a very good option to increase the water yield.

森林砍伐经常被用作通过减少林分蒸散量来增加水供应的策略。为了研究这种稀疏化对西北偏黄土高原落叶松（Larix principis-upprechtii Mayr。）人工林水分平衡的影响，本研究分析了在极度潮湿的情况下稀疏后的林分水平衡组成。和干燥的一年使用水平衡法。通过树液流量测量树的蒸腾量（Et），将其缩放到样地水平。通过从总降水量中减去通流量和茎流量，可以估算出冠层截留损失（E _c）。Unerstory蒸散（ē _û通过在每个图中称重微量测微计来测量）。通过干燥方法手动测量土壤水分的变化。结果表明，由于落叶松人工林穿透量的增加，间伐减少增加了林分水平的土壤水分。在观测期间，间伐引起的E _t和E _c降低，而E _u和水产量增加。关于蒸散（ET）的组成，稀化增加了E _u对ET的贡献，并减少了E _t和E _c对ET的贡献。由于稀疏导致的LAI下降也导致水产量增加以及E _t和E _c均下降。在极端干旱的情况下，只有高强度疏伐才能维持水分生产功能。在当前条件下，减薄至小于844茎/ hm ²可能是提高水产量的一个很好的选择。