单株华北落叶松树冠穿透雨的空间异质性

Spatial Heterogeneity of Throughfall under Canopy of Single Plant of Larix principis-rupprechtii

林水问题是生态水文学研究的核心问题之一。为了研究降雨通过华北落叶松树木冠层的空间分异规律,2016年生长季在1株样树冠层下机械布置了32个雨量筒,测定了22场不同降雨事件的穿透雨量,利用地统计学方法分析穿透雨的空间变异性规律。结果表明:树冠下存在着穿透雨的最小区域和有汇集降雨作用的"漏斗"区域;在比较了不同雨量筒布设方案的穿透降雨变化后发现,在距离树干1/3冠幅半径的同心环上测定的穿透雨量可基本接近整个树冠下的穿透雨量平均值;半方差函数分析表明,穿透雨率的基台值C+C_0随降雨量增大而减小,C_0/(C+C_0)随降雨量的增大而增大,说明较小降雨量时,冠层结构是引起穿透雨空间变异的主要因素;降雨量较大时,冠层结构的影响减弱,其空间分布差异主要受随机因素影响。

There lation of forest and water resource is one of the core problems in ecohydrology.In order to under-stand the spatial heterogeneity of throughfall under the forest canopy,throughfall is measured under the canopy of single tree of Larix principis-rupprechtii during 22 rainfall events,using 32 rain gauges in the growing season(fromJunetoSeptember)of 2016.Throughfall is analyzed by the geostatistical method.The results show that the lowest throughfall area and the funnel area for collecting the rain exist under the different position of canopy and the funnel area alters frequently in different rainfall events.The comparison on throughfall with different rain gauge ar-rangements indicates that the throughfall measured at the concentric circle of 1/3 of canopy radius can reasonably represent the average throughfall under the whole canopy of L.principis-rupprechtii.The analysis of semi-variance of throughfall shows that the sill C+C0 reduces with the increasing of rainfall and the C0/(C+C0)increases with the increasing of the rainfall,which in dicates that canopy structure is a key factor influencing spatial variation of throughfal lwhen the rainfall is lower,however,when the rainfall is higher,the influence of canopy weakens,and the difference of spatial distribution is mainly influenced by random factors.