Spatial variability of throughfall in a Chinese Pine (Pinus tabulaeformis) plantation in northern China

Abstract

The interception of rainfall by vegetation and the subsequent evaporation of intercepted water from the canopy surface play an important role in hydrological processes, and the water and energy balance of forest ecosystems. Spatial variability of interception has different effects on water yield from watersheds located in different climatic and biome regions. In order to explain the spatial patterns of interception, we adopted grid-sampling method to install rain-gauges to measure throughfall. Results show that the coefficient of variation (Cv) of throughfall tends to decline as rain intensity increases. After the canopy is saturated, Cv of throughfall remained at a constant value, which is close to the Cv of the canopy leaf area index (LAI) value 0.18. Thus, the Cv of LAI is regarded as the extremum of that of throughfall. Because of the special characteristic of Chinese pine (Pinus tabulaeformis), and the lower droopy branches, negative values for interception account for only 13% of the total samples. Furthermore, the max is above 70% of gross rainfall.