Large spatial variations in the distributions of and factors affecting forest water retention capacity in China

Abstract The estimation of forest water retention based on observation and experimental data can be used to accurately analyze large variations in the spatial distributions of the water retention capacity across China and explore factors affecting these large spatial variations at different scales. Therefore, we reviewed the relevant peer-reviewed literature to extract water retention parameters and their influencing factors throughout China via a meta-analysis approach. Furthermore, an empirical model and path analysis were used to explore the spatial distributions of and significant factors affecting the canopy interception capacity (CIC), litter maximum water-holding capacity (LWHC), soil water storage capacity (SSC) and forest water retention capacity (WRC) at the national and basin scales. The results showed that the spatial distributions of the CIC and LWHC exhibited opposite trends in China. The average CIC values in the Pearl River Basin (PRB), Southeast Rivers Basin (SERB), Southwest Rivers Basin (SWRB) and Yangtze River Basin (YTRB) were two times higher than those in the Songhua River Basin (SHRB), Liao River Basin (LRB) and Northwest Rivers Basin (NWRB). In addition, the SSC values accounted for approximately 60–85% of the WRC values in the different basins, soil types and forest types. The average SSC values in semi-alfisol and ferralsol were 2.5 times higher than those in semi-hydromorphic soil and pedocal. Moreover, the effects of some factors such as location, terrain and canopy structure on the CIC, LWHC, SSC and WRC values were significant in only certain basins, but these effects were not significant throughout China. The indirect effects of some climatic, location and terrain factors on the CIC, LWHC, SSC and WRC values determined the total effects. These results can contribute to a better understanding of the large spatial variations in WRC and provide a scientific basis for the improvement of the forest water retention function across China.