Rainfall partitioning into throughfall, stemflow and interception loss by two xerophytic shrubs within a rain-fed re-vegetated desert ecosystem, northwestern China

Knowledge of rainfall partitioning into throughfall, stemflow and interception loss by xerophytic shrubs is useful for implementing and evaluating re-vegetation projects, and for hydrologic budget modeling over vast arid desert areas. However, information about rainfall partitioning by xerophytic shrubs and the controlling factors are still under-represented in the literature. This study examined whether morphological features play a significant role in rainfall partitioning, using two xerophytic shrubs that are widely used in re-vegetation in arid areas of China, and evaluated the effects of rainfall characteristics and meteorological variables on rainfall partitioning. Caragana korshinskii is a multiple-stemmed shrub with smooth stems and ovate leaves, while Artemisia ordosica is a highly branched dwarf-shrub with a rough stem and needled leaves. We hypothesized that rainfall partitioning significantly differs between the two shrubs with a higher stemflow production and lower interception loss for C. korshinskii than A. ordosica. Gross rainfall, throughfall and stemflow for the two shrubs were measured during 3 growing seasons between 2011 and 2013 within a re-vegetated desert ecosystem of northwestern China. On average, measured throughfall, stemflow and derived interception loss for C. korshinskii accounted for 74.31%, 8.99% and 16.70% of incident gross rainfall, respectively. Corresponding values for A. ordosica were 74.83%, 2.89% and 22.28%, respectively. Significant differences (P <0.05) in stemflow and interception loss were detected between C. korshinskii and A. ordosica. Rainfall partitioning (in mm) was significantly positively correlated with individual rainfall depth. Stemflow generally did not occur following rainfall events of less than 1.3mm for C. korshinskii and 2.2mm for A. ordosica. Small amounts of rainfall contributed to a lower percent of net rainfall and higher percent of interception loss. The percentages of stemflow and throughfall showed the increased tendency with increasing rainfall intensity, while a decreased tendency for the percentage of interception loss; and after a threshold value of ∼2mmh−1, they tended to be quasi-constant. Meteorological variables such as air temperature, relative humidity and wind speed had no significant correlations with rainfall partitioning. In general, monitoring of rainfall partitioning supported our hypothesis. Gross rainfall characteristics are considered to be sufficient in estimating stemflow and throughfall; while for a better prediction of interception loss, other meteorological variables are suggested to be included.