Rainfall interception by sand-stabilizing shrubs related to crown structure

On the edge of the Tengger Desert in northern China, revegetation has changed the landscape from moving dunes to stabilized dunes covered by shrubs, which further modifies the pattern of rainfall redistribution. To study rainfall interception loss by shrubs and its relationship to rainfall properties and crown structure, throughfalls passing through crowns of Artemisia ordosica Krash. and Caragana korshinskii Kom. were measured using nine PVC cups under the canopy of each of the two shrubs during 73 rain events over a three-year period, with total rainfall of 260.9 mm. Interception losses of gross rainfall by A. ordosica and C. korshinskii account for 15% and 27% of the total on a crown area basis, and 6% and 11% on a ground area basis, respectively. Individual throughfall (T) and interception (I) were significantly related to rainfall amount (P-g), duration (D), and intensity (R). Ratios of throughfall to rainfall (T/P-g) and interception to rainfall (I/P-g) were not only significantly related to P-g, D, and R, but also to shrub species, and interactions of species with crown volume (C-V) and leaf area index (LAI). Under most rain events, interceptions by C. korshinskii with greater C-V and LAI were significantly higher than those by A. ordosica, and more rainfall interception occurred at locations closer to the stems of the two shrubs. For C. korshinskii, I/P-g had a significant positive linear relation with C-V and LAI, while T/P-g had a significant negative linear relation with them. C-V has a greater influence on T/P-g and I/P-g than does LAI. Using a regression method, canopy water storage capacities are estimated to be 0.52 and 0.68 mm, and free throughfall coefficient to be 0.62 and 0.47 for A. ordosica and C. korshinskii, respectively.