干旱区生态环境知识资源中心

More than 40 years of re-vegetation using mainly xerophytic shrubs Artemisia ordosica Krasch. and Caragana korshinskii Kom. at Shapotou Desert Experimental Research Station near Lanzhou, China has resulted in established dwarf-shrub and herbaceous cover on sand dunes. Precipitation, as the sole source of water replenishment in the semiarid area, plays a pertinent role in sustaining the desert ecosystem. A field study was conducted to (a) measure interception loss on shrub canopies during individual rainfall events, (b) determine the canopy storage capacity of individual plants, and (c) explore the relationship between interception and rainfall parameters. The total rainfall and its respective partitions as throughfall were determined and the interception losses in the studied ecosystem were quantified. Interception loss was shown to differ among the xerophyte taxa studied. During the growing seasons, the average shrub community interception loss is 6.9% and 11.7% of the simultaneous overall precipitation, for A. ordosica and C. korshinskii, respectively. Taking into account the observed rainfall conditions and vegetation cover characteristics, it was concluded that the interception loss was 2.7% of the total annual precipitation verified in the period for the A. ordosica community with an average cover of 30%, canopy projection area of 0.8 m(2) and canopy storage capacity of 0.75 mm. In contrast, interception loss for the C korshinskii community was 3.8% with an average cover of 46%, canopy projection area of 3.8 m(2) and canopy storage capacity of 0.71 mm. For individual plants of both shrubs, the proportion of interception loss to gross rainfall decreased notably as the rainfall intensity increased between 0 and 2 min h(-1), while it tended to remain constant at about 0.1-0.2 for A. ordosica and 0.1-0.3 for C. korshinskii when the rainfall intensity was > 2 mm h(-1).