Comparison of Interception Loss in Shrubby and Sub-shrubby Communities in the Tengger Desert of Northwest China
WANG Xin-ping, KANG Er-si, ZHANG Jing-guang, LI Xin-rong(Shapotou Desert Experimental Research Station, CAREERI, CAS, Lanzhou Gansu 730000, China)
Forty years of re-vegetation, mainly by xerophytic shrubs Artemisia ordosica Krasch and Caragana korshinskii Kom, in the Shapotou Desert Experimental Research Station has established a dwarf-shrub and herbaceous cover on stabilized sand dunes. Precipitation, as the sole source of water replenishment in the semi-arid area, plays a pertinent role in sustaining the desert ecosystem. A field study was conducted to measure the interception loss by the shrubs canopy evaporation during individual rainfall events, and determine the rainfall-storage capacity of two plants canopy. The relationship between interception and rainfall parameters is discussed. The importance of vegetation cover can be seen in the distribution of rainfall and interception loss. Xerophyte shrub species could affect interception loss. For the Artemisia ordosica community with an average cover of 34 and the canopy projection of 39 cm×100 cm, the canopy storage capacity is 0.7 mm, and average interception loss is 26^82 of the total annual precipitation. In contrast, for the Caragana korshinskii community with an average cover of 30 and the canopy projection of 40^7 cm×100 cm, the canopy storage capacity is 0^3 mm, and average interception loss is 17 of the total annual precipitation. Both shrubby and sub-shrubby communities appear particular interception patterns, closely relating to the characteristics of rainfall during experimental periods. The proportion of interception loss to gross rainfall decreases with the rainfall intensity increasing when rainfall intensity is less than 0^5 mm5h~(-1). However, the proportion tends to remain constant at about 0^3～0^4 for Artemisia ordosica plant and 0^2～0^3 for Caragana korshinskii plant when the rainfall intensity is more than 1 mm5h~(-1).