沙漠人工植被区土壤蒸发测定

在2003年生长季,应用自制的微型蒸渗仪(Micro Lysimeter)、大型称重式蒸渗仪(Lysimeter)和TDR对比测定沙漠油蒿(Artemisia ordosica)和柠条(Caragana korshinskii)人工植被区与裸沙土壤蒸发,结果表明:在沙漠人工植被区由于植被比较稀疏,土壤蒸发不受植株的遮阴的影响,但不同样地的蒸发量是有差异的,而样地和位置间的互作不显著。为提高蒸发测定精度,建议微型蒸渗仪勤于换土,尤其是在大降水发生之后;将横插式 TDR探头改为竖插式能探测到小降水后的蒸发量。在沙漠区有很大比例的蒸发发生在紧接降水之后。以微型蒸渗仪的测定结果为主,结合大型称重式蒸渗仪的测定结果推算出整个试验期间的裸沙、油蒿和柠条样地的蒸发量为 111 6mm、93 8 mm和99 3 mm,油蒿和柠条样地的蒸发量分别占同期蒸散量的45 1%和43 6%;油蒿和柠条样地均以8月份日蒸发量0 93 mm·d-1和1 10 mm·d-1最高,5月份日蒸发量0 30 mm·d-1和0 28 mm·d-1最低。

Soil Evaporation in Artificially Re-vegetated Desert Area

The experiment based on Micro-Lysimeter combining with Lysimeter and TDR aims to determine the evaporation in Artemisia ordosica and Caragana korshinskii re-vegetated desert area during growth season of 2003 and in bare desert. The results showed that soil evaporation has no relation with overshadow of plant due to thin vegetation. Evaporation amount between A. ordosica and C. korshinskii vegetation is different, but the interaction between locations and vegetations is not significant. As precision is concerned, we suggest that soil in Micro-Lysimeter should be frequently exchanged and the probe of TDR should be inserted vertically instead of horizontally. Most evaporation occurs after precipitation in desert area. Based on the results of Micro-Lysimeter combing with the result of Lysimeter, the evaporations in bare sand and A. ordosica and C. korshinskii vegetated areas are calculated, they are 111\^6 mm and 93\^8 mm and 99\^3 mm in experimental periods, respectively. The evaporation of A. ordosica and C. korshinskii vegetated areas are 45\^1% and 43\^6% of the evapotranspiration. Monthly, the maximum evaporation of A. ordosica and C. korshinskii vegetation is 0\^93 mm\5d~(-1) and 1\^10 mm\5d~(-1 )in August respectively, the minimum evaporation is 0\^30 mm\5d~(-1 )and 0\^28 mm\5d~(-1 )in May respectively.