古尔班通古特沙漠梭梭和白梭梭树干茎流特征

通过对古尔班通古特沙漠2个主要建群种梭梭(Haloxylon ammodendron)和白梭梭(Haloxylon persicum)树干茎流的野外实验观测，分析植株冠层和降雨特征对树干茎流形成的影响，并明确了树干茎流量在降雨再分配中的比例。结果表明：当降雨量≥2.4 mm时，梭梭和白梭梭开始有树干茎流产生。梭梭、白梭梭的树干茎流量随树冠体积的增大而增加，但是，当梭梭树冠体积大于4 m³，白梭梭树冠体积大于1.5 m³时，树干茎流量随树冠体积的增加不再增大，甚至有下降趋势。梭梭和白梭梭的树干茎流量和降雨量之间存在显著正相关，累计树干茎流量分别占降雨总量的9.1%和6.4%。梭梭和白梭梭的集流率均随降雨量增加而增大，能够有效地将树干茎流汇聚到树干基部, 梭梭表现出更强的汇集树干茎流的潜力。

Stemflow of Haloxylon ammodendron and H. persicum in the Gurbantonggut Desert

During the growing season of2012, Stemflow of two dominant plant species, Haloxylon ammodendrom and H. persicum, was studied in Gurbantonggut Desert, Northwestern China. We firstly selected some trees of the two species to be standard tree and surveyed the size of canopy, and then measured the stemflow after every storm of single precipitation. It was showed that the stemflow both emerged when rainfall lager than 2.4 mm for the two species. It was demonstrated that the stemflow increased with the volume of canopy until larger than 4.0 m³ for H. ammodendrom and 1.5 m³ for H. persicum,respectively. Then, it kept invariant and even began decreasing. There was a significant positive correlation of the two species between the size of single rainfall and the stemflow following. To sum up: the accumulated stemflow volume of the two plants proportioned 9.1% and 6.4% of the total rainfall, respectively. The funneling ratio of the two species both increased with the size rainfall. Consequently, the stemflow of H. ammodendron and H. persicum could be effectively funneled down into the soil around the base of stems to collect water to take up, especially for the former in Gurbantonggut Desert.