祁连山典型灌丛降雨截留特征

基于2010年6月至10月的野外试验数据,研究了祁连山金露梅、高山柳、沙棘和鬼箭锦鸡儿灌丛降雨截留特征,分析了降雨量和雨强对灌丛降雨截留过程的影响。结果表明:试验期间共降雨298.6 mm,在降雨量<2.1 mm时,降雨被全部截留,实际发生穿透和茎流的降雨为283.1 mm;金露梅灌丛穿透雨量、茎流量和截留量分别为175.8 mm(62.0%)、9.5 mm(3.4%)和62.0 mm(34.6%),高山柳为179.8 mm(63.5%)、9.1 mm(3.2%)和63.5 mm(33.3%),沙棘分别为148.1mm(52.3%)、22.5mm(8.0%)和52.3 mm(39.7%),鬼箭锦鸡儿分别为170.4 mm(60.2%)、11.8 mm(4.2%)和60.2 mm(35.6%);灌丛穿透雨量、茎流量和截留量均与降雨量呈显著线性正相关(P<0.001);穿透率、茎流率和截留率与降雨量呈指数函数关系(P<0.05);平均雨强与截留率关系以指数函数拟合最好(P<0.05)。在降雨性质相同的情况下,植被形态特征是影响灌丛降雨截留的重要因素。

Characteristics of rainfall interception for four typical shrubs in Qilian Mountain

Rainfall intercepting by vegetation plays an important role affecting the water balance at local and catchment scale due to the control that vegetation canopy exert by modifying both evaporation and the redistribution of incident rainfall. Qilian Mountain is source regions of Heihe River, Shiyang River and Shule River inland river basin. In consideration of widespread shrubs which account for 68% of the whole forest area of Qilian Mountain, the research on rainfall interception process of shrubs for understanding the impact of rainfall characteristics on alpine shrubs and revealing the mechanism of hydrologic cycle and water resources with the impact of the shrub canopy, especially in the mountainous regions of an inland river basin, is very important and necessary. This paper taked the four typical alpine shrubs Potentilla fruticosa, Salix cupularis, Hippophae rhamnoides, and Caragana jubata in Qilian Mountain as test objects, based on the field experimental data from June to October 2010, characteristics of rainfall interception and rainfall redistribution of four typical alpine shrubs in Qilian Mountain was investigated by permanent plot method, and impact of rainfall characteristics on rainfall redistribution of shrubs was analyzed by statistical method. The results indicated that the gross rainfall was 298.6 mm during the experimental period. Rainfall was intercepted entirely by shrubs when rainfall is less than 2.1 mm, gross rainfall which observed throughfall and stemflow was 283.1 mm. The amount of throughfall of P.fruticosa, S.cupularis, H.rhamnoides and C.jubata was 175.8 mm, 179.8 mm, 148.1mm, and 170.4 mm. Throughfall percentages of P.fruticosa, S.cupularis, H.rhamnoides and C.jubata was 62.0%, 63.5% 52.3%, and 60.2%, respectively. Stemflow was 9.5 mm, 9.1 mm, 22.5 mm, and 11.8 mm for P.fruticosa, S.cupularis, H.rhamnoides, and C.jubata, and averaged 3.4%, 3.2%, 8.0%, and 4.2% of the gross rainfall, respectively. Interception was 62.0 mm, 63.5 mm, 52.3 mm, and 60.2 mm for P.fruticosa, S.cupularis, H.rhamnoides, and C.jubata, and accounted for 34.6%, 33.3%, 39.7%, and 35.6% of the gross rainfall, respectively. The amount of thoughfall, stemflow and interception of P.fruticosa, S.cupularis, H.rhamnoides and C.jubata increased in a significant positive linear correlation with increasing rainfall depth(P<0.001).The relationship of throughfall percentage, stemflow percentage and interception percentage of shrubs with rainfall could be fitted with exponential curve (P<0.05). Throughfall percentage and stemflow percentage showed an increase trend with the increasing rainfall, while interception percentage decreased with the increasing rainfall depth. Moreover, interception percentage of shrubs decreased in exponential function correlation with increasing rain intensity (P<0.05). Interception percentage decreased with increasing rainfall intensity, when the rainfall intensity is less than 4 mm/h, the interception percentage was significantly decreased, and then the trend is becoming stable values with increasing rainfall intensity. Interception characteristics of each shrubs was different with others when rainfall characteristics were similar during the experimental period. According to field plot observation, the height, branch angle, canopy morphology and crown projection area all affected canopy interception process of alpine shrubs in Qilian Mountain. In order to analyze intercept capability per leaf area of shrubs, some morphology characteristics parameters, such as leaf area index (LAI), freedom throughfall coefficient, biomass, canopy hold water ability, should be measurement in the next experiment.