祁连山北坡冬季牧场积雪盖度与植被、地形的关系

Relationships between snow coverage,vegetation,and terrain in the winter pasture on the north slope of Qilian Mountains

以祁连山高寒草原为对象,测定4个坡向冬季牧场的坡度、立枯物高度和盖度及积雪盖度,分析积雪盖度与植被和地形特征之间的关系,构建基于植被(立枯物高度和盖度)和地形因素(坡度和坡向)的牧场积雪盖度估测模型,为牧场的管理提供理论依据.通过研究发现:祁连山北坡高寒草原积雪盖度与立枯物高度和盖度呈极显著负相关,与坡度和坡向呈极显著正相关;坡向和坡度与立枯物高度和盖度呈显著负相关,坡向对立枯物积累的负效应比坡度更明显.冬季牧场立枯物盖度对积雪的直接作用最大,坡度通过立枯物盖度对积雪盖度的间接作用其次,坡向和坡度通过立枯物高度对积雪盖度的间接作用显著;坡度对立枯物高度的直接作用高于坡向,其对立枯物盖度的直接作用显著.祁连山高寒草原的积雪盖度可通过植被或/和地形特征的多元线性回归方程很好地估测,基于植被和地形综合因素所建立的最佳积雪盖度估测模型为:SC(%)=70.278+4.210A+0.269S-0.138SLH-0.534SLC(R^2=0.630,P<0.001)(式中,A,S,SLH和SLC分别为坡向、坡度(°)、立枯物高度(cm)和盖度(%)).

In order to provide practical information for pasture management,slope,standing litter height,standing litter coverage,and snow coverage were measured in winter pastures on the north slope of Qilian mountains to determine relationships between these variables,and build estimation models of snow coverage based on vegetation and terrain factors. Results demonstrated that snow coverage was negatively correlated with the height and coverage of standing litter,and was positively correlated with slope and aspect; the slope and aspect of pastures were negatively correlated with the height and coverage of standing litter; the litter accumulation was more significantly correlated with the aspect than the slope. The direct effect on snow coverage from standing litter coverage was the biggest in winter pastures,while the indirect effect on snow coverage from slope ranked second and the slope and aspect had an indirect impact on snow coverage by affecting the standing litter height. The effect on standing litter height from the slope was greater than that from the aspect,and the former had a direct effect on it. The snow coverage of alpine grassland can be estimated using multiple linear regression equations based on the vegetation and terrain factors,with the percent of snow cover = 70. 278 ＋ 4. 210 A ＋ 0. 269 S ＋ 0. 138 SLH ＋ 0. 534 SLC（ R^2= 0. 630,P 0. 001）,where A,S,SLH and SLC are aspect,slope（ °）,standing litter height（ cm） and the coverage（ %）,respectively.