东祁连山河谷高寒草地植被群落特征及其与土壤性状的关系

Relationship between the grassland and soil conditions in the Eastern Qilian Mountains

为探究东祁连山河谷高寒草地植被群落特征与土壤性状的关系,根据研究区河谷地形地貌及河谷高寒草地分布特征,选取了分布在河谷山地阳坡上部和下部、河谷山地阴坡上部和下部及河谷水平阶地的5类不同植被类型的高寒草地为研究对象。研究草地植被群落和土壤性状特征及相关关系。结果表明:河谷中不同坡向、坡位高寒草地植被群落优势种不同,河谷阳坡高寒草地以嵩草属植物为主,阴坡以蓼属植物为主;阴坡植被总盖度高,阳坡低;河谷阴坡下部草层高度最高,而水平阶地最小;植被群落总科数、总属数和总种数均表现为坡下部高于上部,阴坡高于阳坡;地上生物量依次为:阴坡下部>阳坡上部>阴坡上部>阳坡下部>水平阶地;0~60 cm土层地下生物量依次为:阴坡下部>阳坡下部>阴坡上部>水平阶地>阳坡上部。不同高寒草地土壤性状之间有显著差异(P<0.05)。相关分析表明,土壤含水量、容重、孔隙度和全氮等指标与植被总盖度、地上生物量、总科数、草地平均高度有显著的相关关系。可见,研究区河谷高寒草地植被与土壤之间的影响主要表现为土壤含水量、容重、孔隙度和全氮与植被总盖度、地上生物量、总科数、草地平均高度间的相互作用。

This study explored the relationship between the characteristics of the grassland and soil conditions in the Eastern Qilian Mountains.We selected grass and soil from five areas of the mountain valley: the upper shady slope,lower shady slope,upper sunny slope,lower sunny slope and level terraces.Results showed that each site harbored different dominating species;the sunny slope was dominated by Kobresia sedges and the shady slope was dominated by the Polygonaceae flowering plants.Total vegetation coverage was greatest on the sunny slope weakest on the shady slope;grassland height was tallest on the lower shady slope and shortest on the horizontal terrace;the number of genera and species on the lower shady slopes were higher than those on the upper sunny slopes.The biomass above the ground,from greatest to least,was as follows: bottom shady slope > upper sunny slope > upper shady slope > bottom sunny slope > horizontal terraces.Through an examination of 60 cm deep soil,the underground biomass was found to be: bottom shady slope > bottom sunny slope > upper shady slope > horizontal terraces > upper sunny slope.Both the biomass and soil conditions at each site significantly differed (P<0.05).There were significant correlations and interactions between characteristics of the soil (i.e.,moisture content,bulk density,porosity,and total nitrogen content) and the grassland (i.e.,total vegetation coverage,biomass above the ground,grassland heights,and number of genera and species present).Therefore,these results indicated that aboveground soil characteristics were key factors that affected the quality of the grassland.