祁连山排露沟流域青海云杉林更新特征对地形因子的响应

Response of Picea crassifolia forest regeneration characteristics to topographicfactors in Pailugou watershed of Qilian Mountains

为探讨祁连山青海云杉林微地形对天然更新苗的影响,选择祁连山排露沟流域分布的青海云杉为研究对象,采用C-均值模糊聚类分析将该流域15个固定样地的地形参数(海拔、凹凸度、坡度)划分为4种不同的微地形生境,研究微地形生境对更新苗的更新特征(更新苗密度、平均冠幅、平均基径和平均株高)产生的影响。结果表明:(1)该流域的15个固定样地通过聚类分析将微地形生境划分为4类:高海拔陡坡、高海拔斜坡、低海拔凸地和低海拔凹地。(2)不同微地形条件下更新苗密度和平均株高从高到低依次为低海拔凹地、低海拔凸地、高海拔斜坡、高海拔陡坡;更新苗的平均冠幅和平均基径从大到小依次为低海拔凸地>高海拔斜坡>低海拔凹地>高海拔陡坡;在平均株高方面,高海拔陡坡显著低于其他3种微地形。不同的海拔、坡度、坡向、坡位对更新苗的存活率和生长发育过程具有显著性影响。(3)更新苗在不同微地形下大部分表现为聚集分布,聚集强度从高到低表现为高海拔陡坡>低海拔凸地>低海拔凹地>高海拔斜坡。(4)从相关性分析的结果中显示,海拔、坡度、坡位与更新苗之间存在显著相关性(P<0.05)。综上所述,青海云杉林的天然更新受微地形生境的影响较为显著(P<0.05),在低海拔凸地和低海拔凹地中更新苗比较适合定居和生长发育。

In order to explore the influence of microtopography on the natural regeneration of Picea crassifolia seedlings in Qilian Mountains,Picea crassifolia forest was selected as the research object,and the topographic parameters(altitude,convexity and slope)of 15 fixed plots in the watershed were divided into four different microtopographic habitats by C-mean fuzzy clustering,and the effects of microtopographic habitats on the renewal characteristics(renewal seedling density,average crown width,mean base diameter and average plant height)of the regeneration seedlings were studied.The results show that:(1)The average crown width and mean base diameter of regenerated seedlings were in the order of low-altitude convex land>high-altitude slope>low-altitude concave land>high-altitude steep slope.The average plant height on high-altitude steep slopes was considerably lower than that in the other three microtopographies.Thus,different altitudes,slopes,aspects,and slope positions considerably affected the survival rate and growth process of regeneration seedlings.(2)The renewal seedling density and average plant height under different microtopographic conditions were as follows:low-altitude concave land,low-altitude convex land,high-altitude slope,and high-altitude steep slope.(3)Most of the regenerated seedlings showed an aggregated distribution under different microtopography in the order of high-altitude steep slope>low-altitude concave>low-altitude convex>high-altitude slope.(4)The results of the correlation analysis showed that there was a significant correlation between altitude,slope,slope position,and regenerated seedlings(P<0.05).In summary,the natural regeneration of Picea crassifolia forest was significantly affected by microtopographic habitat(P<0.05),and seedlings were more suitable for settlement and growth in low-altitude convex land and low-altitude concave land.