黄土丘陵沟壑区不同侵蚀环境下幼苗库动态变化特征

Dynamic Variation of Seedling Bank under Different Erosion Environments in the Hill-gully Loess Plateau Region

幼苗是植物生活史中一个不可缺失的阶段,对自然植被恢复起着非常重要的作用。为了探索黄土丘陵沟壑区不同侵蚀环境下幼苗库的动态变化特征,选择5种不同侵蚀环境(阳沟坡、阳峁坡、峁顶、阴峁坡、阴沟坡)下的15个样地,通过野外定点跟踪调查,运用单因素方差分析法对幼苗物种数、幼苗密度、物种多样性进行了分析。结果表明:(1)不同侵蚀环境下幼苗物种数从阴沟坡到阴峁坡、峁顶、阳峁坡、阳沟坡依次减少,且幼苗物种组成存在差异;生长季内不同月份间幼苗物种数呈现先波动性增大后降低的动态变化趋势,最大值出现在9月初。(2)不同侵蚀环境间幼苗密度差异性显著,阴峁坡最大,阳沟坡最小;不同月份间幼苗密度具有明显的先升后降的动态变化特征,最大值出现在7月初,最小值出现在4月初或11月中旬。(3)不同侵蚀环境间阴坡幼苗物种丰富多样,阳坡幼苗物种较为单一;不同月份间幼苗物种多样性指数和丰富度指数呈现出4—9月份逐渐增大至峰值,10月初和11月中旬稍有降低的趋势。

Seedling is an indispensable stage in plant life cycle and important in natural vegetation restoration.To explore dynamic variation of seedling characteristics under different erosion environments（sunny gully slope,sunny Mao slope,Mao top,shady Mao slope,shady gully slope）in the hill-gully Loess Plateau region,five different erosion environments and 15plots were investigated monthly,and One-Way ANOVA was used to analyze seedling species number,seedling density,species diversity.The results showed that：（1）the number of seedling species decreased from shady gully slope to shady Mao slope,Mao top,sunny Mao slope,sunny gully slope in different erosion environments and seedling species composition existed differences;in different months,seedling species number increased volatility first and then decreased,the maximum appeared in early September;（2）the difference of seedling density in different erosion environments was significant,shady Mao slope was maximum,sunny gully slope was minimum;in different months,seedling density had obvious dynamic variation characteristics of increasing first and then decreasing.Maximum appeared in early July,minimum appeared in early April or middle November;（3）in different erosion environments,seedling species was rich in shady Mao slope,relatively single in sunny gully slope;in different months,diversity index and richness index increased gradually to the peak from April to September,and then reduced slightly in early October and middle November.