黄土丘陵区沙棘人工林天然化发育过程中的种间联结性研究

采用样地调查法,并通过方差分析、X2检验及共同出现百分率PC计算,对黄土高原丘陵沟壑区经过3a、8 a、13a、25a发育的沙棘群落中主要种群间联结性进行了比较研究。结果表明,灌木层的4个发育阶段,总体关联性都表现出轻微正相关。草本层中,发育3a的群落,总体联结性表现出极显著正相关,但种间关系不够稳定;发育8a 的群落,总体关联性表现出轻微正相关,种间关系不稳定;发育13a的群落,总体关联性表现出极显著正相关,负关联种对减少,种间关系逐步趋于稳定;发育25a的群落,种间关系相对稳定。表明沙棘在黄土高原丘陵区人工林天然化发育的过程中,已实现了自我更新。说明人工林只有经天然化发育过程才能实现持续利用,达到普通生态系统的服务功能。

Interspecific Connectivity in Naturalized Development of Hippophae rhamnoides Plantations in Hilly Loess Regions

The interspecific connectivity of major populations in 3 a,13 a and 25 a Hippophae rhamnoides communities in hilly and gully regions of the Loess Plateau were comparatively examined by quadrat investigation and PC-run variance analysis ,X2 test,and concurrence-percentage computation. The results showed that the overall connectivity appeared to be a slightly positive correlation at the four stages of the shrub layer. In the herbaceous layer of 3 a communities, the overall connectivity appeared to be a significant positive correlation but the interspecific relations were not stable enough;in 8 a communities,the overall connectivity appeared to be a slight positive correlation but the interspecific relation was not stable;in 13 a communities, the overall connectivity appeared to be an extremely significant positive correlation and the negatively-correlated species declined in quantity,so that the interspecific relation appeared to gradually become stabilized; in 25 a communities, the interspecific relation appears relatively stable. It was indicated that H. rhamnoides was capable of regenerating itself in naturalized development of its plantations. It was shown that plantations could be exploited in a sustainable manner only through their naturalized development hence fulfilling their serving function of ordinary eco-systems.