黄土丘陵区刺槐群落林下物种分布对环境因子的响应

以吴起、安塞、米脂、宜川等地刺槐群落为对象,结合种群生态位宽度及土壤、海拔等环境因子探究刺槐林下物种分布特征及其影响因素,分析该地区刺槐林下物种分布对环境因子的响应机制,为黄土丘陵区刺槐林的管理提供科学依据.结果表明:在黄土丘陵区不同生长年限刺槐林中,分布较为广泛的物种有狗尾草、阿尔泰狗娃花、猪毛蒿、硬质早熟禾、茭蒿、苦荬菜、角蒿等.随刺槐生长年限的增加(10年至50年),林下物种优势种的分布更替依次为:茵陈蒿→硬质早熟禾→猪毛蒿→其他(茜草、悬钩子蔷薇等)→茭蒿→狗尾草.对刺槐林下物种分布影响较大的因子依次为土壤全磷含量(25.6%)>海拔(20.3%)>土壤全氮(19.3%).土壤有机碳含量、土壤全氮含量、土壤全磷含量、土壤含水量与刺槐林下物种的分布数量呈正相关,相关程度因种群不同而有所差异.坡向对刺槐林下物种的分布无明显影响.综上所述,地形与土壤因子在刺槐林下物种的分布中均占有重要地位,坡度越大,海拔越高,刺槐林下物种的分布种类越少.其次,土壤全磷含量和海拔是影响刺槐林下物种分布的重要环境因子.刺槐林下物种的分布是土壤养分状况的反映,对刺槐林的管理具有一定的指示作用.

Response of understory species distribution of Robinia pseudoacacia plantation to environmental factors in loess hilly region,China.

We explored the distribution characteristics and influencing factors of understory species in Robinia pseudoacacia plantation in Wuqi, Ansai, Mizhi, Yichuan and other places, in combination with niche breadth, soil, altitude and other environmental factors. We analyzed the response mechanism of species distribution to environmental factor to provide a scientific basis for the mana-gement of R. pseudoacacia plantation in loess hilly region. The results showed that the broadly distributed understory species in R. pseudoacacia plantation were Setaria viridis, Heteropappus altaicus, Artemisia scoparia, Poa sphondylodes, Artemisia leucophylla, Ixeris sonchifolia, and Incarvillea sinensis. With the increasing rehabilitationage, the dominant understory species distribution followed the order: Artemisia capillaries → P. sphondylodes → A. scoparia → others (Rubia cordifolia, Rosa rubus and so on) → A. leucophylla → S. viridis. Results from principal component analysis showed that soil total phosphorus (25.6%), altitude (20.3%) and soil total nitrogen (19.3%) were the key factors influencing understory species distribution in R. pseudoacacia plantation. Soil organic carbon content, soil total nitrogen content, soil total phosphorus content, soil water content and the number of understory species distribution in R. pseudoacacia plantation were generally positively correlated with the degree of correlation varying across different species. There was no correlation between the slope aspect and the understory species distribution in R. pseudoacacia plantation. In conclusion, topography and soil factors played important roles in driving understory species distribution. The steeper the slope, the higher the altitude, the fewer understory species in R. pseudoacacia plantation. Understory species distribution was mainly affected by soil total phosphorus content and altitude. The understory species distribution reflected the differences of soil nutrient status, which had a certain guiding role in the management of R. pseudoacacia plantation.