晋西黄土区不同密度刺槐林下植物多样性评价

Evaluation of understory plant diversity of Robinia pseudoacacia forests with different densities in the loess areas of Western Shanxi

【目的】分析晋西黄土区不同林分密度刺槐人工林下植物的多样性特征及其差异,为确定刺槐人工林的合理林分密度及其健康可持续经营管理提供理论依据。【方法】以山西吉县蔡家川流域5种不同密度(675,1025,1575,2175和2500株/hm^(2))刺槐人工林为研究对象,对其林下灌、草植物的种类、数量及盖度进行调查分析,计算不同林分密度刺槐林植物多样性指数。确定了10项评价指标,采用主成分分析法对各个林分密度刺槐人工林植物多样性进行综合评价。【结果】(1)刺槐人工林群落内灌木和草本植物主要为菊科、蔷薇科及禾本科,重要值较高的植物种主要为黄刺玫(Rosa xanthina)、杠柳(Periploca sepium)、茅莓(Rubus parvifolius)和艾蒿(Artemisia argyi)。(2)随着刺槐人工林密度的增大,林下植物多样性指数呈先增大后减小的趋势,密度适中(1575和2175株/hm^(2))时的刺槐林下植物多样性指数最大,林分密度为1575株/hm^(2)的刺槐林灌木层Shannon-Wiener多样性指数、Pielou均匀度指数与密度为675和2500株/hm^(2)刺槐林间均存在显著差异(P<0.05),林分密度为1575株/hm^(2)的刺槐林草本层Simpson多样性指数、Shannon-Wiener指数与密度为675和2500株/hm^(2)的林分之间差异显著(P<0.05)。(3)对不同密度刺槐林下植物多样性的综合评价结果表明,密度为1575株/hm^(2)时刺槐林的植物多样性综合评价值最高。【结论】晋西黄土区刺槐人工林的适宜林分密度为1185~1785株/hm^(2),该密度刺槐人工林下灌、草植物较为丰富多样,该林分密度可以作为当地刺槐人工林造林及可持续经营的参考。

【Objective】This study evaluated diversity characteristics of Robinia pseudoacacia plantations with different stand densities and analyzed their differences to provide theoretical basis for determining reasonable stand density of Robinia pseudoacacia plantations and their healthy and sustainable ma-nagement.【Method】Robinia pseudoacacia plantations with densities of 675,1025,1575,2175 and 2500 plants/hm^(2)in loess areas of Western Shanxi were investigated.Species,number and cover of understory shrubs and herbs plants,and plant diversity indices were analyzed,10 evaluation indicators were identified,and plant diversity was evaluated using principal component analysis.【Result】(1)The plants of Robinia pseudoacacia forests were mainly from Asteraceae,Rosaceae and Gramineae,and plants with high importance values included Rosa xanthina,Periploca sepium,Rubus parvifolius and Artemisia argyi.(2)With the increase of the density of Robinia pseudoacacia plantations,the plant diversity index of stands tended to increase first and then decrease,with the greatest diversity index at moderate densities of 1575 and 2175 plants/hm^(2).There were significant differences between Shannon-Wiener index and Pielou index of shrub layer of 1575 plants/hm^(2)Robinia pseudoacacia plantations and 675 and 2500 plants/hm^(2)(P<0.05).The Simpson index and Shannon-Wiener index of 1575 plants/hm^(2)were significantly different from those of 675 and 2500 plants/hm^(2)(P<0.05).(3)The evaluation of plant diversity in different stand densities showed that the density of 1575 plants/hm^(2)had the highest overall plant diversity assessment value.【Conclusion】The density of 1185-1785 plants/hm^(2)with high diversity of understory plants was suggested for Robinia pseudoacacia plantations in the loess area of Western Shanxi.