不同密度油松人工林群落特征与物种多样性耦合关系

以黄土高原区油松人工林为研究对象，对比3种不同密度的油松人工林群落特征和物种多样性差异，构建两者间耦合关系模型，探讨不同密度油松人工林经营策略。结果表明:1）不同密度油松人工林群落特征具有差异，高密度（3 400~4 600株·hm^-2）林分的角尺度显著大于中密度（2 200~2 800株·hm^-2）、低密度（1 400~2 100株·hm^-2）林分；低密度林分的混交度、平均胸径和冠幅显著高于中、高密度林分。2）不同密度林分的乔木、灌木和草本物种多样性指数均与其自身显著正相关；低密度林分中，乔木层和灌木层多样性指数、灌木层和草本层多样性指数显著负相关。3）不同植物群落具有不同特征，中、高密度林分物种多样性对群落贡献较高，低密度林分群落植物空间分布合理，生长状况良好。4)通过改善植物群落的空间分布结构和生长状况，可以提升中密度林分群落中乔木、灌木和草本的物种多样性，而在高、低密度的林分中，则需采取其他经营策略。

Coupling Relationship Between Community Characteristics and Species Diversity of Pinus tabuliformis Plantations with Different Densities

Exploring the coupling relationship between community characteristics and species diversity is important to the management of plantation ecosystem,and it is also the theoretical basis of the management improvement of plantations.Taking Pinus tabuliformis plantations in the Loess Plateau as the research objects,the community characteristics and species diversity of the plantations with three different densities were compared,the coupling relationship model between the two was constructed,and the management strategies of P.tabuliformis plantations with different densities were discussed.The results were as follows.1) The community characteristics of P.tabuliformis plantations with different densities were different.The uniform Angle index of high-density plantation (3 400-4 600 trees·hm^-2) was higher than those of medium-density (2 200-2 800 trees·hm^-2) and low-density (1 400-2 100 trees·hm^-2) plantations.The mingling index,mean DBH and crown width of low-density plantations were significantly higher than those of medium and high-density forests.2) The species diversity indices of the trees,shrubs and herbs species of the plantations with different densities were significantly and positively correlated with themselves.In low-density stands,the tree layer’s species diversity index was negatively correlated with shrub layer’s,while the shrub layer’s was negatively correlated with herbs layer’s.3) Different plant communities had different characteristics.Medium and high-density plantations showed a great plant species richness,while low-density plantations showed a great spatial distribution and growth condition.4) In medium-density plantations,species diversity of the trees,shrubs and herbs could be improved by rebuilding the spatial structure and growth condition of plant communities,while in high and low-density plantations,some other management strategies should be adopted.