防风固沙林演变中群落结构与物种多样性特征

The Characteristic of Species Diversity and Community Structure in the Succession Process of the Wind-Breaking and Sand-Fixing Forest

摘要:

西北干旱区生态系统脆弱，人工植被建设对于区域环境的改善以及绿洲系统的维持都是最为重要的。然而，人工群落的稳定性如何则直接关系着其生态效益是否可以持续发挥。本文选择塔里木河地区人工防风固沙林就这一问题开展研究工作，采用重要值为各种群的数量特征测度了造林后群落演替过程中的物种多样性指数，分析了群落发育过程中4龄和7龄不同结构荒漠人工–天然植物群落的物种多样性变化特点，以期为塔里木河下游人工防护林建设中物种配置提供理论依据。结果表明：由于土壤种子库中乡土植物的发生和发育，原来植物种组成简单的人工防风固沙林群落逐渐演变成为人工–天然植物群落，而且群落中的植物种数由原来的6种增加为26种(隶属于12科、25属)；增加了6种灌木或半灌木，13种草本和1种藤本；研究区总体群落物种多样性水平较高，随着群落演替其物种多样性水平呈现低–高–较低的变化趋势；群落的Shannon-Wiener指数与物种丰富度指数的变化趋势基本一致；群落中盐生草(Halogeton glomeratus) + 花花柴(Karelinia caspica)群落的物种多样性较高，而头状沙拐枣(Calligonum caput-medusae) + 胡杨(Populus euphratica)群落的物种多样性最低，可见头状沙拐枣–胡杨群落的物种配置结构不合理。该研究结果可为进一步优化防风固沙林群落结构和提高群落物种多样性及其稳定性提供科学理论依据。 It is very important for planting artificial vegetation to improve the regional environment and maintain oasis ecosystem in the northwest arid area. However, the stability of artificial community is directly related to its continuous ecological benefit. In this paper, the main purpose was to measure the diversity change of 4-year and 7-year artificial-natural plant community with different species composition and the species diversity indices was measured and calculated in order to provide a case for reasonable distributional patterns for artificial plant community in the wind-breaking and sand-fixing forest, in the lower reaches of the Tarim River, Xinjiang, China. The main results are that the artificial-natural communities are formed since several native species naturally occurred to the artificial communities in four years. The species diversity is obviously increased in the artificial-natural communities. And there are all 26 species (belonging to 12 families, 25 genera in the study communities), increasing 6 species of shrub or semi-shrub, 13 kinds of herbaceous species and 1 kind of vine species than that in 2000. The variety trend of Shannon-Wiener index is similar to that of richness changes. Halogeton glomeratus + Karelinia caspica community has the highest diversity and evenness indices while that is contrary in Calligonum caput-medusae + Populus euphratica community. The results may provide the theories cases for the further optimization species composition and improvement species diversity and the stability of artificial plant community.