不同种植年代油松林植物多样性及土壤养分变化

Plant species diversity of different age Pinus tabulaeformis plantations and its relations with soil fertility

通过样地调查,以空间代替时间的方法,对黄土高原马栏林区不同恢复阶段油松人工林群落物种多样性和土壤养分的变化进行了研究。结果表明:马栏林区油松人工林物种丰富度、多样性和均匀度都在波动中随着恢复年限的增加逐渐增加,物种丰富度在种植30年左右的油松林内达到最大,物种均匀度指数和优势度指数在种植20年左右的油松林内达到最大;人工种植油松林在很大程度上改变了群落面貌,物种组成和群落结构均与撂荒地有较大不同,撂荒地与油松林群落物种组成相似性较小,种植22年与28年的油松林Sorensen指数最大。油松人工林种植20年后物种组成已经基本稳定,在恢复后期物种组成变化不大;种植油松对恢复土壤肥力有一定的帮助,种植28年油松林土壤的有机质、全氮和碱解氮含量都较其它种植年代高,随着恢复年限的增加,油松人工林腐殖质不断增厚,土壤的pH值也有所增加,土壤越来越偏碱性。

By adopting the concept of space as a substitute for time, a field investigation was conducted in the Malan forest region on Loess Plateau to study the plant species diversity of Pinus tabulaeformis plantations at different restoration stages and the changes of soil fertility. The results showed that the species richness, diversity and evenness of P. tabulaeformis plantations increased with the increasing year of restoration, with the largest species richness in about 30 years old plantation and the biggest species evenness and dominance in about 20 years old plantation; the planting of P. tabulaeformis changed the features of plant community, with the species composition and proportion being quite different from those of wasteland, and the 22 and 28 years old P.tabulaeformis＇plantations had the biggest Sorensen index; planting P. tabulaeformis had definite contribution to soil fertility, e.g. , 28 years old P. tabulaeformis plantation had higher contents of soil organic matter and available nitrogen than the others, and with the increasing year of restoration, soil humus layer became thicker and soil pH increased.