围封对固沙樟子松林下植被群落数量特征及多样性的影响

Effects of Enclosure on Quantitative Characteristics and Species Diversity of the Understory Vegetation Community in the Pinus sylvestris var.Mongolica Sandy-fixation Plantation

为揭示围封对人工樟子松固沙林林下植被群落及生态系统的影响,选择章古台围封37年生和46年生固沙樟子松林为研究对象,以邻近未围封林地为对照,采用野外调查法研究不同条件下樟子松林下植被的群落特征与物种多样性。结果表明:研究区共发现林下植被58种,分属18科42属,围封条件下促进禾本科植物与多年生植物种有所增加,多年生及灌木植物的重要值增大。围封降低先锋物种的重要值,明显增加羊草的重要值。围封有利于增加固沙樟子松林下植被群落的平均盖度、高度和生物量,而且随着围封年限的增加呈现不同程度的增长趋势;林下植被群落的物种多样性指数、优势度指数、均匀度指数在半围封5年较未围封状态略高,而在全围封10年则均低于未围封状态。因此,围封有利于樟子松林下植被群落的恢复与生长,适度的围封有利于林下群落多样性,进而保障群落的演替及生态系统稳定性的维持。

In order to reveal influences of enclosure on the understory vegetation community and the ecosystem of artificial Pinus sylvestris var.mongolica sand-fixing forest,the forests of 37-year-old and 46-year-old Pinus sylvestris var.mongolica at Zhanggutai were enclosed and selected as the research objects,and the adjacent unclosed forest was selected as the control.The community characteristics and species diversity of understory vegetation communities under different conditions were studied by field investigations.The results showed that 58 species of undergrowth vegetations of 18 families and 42 genera were found in the study area.Under enclosure conditions,the numbers of Gramineae and perennial plants increased,and the important values of perennial and shrub plants increased.The enclosure decreased the important value of pioneer species and increased the important value of Leymus chinensis significantly.The enclosure increased the average coverage,height and biomass of the understory vegetation community of the Pinus sylvestris var.mongolica forests,and different growth trends were showed with increasing of enclosure years.Species diversity index,dominance index and evenness index of the understory vegetation community in the half-enclosed of 5 years were slightly higher than those in the unclosed condition,but those in the full-enclosed of 10 years were lower than those in the unclosed state.Therefore,the enclosure is conducive to the restoration and growth of the understory vegetation community of the Pinus sylvestris var.mongolica,and the moderate enclosure is conducive to increase diversity of the understory community and thus ensures the succession of community and maintains the ecosystem stability.