黄土丘陵区人工柠条林下草本植物物种多样性研究

摘要

In order to provide theoretical basis for the management of Caragana microphylla plantations,the space-time alternative method was used to study the species composition and diversity of herbaceous plants under the plantations of C.microphylla in loess hilly region.The results indicated that 1) with the growth of C.m icrophylla,the species replacement occurred all the time.In 30 a plantation,the herbaceous species was most abundant.Perennial herbs were the main life form under C.microphylla plantations with different ages.2) With the growth of C.microphylla,the species richness index,Shannon-Wiener index and evenness index showed similar changing patterns,all increased in 10-30 a and reduced in 30-40 a and had increasing trends in 40-50 a plantations.Simpson index showed the opposite trend with C.microphylla growth.3) The community similarity coefficient increased with the C.microphylla growth,and higher similarity coefficient was found between the two adjacency years.Compared to the abandoned land,the community similarity coefficient reduced gradually,while compared to the natural Sophora davidii community,the similarity coefficient was the highest in 30 a plantation,and the value was 0.895 8,indicating that 30 a C.microphylla community had a higher stability.It was suggested that the appropriate cutting should be conducted in 30 a plantation to maintain the C.microphylla community at a higher stage which was consistent with the natural forest,and to make a smooth replacement for herbaceous plants to play the ecological function sustainably.%人工林林下物种的组成对整个人工林群落的稳定性及生态环境的影响至关重要,采用时空替代法,对黄土丘陵区不同生长年限的人工柠条林下草本植物物种组成及多样性进行研究,为黄土丘陵区人工柠条林的抚育管理提供科学、合理的理论依据.研究表明,1)随着柠条林的生长,柠条林下草本植物种类在不断地更替,植物种类以30 a柠条林最为丰富,各生长年限柠条林下草本生活型均以多年生草本为主;2)柠条林下草本丰富度指数(S)、Shannon-Wiener多样性指数(H')、Pielou均匀度指数(Jsw)的变化随柠条生长年限的增加变化一致,表现为在10～30 a时多样性指标随柠条林龄增加而增加,30～40 a时指标随柠条林龄增加开始下降,40～50 a时指标又随柠条林龄增加有增加趋势.生态优势度Simpson(D)指数变化则刚好相反;3)随柠条林龄的增加,柠条林群落相似性系数增加,且相邻2 a之间有较高的相似性系数.不同年份柠条林群落与撂荒地相比,相似性系数逐渐降低,与天然狼牙刺相比,30 a柠条林的相似性系数最高,值达0.895 8,说明在30 a时柠条林群落的稳定性较高.在柠条林生长至30 a左右时,可适当对林分进行抚育砍伐,使柠条林群落的稳定性维持在一个较高的、与天然林大致保持一致的阶段,植物种类更替平稳,生态功能持续发挥.