广西油茶人工林林下植物多样性区域变化规律

为揭示广西油茶林植物多样性的区域变化规律,以广西7个区域具代表性的油茶林为研究对象,采用典型抽样法,对油茶林林下植被进行了调查,并对比分析了群落物种组成、结构特征和物种多样性。结果表明:(1)油茶林林下植被灌草层科数、属数、种数最多的是三江县油茶林(SJ)、较少的是巴马县油茶林(BM)和来宾市油茶林(LB);除巴马县油茶林(BM)灌木层优势种为共有种,其他区域油茶林的灌木层、草本层优势种均为交叉种。(2)多样性指数方面灌木层仅Margalef指数差异显著,草本层Margalef指数、Simpson指数、Shannon-Wiener指数差异显著。(3)通过回归分析,纬度与灌木层(单一种数量)、草本层(科数、属数、种数、单一种数量)以及总数量(属数、种数)、年均温度与草本层(科数、属数、种数、单一种数量)、有效积温与草本层(属数、种数、单一种数量)、年均降雨量与灌木层单一种数量之间的趋势模拟呈二次曲线关系。(4)不同区域油茶林物种相似性不高,通过相似系数矩阵进行聚类分析三江县油茶林(SJ)、贺州市八步区油茶林(HZ)、岑溪市软枝油茶种子园油茶林(CX)、南宁市油茶林(NN)为一类,凤山县油茶林(FS)、巴马县油茶林(BM)和来宾市油茶林(LB)为一类。广西油茶人工林林下植物多样性的区域变化规律可能与不同区域的生境异质性有关。

Variations of undergrowth species diversity on Camellia oleifera plantations in Guangxi

In the present study, we selected seven typical Camellia oleifera plantations in Guangxi to examine the diversity of their undergrowth species. Specially, we focused on the study of its species composition, structural features and diversity. Our results are as follows. First, Sanjiang (SJ) had the most abundance number of families, genera and species of shrubs and herbs in the C. oleifera community, whereas Bama (BM) and Laibin (LB) had relatively least abundance number. In addition, the common species were dominant only in the BM shrubs layer, while the dominant species of shrubs and herbs in all other communities were cross-species. Secondly, the difference in Margalef index was only significantly among shrubs diversity. In contrast, the difference in the indexes of Margalef, Simpson and Shannon-Wiener for herbs diversity were all significant. Thirdly, the regression analysis showed that the relationship between latitude and numbers of single-species in shrubs layer, families, genera, species, and single-species in herbs layer and the total genera and species exhibited a quadratic model. Similarly, the tendency between the average annual temperature and the numbers of families, genera, species, and single-species in herbs layer, the effective accumulative temperature and the numbers of genera, species, and single-species in herbs layer, the average annual rainfall and the number of single-species in shrubs layer also showed quadratic model. Finally, the species in different C. oleifera communities were observed to show a few similarities. Cluster analysis with similarity metrics showed that the undergrowth species of the plantations in SJ, Babu district in Hezhou (HZ), Cenxi soft branch Camellia oleifera seed orchard (CX) and Nanning (NN) were classified into the same class, while the undergrowth species of the plantations in Fengshan (FS), BM and LB belonged to another class. In summary, the regional variation of undergrowth species in Guangxi C. oleifer plantations was closely related with the habitat heterogeneity in different areas.