庙岛群岛南五岛灌木群落结构及其对环境因子的响应

该研究对山东省庙岛群岛南五岛灌木植被及环境因子进行调查,运用TWINSPAN等级划分法和多元分析技术研究调查区域内灌木的植被分布、群落结构及其与环境因子间的关系。结果显示:(1)调查期间庙岛群岛南五岛共发现灌木27种,隶属于15科23属,荆条、扁担木、酸枣为优势种。(2)灌木群丛主要被划分为6个群丛,即桑群丛、刺槐-柘树群丛、酸枣群丛、扁担木群丛、荆条群丛、紫穗槐群丛。(3)应用典范对应分析(CCA)并采用向前引入法对环境因子进行逐步筛选,Monte Carlo置换检验结果显示,乔木层盖度、土壤pH是影响庙岛群岛南五岛灌木空间分布的关键环境因子。研究认为,CCA二维排序结果与TWINSPAN分类结果较为一致,庙岛群岛南五岛森林灌木群落主要分布于乔木层盖度适中、偏酸性土壤的环境下。

Population Structure of Shrub in the Southern Five Islands of Miaodao Archipelago and Its Response to the Environmental Factors

The shrubs of islands also play a significant role in ecosystem since they are resistant to climatic conditions,especially to drought and salinity.The quantitative research on ecological relationship between vegetation and the environment at landscape and region scale has been developed rapidly,and that became one of the focuses of vegetation science.The paper aims to describe the composition and distribution of shrub in the southern five islands of Miaodao Archipelago and explain the influence of environment factors on the shrub population and give the reference for vegetation recovery.Based on the investigations of shrub vegetation species and environmental factors of southern five islands of Miaodao Archipelago in Shandong Province,the relationship between eco-environmental factors and the shrub species composition as well as their population structure in the survey area was investigated by using correlation analysis,canonical correspondence analysis (CCA),and two-way indicative species analysis (TWINSPAN).The result showed that:(1)27 shrub vegetation species belonging to 15 families and 23 genera were observed during the study period in the islands.The dominant families are Leguminosae and Moraceae.The highest frequency of the species is Vitex negundo var.heterophylla,which contributed up to 66.67% of the stations.Ziziphus jujuba var.spinosa and Grewia biloba var.parviflora were also found in more than 50% of the stations.(2)By using TWINSPAN,the population of shrub layer were classified into six types,they are Morus alba population,Robinia pseudoacacia-Cudrania tricuspidata population,Ziziphus jujuba var.spinosa population,Grewia biloba var.parviflora population,Vitex negundo var.heterophylla population and Amorpha fruticosa population.(3)Multivariate ordination techniques were used to analyze the effects of environment variables on the shrub community by CANOCO version 4.5.The environmental factors were analyzed,which include slope,aspect,coverage,soil water,pH,available nitrogen and available potassium,available phosphor,respectively.All of these environmental variables were ln (x+1) transformed before analysis except for pH.The results of canonical correspondence analysis (CCA) with forward selection indicates that tree coverage(F=3.19,P=0.004) and pH (F=2.01,P=0.014) were the most important environmental factors which influence shrub distribution in the southern five islands of Miaodao Archipelago during the study periods.