浙江江山公益林物种种间关系及CCA排序

Interspecific relationship and canonical correspondence analysis of the dominant species in ecological service forest of Jiangshan City in Zhejiang Province

利用浙江省江山市80个公益林固定小班监测数据,基于生态位理论、种间联结、CCA排序方法对研究区内群落优势种种间关系及其与环境的关系进行研究。结果表明:江山市公益林群落中杉木、檵木、紫萁分别在乔木、灌木、草本层中占优势地位;石栎与青冈、隔药柃与山苍子、蕨与海金沙的生态位重叠指数值分别在乔、灌、草本层中最大;而CCA协变量矩阵偏典范对应分析说明物种分布主要受海拔、坡度、坡向(光照强度)以及腐殖质厚度的影响,总体上可以对89.44%的环境因子进行解释。并且还表明,生态位宽度较大的物种其生态位重叠值较大,并在CCA排序图物种集中区分布。反之,生态位重叠较小,在CCA排序图中将偏离物种集中区;除此之外,在CCA排序图上,物种间的距离与其生态位重叠值的大小及种间联结均有密切的关联,若未存在显著的联结性,随物种间的生态位重叠值越高,其在CCA排序上的距离越近,若存在显著联结性,则正相关缩小距离,负相关拉大距离。

Ecological public welfare forests have provided many more ecological benefits to human beings than commercial woodlands, thus, planting trees for ecological public welfare forests has been a major component of ecological restoration in Zhejiang Province in the 21st Century. In this study, the main objective was investigating plants＇ interspecific and environmental relationships to further the assessment of plant species distribution changes in ecological welfare forests. We used inventory monitoring data from 80 permanent sample plots, based on a stratified sampling technique applied to 5.256 × 10^4 hm2 of ecological public welfare forests in Jiangshan city in Zhejiang province. We employed a niche theory conceptual model, interspecific relations, and Canonical Correspondence Analysis （CCA） to investigate the interspecific relationships among dominant species and the relationships between species and their environments. The results showed that Cunninghamia lanceolata, Eurya muricata, and Funaria hygrometrica were the dominant species of the tree layer, shrub layer, and herb layer, respectively. The largest niche overlap was observed between Cyclobalanopsis glauca and Lithocarpus glabra , between Eurya muricata and Litsea cubeba , and between Pteridium aquilinum and Lygodium japonicum for the tree layer, shrub layer, and herb layer, respectively. The relationships between species and their environmental factors indicated that elevation and slope were the most important environmental factors affecting plant species distribution, and the aspectand the thickness of humus also influenced species distribution in our study area. The uniqueness of this study is introducing the species-environment relations （CCA） into the analyzing framework to solve the complex inter-species, intra-species, and plant-environment relationships to enrich niche theory. This study also demonstrated that importance values were directly correlated with the breadth of ecological niches. In general, the higher the niche overlap between two species, the more similar the environmental conditions in which they were found. In addition, the analysis showed that the distribution frequency was an important factor affecting the niche breadth and species niche overlap. We observed positive relationships between the distribution frequency and the niche overlap probabilities, namely, the higher the distribution frequency the higher the probability of species niche overlap. Furthermore, the interspecific relationships reflected the interconnectedness of different species in the spatial distribution and represented mutual attraction or repulsion between species and their environment. In our study area, most of the interspecific relationships between the dominant species showed a positive correlation. There were many factors, including local climate, soil types, topography, and landforms, that influenced the distribution of plant species in a given community. In summary, this study found the following general patterns for interspecific relationships： if species have a narrow niche, they also have a narrower spatial distribution, and specialize on certain resources with less overlap with other species in the CCA sequencing diagram, characterized as a tendency of deviating from the high species distribution areas. However, if species have a wide niche, they also have a wider distribution range and greater overlaps with other species, and occupy a majority of the species distribution area on the CCA sequencing diagram. For a given species, if it does not have significant interactions with other species, the higher its niche overlap values are with another species, the closer the distances betweenthe species on the CCA sequencing diagram. If there is a positive shorter distances among species on the CCA sequencing diagram correlation, this correlation is significant and there are ; while if there is a negative correlation, this negative correlation is also significant and the distances are longer among species on the CCA sequencing diagram. Our study not only indicates the complex interspecific and species-environment relationships for constructing ecological public welfare forests in subtropical regions, especially in China, but also provides recommendations of how to use our research in practice,including providing feasible suggestions to protect species diversity and accelerate positive community succession.