吉林灌木群落物种多样性与气候和局域环境因子的关系

为了研究气候和局域环境因子对物种多样性的相对作用大小,以及验证两种均匀度地理格局的假说在半湿润地区次生灌丛的适用性,对吉林东、南部地区的灌木群落进行了研究。共调查森林破坏后形成的次生灌丛样方45个,结合气候数据和局域环境因子数据,研究了气候、局域环境因子对群落、灌木层、草本层的物种丰富度、均匀度的影响,以及对不同水分生态型(旱生、旱中生、湿中生)灌木影响的差异。结果表明:1)吉林次生灌丛的群落、草本层物种丰富度,以及草本层均匀度,随纬度增加而显著上升。2)对物种多样性和气候、局域环境因子的分析表明,群落、草本层物种数主要受局域环境因子而不是气候的影响;其物种丰富度与纬度的反常关系,是由于灌木层盖度随降水增加而上升,从而导致物种数下降。灌木层物种数与纬度、气候因子的相关性不显著,则是由于不同水分生态型对气候梯度的响应不一致,反映出功能群对多样性格局的影响。3)群落、灌木层均匀度主要受气候因子的影响;而草本层均匀度主要受局域环境因子的影响,降水同样通过对灌木层盖度的影响间接作用于草本均匀度。但群落、灌木和草本层的结果,都支持均匀度随着环境条件改善而增加的假说,而不支持随着生产力增加、竞争加剧,从而导致均匀度下降的假说。结果表明,物种丰富度和均匀度的影响机制存在很大差异,但二者都受到局域环境因子的强烈影响。气候通过局域生物因素(如盖度、生活型)间接作用于多样性格局,是气候对多样性影响的一个重要方面,但尚未得到应有的重视。由于局域生物因素也随气候而变化,仅研究多样性和气候的表面关系,将无法准确预测气候变化对多样性的影响。

Relationship between shrub species diversity and climate and local environmental factors across Jilin

The aim of this research was to study the relative effects of climate and local environmental factors on species diversity and test the applicability of the hypothesis of the evenness of two geographic patterns on a secondary shrub community in sub-humid environments. This research investigated 45 samples from secondary irrigation areas after forest damage in the eastern and southern areas of Jilin. Climate data and local environmental factors were used to study their effects on the species richness and evenness of the community, shrub layer, and herb layer. Different water ecotypes (xero-, mesoxero- and phreatophyte) were also analyzed separately to examine how the effects of climate and local environmental factors on the species richness and evenness differed among functional groups.The results showed that: 1) Community, herb layer species richness, and herb layer evenness, increased significantly with increasing latitude. 2) Community and herb species richness are mainly affected by local environmental factors rather than climate. The abnormal relationship between species richness and latitude is owing to increasing shrub layer cover with increasing precipitation, leading to decreased species richness. The correlation between shrub species richness and latitude and climate factors was not significant, because the response of different water ecological regimes to the climate gradient was inconsistent, which reflects the influence of functional groups on diversity patterns. 3) The evenness of the community and shrub layer was mainly affected by the climate factors. The evenness of the herb layer was mainly affected by the local environmental factors. The precipitation also indirectly affected herb evenness through the influence of the shrub layer. However, the results of the community, shrub, and herb layers all support the hypothesis that evenness increases with improving environmental conditions. The results of this study showed that the mechanism of species richness and evenness is very different, but both are strongly influenced by local environmental factors. Climate indirectly acted on the diversity of the pattern through local biological factors (such as coverage, lifestyle); therefore, the effect of the climate on diversity is important, but has not received due attention. Since local biological factors also change with climate, only studying the surface relationship of diversity and climate will not accurately predict the impact of climate change on diversity.