山西吕梁山草本群落物种多样性的海拔梯度格局及与环境因子的关系

Patterns of species diversity in herbaceous communities at different altitude gradients and their relationships with environmental factors in Lüliang Mountains in Shanxi Province, China

关键词:  吕梁山, 草本群落, 物种多样性, 海拔梯度, 环境因子

Key words:  LV liang Mountains, herbaceous community, species diversity, altitude gradient, environmental factors

摘要:

山地草本群落物种多样性的海拔梯度格局及其与环境因子的关系一直是生态学和地理学研究的热点问题。为探究吕梁山草本群落不同尺度物种多样性(α、β、γ多样性)的海拔梯度格局及其与环境因子的关系,该研究采用样方法在吕梁山从北向南选取管涔山、关帝山、五鹿山,并对每个山地划分出高、中、低3个海拔梯度,对草本群落物种多样性和环境因子进行调查分析。结果表明:(1)α多样性随海拔升高呈先升后减的单峰变化格局,峰值出现在中海拔; β多样性中Cody指数在1 900～2 000 m间出现峰值,而Bray-Curtis 指数出现最小值,表明1 900～2 000 m海拔带是草本群落物种更新速率和组成变化较快的过渡地带; γ多样性随海拔升高也呈先升后减的单峰变化格局(R²=0.406,P<0.01)。(2)海拔对温度、湿度变化的影响极其显著(P<0.01); 海拔、温度、湿度等环境因子共同影响物种的α多样性,其中海拔是主要影响因素(P<0.05),温度、湿度影响不显著(P>0.05)。综上所述,吕梁山草本群落多样性在海拔梯度上多表现为 “中间膨胀”变化格局,海拔变化是影响多样性变化的主要因素。

Abstract:

Patterns of species diversity in mountain herbaceous communities at different altitude gradients and their relationships with environmental factors was an enduring hot topic in ecological and geographical researches. This topic was explored in the context of the mountains of Guancen, Guandi, and Wulu that extend from north to south across the Lüliang Mountain range in Shanxi Province in China. Each mountain was divided into three altitude gradients: high, middle and low. During the vegetation growing season in 2018, an investigation was conducted on the growth characteristics indicators of plants and hydrothermal factors located at these altitude gradients and species diversity index values(α-, β-, and γ-diversity)were calculated to explore the patterns of species diversity at different altitude gradients and their relationships with environmental factors. The results were as follows:(1)Unimodal patterns of variation for α-diversity(calculated using the Simpson, Shannon-Wiener and Pielou indexes)that corresponded to increasing altitudes, with the highest species diversity occurring at the mid-altitude gradient; The results calculated for β-diversity using different indexes revealed the highest value for the Cody index and the lowest value for the Bray-Curtis index at altitudes between 1 900 and 2 000 m, indicating that areas located between 1 900 and 2 000 m form a transition zone in which the herbaceous community undergoes a rapid process of species renewal and changes in its composition; The results for γ-diversity indicated a pattern of unimodal variation in relation to altitude.(2)Changes in altitude gradient had highly significant impacts on changes in temperature and humidity(P<0.01); Various environmental factors, notably altitude, humidity, and temperature had a combined effects on changes in the values of the α-diversity indexes, with altitude being the main influencing factor(P<0.05), and changes in temperature and humidity had no significant effects on species diversity(P>0.05). Therefore, species diversity within the herbaceous community in the Lüliang Mountains predominantly showed a “mid-altitude bulge” pattern, with altitude being the main factor affecting changes in species diversity. The finding of this study can contribute to refining and expanding studies of herbaceous communities in this region and provide inputs for advancing the systematic conservation and management of herbaceous resources.