山西吕梁山草本群落对模拟增温的响应及与环境因子的关系

Response of Herb Community to Simulated Warming and Its Relationship with Environmental Factors in Lüliang Mountain,Shanxi,China

【目的】为探究全球气候变暖背景下,山地森林群落结构与格局的动态变化及其与环境因子的关系。【方法】以吕梁山不同海拔梯度下的林下草本群落为研究对象,采用开顶式增温箱设置低(OTC1)、高(OTC2)两种幅度的野外模拟增温实验,探讨了不同增温处理下吕梁山草本群落物种多样性与生物量随海拔梯度的响应特征及其与环境因子的关系。【结果】①在OTC1和OTC2处理下,空气温度均呈增加趋势(分别增加了0.27%和3.33%),而土壤温度变化幅度不一致(分别减小了1.01%和增加了0.95%),土壤pH值呈减小趋势(分别减小了0.3和0.2);空气温度增幅随纬度升高极显著减小(P=0.006),土壤温度增幅随海拔升高显著减小(P<0.05),土壤pH值随海拔升高极显著降低(P<0.001)。②Simpson指数、Shannon指数和Patrick指数随温度升高呈下降趋势,Pielou指数随温度升高略有上升;OTC1处理促进物种多样性增加,而OTC2处理抑制物种多样性。③地上生物量随空气温度升高而增加(R^2=0.244,P<0.01),其中OTC1处理使生物量增加了50.78%,OTC2处理使生物量增加了42.29%,且地上生物量增幅随海拔升高而减小。④RDA分析得到,各排序轴的特征值总和在OTC1和OTC2处理下分别增加了5.31%和54.11%。【结论】随温度升高草本植物与环境因子相关性增强,且过度增温可使物种趋于单一化发展,引起群落物种更替。

【Objective】In order to explore the dynamic changes of mountain forest community structure and pattern and its relationship with environmental factors under the background of global warming.【Method】Taking the undergrowth herb community in different elevation gradients in Lüliang Mountain,and the research object,the open-top chambers are setted as low(OTC1) and high(OTC2) warming devices to carry out the simulated warming expriments.It is investigated that how species diversity and biomass of the Lüliang Mountain herb community respond to altitude gradient changing and what is the relationship between that and environmental factors.【Result】The results show(i) Under the treatment of OTC1 and OTC2,the air temperature increased by 0.27 % and 3.33 %,respectively,the soil temperature decreased by 1.01 % and increased by 0.95 %,and the soil pH decreased by 0.3 and 0.2,respectively.In addition,under the OTC2 treatment,the air temperature increase was significantly reduced with the increase of latitude(P=0.006),the soil temperature increase decreased significantly with the increase of elevation(P<0.05),and the soil pH decreased significantly with the increase of elevation(P<0.001).(ii) The Simpson index,Shannon index and Patrick index decreased with temperature increasing,and the Pielou evenness index increased slightly with temperature increasing;OTC1 treatment promoted species diversity,while OTC2 treatment reduced species diversity.(iii) The aboveground biomass increased with the increase of air temperature(R^2=0.244,P<0.01),among which the biomass increased by 50.78 % under OTC1 treatment,and the biomass increased by 42.29 % under OTC2 treatment,and the aboveground biomass increased with altitude decreasing.(iv) The sum of the characteristic values of RDA sorting axes increased by 5.31 % and 54.11 % respectively under OTC1 and OTC2 treatments.【Conclusion】With the increase of temperature,the correlation between herbaceous plants and environmental factors is enhanced,and excessive warming can lead to the singular development of species,causing community species replacement.