贺兰山东、西坡群落植物叶N、P化学计量沿海拔梯度的格局及群落构建机制

The Pattern of Leaf N and P Stoichiometry of Plant Communities Along the Elevational Gradient on the East and West Slopes of Helan Mountain and the Community Construction Mechanism

为了研究贺兰山不同气候类型群落植物叶N、P化学计量沿海拔梯度的格局及群落构建机制,以贺兰山东、西坡沿不同海拔梯度的群落植物为研究对象,分析群落植物叶片N、P质量分数的加权平均值与海拔的关系,并通过构建零模型,探究沿海拔梯度贺兰山东、西坡植物群落构建机制。结果表明:贺兰山东坡植物叶片N质量分数和N、P质量分数比的群落加权平均值随着海拔的升高,呈现先增加后降低的趋势,并在海拔1600~2000 m处最高;东、西坡叶片P质量分数均随海拔升高逐渐增加。贺兰山东坡群落叶片N质量分数在中海拔(2000 m左右)处发散,在中高海拔(2600 m左右)处收敛;叶片P质量分数在中高海拔(2600 m左右)处最收敛,叶片N、P质量分数比在中低海拔(1700 m左右)处最发散。而贺兰山西坡植物叶片N质量分数在中高海拔(2600 m左右)处最发散,叶片P质量分数在中高海拔(2700 m左右)处最发散。环境因子不是贺兰山东坡群落构建的主要驱动因素,而是贺兰山西坡群落构建的主要驱动因素,其中,土壤N、P质量分数显著影响叶片N、P化学性状的群落加权方差。

To investigate the pattern of leaf N and P stoichiometry of plant communities along the elevational gradient in different climatic types of Helan Mountain and the community construction mechanism,the communities of plant species along different elevational gradients on the east and west slopes of Helan Mountain were selected as the research object.The weighted average values of leaf N and P mass fractions of the plant communities were analyzed in relation to elevation.Additionally,a null model was constructed to explore the community construction mechanism along the elevational gradient of the east and west slopes of Helan Mountain.The results showed that on the east slope of Helan Mountain,the weighted average values of leaf N mass fraction and the N∶P mass ratio in the plant communities increased with elevation,showing a trend of first increasing and then decreasing,reaching the peak at an elevation of 1600-2000 m.The leaf P mass fractions on both the east and west slopes increased gradually with elevation.On the east slope,the leaf N mass fraction of the plant community diverged around the mid-elevation(approximately 2000 m)and converged around the mid-high elevation(approximately 2600 m).the leaf P mass fraction of the plant community converged around the mid-elevation(approximately 2600 m),and the N∶P mass ratio diverged around the mid-low elevation(approximately 1700 m).On the west slope of Helan Mountain,the leaf N mass fraction of the plant community diverged at the mid-high elevation(around 2600 m),while the leaf P mass fraction diverged at the mid-high elevation(around 2700 m).The environmental factors were found to be the main driving force for the construction of the plant community on the west slope of Helan Mountain,rather than the primary driving force for the construction of the plant community on the east slope.Among,soil N and P mass fractions significantly impacted the weighted variance of leaf N and P chemical traits in the plant community.