纬度梯度下不同群系羊草种群数量特征

Quantitative characteristics of Leymus chinensis populations in different groups across a latitudinal gradient

大尺度地理空间和局域尺度微生境植物种群数量特征的比较研究,对解释多变环境植物的趋异适应具有重要意义。在我国北方的天然草原,采用单位面积和大样本取样法,比较纬度梯度下不同群系羊草种群数量特征,进一步分析种群数量特征与纬度的关系。结果表明:纬度梯度上,草甸群系和草甸草原群系羊草的种群密度、种群生物量和种群高度分别为709~1536和661~1109株·m^(-2),366.92~726.40和330.59~410.72 g·m^(-2),56.28~73.49和43.27~68.87 cm,总体上草甸群系均高于草甸草原群系(P<0.05)。随着纬度的增加,不同群系羊草种群数量特征均表现出增加的趋势,种群数量特征与纬度间均较好地符合y=ax的指数函数关系,R^(2)在0.7806~0.9373,拟合方程均达到显著水平。因此,无论在大尺度地理空间,还是局域尺度微生境间羊草种群均表现出明显的适应性调节,局域尺度的不同群系间羊草种群数量特征差异稳定,大尺度的纬度间羊草种群数量特征又表现出一致的规律性。

Comparative studies on the quantitative characteristics of plant populations in large(geographical space)and local scales(microhabitats)are important to explain the divergent adaptation of plants across changing environment.In the natural grasslands of northern China,we used sampling methods of unit area and large sample sizes to compare the quantitative characteristics of populations in different groups of Leymus chinensis along a latitudinal gradient.We further analyzed the relationship between the quantitative characteristics of populations and latitude.The results showed that along the latitudinal gradient,population density,population biomass,and population height of L.chinensis in the meadow groups and meadow steppe groups were 709-1536 and 661-1109 tillers·m^(-2),366.92-726.40 and 330.59-410.72 g·m^(-2),56.28-73.49 and 43.27-68.87 cm,respectively.All the indices in the meadow groups were generally higher than the meadow steppe groups(P<0.05).With increasing latitude,the quantitative characteristics of L.chinensis populations in different groups showed an increasing trend.The relationships between the quantitative characteristics of populations and latitude all better agreed with the exponential function of y=ax(R^(2)=0.7806-0.9373,P<0.05).Thus,L.chinensis populations showed obvious adaptive regulation at both large and local scales.The differences in the quantitative characteristics of L.chinensis populations between different groups in local scales were stable,while the quantitative characteristics of L.chinensis populations showed consistent regularity in large-scale latitude.