关键词: 羊草, 种群, 群系, 趋异适应

Abstract: 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=a_x (R²=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.

Key words: Leymus chinensis, population, group, divergent adaptation