ABSTRACT
The trade-off between leaf size and number is the basis for plant growth strategies. It is of great significance to study the underlying mechanism of leaf size and number trade-offs for well understanding plant growth strategies. In this study, leaf size was expressed by the dry mass of single leaf, while leafing intensity was expressed by the number of leaves per unit stem volume. We used standardized major axis regression analysis method to examine the trade-off relationship between leaf size and number in Hulunbuir grassland. There was a significant negative isometric-growth trade-off between leaf size and number in Chenqicuogang (typical steppe) and Chenqibayi (meadow steppe). There was a significant negative allometric-growth trade-off between leaf size and number in Xeltala (meadow steppe). The underlying mechanism of the relationship between leaf size and number depended on the leaf and stem biomass allocation mechanism and the changes of the stem tissue density.
