Leaf has the fundamental functions of capturing light energy and assimilating carbon in most plants, and the differences between the ways by which it acquires processes and invests resources can have very great effects on the species composition and functioning of an ecosystem. It has been widely agreed that leaf traits such as specific leaf area (SLA) and leaf nutrient contents are sensitive indicators of environmental conditions. The variation and the relation between SLA and leaf nutrient content of plant can represent the responses and adaptations of the plant to climatic and environmental conditions. The study was carried out to investigate the variation of the SLA and leaf nutrient content of plants growing on slopelands with different farming abandoned periods in the Loess Plateau with the purpose of finding out their variation to their sites and species the plants significant difference in SLA and the ranges of their SLA differently varied; their carbon, nitrogen and phosphorous contents, and C/N, N/P and C/P ratios varied consistently in slopelands with different farming abandoned periods, indicating that in different plant species the leaf-reated factors varied with environmental conditions in a complex manner. On the grassland plants, the SLA was negatively correlated with the leaf carbon contents and appeared extremely significantly positively correlated with the leaf N and leaf P (P<0.01).
The realtions of the SLA and the leaf nutrients to soil physical and chemical properties varied depending the plant species and analysis considering all the plants indicated that the SLA did not appeared remarkably correlated with soil physical and chemical properties but closely related to the leaf nuritent content. Therefore, the habitat differences may be the important reasons for the variations in leaf sturcture and leaf nutrient concentration, and because the leaf trait-regulating factors were very complex, each species has its adaptaiton mechanism to the habitat conditions.