Abstract: To study the plant density-dependent regulation pattern is of significance to the development of plant ecology and to give guidance to the rational density in forestry, agriculture, animal husbandry, and restoration of degraded ecosystems. This paper reviewed the recent researches on the -3/2 and -1/2 self-thinning rules, the instability and dispute of self-thinning exponent, and the relationships between self-thinning rules and density regulation exponent, summarized the responses of density regulation exponent to environmental changes such as water gradient, salt concentration, altitude, and light condition, and discussed the positive and negative interactions among individual plants and the relationships of plant density regulation mechanisms in ecological field with plant morphology, coverage and environmental changes. The study of self-thinning exponent had experienced invariable, variable, and change with environment. The future research trend of plant density-dependent regulation pattern was proposed from the aspects of WBE (West, Brown and Enquist) model and metabolic ecological theory (MET), plant neighbor effect, belowground and aboveground integration, rhizospheric microbial regulation to plant interaction, and combination of macro and micro levels.

Key words: Elevated CO₂ concentration, Pinus koraiensis, Pinus sylvestriformis, Fraxinus mandshurica, Soluble sugar, Starch, Total nitrogen