揭示次生演替过程中的土壤C:N:P计量学变化及其驱动机制是明确森林次生演替变化规律的重要内容，然而当前的研究很不深入，仍然停留在表象认识阶段，对变化效应的认识分歧较大，对驱动机制的认识肤浅，缺乏研究。因此，本项目将选择川西林区代表性森林次生演替过程，综合应用时间序列、动态定位监测与BACI实验这三种方法，聚焦土壤C:N:P化学计量变化及其生物驱动机制，开展4个内容的研究，试图明确三方面的科学问题：森林块状皆伐及其迹地早期演替中土壤C:N:P化学计量变化与趋势、阔叶林更新与人工林演替过程中土壤C:N:P化学计量演变趋势及其差异性以及驱动土壤C:N:P化学计量变化的生物源（树种替代、地上底下凋落物、根系与土壤微生物）综合作用过程与机理，并综合评估代表性林业实践活动（采伐、造林与自然更新）对土壤C:N:P化学计量变化的影响后果，为森林恢复与次生林持续经营管理提供土壤学证据。

Changes of soil C:N:P stoichiometry have yet to be fully described and the relevant researches are scarce, resulting in seriously deficient knowledge in its change during forest secondary succession and the biological manipulating mechanism. Therefore, the study in current application would be conducted in western Sichuan forest region and focused on the change of soil C:N:P stoichiometry during forest secondary succession and the biological manipulating mechanism. We try to answer three scientific questions: 1) How does soil C:N:P stoichiometry change on early vegetation succession after patch clear-cut to subalpine forests? 2) How, and what differences, does soil C:N:P stoichiometry change between the developments of spruce plantation and regenerated deciduous forests after patch clear-cuts to subalpine forests? and 3) how do biological factors drive the soil C:N:P stoichiometry changes? The diachronic and chronosequence approaches would be used comprehensively to explore the first two questions and further the BACI approach would be applied to explore the third question. The final destination would be to understand the soil consequences of the several typical forestry practices (clearcut, reforestation and natural regeneration) providing as testimonies for the improvement on forestry management and forest restoration in the regions.