基于生态化学计量学的退耕植物-土壤-微生物系统协同演变机制研究

Vegetation succession was one of the most important measure to recovery the structure and function of the degraded ecosystem, integrated analyses the coordinative mechanisms of plant-soil-microbe systems during vegetation restoration had very important science meaning to reveal the reason for vegetation succession and promote vegetation succession rate. The present research selected a chronosequence of herb community vegetation since land abandonment in Loess Plateau as research objectives. Based on the study of the carbon, nitrogen and phosphorus concentration and their stoichiometry characteristics of plant-soil-microbe systems of the dominant species during vegetation succession, we focused on the coupling relationship of ecological stoichiometry characteristics of plant-soil-microbe systems and its evolution rule of the overlapping species in the vegetation succession processes. Using ecological stoichiometry homeostasis theory, we analysis the carbon, nitrogen and phosphorus cycling rules of the plant-soil-microbe systems during vegetation succession. We intended to reveal the plant-soil-microbe coordinative mechanisms of ecological stoichiometry properties during vegetation succession, and clarify the mechanism of vegetation succession from the aspect of ecological stoichiometry. We hope that the research would provide scientific basis and technical support for ecological restoration in the Loess Plateau.

植被恢复演替是修复退化生态系统结构和功能的重要措施，系统分析植被恢复过程中植物-土壤-微生物系统的协同响应关系对于揭示植被演替的原因以及促进植被恢复演替具有重要的科学意义。本研究以黄土丘陵区退耕地草本植被演替序列为研究对象，在分析植被演替不同阶段优势草本植物-土壤-微生物系统碳氮磷含量及其化学计量特征的基础上，重点研究植被演替过程中共有种植物-土壤-微生物系统生态化学计量特征耦合关系及其演变规律，应用内稳态理论分析植被演替过程中植物-土壤-微生物系统碳氮磷元素循环转化规律，揭示植被演替过程中植物-土壤-微生物系统生态化学计量特征协同演变机制，从生态化学计量学的角度阐明退耕植被演替机制，为黄土丘陵区退耕地植被恢复提供科学依据和技术支撑。

针对退耕植被恢复演替过程中植物-土壤-微生物系统协同演变机制缺乏系统研究这一问题，本项目以黄土丘陵区退耕植被恢复演替群落根际微生态系统为研究对象，系统分析了植被演替过程中植物、土壤、微生物群落性质演变规律，阐明了植被恢复演替根际微生态系统生态化学计量特征协同演变机制。研究发现：①随着退耕植被演替进行，物种丰富度指数和多样性指数呈先增大后减小趋势，地上生物量、根系生物量和根冠比呈逐渐增大的趋势。②退耕植被演替过程中优势种根际土壤有机碳和全氮含量随演替年限的增加而增加，且高于伴生种根际土壤有机碳和全氮含量。单位有机碳BG、NAG、LAP和AP的比酶活性随演替年限的增加而显著降低，优势种植物根际单位有机碳比酶活性均低于伴生种植物。③非根际土壤BG活性的温度敏感性（Q10）值和根际土壤BG、NAG、LAP和AP酶活性Q10值随植被演替变化显著。不同温度区间的Q10值在非根际土壤间存在显著差异，而在根际土壤间不存在显著差异。④植被演替对土壤C:P、N:P、aN:aP以及土壤酶化学计量有显著影响，土壤酶C:N和C:P在演替前22年呈下降趋势，之后呈上升的趋势。土壤养分含量和养分化学计量与酶活性和酶化学计量显著相关。土壤微生物群落在植物演替过程中呈内稳性，微生物养分代谢受到氮和磷的共同限制，尤其是磷。⑤不同演替阶段植物-土壤-酶的化学计量特征有显著差异。土壤BG、NAG、AP活性和酶C:N的变化对植物组织的养分含量和化学计量特征有显著影响，根际土壤酶活性的变化是植被恢复演替的重要驱动因素。