摘要:明确植物和微生物在植被恢复过程中的内稳态特性，对反映生物随恢复环境变化的适应性和阐明生态系统养分循环规律有重要意义。以黄土丘陵区恢复5年、10年、20年、30年和45年的刺槐（Robinia pseudoacacia）人工林为研究对象，测定刺槐叶片、土壤和微生物生物量C、N、P含量及其化学计量学指标，重点揭示了叶片和微生物生物量养分在恢复过程中随土壤养分变化的稳态性特征。结果表明：（1）随着恢复年限的增加，土壤、叶片和微生物生物量C、N、P含量表现为增加趋势；（2）不同恢复年限叶片、土壤、微生物生物量C：N分别为17.03-26.03、9.55-16.94、5.57-10.76、C：P分别为465.04-634.48、19.89-65.81和39.64-110.53、N：P分别为17.89-37.03、1.24-4.68和7.15-10.26，除叶片C：N随恢复年限增加而降低外，其他指标均表现为随恢复年限增加而增加或先增加后降低；刺槐林生长后期可能面临P限制；（3）叶片和微生物生物量C、N、P及其计量比大部分指标与土壤指标的关系能够被内稳态模型很好地模拟（P < 0.01）；其中叶片N：P、微生物C、N对土壤养分变化较为敏感；其他指标比较稳定。研究表明植物和微生物在面对土壤养分变化时均会通过自我调节呈现内稳态性，说明刺槐在黄土丘陵区有较好的适应性；微生物对土壤养分的变化比植物更加敏感，其养分和计量比指标能较好地指示土壤恢复状况。



Abstract:The homeostasis characteristics of plants and microbes during vegetation restoration are important indicators of the ability of organisms to adapt to environmental changes and also provide insights into ecosystem nutrient cycling. The aim of the present study was to investigate the C, N, and P contents and ecological stoichiometric ratios (leaves, soil, and soil microbial biomass) of five Robinia pseudoacacia forests in the Loess Hilly Region of China, selected based on their restoration ages (i.e., 5, 10, 20, 30, and 45 years). The homeostasis characteristics of leaves and soil microbial biomass along with stand ages were emphatically revealed. Each of the forest included three replicate lands. Each replicate land included three sample plots (20 m×20 m), and soil samples were collected from five points in each plot by using a soil auger (4 cm diameter), before being homogenized and analyzed. Leaves samples were collected from 10 individual trees in each sample plot. Vegetation surveys included five randomly selected plots (1 m×1 m) at each site. The results showed that:(1) The C and N contents of the leaves, soil, and soil microbial biomass all increased with recovery duration (P < 0.01), and the P contents increased, although not significantly. (2) The C ∶ N ratios of the leaves, soil, and microbial biomass were 17.03-26.03, 9.55-16.94, and 5.57-10.76, respectively, whereas the C ∶ P ratios were 465.04-634.48, 19.89-65.81, and 39.64-110.53, and the N ∶ P ratios were 17.89-37.03, 1.24-4.68, and 7.15-10.26, respectively. All stoichiometric characteristic ratios showed mostly increase trends with the increase of the recovery age, except for the leaf C ∶ N was decreased (P < 0.01). (3) The relationships between C, N, and P contents and their ratios in the leaves and microbial biomass with corresponding soil parameters can be adequately simulated using an internal homeostasis model (P < 0.01). Only leaf N ∶ P and microbe C and N contents were sensitive to changes in the soil nutrient contents. These results indicate that plants and microbes reach homeostasis by self-regulation, regardless of soil nutrient changes, thereby suggesting that R. pseudoacacia forests in the Loess Hilly Region are well adapted to environmental change. However, compared to plants, soil microbes were more sensitive to environmental changes, indicating that soil microbial biomass nutrient content can be used as an indicator of soil restoration status in R. pseudoacacia forests.





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