黄土高原退耕草地演替过程中土壤及微生物碳氮磷化学计量关系时空变化

Temporal and Spatial Variations of Soil and Microbial Carbon,Nitrogen and Phosphorus Stoichiometric Relationships During the Succession of Rehabilitated Grassland on the Loess Plateau

为系统性探究黄土高原退耕草地演替过程中土壤及微生物碳(C)、氮(N)、磷(P)生态化学计量关系时空变化格局,本研究收集了2000年至2021年期间发表的黄土高原退耕草地演替文献,筛选出3个不同草地恢复研究区的17个长期演替序列,整合分析了土壤及微生物C、N、P含量及其化学计量的时空变化特征及影响因素,结果表明:(1)黄土高原退耕草地土壤及微生物C和N含量随演替进程显著升高,但P含量则无显著变化趋势。同时,土壤及微生物C、N和P的化学计量比(C∶N∶P)均随演替进程发生变化,但相较于土壤C∶N∶P变化,微生物C∶N∶P在整个演替过程中相对稳定。此外,土壤与微生物化学计量不平衡性及微生物熵等指标随演替进程呈增加趋势,表明在演替后期土壤养分质量和微生物养分利用效率均在逐渐降低,不利于微生物的可持续性发展;(2)不同研究区微生物N增长速率有所不同,这是由不同研究区之间海拔高度不同引起的局地温度和降水差异所导致的,具体表现为海拔较低的研究区微生物N增长速率更高。总之,该研究系统地探究了黄土高原退耕草地演替过程中土壤及微生物C、N、P养分含量及化学计量特征的变化趋势,并确定了关键调控因素为区域尺度气候及地形因子。

This study aimed to investigate the temporal and spatial variation patterns of soil and microbial carbon(C),nitrogen(N),and phosphorus(P)eco-stoichiometry during the succession of rehabilitated grassland on the Loess Plateau.Relevant research conducted on the Loess Plateau from 2000 to 2020 were collected,confirming seventeen long-term succession sequences from three different grassland restoration study areas.Subsequently,we integrated and analyzed the temporal and spatial changes in stoichiometric characteristics,along with the critical influencing factors on the contents and stoichiometry of soil and microbial C,N,and P.The results showed that:(1)Soil and microbial C and N contents exhibited a significant increase during the succession of rehabilitated grassland on the Loess Plateau,while P content showed no significant changes.The soil and microbial C∶N∶P ratios also changed throughout the succession process.However,compared with the huge variation of soil C∶N∶P ratios,microbial C∶N∶P ratios remained relatively stable during the entire succession process.In addition,the stoichiometric imbalance between soil and microorganisms,along with the microbial quotient,increased during the succession process.This indicated that both the quality of soil nutrients and the nutrient utilization efficiency of microorganisms gradually decreased in the later stages of succession,potentially interfering with the sustainable development of microorganisms;(2)The increase rates of microbial N varied among different study areas due to the differences in temperature and precipitation resulting from varying altitudes.Particularly,study areas with lower altitudes exhibited higher microbial N increase rates.In conclusion,our research system‐atically explored the trends of soil and microbial C,N,and P,and their stoichiometry changes during the succession of the rehabilitated grassland on the Loess Plateau.Additionally,we identified key regulatory factors,including regional-scale climate and topographic factors.