【作者】 王丽；

【导师】 孟晨；

【作者基本信息】 宁夏大学 ， 生态学， 2025， 硕士

【摘要】 荒漠草原生态系统严重退化,合理的放牧管理策略对于恢复土壤健康、提高生态系统稳定性至关重要。以往关于放牧管理的研究局限于全面禁牧及放牧强度管控等方面,针对不放牧-围封交替管理的研究较少。本研究以宁夏盐池县荒漠草原为研究对象通过野外监测（放牧和围封管理的人工柠条林、天然柠条林、草地）土壤团聚体及碳氮组分变化特征,以及针对天然草地模拟放牧-围封交替管理（放牧3天围封3天、放牧6天围封6天,放牧12天围封12天,放牧24天围封24天,全面放牧,全面围封）牲畜践踏行为对土壤团聚体及碳氮组分的影响,为荒漠草原的科学管理和生态系统可持续恢复提供科学依据。研究结果表明:（1）相较于全面围封,放牧-围封交替管理动物踩踏增加了土壤速效氮（AN）和速效钾（AK）含量,但降低了速效磷（AP）含量。3天放牧-围封交替管理下土壤团聚体聚合度、稳定性更优。（2）放牧显著增加了0～20 cm土层土壤有机碳（SOC）、惰性有机碳（IOC）和可溶性有机碳（DOC）含量（P<0.05）,对易氧化有机碳（ROC）无显著影响。放牧草地、放牧人工柠条林土壤有机碳（SOC）、可溶性有机碳（DOC）含量高于围封草地、围封人工柠条林。（3）放牧对氮组分的影响集中体现在表层土壤（0～10 cm）。放牧显著提高各样地0～10 cm土层全氮（TN）、可溶性有机氮（SON）和硝态氮（NO_<sup>--N）含量（P<0.05）,但对铵态氮（NH₄⁺-N）无显著影响（P>0.05）。（4）团聚体粒径组成与分形维数对土壤养分有效性及pH具有调控作用。大粒径团聚体（>0.25 mm）、MWD、GMD与SOC、TN、pH呈正相关,与AN、AP、EC呈负相关。（5）团聚体拓扑参数对SON、TN、NH₄⁺-N的积累有促进作用,但高球度与等效直径可能抑制TN与NH₄⁺-N含量团聚体数量密度、长度密度、体积密度和周长与SOC、IOC、DOC、ROC积累呈正相关,平均等效直径和球度与其呈负相关。合理放牧-围封交替管理（如3天放牧-围封交替管理）可优化荒漠草原土壤团聚体结构,提升碳氮固存能力,通过调控团聚体拓扑特征促进土壤养分循环。建议结合围封恢复与周期性放牧,平衡土壤健康,为荒漠草原可持续管理提供科学依据。更多还原

【Abstract】 The desert steppe ecosystem has undergone severe degradation.Rational grazing management strategies are crucial for restoring soil health and enhancing ecosystem stability.Previous studies on grazing management have been limited to aspects such as total grazing prohibition and grazing intensity control,with relatively few focusing on different grazing-enclosure alternate management.This study targeted the desert steppe in Yanchi County,Ningxia.Through field monitoring of the changing characteristics of soil aggregates and carbon-nitrogen components in artificially planted Caragana korshinskii forests,natural Caragana korshinskii forests,and grasslands under grazing and enclosure management,as well as simulating the effects of livestock trampling behavior on soil aggregates and carbon-nitrogen components under different enclosure-grazing alternate management scenarios（grazing for 3 days and enclosing for 3 days,grazing for 6 days and enclosing for 6 days,grazing for 12 days and enclosing for 12 days,grazing for 24 days and enclosing for 24 days,total grazing,and total enclosure）in natural grasslands,this study provides a scientific basis for the scientific management and sustainable restoration of the desert steppe ecosystem.The research results indicate:（1）Compared with total enclosure,the alternate grazing-enclosure management with animal trampling increased the content of available nitrogen（AN）and available potassium（AK）in the soil but decreased the content of available phosphorus（AP）.The soil aggregate polymerization degree and stability were better under the 3 days alternate grazing-enclosure management.（2）Grazing significantly increased the content of soil organic carbon（SOC）,inert organic carbon（IOC）,and dissolved organic carbon（DOC）in the 0～20 cm soil layer（P<0.05）,with no significant effect on readily oxidizable organic carbon（ROC）.The content of SOC and DOC in grazed grasslands and grazed artificially planted Caragana korshinskii forests was higher than that in enclosed grasslands and enclosed artificially planted Caragana korshinskii forests.（3）The impact of grazing on nitrogen components was mainly concentrated in the surface soil（0～10 cm）.Grazing significantly increased the content of total nitrogen（TN）,dissolved organic nitrogen（SON）,and nitrate nitrogen（NO_<sup>--N）in the 0～10 cm soil layer of all plots（P<0.05）,but had no significant effect on ammonium nitrogen（NH₄⁺-N）（P>0.05）.（4）The particle-size composition and fractal dimension of soil aggregates regulated soil nutrient availability and pH.Large-sized aggregates（>0.25 mm）,mean weight diameter（MWD）,and geometric mean diameter（GMD）were positively correlated with SOC,TN,and pH,and negatively correlated with AN,AP,and electrical conductivity（EC）.（5）The topological parameters of soil aggregates promoted the accumulation of SON,TN,and NH₄⁺-N.However,high sphericity and equivalent diameter might inhibit the content of TN and NH₄⁺-N.The number density,length density,volume density,and perimeter of aggregates were positively correlated with the accumulation of SOC,IOC,DOC,and ROC,while the average equivalent diameter and sphericity were negatively correlated.Rational alternate grazing-enclosure management（such as the 3 days alternate grazing-enclosure management）can optimize the soil aggregate structure in the desert steppe,enhance the carbon and nitrogen sequestration capacity,and promote soil nutrient cycling by regulating the topological characteristics of aggregates.It is recommended to combine enclosure restoration with periodic grazing to balance soil health,providing a scientific basis for the sustainable management of the desert steppe.更多还原