【作者】 王晶；

【导师】 吕昌伟； 樊庆云；

【作者基本信息】 内蒙古大学 ， 资源与环境（专业学位）， 2025， 硕士

【摘要】 有机磷（OP）是草地生态系统养分循环的关键要素,其赋存特征和周转过程与生态系统的生产力与稳定性紧密关联。本文以蒙古高原土壤为研究对象,基于OP赋存特征及其驱动机制的生态环境意义,分析了不同级分土壤团聚体中OP的分布与赋存特征,综合考虑土壤理化性质、植被、气候和地形共四类（15项）环境因子,初步探讨了OP形态的空间分布格局及其主导因素,结合结构方程模型和多元线性回归模型揭示了各环境因素对OP赋存的影响路径和相对贡献,为蒙古高原土壤团聚体OP动态变化及草地生态系统功能维持提供了理论基础,主要结果如下:（1）蒙古高原表层土壤总有机磷（TOP）含量为0.11–0.78 mg/g,矿物质结合态有机质（MAOM）土壤组分是土壤OP的主要赋存载体（占全土TOP的83.3%）。土壤TOP含量呈现出草甸草原、典型草原、荒漠草原递减的分布格局。从OP活性来看,中等活性有机磷（MLOP）含量最高,非活性有机磷（NLOP）次之,活性有机磷（LOP）最低。Fulvic acid-OP是OP的主要赋存形态（占TOP 30.5%）,在MAOM和POM土壤组分中均占主导地位,而CPOM土壤组分中Na HCO₃-OP占比更高（44.3%）,反映了大团聚体对OP的保护能力较弱。各OP组分与TOP的空间分布特征一致。（2）结果表明,不同活性OP与环境因子关系密切。PLS-SEM结果显示土壤理化性质对全土和MAOM土壤组分中的OP具有显著的直接调控作用（路径系数0.87、0.78）;相较而言,气候、地形和生态因子对OP的直接影响较弱,但可通过改变土壤环境间接影响OP。多元线性回归结果表明,MAOM土壤组分中LOP主要受p H控制;全土和MAOM组分中MLOP受Ca和Fe的影响显著,NLOP在全土中以Al固定为主,而在MAOM组分中Fe的影响更强,这些差异主要源于OP组分的化学活性特征及其在不同赋存环境中的稳定机制。（3）研究结果凸显了不同活性OP在草原生态系统中的重要作用（贡献率17.4%）,其中MLOP的影响最为显著（贡献率为8.8%）。这与其在TOP中的高占比（44.6%）及其作为活性磷的重要来源有关;NLOP次之,LOP最低。虽然LOP的贡献率不高,但其作为土壤速效磷源仍具有重要价值。更多还原

【Abstract】 Organic phosphorus（OP）is a key element in the nutrient cycling of grassland ecosystems.Its occurrence characteristics and turnover processes are closely linked to the productivity and stability of ecosystems.Based on the ecological and environmental significance of OP occurrence characteristics and its driving mechanisms,this study focuses on the Mongolian Plateau,analyzing the distribution and occurrence characteristics of OP in soil aggregates of different fractions.The study comprehensively considers four categories of environmental factors（15 items in total）:soil physicochemical properties,vegetation,climate,and terrain.The spatial distribution patterns of OP forms and their main driving factors were preliminarily explored.By using structural equation modeling and multiple linear regression models,the study reveals the influence paths and relative contributions of various environmental factors on OP occurrence.The results provide a theoretical foundation for the dynamic changes in OP in Mongolian Plateau soil aggregates and for the maintenance of grassland ecosystem functions.The main results are as follows:（1）The total organic phosphorus（TOP）content in the surface soil of the Mongolian Plateau ranges from 0.11 to 0.78 mg/g.The MAOM（microaggregated organic matter）soil fraction is the primary carrier of OP in the soil（accounting for 83.3%of TOP）.The distribution of soil TOP content shows a decreasing pattern from meadow steppe,typical steppe,to desert steppe.In terms of OP activity,moderately labile organic phosphorus（MLOP）has the highest content,followed by non-labile organic phosphorus（NLOP）,and labile organic phosphorus（LOP）has the lowest content.Fulvic acid-OP is the dominant form of OP（accounting for 30.5%of TOP）,and it is predominant in both MAOM and POM（particulate organic matter）fractions,while Na HCO₃-OP is more abundant in the CPOM（coarse particulate organic matter）fraction（44.3%）,indicating weaker protection of OP in large aggregates.The spatial distribution patterns of each OP component are consistent with the distribution of TOP.（2）The results indicate a close relationship between different active OP and environmental factors.PLS-SEM（partial least squares structural equation modeling）results show that soil physicochemical properties have a significant direct regulatory effect on OP in both Bulk Soil and MAOM fractions（path coefficients of 0.87 and 0.78,respectively）.In contrast,climate,terrain,and ecological factors have a weaker direct impact on OP but can indirectly influence OP by altering the soil environment.Multiple linear regression results show that in the MAOM soil fraction,LOP is primarily controlled by p H;MLOP in both Bulk Soil and MAOM fractions is significantly influenced by Ca and Fe,while NLOP in Bulk Soil is primarily fixed by Al,and in MAOM fractions,the influence of Fe is stronger.These differences are mainly due to the chemical activity characteristics of OP components and their stability mechanisms in different occurrence environments.（3）The research highlights the important role of different active OP in grassland ecosystems（with a contribution rate of 17.4%）,with MLOP having the most significant impact（contribution rate of 8.8%）.This is related to its high proportion in TOP（44.6%）and its importance as an active phosphorus source.NLOP follows,and LOP has the lowest contribution.Although LOP has a low contribution rate,it still holds important value as a source of readily available phosphorus in the soil.更多还原