林下植被管理措施对尾巨桉人工林土壤质量的影响OA

[Objective]Understory vegetation is frequently removed during long-term stand management to promote the growth of target tree species.This study aims to investigate the effects of different understory vegetation management measures on soil physicochemical and biological properties in Eucalyptus urophylla×grandis and to assess associated changes in soil quality,while thereby providing a theoretical basis for the scientific management of Eucalyptus plantation understory vegetation.[Method]The research was conducted in a fourth-generation E.urophylla×grandis plantation(plant spacing:2 m×3 m)in Nanning,Guangxi Zhuang Autonomous Region,China.Three understory vegetation removal methods were applied:artificial tending,herbicide tending,and a combination of artificial and herbicide tending.Soil samples were collected in August 2023 from three depth layers[0,10),[10,20),[20,40)cm in plots subjected to each treatment.The samples were analyzed to determine differences in soil physicochemical and biological properties.Soil quality was comprehensively evaluated using the total dataset(TDS)and a minimum dataset(MDS)approach.The accuracy of the newly established MDS was validated through linear regression analysis.[Result]Different understory vegetation management measures led to distinct differences in soil properties and overall soil quality.The forest land soil receiving artificial tending maintained superior physical properties,in the 0-10 cm soil layer,bulk density was significantly lower,while total porosity and maximum water-holding capacity were significantly higher compared to artificial and herbicide tending forest land.However,capillary porosity,capillary water-holding capacity,and field water-holding capacity were not significantly affected by the different understory vegetation management measures.Within the 0-40 cm soil layer,the contents of soil organic matter,total nitrogen,alkaline hydrolyzed nitrogen,available potassium,microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),and microbial biomass phosphorus(MBP)generally followed the order:artificial tending＞artificial and herbicide tending＞herbicide tending.In contrast,the available phosphorus content showed the opposite trend:herbicide tending＞artificial and herbicide tending＞artificial tending.With increasing soil depth under the same management practice,total porosity,non-capillary porosity,maximum water-holding capacity,and the contents of organic matter,total nitrogen,total phosphorus,available nutrients,and microbial biomass decreased significantly,whereas bulk density increased significantly.Using soil MBC,MBN,and MBP as key biological indicators,a minimum dataset was constructed,comprising MBP,MBC,capillary water-holding capacity,non-capillary porosity,and pH.Soil quality evaluation based on this MDS yielded results consistent with those from the TDS.The soil quality index under different treatments followed the order:artificial tending＞artificial and herbicide tending＞herbicide tending.[Conclusion]Artificial removal of understory vegetation maintained better soil quality,whereas herbicide application led to further decline in the soil quality of plantation forests.The management of Eucalyptus plantations should prioritize artificial tending,and herbicide use should be minimized to maintain soil quality and ensure the long-term,high-quality management of these Eucalyptus plantations.