Nutrient Characteristics Of Grassland Growing Season And Browning Stage In Buha River Basin Of Qinghai

Grassland is an important natural resource,a material basis for the development of grassland animal husbandry,and an important ecological function.The grassland area of the Qinghai Lake Basin accounts for 75%of the total area of the basin.The quality of the grassland determines the health of the Qinghai Lake water system.Among them,the Buha River Basin is an important part of the Qinghai Lake Basin.This thesis takes the alpine grassland and alpine meadow with wide distribution area in Buha River Basin of Tianjun County,Qinghai Province as the research object.At the same time,considering the serious degradation of alpine grassland in this area,it is necessary to add alpine degraded grassland treatment?referred to as?degraded grassland??.The coverage is less than 50%.The nutrient seasonal dynamics of different grassland vegetations and the characteristics of soil nutrient changes in the corresponding period are analyzed in terms of the two key growth stages of vegetation growth period and yellowing period.The law of nutrient supply and demand balance provides a theoretical basis for the rational use of grassland resources and the integrated management of river basin ecosystems.The main results are as follows:1.The changes of carbon?C?,nitrogen?N?and phosphorus?P?contents in the aboveground parts of the three grassland vegetations were consistent with those of the dominant species.There was no significant change in plant C content during the growing season?July?,N and P.The content decreased significantly during the browning period?September?.The content of C in the underground part of the plant increased significantly compared with the growth period,N did not change significantly,while the P content decreased significantly.2.The changes of C:N and C:P of the aboveground parts of the three grassland species were the same as those of the dominant species,both of which showed a significant increase in the yellowing stage compared with the growth period,while the underground part C:N showed no significant change,and the C:P increased significantly in the yellowing stage.high.The N:P yellowing stage of the aboveground part of the three grassland types showed no significant change compared with the growing season,while the underground part and dominant species of the alpine grassland and degraded grassland increased significantly in the yellowing stage.3.There was no significant difference in the transport capacity between the C and P parts of the grassland and the dominant species and the underground part N.The transport capacity of the aboveground part of the alpine steppe was significantly higher than that of the other two types of grassland,while the transport capacity of C and P in the alpine meadow was significantly higher.In the other two grasslands.4.The contents of soil SOC,TN,TP,NH₄⁺-N,NO₃^--N,AP and MBC,MBN and MBP were significantly affected by grassland type or vegetation status,and the overall performance was alpine meadow>alpine grassland>degraded grassland.In the growing season,the NH₄⁺-N content of the three grassland types increased significantly in the yellowing stage of the plant community,while the soil NO₃^--N content decreased significantly.The AP content in the alpine meadow soil did not change between the growing season and the browning stage.Significantly,the AP content of the alpine grassland soil increased significantly compared with the growth period,while the degraded grassland was the opposite.The contents of MBC and MBP in the alpine steppe and degraded grassland decreased significantly in the browning stage,while the contents of MBC and MBP in the alpine meadow increased significantly in the yellowing stage.The MBN content in the three grasses decreased significantly in the yellowing stage.