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Northwest A&F University (2017)

Impact of Chinese Pine Plantation on Soil Enzymatic Activities and Microorganism in the Loess Plateau

黎氏娴(LE THI HIEN)

Titre : Impact of Chinese Pine Plantation on Soil Enzymatic Activities and Microorganism in the Loess Plateau

Auteur : 黎氏娴(LE THI HIEN)

Grade : Master’s Theses 2017

Université : Northwest A&F University

Résumé partiel
Chinese pine(Pinustabulaeformis Carr.)represents the most predominant pioneer tree species for artificial reforestation and is widely planted due to its high stress tolerance to cold,drought,and poor quality of soil in the Loess Plateau of northwest China.The previous studies found that the changes with the development of afforestation of Chinese pine and seasonal variations will have a series of changes on soil physical and chemical properties,which will have a deeply effect on soil microbial biomass and soil enzyme activity,subsequently affect to the growing of Chinese pine plantation and seedling regeneration.To date,however,little studies had been conducted in this field,especially in relation of the impact mechanism.Hence,it is necessary to understanding the seasonal variations of soil environmental effects on the Chinese pine plantation development and generation characteristic of forest renewal.The present study was to explain the effects of Chinese Pine plantation on soil enzymatic activities and microbial biomass and its seasonal shifts coinciding with forest development in the Loess Plateau.In addition,such information will be helpful in future studies investigating the effects of soil restoration on forest ecosystems and fertility.We studied on soil physio-chemical properties,four types of soil enzyme activities,microbial biomass carbon(Cmic)and nitrogen(Nmic)during four seasons in Chinese pine plantations aged 8(PF8),22(PF22),and 42(PF42)years at Fuxian county in the middle of Loess Plateau,China.The natural secondary Chinese pine forest sites which was aged more than 70 years(NF)was considered as the control.Final,the Chinese pine regeneration characteristic has investigated in two types of Chinese pine forest,where the seeding germination was observed,there are in Chinese pine plantation forest 42 years and natural forest.Both of forest age and sampling season had significant effects on almost soil physiochemical properties except TN.The values of soil p H,TN,SOC and P were found to be higher in the summer,whereas the ratio of C and N reached a peak in autumn but not in soil moisture or porosity.The variability in the soil physio-chemical properties were dissimilar across Chinese pine forest ages.For example,the values of BD,t,NO3—N,NH4+-N,TN,TP,and P decreased due to forest development in the order of PF8 > PF22 > PF42.In contrast,the variation in the values of SMC,porosity,TK,K,and SOC gradually increased when the forest matured from PF8 to PF42.The content of soil nutrient elements in the natural secondary forest of Chinese pine was higher than that of Chinese pine plantation forest,and the seasonal variation was higher in summer and autumn than in spring and winter.Both of Cmic and Nmic were higher in summer season than autumn,spring and winter seasons.This can be understood as : the surviving biomass can utilize the cell debris ;the strong photosynthetic capacity of plants in summer led to increased carbohydrate secretion of roots,and promote soil microbial activity increased.The concentration of Cmic in the forest development was systematically increased from PF8 < PF42 < PF22.The higher content of microbial biomass C from PF8 to PF22 than in PF42,this point suggested that the accumulation of microbial biomass mainly occurred at early successional stages.While the content of Nmic was gradually decreased from PF8 > PF22 > PF42.The concentration of Nmic decreased from PF8 to PF42,this may be due to the rapid rate of N mineralization and N leaching in the temperate plantation forest soils.The highest values of both Cmic and Nmic concentrations occurred in the NF as compared to the three stages of Chinese pine plantation forest.In contrast,lower values were found in the NF than all stages of plantations in Cmic/Nmic,Cmic/SOC,and Nmic/TN

Mots clés : Chinese pine plantation forest; soil enzyme activity; soil microbial biomass; natural regeneration;

Présentation (CNKI)

Page publiée le 28 janvier 2018