土壤有效养分和微生物特征对短期不同放牧强度的响应

Response of Soil Available Nutrients and Microbial Characteristics to Short-Term Grazing Intensities

为了探究放牧持续时间和强度对草地的可利用养分和微生物特征的影响。本研究于2016年8月在山西省右玉县境内的农牧交错带草地设置了不放牧(0羊单位·hm^(-2)·生长季^(-1))、轻度(2.35羊单位·hm^(^(-2))·生长季^(-1))、中度(4.80羊单位·hm^(-2)·生长季^(-1))和重度(7.85羊单位·hm^(-2)·生长季^(-1))4个放牧强度的试验。在连续4个生长季放牧处理后,于2020年的5—9月测定表层0~10 cm的土壤可溶性有机碳(Dissolved organic carbon,DOC)、可溶性氮(Dissolved nitrogen,DN)、微生物生物量碳(Microbial biomass carbon,MBC)、微生物生物量氮(Microbial biomass nitrogen,MBN)及细菌和真菌的丰度。结果表明:4年不同强度的放牧处理对土壤可利用养分和微生物特征都没有产生显著影响,但是土壤有效养分与土壤微生物特征受生长季降水和温度的影响显著(P<0.05),具有明显的季节动态,说明短期不同的放牧强度尚未对农牧交错带天然草地养分循环产生显著影响,需要继续进行长期试验监测来观察放牧对草地生态系统结构与功能的影响。

To explore how grazing duration and intensities affect the available nutrients and microbial characteristics of grassland,we set up 4 grazing intensities including:no grazing(0 sheep unit·hm^(-2)·growing season^(-1)),light(2.35 sheep unit·hm^(-2)·growing season^(-1)),moderate(4.80 sheep unit·hm^(-2)·growing season^(-1))and heavy(7.85 sheep unit·hm^(-2)·growing season^(-1))in the grassland of the agro-pastoral ecotone in Youyu County,Shanxi Province in August 2016.The soil soluble organic carbon,soluble nitrogen,microbial biomass carbon/nitrogen and the abundanc of soil bacteria and fungi in the soil(0~10 cm)during growing season(May—September)in 2020 after 4 years grazing treatments.The results showed that 4-year grazing treatments of different intensities had no significant effect on soil available nutrients and microbial characteristics,but soil available nutrients and soil microbial characteristics were significantly affected by precipitation and temperature during the growing season(P<0.05).We found that different grazing intensities in short term had no significant impact on the nutrient cycling of natural grassland in the agro-pastoral ecotone.Long term experimental monitoring are needed to continue observing the impact of grazing on the structure and function of grassland ecosystem.