禁牧年限对退化伊犁绢蒿荒漠土壤有机碳库和微生物碳、氮的影响

Effects of Grazing Exclusion Times on Soil Organic Carbon Storage and Microbial Biomass Carbon and Nitrogen in Degraded Seriphidium transiliense Desert

【目的】明确伊犁绢蒿(Seriphidium transiliense)荒漠土壤有机碳库和微生物量碳氮对禁牧年限的响应规律,为退化荒漠的恢复、管理和利用提供科学依据。【方法】采用空间序列代替时间序列的方法,以中度退化伊犁绢蒿荒漠为对象,研究不同禁牧年限(禁牧1、4和11 a)下荒漠有机碳库(SOC)、微生物量碳(MBC)和微生物量氮库(MBN)的变化特征。【结果】(1)与自由放牧区相比,禁牧区0~30 cm土壤有机碳储量显著下降了13.3%~24.3%,0~10 cm有机碳储量随着禁牧年限的增加呈先下降后上升的变化趋势。(2)随着禁牧年限的增加,0~30 cm土壤微生物量碳储量呈先降后升的变化趋势,而土壤微生物量氮对禁牧的响应不明显(P>0.05),微生物量碳可以作为衡量退化荒漠恢复的早期指标。【结论】短期禁牧不利于退化伊犁绢蒿荒漠土壤的恢复,而长期禁牧能有效提高土壤质量。禁牧是恢复退化荒漠最经济、最方便的途径。

[Objective] This project aims to reveal the response of desert organic carbon storage and microbial biomass carbon and nitrogen to grazing exclusion times in order to provide scientific basis for restoration, management and utilization of degraded desert.[Method]The method of spatial sequence instead of the time series was used, and the soil organic carbon storage （SOC）, microbial biomass carbon （MBC） and nitrogen （MBN） under different grazing exclusion times （1 a, 4 a and 11 a） in degraded desert of Seriphidium transiliense were studied.[Result]The results showed that： （1） The SOC in grazing exclusion area in 0-30 cm layer decreased by 13.3%-24.3% compared with the freely grazing area, but the SOC in 0-10 cm layer decreased at first and then increased with grazing exclusion times increased.（2） With the increase of grazing exclusion times, the MBC storage in 0-30 cm layer decreased at first and then increased, but the MBN storage was not significantly different for grazing exclusion （P〉0.05）, and the MBC could be used as an early indicator to measure the recovery of degraded desert.[Conclusion]Short-term grazing exclusion is not effective to recover the soil of S.transiliense desert but the long-term grazing exclusion can effectively improve soil quality.In a word, grazing exclusion was the most economical and convenient way to recover the degraded desert.