Characteristics and Impact Factors of Grassland Drought and Forage Yield in Southern Foothills of Qilian Mountains
Understanding the characteristics and patterns of spatial and temporal changes in soil moisture is important for fully utilizing soil moisture resources and coping with climate change.In this study,the interannual and seasonal trends of soil relative humidity in alpine grassland and the seasonal changes of soil drought in natural grassland were analyzed using the monitoring data of grassland soil moisture in the thawing period from 2004 to 2022 at Tianjun Ecological and Meteorological Observatory in alpine grassland of the southern foothills of the Qilian Mountains.The correlation between overall soil relative humidity and pasture yield of the grassland was analyzed in conjunction with the comparison of pasture yield inside and outside the fence.The results showed that the relative soil humidity in the alpine grassland of the southern foot of Qilian Mountains had obvious characteristics of month-to-month and seasonal changes within the year,and from 2004 to 2022,the overall relative soil humidity in the year,season and month showed an increasing trend year by year,and the degree of aridization of the soil was reduced.Although the frequency and degree of occurrence of drought varied among seasons in the alpine grassland of the southern foothills of the Qilian Mountains,the probability of consecutive droughts in spring,summer and fall was also higher.The frequency of drought in all seasons was light drought＞moderate drought＞severe drought＞extreme drought,and the frequency of moderate drought and severe drought in spring was as high as 34.8%,with the late spring and early summer being the driest time of the year.2004 to 2022 pasture yields inside and outside the fence showed a significant increasing trend(P<0.05),and the rate of change of the increase of the pasture yields in the fence was 1.6 times of those of the outside of the fence.The analysis of the correlation between meteorological factors,soil relative humidity and pasture yield showed that the construction of the overall soil relative humidity and pasture yield model had a good use value,and could be popularized and applied in practical work.
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