Characteristics of Decomposition and Nutrient Release of Leymus chinensis Litter under Different Enclosure Measures in Desert Steppe
Enclosure is an effective management method for ecological restoration of degraded grassland.After enclosure,the vegetation community changes,which affects the above-ground biomass and litter production.Studying the characteristics of litter decomposition and nutrient release can provide scientific theoretical support for the subsequent restoration and management of desertification grassland.The decomposition and nutrient release of Leymus chinensis litter under two enclosure measures were studied by selecting seasonal enclosure and complete enclosure of desert steppe and setting up a natural decomposition experiment of L.chinensis litter bag.The results showed that:1)The decomposition constant of seasonal enclosure(k=0.025 87),was greater than that of complete enclosure(k=0.018 32).The decomposition of L.chinensis litter under seasonal enclosure measures was faster,and the decomposition rate showed a trend from slow to fast.The turning point of decomposition was the 180 th day.2)The decomposition process of L.chinensis litter can be well fitted to the Olson index regression model(R2＞0.97).Through simulation,under seasonal enclosure and complete enclosure measures,50％decomposition of L.chinensis takes 2.23 years and 3.15 years respectively,and 95％decomposition takes 9.65 years and 13.62 years respectively.Seasonal enclosure has obvious advantages.3)The element release of seasonal enclosure and complete enclosure showed the lowest organic carbon(OC)value,which was 44.24％and 52.13％,respectively.The total nitrogen(TN)accumulation index was 71.67％and 61.35％,respectively.The total phosphorus(TP)content was 77.41％and 57.08％,respectively.The change of carbon-nitrogen ratio was less than that of complete enclosure,and the change of nitrogen-phosphorus ratio was the opposite.The results showed that seasonal enclosure was beneficial to the decomposition of L.chinensis litter in desert steppe.The enrichment of C,N and P elements is closely related to the release and decomposition of litter.The effect of seasonal enclosure is obviously better than that of complete enclosure.
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