Effects of Grazing and Mowing on Carbon and Nitrogen Content of Vegetation and Litter in Mountain Steppe at Different Altitudes
In order to explore the effects of grassland use on grassland vegetation and litter C and N in the mountainous grassland of the Tianshan Mountains,two grassland use methods of grazing and mowing and four altitude gradients(1 600 m,1 700 m,1 800 m,1 900 m)were set up in the mountainous grassland in the middle of the northern slope of the Tianshan Mountains.Then,its correlation was analyzed.The re-sults showed that the aboveground biomass and litter stock of grazing land were significantly higher than those of the other three elevations at an altitude of 1 600 m,the mowing land at an altitude of 1 700 m was significantly lower than that of the other three altitudes,the vegetation coverage was significantly higher than that of 1 900 m and 1 800 m above sea level,the aboveground biomass and vegetation coverage of grazing land at the same altitude were significantly lower than those of mowing,and the amount of litter was significantly lower than that of mowing at 1 800 m and 1 900 m above sea level(P<0.05);With the increase of altitude,grazing land gradually decreased the number of grasses,and the number of weeds in-creased,and the most grasses in the mowing land were increased.The C content and C∶N of grazing land vegetation decreased with the increase of altitude,and the N content increased with the increase of altitude,the C content of vegetation in the mowing land did not change significantly with the increase of altitude,the N content was significantly higher than those of the other three altitudes at 1 800 m,and the C content and C∶N content of litter in the grazing land decreased with the increase of altitude,and the N content was significantly lower than that of the other three altitudes at 1 600 m(P<0.05).The correlation analysis showed that the vegetation and litter C∶N grazing in the mountain grassland were significantly positively correlated with aboveground biomass,litter presence and vegetation coverage(P<0.01),and the correla-tion between vegetation and litter C and N content was high.The mowing vegetation and litter C∶N were significantly positively correlated with vegetation coverage(P<0.05),litter C∶N was significantly nega-tively correlated with aboveground biomass(P<0.01)and litter(P<0.05),and there was no significant correlation between vegetation and litter C and N contents.The comprehensive analysis showed that the increase of mowing altitude would affect the dominant vegetation community for grazing use,and the high-er the altitude,the lower the carbon and nitrogen content of grazing vegetation and litter.
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