不同放牧强度对西藏高寒草甸植被群落及土壤养分的影响

发布时间：2018-07-05 05:53

本文选题：西藏高原 + 牦牛　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：本试验在西藏林芝工布江达县邦杰塘草原试验站进行,试验设置5个处理,对照即零放牧(NG)、延迟+适度放牧(DMG)、适度放牧(MG)、延迟+重度放牧(DHG)、重度放牧(HG),研究西藏高寒草甸在不同放强度下,草地植被群落的丰富度、盖度、均匀度、高度、生物量、密度和土壤理化性质的变化,研究结果如下:(1)在不同放牧条件下,高寒草甸植物群落结构变化显著(P0.05)。重度放牧(HG)时,植物群落的盖度、均匀度和丰富度显著减少,与适度放牧(MG)和对照(NG)差异显著(P0.05);草地生物量在适度放牧(MG)、延迟+适度放牧(DMG)区最高,与对照之间差异显著(P0.05),重度放牧(HG)对紫花针茅和高山嵩草的高度、盖度和密度的影响差异达到显著水平(P0.05)。(2)在重度放牧(HG)下,高寒草甸土壤层0~10 cm处,土壤含水量与对照差异不显著(P0.05);随着放牧强度的增加,家畜对草地践踏增加,草地硬度变大,土壤透气性变差;随放牧强度的增加土壤体积质量、总孔隙度和毛管孔隙度显著增加(P0.05),且随土层深度的增加而减少,其差异达到显著水平(P0.05)。(3)随着放牧强度的增加,土壤中速效氮、速效钾、全氮和全磷含量减少;全钾含呈先增加后减小的趋势;重度放牧和延迟+重度放牧显著降低了土壤中速效氮、速效磷和速效钾及全氮、全钾的含量;土壤有机质含量随着放牧强度的增加而逐渐减少;不同的放牧强度对土壤pH值影响不显著(P0.05)。(4)随着放牧强度的增加牦牛增重量降低,重度放牧(HG)时牦牛增重量明显低于适度放牧(MG);暖季放牧时,牦牛增重量显著增加(P0.05),而在适度放牧(MG)时,牦牛增重量明显高于重度放牧(HG)。(5)随放牧强度的增加家畜体重和植被总盖度显著下降(P0.05),而高寒草甸生物量和家畜增重量在适度放牧时达到最高,在重度放牧下,草地的生物量和牦牛增重量显著降低。
[Abstract]:The experiment was carried out at the Bang Jie Tang prairie experimental station of Gongbujiangda County, Linzhi, Tibet. Five treatments were set up in the experiment. In contrast, zero grazing (NG), delayed moderate grazing (DMG), moderate grazing (MG), delayed heavy grazing (DHG), heavy grazing (HG) were used to study the richness, coverage, evenness, height, biomass of grassland vegetation community in Tibetan alpine meadow under different radiation intensities. The changes of density and soil physical and chemical properties were as follows: (1) under different grazing conditions, the plant community structure of alpine meadow changed significantly (P0.05). Under heavy grazing (HG), the coverage, evenness and richness of plant community decreased significantly, which was significantly different from that of moderate grazing (MG) and control (NG) (P0.05), and the biomass of grassland was the highest in moderate grazing (MG) and delayed moderate grazing (DMG). The effect of heavy grazing (HG) on the height, coverage and density of Stipa lanceolata and Kobresia alpine reached a significant level (P0.05). (2). Under heavy grazing (HG), the soil layer of alpine meadow was 0 ~ 10 cm. There was no significant difference between soil moisture content and control (P0.05); with the increase of grazing intensity, livestock trampled on grassland increased, grassland hardness increased, soil permeability became worse; with the increase of grazing intensity, soil volume quality, The total porosity and capillary porosity increased significantly (P0.05), and decreased with the increase of soil depth. The difference reached a significant level (P0.05). (3). With the increase of grazing intensity, the contents of available nitrogen, available potassium, total nitrogen and total phosphorus decreased with the increase of grazing intensity. The contents of available nitrogen, available phosphorus, available potassium, total nitrogen and total potassium in the soil decreased significantly with the increase of grazing intensity, and the content of organic matter in the soil gradually decreased with the increase of grazing intensity. The effect of different grazing intensity on soil pH value was not significant (P0.05). (4). With the increase of grazing intensity, the weight gain of yak decreased, while that of heavy grazing (HG) was significantly lower than that of moderate grazing (MG), and that of warm season grazing was significantly lower than that of moderate grazing (MG). The weight gain of yak was significantly increased (P0.05), but at moderate grazing (MG), The weight gain of yak was significantly higher than that of heavy grazing (HG). (5). With the increase of grazing intensity, the body weight and total vegetation coverage of yak decreased significantly (P0.05), while the biomass and weight gain of alpine meadow reached the highest in moderate grazing. The biomass of grassland and weight gain of yak decreased significantly.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812

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