不同强度放牧对东祁连山高寒灌丛土壤理化特征的影响

Effects of long-term grazing with different intensitieson soil physicochemical characteristics of alpineshrub in the eastern Qilian Mountains

摘要:

为明晰高寒灌丛土壤理化性质对不同强度放牧的响应,在东祁连山选取连续30年以不同强度放牧(轻度(LG)、中度(MG)和重度放牧(HG))的高寒灌丛,研究其土壤理化特征的变化规律。结果表明:(1)随放牧强度的增加,0~30 cm各土层土壤含水量、全氮均呈现出降低趋势,而土壤容重和紧实度均呈增加趋势。(2)随放牧强度增加,0~30 cm各土层土壤有机碳、速效氮和全钾含量均呈先增后降的单峰性变化趋势。(3)随放牧强度增加,0~10和10~20 cm土层速效磷含量均呈先增后降的单峰型变化趋势,且各样地间差异显著。(4)土壤理化因子相关性分析表明,土壤全氮、速效磷和速效钾在不同放牧强度样地均呈极显著正相关。综上,长期重度放牧致使高寒灌丛草地土壤肥力低下,而长期中等强度放牧利用能有效增加高寒灌丛草地土壤的养分含量,是该区乃至相似生态区域的理想放牧选择。

Abstract:

In order to clarify the response of soil physical and chemical properties to long-term grazing with different intensities,alpine shrub grassland with different grazing intensities (light grazing (LG),moderate grazing (MG) and heavy grazing (HG)) for 30 consecutive years in the eastern Qilian Mountains was selected as the research object to study the changes of soil physical and chemical characteristics.The results showed that :(1) With the increase of grazing intensity,the soil moisture content and soil total nitrogen content in all soil layers of 0~30 cm showed a decreasing trend,while the soil bulk density and compactness showed an increasing trend.(2) The soil organic carbon content,available nitrogen and total potassium in 0~10,10~20 and 20~30 cm soil layer exhibited a hump-shaped pattern of increasing first and then decreasing in response to the increase of grazing intensity.(3) With the increase of grazing intensity,the content of available phosphorus in 0~10 and 10~20 cm soil layer showed a hump-shaped pattern of increasing first and then decreasing,and there were significant differences among different plots.(4) Correlation analysis of soil physical and chemical factors showed that soil total nitrogen,available potassium and available phosphorus were positively significantly correlated in plots with different grazing intensities.In conclusion,long-term heavy grazing resulted in low soil fertility in alpine shrub grassland,while long-term moderate intensity grazing could effectively increase the nutrient content in alpine shrub grassland,which was an ideal grazing choice for this area or even similar ecological areas.