古尔班通古特沙漠土壤养分空间分异与干扰的关系

对干扰条件下古尔班通古特沙漠土壤养分空间分异特征进行了研究。分析土壤养分的变化趋势,及干扰与植被和土壤养分之间的关系。研究表明:沙漠边缘至沙漠腹地,全N、全P和全K含量、EC、总盐,可溶性离子HCO-3、SO2-4及Ca2+呈增加趋势。CO2-3、Mg2+、 Cl-、Na+4种离子含量较低,变化规律不明显。除全K含量随公路里程呈较连续的增加外,其他养分条件在公路里程25—75 km ,80—125 km和大于125 km的范围内的变化趋势都呈现高\?低\?显著增高的波动过程,分析表明这种波动性的变化是由干扰造成的。干扰因子数与生物结皮盖度呈显著负相关,但与植物种类与植物盖度都达到了显著正相关的水平。除与pH值呈正相关外,干扰因子数与土壤养分指标都呈负相关,其中与全K、全P、全N和EC的负相关接近于显著或极显著水平。随公路里程增加,生物结皮呈现从地衣苔藓藻类地衣地衣苔藓的过渡,这与土壤养分条件和干扰因子数相对应。人类活动是导致彩克沙漠公路里程80—125 km范围沙漠土壤养分条件的降低的主要原因,受水源和居住地的影响,该段沙漠人类放牧活动影响的最大范围为里程125—145 km之间。人类在沙漠活动的加强会增加沙漠生态干扰源和干扰强度,最终降低沙漠土壤的养分条件。

Relation Between Disturbance and Spatial Heterogeneity of Soil Nitration in Gurbantunggut Desert

Focusing on distribution of soil nutrient in the Gurbantunggut desert influenced by disturbance,the paper analyzed the trend of soil nutrient distribution and the correlation between disturbance and vegetation cover.The results showed that the total N,total P,total K and soluble salt,such as HCO-3,SO24and Ca2+,increase from the rim to center of desert while the values of CO2-3,Mg2+,Cl-and Na+ are very low and show no remarkable trend.All nutrients show a high-low-high fluctuation at milestone K25-K75 km,K80-K125 km and farther than K125 km from Cainan with the exception of total K whose value continuously increases.The fluctuation is caused by disturbance factors,the number of which has a significantly negative correlation with crust area,and a significantly positive correlation with plant species and vegetation coverage.All soil nutrient parameters have negative correlation with disturbance factors aside from pH which has a positive correlation with that.The correlation coefficients between total K,total P,total N,electric conductance and disturbance factors are significant or nearly significant.The crust type along the sampling line are algae,lichen and moss,respectively,which are consistent with soil nutrient and disturbance number.The low soil nutrient between K85-K125 km is mainly caused by human activities.Limited by water source and habitation,the farthest distance of grazing trace in this area is between K125-K145 km.The increasing human activities will fortify the disturbance number and intensity in desert,which decrease the soil nutrient in desert.