火烧对拉萨地区湿草甸湿地土壤养分特征的影响

基于对拉萨地区典型湿草甸火烧样地与对照样地内表层土壤pH、有机质、全量及速效养分含量特征的对比分析,初步探讨了火烧干扰对高原湿草甸表层土壤特征的影响. 结果表明:土壤pH在6.06~6.85之间,火烧干扰导致土壤pH升高；土壤中w(全氮)、w(全钾)分别为2.35~5.34、23.33~28.72g/kg,火烧干扰使其值下降；火烧对土壤中w(全磷)无明显响应；火烧后土壤中w(有机质)(53.97~144.57g/kg)下降,并且与土壤中w(全氮)的变化趋势一致. 土壤中w(速效氮)的季节性差异较大,火烧干扰使生长季初期表层土壤中的w(速效氮)减少,而在生长季旺盛期则增加,w(速效氮)占w(全氮)的比例变化一致；w(速效磷)在2个生长阶段总体增加,占w(全磷)的比例升高,以平地中变化最为明显；w(速效钾)及其占w(全钾)的比例在生长季初期显著增加,后期则下降明显. 

Effects of Fire Burning on Wet Meadow Soil Nutrient Conditions in Lhasa

Influence of fire on alpine wet meadow surface soil in Lhasa area was studied by analyzing the surface soil pH, organic matter, total and available nutrients of the burned and control plots. The results showed that the pH of samples varied from 6.06to 6.85which increased after fire burning; and the organic matter (from 53.97to 144.57g/kg), total nitrogen (from 2.35to 5.34g/kg) and potassium (from 23.33to 28.72g/kg) content decreased after fire while the total phosphorus content showed no obvious response to burning. Available nutrients content was different between seasons. The available nitrogen content of soil reduced after burning in the early growing season and increased at vigorous stage, and the ratio of available nitrogen and total nitrogen showed the same trend during the growing season. Available phosphorus content and the ratio of available phosphorus and total phosphorus increased, and this trend was more obvious in the flat plots. The available potassium and the ratio of available potassium and total potassium increased at the early growing season and decreased later at the vigorous stage.