低强度林火对兴安落叶松林土壤理化性质的影响

Effects of Low-intensity Forest Fires on Soil Properties of Larix gmelinii

[目的]探讨低强度林火对兴安落叶松林土壤理化性质的影响。[方法]依据地表可燃物损耗量来判断林火强度,在大兴安岭松岭林区落叶松林混交林火烧迹地选择低强度林火迹地为样地,对低强度林火迹地与对照样地的土壤理化性质进行3 a连续测定和比较分析研究。[结果]低强度林火主要影响森林土壤A层容重,没有对土壤B层产生显著影响;低强度林火燃烧后土壤A层持水量和贮水能力减小,火烧虽然没有改变土壤B层的有机质,但孔隙度相差明显;低强度林火提高了A层土壤pH,随时间的推移土壤pH从6.4恢复到5.4,说明低强度林火对土壤pH影响有限;低强度林火对土壤有机质再分配是有影响的,不单纯地表现为减少趋势,可能更多的是分解;土壤营养元素中以N素最易挥发,火烧后迹地土壤A层全N量下降;低强度林火对速效K含量增加只限于一个生长季。火后Ca,Mg和P的含量的变化结果与K近似。[结论]有计划地实施低强度林火对森林具有一定的保护作用。

[Objective] The effects of low-intensity forest fires on soil properties of Larix gmelinii were studied.[Method] Soil physical and chemical characters of mixed deciduous pine forest under low-intensity forest fire at XinLin district,Daxinganling region were investigated for 3 years.[Result]Low intensity mainly affects A layer Volume weight,and has no significant effection on forest soil of B layer.After low intensity forest fire,the water-holding capacity of A layer was descent,and the forest fire didn＇ t change the organic matter,but the porosity of soil has been changed.Low-intensity forest fire can improve the soil pH of A layer.With the time passed,the pH of soil restored from 6.4 to 5.4,the low-intensity fires have a limited impact on soil pH.Low intensity forest fire can affect the soil organic matter redistribution,which has more important impact on organic matter is decomposition.After low-intensity forest fire,the enhance of nitrogen mineralize rate led to a decrease of nitrogen in A layer.The enhance of available K after low-intensity fires can only continue one growing season.The content changes of Ca,Mg and P were similarly to K after low-intensity forest fire.[Conclusion]The implementation of the planted low intensity fires has certain protective effect on forest.