火烧强度对西南亚热带林地土壤理化性质的影响

Effects of Burning Intensity on Soil Chemical and Physical Properties inSouthwest subtropical Forests

为阐明火烧强度对西南亚热带山地森林土壤理化性质的影响,本研究通过采集和分析四川西昌“3·30”火烧迹地不同火烧程度(未过火、低度、中度和重度)的土壤,发现重度火烧极显著增加了土壤容重;火烧显著增加了土壤速效磷和速效钾含量,显著降低了土壤全氮和碱解氮含量,但是对土壤pH值、有机碳、全钙、全镁、全钾和全磷含量无显著影响。通过对比分析火烧对不同纬度林地土壤理化性质的影响,发现火烧对亚热带地区森林土壤的影响与北方存在差异,主要表现为火烧后进入土壤的碱基离子和未完全燃烧的有机物相对较少,导致有机碳、全钙、全镁和全钾含量的变化不显著,而高温导致碱解氮含量显著降低。本文的结果不仅凸显了林火对不同气候条件下森林土壤性质影响的差异,而且可为亚热带地区火烧迹地植被恢复过程中的养分管理提供科学依据。

Wildfire is an important factor of impacting soil chemical and physical properties.Knowledge of the effects of burning intensity on soil organic carbon and nutrients in southwest subtropical forests of China remains scarce,although forest fires occur frequently in this region where soil properties are significantly different from north areas.To clarify the variations in soil organic carbon and nutrients with burning intensity,we collected soil encountered different burning intensities(unburned,low,medium and high intensity of burning)in the“2020.3.30 Forest Fire”area in Xichang City,Sichuan Province,southwest China in late March 2021.Results showed that the concentration of available phosphorus(P)and potassium(K)in soil significantly increased with burning intensity,although pH and the concentration of total calcium,magnesium,K and P,organic carbon(C)and inorganic and organic P did not change significantly after one year of the fire.Fire disturbance significantly reduced the concentration of soil total and available N.High intensity of fire disturbance significantly increased bulk density(BD)of soil,although BD did not change significantly under low and medium intensity of burning.Some of the above variations caused by burning differed from those in north forests with a lower temperature.The differences were likely ascribed to the different climates and the thickness of organic horizons between subtropical and northern forests.The results not only highlight the difference in the effects of fire on soil properties between subtropical and north forests,but also support the soil nutrient management during vegetation restoration in burned areas of subtropical forests.