炼山对华西雨屏区杉木林采伐迹地土壤理化特征的影响

炼山在华西雨屏区造林时广泛应用,杉木林采伐迹地炼山后的土壤理化性质研究鲜有报道.本文以华西雨屏区28 a生杉木林（对照）及其采伐迹地为研究对象,通过传统的炼山方式后采样测定土壤pH值、全N、P、K及其有效性以及Ca和Mg含量等,旨在阐明炼山对华西雨屏区杉木采伐迹地土壤的理化性质短期效应.结果表明：炼山能显著提高土壤pH值,能显著增加土壤0～40 cm层的全N含量.不同土层的P含量对炼山的响应不同,炼山后表层土（0 ～20 cm）的全K含量呈现先增加后减少的趋势,中层土（20 cm～40 cm）是先下降、后增加,底层土（40 cm～60 cm）持续下降.炼山后土壤中速效N、有效P的含量均先增加、后降低,而速效K的含量先下降,后增加.炼山后的土壤表层Ca含量显著增加,但对土壤中层和底层土的Ca含量影响趋势无规律.土壤各层中的Mg含量在炼山后明显下降.

Effects of Slash Burning on Soil Physical and Chemical Traits of Chinese Fir Plantations in the Rainy Area of Southwest China

Slash burning, a traditional land-clearing method, has been widely applied in planting in Rain- y Area of Southwest China fir forest. Slash burning not only burns the harvesting residues and the ground vegetation, but also changes nutrients in soil. In this paper, the slash burning experiment was conducted on the deforested land of the 28-old-year Chinese fir forest, aiming to study its short-term effects on soil nutrients. The results showed that （1） Slash burning significantly increased pH value of soil. （2） After slash burning, total soil N, P and Ca concentrations in soil were significantly increased. After 9 months, total soil N, P and Ca concentrations in soil were slightly increased. After slash burning, K and Mg in soil increased at first and then decreased ; after 9 months, total K concentration of 20 cm - 40 cm layer increased than that of the control, and total K concentration in the other layers decreased than that in the control. Mg concentration of 0 ~ 20 cm layer significantly increased, and Mg concentration of the other layers decreased than that of the control. （3） At the beginning of slash burning, soil available N concen- tration slightly increased. After 7 months, it increased significantly, and soil available N concentration increased higher than the control after 9 months. After slash burning, available P concentration was sig-nificantly higher than that of control. Soil available K concentration in the soil of 20 cm -40 cm, 40 cm - 60 cm in early slash burning decreased, and then increased. After 9 months, available K in 20 cm 40 cm soil was less than that in control, but that in the other two layers was higher than that in control.