不同间伐强度对长白落叶松-红松林植物多样性和土壤特性的影响

为了提高长白落叶松-红松林的生产力和生物多样性,2005年秋对长白落叶松人工林进行疏伐,伐后林冠下栽植4年生红松。2012年秋又对上层长白落叶松进行生长伐,设计轻度、中度和强度3种间伐强度和1组未间伐林分(对照),分析5年后不同间伐强度对林下植物多样性和土壤理化性质的影响。结果表明:①抚育间伐能提高林下植物多样性,林下灌木层植物丰富度随着间伐强度的增加而增加,轻度、中度和强度间伐差异显著(p<0.05)。林下灌木层植物多样性指数随着间伐强度的增加而增加,对照与中度间伐、强度间伐差异显著(p<0.05),但中度间伐和强度间伐差异不显著。林下草本层植物的丰富度和多样性指数随着间伐强度的增加而增加,各间伐强度均与对照差异显著(p<0.05),但轻度间伐和中度间伐差异不显著。②适度抚育间伐能改善土壤的理化性质,随着间伐强度的增加,土壤容重有所降低,土壤孔隙度和持水量有所提高;土壤pH值呈现先升高后略有降低的趋势,全K、速效K、全P、速效P、全N、速效N含量先升高后略有降低,其中中度间伐效果最好。综合考虑,对长白落叶松林分进行中度间伐较为适宜。

Effects of different thinning intensity on understory plant diversity and soil characteristics of Larix olgensis-Pinus koriensis mixed forest

In order to improve the forest productivity and biodiversity,the Larix olgensis plantation was thinned in the autumn of 2005,then the 4 years old Pinus koriensis were afforested under canopy.Three different thinning intensities(light,medium and heavy)were carried out in 2012 and no-thinning was taken as control.The influences of thinning intensities on understory plant diversity and soil physiochemical properties were studied five years later.The research results indicated that:(1)Thinning could improve the understory plant diversity,the abundance index of shrub increased with the thinning intensity,and the differences among treatments were significant(p<0.05).The Shannon-Wiener index of shrub layer increased with the thinning intensity,and there were significant differences(p<0.05)between the control and the medium intensity,as well as between the control and heavy thinning intensity,but there was no significant difference between the medium intensity and heavy intensity.The abundance index and the Shannon-Wiener index of herb layer increased with the thinning intensity.There were significant differences(p<0.05)between the control and three different thinning treatments,but there was no significant difference between the light and medium thinning intensity.(2)Moderate thinning could improve physiochemical properties of soil,with the increasing of thinning intensity,the soil bulk density reduced,the soil porosity increased,the soil moisture capacity increased.The soil pH value increased firstly and then reduced.The contents of total N、P、K and the available N、P、K increased firstly and then reduced slightly.In conclusion,medium thinning intensity was suitable for Larix olgensis forest stand.