不同干扰强度对栲类次生林土壤物理性质的影响

Effects of Different Disturbance Intensities on Soil Physical Properties of Castanopsis Secondary Forest

通过设置BCK处理(不择伐)、GTN处理(择伐乔木总数20%以内小乔木,采伐物全部回归林地,均匀覆盖在地表,下同)、GTT处理(择伐20%~30%)、GTF处理(择伐30%~40%)4个干扰等级,测定分析土壤容重、非毛管孔隙、总孔隙、田间持水量、饱和持水量、土壤机械组成和水稳性团聚体含量等物理性质指标,探讨明溪县夏坊栲类次生林在不同干扰强度下土壤物理性质的变化情况。结果表明:GTN、GTT处理与BCK处理间主要物理性质差异不明显。GTF处理与BCK处理相比,在0~20 cm土层,土壤容重显著增加(P<0.05);非毛管孔隙和毛管孔隙未达显著差异,总孔隙度显著降低(P<0.05);田间持水量和饱和持水量差异均不足1%;土壤机械组成没有受到影响;水稳性团聚体含量增加2.97%,差异未达显著水平。在20~40、40~60 cm土层,同一土层不同处理间土壤物理性质差异更小,趋于弱化。择伐强度在30%范围内,土壤物理性质与不择伐的栲类次生林土壤物理性质间没有明显变化;择伐强度超过30%时,对部分土壤物理性质(0~20 cm土层的土壤容重和总孔隙度)有显著影响。为了促进栲类次生林林木生长和增强其生态功能,适度择伐是可行的。

This paper reports the changes in soil physical properties of Castanopsis secondary forests under different disturbance intensities with four levels:BCK treatment(no selection cutting),GTN treatment(selection cutting of small trees within 20%of the total number of trees,with all the harvested material returned to the forest field and covered on the ground surface,hereinafter the same),GTT treatment(selection cutting of 20~30%)and GTF treatment(selection cutting of 30~40%).The results were as followes:there was a significant difference in soil bulk weight between GTF treatment and BCK treatment in 0~20 cm soil layer(P<0.05),the difference between non-capillary pore space and capillary pore space was not significant,and there was a significant difference in total porosity(P<0.05);the difference between field water holding capacity and saturated water holding capacity was less than 1%.The mechanical composition of the soil was not affected,and the content of water stabilizing agglomerate did not reach a significant level,but GTF treatment instead increased by 2.97%compared with BCK treatment.In other treatments,the differences in soil physical properties among the same soil layer were becoming smaller and tended to be weaker.The intensity of selection cutting in the range of 30%did not lead to significant changes between soil physical properties and those of the Castanopsis secondary forests that were maintained in their original state.When the intensity was more than 30%,the effect was significant on several soil physical properties(0~20 cm bulk weight and total porosity).In order to promote the growth of castanopsis secondary forest and enhance their ecological functions,moderate tending cutting can be feasible.