抚育间伐对云南松林分土壤理化性质的短期效应分析

Analysis of Short-term Effects of Tending and Thinning on Soil Physical and Chemical Properties of Pinus yunnanensis

为探究云南松林分抚育间伐(采伐强度为53%)和未抚育间伐不同土壤层(0~20 cm、20~40 cm、40~60 cm)的理化性质以及抚育间伐对云南松林分土壤性状的短期效应。在作业小班内进行调查,选择具有代表性的地段设置抚育样地和对照样地。结果表明:①抚育后土壤物理性质容重、毛管持水量、总孔隙度和田间持水量并未出现显著变化;土壤中N、P含量在各组抚育后没有差异,且不存在显著性差异;K含量随土层深度加深而增加,而C含量随土层深度加深显著降低,降幅约为20%;②随着土壤土层的加深,土壤容重增加,而土壤毛管持水量、总孔隙度和田间持水量降低(33%、16%、25%),并只在0~20 cm和40~60 cm下低于抚育前;土壤N、P、K含量没有显著变化,仅土壤C含量降低(31%);③云南松林C∶N为52.5±36.81,高于中国平均值11.9%,而C∶P和N∶P均低于全国的平均水平;间伐对土壤C∶N影响不显著,但土壤深度对C∶N影响显著,并随着土层深度的增加土壤C∶N值降低。抚育间伐在短期内不会对云南松林分土壤理化性质产生显著影响。研究结果与国内土壤平均值相比,该研究区森林土壤氮含量较低。该地区土壤存在氮素普遍缺乏的问题,有可能是限制该地区林分生产力的一个因子。

This paper explores the physicochemical properties of different soil layers(0~20 cm,20~40 cm and 40~60 cm)of Pinus yunnanensis stands with thinning intensity of 10.8%and without thinning,and the short-term effects of thinning on soil characteristics of Pinus yunnanensis stands.The investigation was carried out in the small class,and the representative plots were selected to set up tending sample and control sample plots.Result:①After tending and thinning,soil physical property bulk density,capillary water capacity,total porosity,and field water capacity did not change significantly;The contents of N and P in the soil were flat among different treatment plots,and there was no significant difference.The content of K increased slightly with the deepening of soil depth,while the content of C decreased significantly with the deepening of soil depth.②With the deepening of the soil layer,soil bulk density increased,while soil capillary water capacity,total porosity,and field water capacity decreased,and were only slightly lower than the control group at 0~20 cm and 40~60 cm respectively.The N,P,K content of soil did not change significantly.Only the C content decreased.③The C∶N of Pinus yunnanensis forest was 52.5±36.81,higher than the average value of 11.9 in China,while C∶P and N∶P was lower than the national average level.Thinning had no significant effect on soil C∶N,but soil depth had a significant effect on C∶N,which decreased with the increase of soil depth.Tending intercropping has no significant effect on soil physical and chemical properties of Pinus yunnanensis stands in a short period.The results indicated that there was a general lack of nitrogen in the soil,which might be a factor limiting the stand productivity in this region.