土贡松采种母树林土壤物理特征分析

Analysis on Soil Physical Characteristics of Pinus massoniana Seed Production Stand

为揭示赋予土贡松优良生长表现的土壤环境特征,分别从土贡松采种母树林的上、中、下坡位挖取土壤剖面采集0~20,20~40,40~60 cm土层土壤样品测定土壤容重、持水量和孔隙度。结果表明,在0.05或0.01显著性水平上,坡位、土层以及二者的交互效应对土贡松采种母树林土壤容重、3个持水量因子(毛管持水量、最小持水量和最大持水量)、总孔隙度和毛管孔隙有显著影响,坡位对非毛管孔隙有显著影响。Duncan多重比较显示,下坡的容重明显低于中、上坡,上坡的毛管持水量和最大持水量明显低于中、下坡,最小持水量在中、上坡间差异显著,上坡的总孔隙度明显低于中、下坡,非毛管孔隙则是下坡明显高于上坡,中坡的毛管孔隙明显高于其他坡位。多重比较表明,0~20 cm土层的容重明显低于其他2个土层,0~20 cm土层的3个持水量因子、总孔隙度和毛管孔隙与其他2个土层有显著差异,不同土层间非毛管孔隙差异不大。土壤容重和持水量、孔隙度各指标之间存在明显的负相关关系。研究表明,土贡松采种母树林上坡土壤容重大,土壤较为紧实,孔隙度小,通气性较差,容易影响土壤中根系和微生物的活动;较低坡位土壤则疏松,透气能力强,孔隙度和持水量较大,可以容纳更多的水分,从而有利于土壤生物活动。同理,土层深度也可作用于土贡松采种母树林土壤生物活动。

For revealing soil environmental characteristics endowing Masson Pine with excellent growth performance, soil samples were collected from three soil horizons（0-20 cm, 20-40 cm and 40-60 cm）through digging soil profiles at upper, middle and lower slope positions in the Masson Pine seed production stand for mearsuring soil bulk density, water-holding capacity and porosity,respectively. The result showed that slope position, soil horizon and their interaction had significant effects on soil bulk density, three water-holding capacity factors（capillary water-holding capacity, minimum water-holding capacity and maximum water-holding capacity）, total porosity and capillary porosity of the seed production stand at the significance level of 0.05 or 0.01, noncapillary porosity was effected by the slope location at the 0.01 level. Duncan＇s test indicated that the bulk density of lower slope was the lowest in the three slope positions, the slope with the lower capillary and maximum water-holding capacity was the upper one, significant difference in the minimum water-holding capacity was observed between the middle and upper slopes, the total porosity of upper slope was obviously less than other two slopes, the lower slope was clearly different from the upper counterpart in noncapillary porosity, the middle slope was superior to other two slopes in the capillary porosity. The Duncan＇s test also showed that the top soil horizon（0-20 cm）was markably lower than the two deeper horizons, the three factors for water-holding capacity, total porosity and capillary porosity in the 0-20 cm horizon significantly differed from those in the 20-40 cm and 40-60 cm horizons, differential lack in the noncapillary porosity occurred amoung the three soil horizons. The bulk density had significantly negative linkages with the indices of water-holding capacity and porosity. The results suggest that in the stand, the bulk density is high at the upper slope where the soil usually compacts more,accompanied with poor porosity and ventilation, further easily influencing on activity of roots and microbes; the soil at the lower slope positions is loose, and superior in air ventilation, a high soil porosity and water-holding capacity can maintain more water, being propitious to the activity of soil organisms. In like manner, the soil depths may excert effects on the soil biological activity of the Masson Pine seed production stand.