桂西南蚬木林凋落物和表土理化性状分析

Physicochemical Properties of Litter and Surface Soil in Excentrodendron hsienmu Forest in Southwestern Guangxi,China

为保护蚬木(Excentrodendron hsienmu)群落,了解其生长环境特征,调查广西6个以蚬木为优势物种的林区,分析其凋落物和表土的理化性状。结果表明:凋落物生物量、最大持水率、最大持水量、最大拦蓄量、有效拦蓄量平均分别为12.56 t/hm^2、176.87%、21.78 t/hm^2、16.35 t/hm^2、13.08 t/hm^2,且不同地区间差异显著(P<0.05),凋落物持水动态规律为持水量和持水率与浸泡时间呈对数关系、吸水速率与浸泡时间呈幂函数关系;凋落物有机碳、全氮、全磷、全钾平均值分别为408.84、14.92、0.63、1.06 g/kg,在不同地区间除有机碳其余指标差异显著(P<0.05);0~10 cm表层土壤平均容重为0.81 g/cm^3,非毛管孔隙度、毛管孔隙度、总孔隙度、非毛管持水量、毛管持水量、最大持水量平均值分别为7.49%、50.02%、57.51%、82.37 t/hm^2、500.23 t/hm^2、575.11 t/hm^2,且不同地区间差异显著(P<0.05),土壤持水量的变化规律与相应的孔隙度一致;土壤pH值为7.42,呈弱碱性,土壤有机质、全氮、全磷平均值分别为145.25、7.03、1.14 g/kg,等级为1级;而全钾平均值为5.85 g/kg,等级为5级。不同地区间土壤养分指标差异显著(P<0.05)。综合看来,蚬木林具有涵养水源、改良土壤等生态功能。

To protect natural Excentrodendron hsienmu community,physicochemical properties of litter and surface soil in six E.hsienmu forests were investigated in Southwestern Guangxi.Results showed that significant differences existed among different E.hsienmu forests in such indexes as biomass,maximum water-holding rate,maximum water-holding capacity,maximum retain capacity,effective retain capacity of litters,and the average content were 12.56 t/hm2,176.87%,21.78 t/hm2,16.35 t/hm2,13.08 t/hm2,respectively.The water-holding capacity and water-holding rate of litters changed logarithmically,while the water-absorption rate assumed a power function of soaking time.The average contents of organic carbon,total N,total P and total K of litters were 408.84 g/kg,14.92 g/kg,0.63 g/kg and 1.06 g/kg,respectively.These indexes except for organic carbon were significantly different among different forests(P<0.05).Topsoil bulk density(0 to10 cm layer)was only 0.81 g/cm3,and non-capillary porosity,capillary porosity,total porosity,non-capillary water-holding capacity,capillary water-holding capacity,and maximum water-holding capacity were 7.49%,50.02%,57.51%,82.37 t/hm2,500.23 t/hm2 and 575.11 t/hm2,respectively.Significant differences of these indexes occurred among different forests(P<0.05).The change regularity of soil water-holding capacity was the same as the corresponding porosity.Soil pH was weak alkaline with an average of 7.42.The average content of soil organic matter,total N and total P at level one were 145.25 g/kg,7.03 g/kg and 1.14 g/kg,respectively.The average content of total K at level five was 5.85 g/kg.These indexes were sig?nificantly differenct among different forests(P<0.05).In general,E.hsienmu forest played a functional role in water conservation and improvement of soil conditions.