林分密度对侧柏人工林细根形态的影响

以徐州林场50年生侧柏人工林为研究对象,采用挖掘法获取土壤根系样品,探究林分密度对侧柏人工林不同根序细根形态的影响。结果表明:细根的直径和根长随着根序上升而显著增大,而比根长则随着根序的上升而显著减小。低林分密度(1 679株/hm2)与中林分密度(2 250株/hm2)相比显著减小了表层土壤1、2级细根的平均直径和平均根长,亚表层土壤3级细根的根长,显著增大了亚表层土壤2级细根的平均比根长;高林分密度(3074株/hm2)比中林分密度显著增大了2级根的平均比根长。与高林分密度相比,低林分密度显著减小了表层土壤1、2级细根的平均直径,增大了亚表层土壤5级细根的平均直径。

Effects of stand density on fine root morphology in Platycladus orientalis plantations

An experiment was conducted to study the effects of stand density on fine root morphology in 50-year Platycladus orientalis plantations in Xuzhou Forest Region.Result showed that,with the ascent of root orders,P.orientalis’s mean fine root diameter and length increased significantly(p<0.05),while the mean SRL decreased significantly(p<0.05).Stand density had significant influence on root morphology and biomass for Platycladus orientalis plantations(p<0.05).Compared with the medium stand density(2 250 trees/hm2),the mean length and mean diameter of the first and second order roots of low-density stands(1 700 trees/hm2) in surface soil and the mean length of third order roots of low-density stands in subsurface soil were decreased significantly while the mean SRL of second order roots of low-density stands was increased significantly.The mean SRL of second order roots of high-density stands(3 074 trees/hm2) was increased significantly compared with the medium stand density.Compared with the high-density stand,the mean diameter of the first and second order roots of low-density stands in surface soil were decreased significantly and the fifth order roots of low-density stands was increased significantly.