三倍体毛白杨人工林浅层土壤细根对地下滴灌不同水分处理的响应

Response of the Fine Roots of Triploid Populus tomentosa to Different Subsurface Drip Irrigation Treatments in Shallow Soil Layers

在三倍体毛白杨(triploid Populus tomentosa)人工林中,采用根钻法对不同地下滴灌(SDI)处理T1、T2、T3(分别以-25、-50、-75 kPa作为灌溉起始土壤水势阈值)和不灌溉(CK)条件下林地0～30 cm土层细根形态特征进行研究。结果表明:垂直方向上,4种处理下细根的生物量、根长密度、表面积和体积均随土壤深度的增加而显著减小,SDI没有改变林木细根的垂直分布格局。SDI显著提高了林地20 cm<H≤30 cm土层细根生物量和体积,如T2处理下,20 cm<H≤30 cm土层细根生物量和体积分别为0.293 mg.cm-3和0.620 mm3.cm-3,分别较CK显著增加了112.31%和91.64%,同时促使细根比根长和组织密度在各土层中分布趋于一致,以有利于各土层细根全部发挥其吸收和伸展功效,这是SDI提高林分生产力的主要原因之一。

A field experiment was conducted to investigate the fine root morphology of triploid Populus tomentosa at 0-30 cm soil layers under different subsurface drip irrigation（SDI） treatments of T1,T2 and T3 with-25,-50 and-75 kPa of the soil water potential threshold,respectively,in comparison with non-irrigation treatment.In the vertical direction,the fine root biomass,root length density,root surface area and root volume significantly decrease with the depth by four treatments.SDI can not change the vertical distribution pattern of the fine root.SDI can significantly raise the fine root biomass and volume at 20-30 cm soil layer,and the fine root biomass and volume under T2 treatment are 0.293 mg·cm-3 and 0.620 mm3·cm-3,respectively,significantly higher 112.31% and 91.64% than those under CK treatment.SDI can make the fine specific root length and the fine root tissue same in all soil layers.The functions of absorbing and stretching the fine root in each soil layer are the main reasons why SDI can improve the forest productivity.