青杨人工林根系生物量、表面积和根长密度变化

在植物生长季节，采用钻取土芯法对秦岭北坡50年生青杨人工林根径≤2 mm和2～5 mm根系的生物量、表面积和根长密度进行测定.结果表明：在青杨人工林根系(＜5 mm)中，根径≤2 mm根系占总生物量的77.8%，2～5 mm根系仅占22.2%;根径≤2 mm根系表面积和根长密度占根系总量的97%以上，而根径2～5 mm根系不足3%.随着土层的加深，根径≤2 mm根系生物量、表面积和根长密度数量减少，根径2～5 mm根系生物量、表面积和根长密度最小值均分布在20～30 cm土层.≤2 mm根系生物量、表面积和根长密度与土壤有机质、有效氮呈极显著相关，而根径2～5 mm根系的相关性不显著.

Changes of root biomass, root surface area, and root length density in a Populus cathayana plantation

By using soil core method, the biomass, surface area, and length density of roots ≤2 mm and 2-5 mm in diameter in a 50-year-old Populus cathayana plantation on the northern slope of Qinling Mountains were determined during growth season. Among the roots ＜5 mm in diameter, those ≤2 mm and 2-5 mm in diameter accounted for 77.8% and 22.2% of the total root biomass, respectively. The surface area and length density of the roots ≤2 mm in diameter accounted for more than 97% of the total, and those of the roots 2-5 mm in diameter only occupied less than 3%. The biomass, surface area, and root length density of roots ≤2 mm in diameter decreased with soil depth, while those of the roots 2-5 mm in diameter were the least in 20-30 cm soil layer. The biomass, surface area, and length density of roots ≤ 2 mm in diameter were significantly correlated with soil organic matter and available nitrogen, but no significant correlations were found for the roots 2-5 mm in diameter.