刺槐和油松根系密度分布特征研究

通过分层挖掘法,对20龄刺槐、油松林根系密度的空间分布进行了研究.结果表明:油松主根和副主根粗壮发达,水平根系形成构架根;刺槐水平根极为发达,无明显主根.刺槐和油松根系重量、长度和体积密度的垂直分布趋势基本相同,随土层深度增加而降低.0～60 cm土层的根长和根重密度占总根量密度的70%以上,粗根(直径＞3 mm)在上层所占比例比下层略大,细根(直径＜1 mm)和较细根(直径1～3 mm)在各土层分布较为接近,总根量中粗根占较大比重.刺槐和油松林下土壤干密度随深度加深而增大,油松林下土壤含水量高于刺槐林,土壤干密度低于刺槐林.与刺槐林地相比,油松林地的土壤物理性质得到了明显改善,增强了土壤的抗旱、保墒能力.

Study on the Distribution of Root Density of Robinia pseudoacacia L. and Pinus tabulaeformis Carr.

In this paper,the spatial distribution of root density of the 20-year forests of Robinia pseudoacacia L.and Pinus tabulaeformis Carr.in rhizosphere is lucubrated using the hierarchical digging method.The results show that the main roots and paraxial roots of the forests of Pinus tabulaeformis Carr.are developed and vigorous,and the root framework is mainly composed of the horizontal roots;the hierarchical roots of the forests of Robinia pseudoacacia L.are extremely developed without obvious main roots.The vertical distribution of root weight,length and volume density of Robinia pseudoacacia L.is close to that of Pinus tabulaeformis Carr.,that is their root weight,length and volume density are increased with the increase of the soil depth.The proportion of roots length and density in soil depth of 0~60 cm occupies over 70% of the total,the proportion of thick roots(>3 mm in diameter) in upper soil layer is slightly higher than that in lower one,the proportions of thin roots(1~3 mm in diameter) and thinner roots(<1 mm in diameter) in upper and lower soil layers are close to,and the proportion of thick roots is high in the total root weight.The dry density of soil under the forests of Robinia pseudoacacia L.and Pinus tabulaeformis Carr.increases with the increase of soil depth,the soil moisture content under the forests of Pinus tabulaeformis Carr.is higher than that under the forests of Robinia pseudoacacia L.,but the dry density of soil under the forests of Pinus tabulaeformis Carr.is lower than that under the forests of Robinia pseudoacacia L.The soil physical properties under the forests of Pinus tabulaeformis Carr.are significantly improved,thus the drought resistance and soil moisture conservation capacity are increased compared with that under the forests of Robinia pseudoacacia L.