河北片麻岩山区核桃×苜蓿模式早期细根分布特征

摘要

以河北片麻岩山区退耕地核桃(Juglans Regia)×苜蓿(Medicago sativa)模式为研究对象,采用挖掘取样法,研究了果草复合系统早期细根根系密度的空间分布特征,并比较分析了单作和间作模式下核桃细根分布的差异.结果表明:间作模式下核桃细根根系在垂直方向和水平方向上均呈现“低高低”的二次多项式分布,集中分布于20～60 cm(垂直)、10～80 cm(水平);苜蓿细根在垂直方向和水平方向上分布分别呈现负指数型和指数型分布,集中于0～30 cm(垂直)、110～150 cm(水平);在垂直深度0～20 cm和水平距离100～150 cm范围内,苜蓿核桃相对重叠比大于1,苜蓿根系占据主导地位,核桃根系则在较深垂直空间和较近林带具有明显优势;与核桃单作模式相比,果草间作模式下核桃细根从量上有所减少,在垂直方向上分布变深,在水平方向上亦有所下降.核桃苜蓿间作模式下细根分布具有一定的交织区域,存在竞争.%By taking juglans regia ×Medicago sativa in a mountainous area with gneiss of Hebei as the research object,the characteristics of root spatial distribution in juglans regia × Medicago sativa pattern and the differences of fine roots distribution between juglans regia monoculture pattern and juglans regia intercropping pattern were studied by digging root sample.Results showed that:fine roots of Medicago sativa showed the quadratic polynomial characteristics in both horizontal and vertical direction,and the distribution increased from the topsoil to the deeper soil,and then decreased in the much deeper soil in the vertical direction,converging in 20～ 60 cm.The distribution in the horizontal direction also showed the same variation trend with that in the horizontal direction,converging in 10～80 cm.The fine roots of Medicago sativa presented negative exponential and exponential distribution in the vertical and horizontal directions,converging in 0～30 cm(vertical) and 110～150 cm (horizontal).The relative overlap ratio between Medicago sativa root and juglans regia root was greater than 1 within a vertical depth of 0～20 cm and the vertical of 100～150 cm,which meaned that Medicago sativa roots was dominant.Conversely,juglans regia root system had distinct preponderance in the deeper vertical space and closer horizontal distance.Compared with monoculture models,the amount of fine roots of juglans regia decreased in fruitgrass intercropping models,and so did in the horizontal direction,while the roots distribution was deeper in the vertical.There was a significant correlation between soil moisture and root distribution.According to our analysis,fine roots distribution had an overlap area in Juglans regia × Medicago sativa model,which meaned a competition between Juglans regia and Medicago sativa.In practice,we could solve this problem by regulating linespacing and water management.