渭北主要造林树种细根生长及分布与土壤密度关系

Study on Relations of Growth and Vertical Distribution of Fine Root System of Main Planting Tree Species to Soil Density in the Weibei Loess Plateau

采用野外样地调查和盆栽试验的方法 ,研究了土壤密度对渭北主要造林树种细根生长及分布特征的影响。结果表明 ,在 0～ 10 0cm的深度内 ,不论是阴坡还是阳坡 ,油松林地的土壤密度均表现出随土层的加深逐渐增大的趋势 ;刺槐林地的土壤密度大于油松林地 ,且各土层间的差异不大。油松林地各土层土壤密度与不同径级根系长度存在显著的负相关关系。盆栽基质密度对不同树种苗木根系的生长和发育的影响虽各异 ,但在基质密度和孔隙度适中的条件下均生长良好 ,生物量达到最大。盆栽基质的密度对刺槐和油松根系的生长和发育的影响最显著 ;侧柏和山杏的细根生长发育受土壤密度的影响较小 ,其根系生物量在不同密度的基质中没有明显变化。

In this study influence of woodland soil density on growth and distribution of fine root system of main planting tree species in the Weibei Loess Plateau was conducted by means of pot culture and field survey. Results indicated that in the woodland of \%Pinus tabulaeformis\%, soil bulk density increased with the depth on different sites; while in the woodland of \%Robinia pseudoacacia\%, soil bulk density was bigger than that in \%P. tabulaeformis\%, and there was no clear difference across the profile. Further analysis implied that there existed negative correlations between soil density and the length root of system with different diameter class in the woodland of \%P.tabulaeformis.\% Results from pot culture indicated that although effects of medium density of pot culture on fine roots growth and development of seedlings were different for different tree species, all the seedlings could grow better under the conditions of medium with mid_level density and porosity, and had the maximum biomass. Medium density of pot culture had significant effects on the growth and development of \%P.tabulaeformis\% and \%R. pseudoacacia\% seedlings' roots, especially on that of \%P.tabulaeformis.\% But it had less effect on that of \%Platycladus orientalis\% and \%Prunus armeniaca\% var. \%ansu,\% whose fine root biomass changed little in different densities of medium.