苏北淤泥质海岸主要造林树种根系研究

本文报道了苏北淤泥质海岸带主要造林树种(刺槐、水杉等)的根系与立地条件和林木生长以及土壤抗冲性、抗蚀性关系的研究结果,表明刺槐根系不耐水湿,当生长季土壤潜水位埋深小于1.0m时,主根发生分叉、转向或被淹死,为水平根型;在周期性潜水位升降活动频繁处,水杉根系有再生现象;遇通透性差的紧沙层,刺槐根系难于穿过,集中在其上层,而水杉根系有较强的穿插能力,紧沙层中由垂直根系联结,有明显成层分布特点。细根和吸收根量随土壤含盐量的降低和有机质、氮、磷含量的增高而增加。

ROOT RESEARCH ON THE MAIN AFFORESTATION TREE SPECIES ON THE LITTORAL REGION IN NORTHERN JIANGSU PROVINCE

Based on site classification to the studying area, the paper deeply analyses the relation between tree roots and site conditions and the influence of roots to tree growth as well as the function of soil and water conservation of tree roots. The results show as follows; (1) When the depth of soil layer on the water table is shallower than 1 meter, the tree' s roots are difficult to form their root systems following their genetic characters, especially Robinia pseudoacacia, its main vertical roots will branch or turn direction of growth on the water table, and perhaps die of water drowning. So that the root system shows a horizontal form. When the soil depth is thicker than 1. 5 meters, the vertical root will grow well and deeply, generally, the depth is 1. 25-1. 5 meter. (2) When the obstacle layer of soil appears in the upper soil, ftobmia Pseudoacacia' s roots are difficult to pass through and all of the roots gather in the upper soil. Because the roots of Metasiquoia glyptostroboides have stronger ability to pass through the tighter soil layer, there are not only some bigger vertical roots in the layer, but also many thinner roots under the obstacle layer, their roots are distributed in different soil layers. (3) The quantity of roots, especially, the roots which are thinner in diameter than 2 mili- meters, decreases with the increase of soil salt content and with the decrease of soil organism, Nitrogen and phosphorus content. (4) The growth quantity of trees and capability of prevention of soil erosion is increases with the increase of root quantity. The paper also presents some important suggestions which will have a great significance to the correct selection of afforestation tree species in the construction of protective forestry along the coast belt.