沙地杨树刺槐人工混交林的改良土壤功能及养分互补关系

杨树刺槐混交林是我国北方地区沿河及滨海沙地上成功的固氮树种和非固氮树种人工混交林。本文在简单介绍混交林生长情况的基础上，主要对林地土壤养分改良及其种间Ｎ、Ｐ养分互补关系进行了阐述。指出杨树刺槐混交林生产力提高主要是因为林地土壤养分（特别是Ｎ素养分）的极大改善及树种间Ｎ、Ｐ养分的互补。混交林土壤Ｎ素养分水平提高的根本原因是林地土壤微生物活性高，加快了含Ｎ较高枯落物分解速度，增强了土壤氨化及硝化强度。而杨树刺槐种间的Ｎ、Ｐ养分互补则主要表现在混交林中杨树可将吸收入体内的Ｐ素通过根系接触转移给相邻的刺槐，而刺槐则可将固定的Ｎ素通过根系接触转移给杨树，而且Ｎ、Ｐ转移的强度很大。这种奇妙的树种间养分互补机制对杨树刺槐混交林幼林期生产力提高是有重大意义的。

THE SOIL AMELIORATION EFFECT OF POPLAR-BLACK LOCUST MIXED PLANTATION ON SAND SOIL AND THE INTERACTION OF MUTUAL SUPPLEMENT OF NUTRIENT BETWEEN TREE SPECIES

The mixed plantation of poplar ( Populus spp.) and black locust ( Robinia pseudoacacia L.) is one of the successful mixed stands of nitrogen-fixing and non-nitrogen-fixing species on poor sandy sites along the river and besides sea in the north of China. The growth and yield of the mixture is briefly introduced in this paper. The soil amelioration and the interaction of mutual supplement of nutrient between tree species are mainly discussed in this paper. It shows that the yield improvement is mainly due to the soil nutrient amelioration (especially nitrogen nutrient) and the interaction of mutual supplement of N and P nutrient. The main reason of the soil nitrogen nutrient improvement is the high speed of litter decomposition and high ammonification and nitrification intensity because of the increased activity of soil microorganism. The interaction of mutual supplement of N and P nutrient between tree species is realized mainly through the mechanism that poplar trees can transfer phosphorus to black locust trees by root-contacting and black locust can transfer nitrogen to poplar trees also by root-contacting. The transfer intensity of N and P is very high. This kind of marvelous interaction between tree species in very important to the yield improvement in the young mixtures.