桉树人工林生态系统养分循环和平衡研究Ⅲ. 桉树人工林生态系统的养分平衡

在当地现行的生产技术规程和营林措施的条件下，刚果W5桉树人工林生态系统中，N和K的收支帐为亏损，P、Ca、Mg为盈余。在一个轮伐期内，每公顷养分质量的收入中，N为327．13kg／hm^2，P为110．48kg／hm^2，K为206．13kg／hm^2。，Ca为679．53kg／hm^2，Mg为173．72kg／hm^2；每公顷养分质量的支出中，N为366．59kg／hm^2，P为35_3lkg／hm^2，K为212．22kg／hm^2，Ca为452．77kg／hm^2，Mg为79．52kg／hm^2。但这仅仅是一种表观数字。桉树人工林生态系统养分不平衡的主要原因，是桉树凋落物和采伐剩余物不能回归土壤，以及严重的水土流失。解决问题的关键是转变思想认识，制定有效的措施，使桉树凋落物和采伐剩余物回归土壤，同时在桉树行间间种豆科绿肥牧草。

The nutrient cycling and balance of eucalyptus plantation ecosystem Ⅲ. The nutrient balance of eucalyptus plantation ecosystem

The nutrient balance in eucalyptus plantation ecosystem in Leizhou Peninsula, China, is discussed in this paper. According to the production procedure and afforestation measure, the nutrients N and K are deficit, and P, Ca and Mg are surplus. In a felling round, the input for N is 327.13 kg/hm2, P 110.48 kg/hm2, K 206.13 kg/hm2, Ca 679.53 kg/hm2, Mg 173.72 kg/hm2; the output for N is 366.59 kg/hm2, P 35.31 kg/hm2, K 212.22 kg/hm2, Ca 452.77 kg/hm2, Mg 79.52 kg/hm2. But that is only an apparent figure. The loss of balance in nutrients in the ecosystem rises from the two aspects, one is that the litter and felling residue can not return to soil, and the other is that there is severe soil and water loss. The key to solve this problem is to change the ideological understanding, lay down effective measure for the return of litter and felling residue to soil, and interplant leguminous green manure and herbage in the inter-rows of eucalyptus.