DOC《南京林业大学》

南京林业大学 本科毕业设计(论文) 题目:水分对滩地杨树人工林土壤氮转化及养分淋溶的影响 学院:森林资源与环境学院 专业:林学(植物资源利用) 学号:

080101501 学生姓名: 陈晨指导老师: 田野职称: 副教授二一二年五月十八日 摘要本文以南京市浦口区沿江镇的长江滩地具有季节性淹水特点的8年生杨树人工林为研究对象,通过室内培养实验,对间伐和不间伐林分的土壤在不同水分状态下的pH值以及氮转化特征等进行比较研究,探讨间伐与水分条件对林地内土壤氮的矿化、硝化和潜在的流失可能性进行评价.

主要研究结果如下: 1) 在不同的间伐处理下,pH值变化的趋势基本相同,在第一周上升之后呈下降趋势.在试验第四周,淹水处理的pH显著高于正常水分状态和饱水状态,其他处理之间基本上不存在显著差异. 2)不同间伐条件下氮的矿化量差异不明显.在不同的水分处理下土壤硝态氮含量的变化有显著性的差异,淹水处理在第一周的硝化速率要低于其他两种处理,其后速度开始加快并最终硝化总量高于其他两种处理.由于无机氮中硝态氮占比例较高,且硝态氮易溶于水,因此无机氮的含量变化及水溶性硝态氮、水溶性无机氮的含量变化与硝态氮含量变化基本相同. 3)水溶性铵态氮为持续下降趋势,在不同的间伐处理下,水溶性铵态氮的变化出现差异,间伐处理下反应的速度要高于对照. 4)土壤中氮的矿化量越高,水溶性氮的生成量也越高,硝态氮的矿化量和水溶性硝态氮的生成量也与之呈非常显著的正相关习惯,可溶性铵态氮的生成量则与其呈显著的负相关. 关键词:长江滩地;

水分条件;

间伐;

氮矿化;

氮溶出 Abstract For the feature of thinning characteristics, and seasonal flooding of 6-year-old poplar plantation in the flood land of Yangtse river in the Pukou of Nanjing. The experiment was designed to know the number of associated between pH variation, loss amount and the amount of mineralization of nitrogen. Concluded that woodland in seasonally flooded conditions will be a substantial loss of nitrogen and cause eutrophication. The results are as follows: 1) In the different thinning treatments, the pH changes in the trend is basically the same. It downward trends after the rise in the first week. In the fourth week of the experiment, the pH of waterlogged significantly higher than normal moisture status and water-saturated state, basically there is no significant difference between the other treatments.Different thinning treatment and different water treatments, the loss of inorganic nitrogen were significantly different. 2) Thinning under the conditions of nitrogen mineralization rate differences are not obvious. Changes in soil nitrate content in the different water treatments, the sex differences in waterlogged during the first week of the nitrification rate is lower than the other two treatments and subsequently began to accelerate and eventually the nitrification total is higher than the other two treatments. Higher proportion of inorganic nitrogen in the nitrate and nitrate soluble in water, inorganic nitrogen content and water-soluble nitrate content of water-soluble inorganic nitrogen and nitrate content is basically the same. 3) Water-soluble ammonium nitrogen for continuing the downward trend in the different thinning treatments, the changes in water-soluble ammonium nitrogen differences, thinning of the reaction is faster than the control. 4) Soil nitrogen mineralization higher the amount, the higher the amount of generation of water-soluble nitrogen, nitrate nitrogen mineralization rate and amount of generation of water-soluble nitrate with was a very significant positive correlation habits, soluble formation of ammonium their was a significant negative correlation. Key word: The flood land of Yangtse river;