苏北沿海不同林分土壤氮素矿化及酶活性研究

发布时间：2018-05-12 12:07

本文选题：氮矿化 + 土壤酶活性　；参考：《南京林业大学》2017年硕士论文

【摘要】：土壤氮矿化速率常被作为反映土壤供氮能力的重要指标,分析不同林分类型土壤氮矿化能力以及土壤矿质氮与土壤酶活性的相关关系,对提高防护林的经营水平有重要意义。选取苏北沿海地区杨树和桑树混交林,柳树以及女贞、栾树纯林为研究对象,采用原位封顶连续培养法测定土壤矿质氮在林分生长季节中的变化,同时对4种林地土壤酶活性及土壤理化性质进行分析比较。研究结果表明:(1)4种不同林分土壤理化性质表现出一定的差异性,土壤有机质、氮含量表现为:柳树林混交林女贞林栾树林。土壤理化指标沿土层显现出垂直分布的规律。(2)4种林分下土壤中氨态氮含量大于硝态氮,其中氨态氮约占土壤矿质氮的69.2%。不同林分土壤氨态氮含量表现为表层最大,并且随着土层向下呈逐渐减少的趋势。表层土壤中氨态氮含量为混交林柳树林女贞林栾树林。不同林分类型在生长季节表层土壤中氨态氮和硝态氮都呈现出一定的季节变化,在9月份含量都相对较高。土壤中的氨态氮含量变化与硝态氮的变化一致。(3)4种林分土壤氮矿化的季节动态研究结果表明,土壤氨化量、硝化量变化趋势相似,二者含量均在7月份达到最大值,且明显高于其他培养季节。混交林林地土壤中氨化量和硝化量均比其他林分高。在林分生长季节,4种林分土壤中的氨化量均高于硝化量。土壤氮矿化速率大小为混交林柳树林女贞林栾树林,4种林分土壤净硝化速率季节变化趋势与净矿化速率的趋势相似,尤其表现在表层土壤方面。经计算,4种林分土表层壤中净矿化速率远高于净硝化速率。土壤氨化量、硝化量和矿化速率均随着土层向下呈现逐渐降低的趋势。(4)对4种林分类型土壤酶活性月际动态变化研究表明,不同林分土壤酶活性变化情况不一,存在一定差异性。各林分在生长季节脲酶活性均是逐渐升高的,只有在七月份有一个小幅度的降低。过氧化氢酶蔗糖酶、蛋白酶在7月份达到最高值。由方差分析可知,女贞林、栾树林与混交林、柳树林之间存在极显著差异(P0.01)。沿土层垂直方向上,表层土壤酶活性最大,且呈现递减趋势。同一样地土壤酶活性在不同土层间存在显著差异(P0.05)。(5)相关性分析表明:土壤酶与氮矿化速率、氨化量、硝化量间有显著相关性(P0.05)。土壤氮矿化速率与养分因子有显著相关性(P0.05),而与土壤含水率和PH值间无显著相关性(P0.05)。土壤酶活性与土壤养分间的相关性很好,这也说明,土壤酶活性可以用来反映土壤肥力。
[Abstract]:The rate of soil nitrogen mineralization is often used as an important index to reflect the ability of soil nitrogen supply. It is important to analyze the relationship between soil nitrogen mineralization ability of different stand types and soil enzyme activity in order to improve the management level of shelterbelt. The pure forests of poplar and mulberry trees, willow, privet and Luan are selected as the research objects in the coastal area of northern Jiangsu Province, and the changes of soil mineral nitrogen in the growing season of stands were determined by continuous culture method of in situ capping. At the same time, the soil enzyme activity and soil physical and chemical properties of four kinds of forest land were analyzed and compared. The results showed that the soil physical and chemical properties of four different stands were different, and the contents of soil organic matter and nitrogen were as follows: Luan forest of Ligustrum virginum forest in mixed willow forest. The soil physicochemical index showed vertical distribution rule. The content of ammonia nitrogen in soil was higher than that of nitrate nitrogen under four stands. Ammonia-N accounted for 69.2% of the mineral nitrogen in soil. The content of NH3-N in different stands was the highest in the surface layer and decreased gradually with the soil layer down. The content of NH3-N in surface soil was mixed willow forest and Luan forest. Different stand types showed seasonal changes in both ammonia and nitrate nitrogen in topsoil during growing season, and the contents of ammonia and nitrate were relatively high in September. The seasonal dynamic study of nitrogen mineralization in four stands showed that the change trend of soil ammoniation and nitrification was similar, and both of them reached the maximum in July. And it was obviously higher than other culture seasons. The amount of ammoniation and nitrification in mixed forest soil was higher than that in other stands. The amount of ammoniation was higher than that of nitrification in the soil of four stands in the growing season. The soil nitrogen mineralization rate was similar to that in the surface soil, especially in the surface soil. The net mineralization rate in the surface soil of the four forest stands was much higher than that in the nitrification soil. Soil ammoniation amount, nitrification rate and mineralization rate all showed a decreasing trend along with the soil layer downward. The monthly dynamic changes of soil enzyme activity of four stand types were studied. The results showed that the change of soil enzyme activity was different among different stands. There are certain differences. The urease activity of each stand increased gradually in the growing season, and only decreased by a small margin in July. Catalase, sucrase, protease reached its highest value in July. According to the analysis of variance, there was a significant difference between Ligustrum privet forest, Luan forest and mixed forest and willow forest. In the vertical direction of soil layer, the enzyme activity of surface soil was the largest, and showed a decreasing trend. The correlation analysis between soil enzyme activity and nitrogen mineralization rate, ammoniation rate, nitrification amount in different soil layers showed that there was a significant correlation between soil enzyme activity and nitrogen mineralization rate (P 0.05). There was a significant correlation between soil nitrogen mineralization rate and nutrient factors, but no significant correlation with soil moisture content and PH value. The correlation between soil enzyme activity and soil nutrients is very good, which also indicates that soil enzyme activity can be used to reflect soil fertility.
【学位授予单位】：南京林业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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