IMHE OpenIR  > 山地表生过程与生态调控重点实验室
川西典型亚高山生态系统土壤N素转化特征及苔藓的影响
Alternative TitleSoil Nitrogen Transformation and Effects of Mosses in Typical Subalpine Ecosystems of Western Sichuan
李安迪
Subtype硕士
Thesis Advisor孙守琴
2018
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline自然地理学
Keyword土壤N素转化 N矿化速率 苔藓固氮 N2O排
Abstract森林土壤氮(N)素转化是整个森林生态系统N循环最重要、最活跃的组成部分,苔藓植物在森林生态系统中扮演着重要的生态作用角色。本研究以青藏高原东缘的贡嘎山为对象,分析了亚高山生态系统常绿-落叶阔叶混交林、针阔混交林和暗针叶林三种不同森林类型土壤N素累积、形态组成、分布和转化特征;并以暗针叶林为例,从土壤N2O排放、土壤N素含量、组成和转化特征的角度,分析了苔藓植物对典型亚高山生态系统土壤氮素循环和形态转化的影响;同时从苔藓植物的固氮作用、苔藓植物对大气N沉降的拦截作用,以及苔藓作用下土壤理化和微生物性质的变化等方面阐释苔藓植物对土壤N转化的作用机制。主要研究结果如下:(1)亚高山生态系统不同森林类型土壤N素累积和转化特征具有明显差异。本研究涉及的三种森林类型中,针阔混交林土壤总氮、溶解性氮和微生物量氮含量均最高,其次和常绿-落叶阔叶林,暗针叶林土壤总氮含量最低。三种森林类型土壤无机氮均以氨氮为主,但其含量在三种森林类型间无显著差异;相反,NO3-含量受森林类型的影响显著,常绿-落叶阔叶林与针阔混交林和暗针叶林相比其NO3-含量较低。(2)土层厚度对土壤N素累积和转化具有显著影响。无论是常绿-落叶阔叶林、针阔混交林还是暗针叶林,0-5 cm土层总氮、溶解性氮和微生物量氮含量均显著高于5-15 cm土层。(3)贡嘎山亚高山生态系统土壤氮素矿化以氨化为主,但不同森林类型和不同土层之间氨化、硝化和总矿化速率均存在显著差异。常绿-落叶阔叶林、针阔混交林和暗针叶林三种森林类型中,土壤氨化速率针阔混交林最高;土壤硝化速率暗针叶林最高,常绿-落叶阔叶林最低。(4)地表覆被类型对土壤氮素累积及转化过程均具有显著影响,而且不同类型苔藓对土壤氮转化过程的影响也尽相同。本研究涉及几种覆被斑块中,赤茎藓和锦丝藓斑块土壤总氮和溶解氮含量与草本植物相当或者更高,二者均显著高于裸地;而毛灯藓和星塔藓斑块土壤总氮及各组分含量与裸地均无显著差异。但无论是何种覆被,0-5 cm土层总氮、溶解性氮、氨氮和硝氮含量及土壤氮矿化速率均显著高于5-15 cm土层。(5)与裸地相比,苔藓斑块土壤N2O排放速率显著高于裸地,但其随季节的变幅相对于裸地较小,证明了苔藓覆被对土壤N2O排放的缓冲作用。不同覆被类型下土壤净氮矿化速率具有显著差异。本研究涉及几种覆被类型中,赤茎藓斑块土壤氮矿化速率最高,显著高于草本斑块,且二者均明显大于裸地,毛灯藓和星塔藓斑块土壤氮矿化速率与裸地相比无显著差别。随着土壤深度增加,五种覆被斑块土壤净氮矿化速率均下降。(6)亚高山暗针叶林的几种优势苔藓植物中,仅在锦丝藓和塔藓中检测到了固氮活性,其中9-10月两种苔藓的固氮速率最高可达0.572±0.045 mol N2 m-2 d-1和0.393±0.049 mol N2 m-2 d-1。(7)亚高山暗针叶林苔藓植物对大气氮沉降没有表现出明显的截留作用;相反,苔藓植物的存在增加了暗针叶林土壤N素输入。苔藓植物层对土壤NH4+-N和NO3--N的输入速率分别为:72.02 mg m-2 mon-1和5.04 mg m-2 mon-1。(8)本研究涉及的地表植物斑块种,赤茎藓和草本斑块与裸地相比,其土壤具有更高的微生物量。此外,草本和赤茎藓斑块与裸地以及毛灯藓、星塔藓斑块相比,其土壤蛋白酶、脲酶、氨单加氧酶、硝酸还原酶等氮转化相关酶类活性均显著高于裸地,暗示了苔藓和草本植物影响土壤氮素转化过程中微生物途径的重要性。
Other AbstractForest soil nitrogen (N) transformation is the most important and active part of the N-cycle in the entire forest ecosystem. While the bryophytes play an important ecological role in the forest ecosystem. In this study, soil N accumulation, composition and distribution were analyzed in three different forest types in the Gongga Mountain: evergreen-deciduous broad-leaved forest, mixed coniferous and broad-leaved forest, dark coniferous forest. And in coniferous forest, the characteristics of the soil transformation were used to analyze the effects of bryophytes on soil nitrogen cycling and morphological transformation in a typical subalpine ecosystem from the standpoint of soil N2O emission, soil N content, composition and transformation characteristics. At the same time, the mechanism of bryophyte N-transformation was explained from the nitrogen fixation of bryophytes, the interception effect of bryophytes on atmospheric N deposition, and the change of soil physicochemical and microbial properties under bryophytes. The main findings are as follows: (1) The characteristics of nitrogen accumulation and transformation in different forest types of subalpine ecosystems are significantly different. Among the three forest types involved in this study, the soil total nitrogen, total soluble nitrogen and microbial biomass nitrogen content in coniferous and broad-leaved mixed forest were the highest, followed by the lowest soil total nitrogen content in evergreen-deciduous broad-leaved forest and dark coniferous forest. The soil inorganic nitrogen in the three forest types was dominated by ammonia nitrogen, but its content was not significantly different among the three forest types. On the contrary, the NO3-content was significantly affected by the type of forest, and the evergreen-deciduous broad-leaved forest was mixed with coniferous and broad-leaved mixed forests. Compared with coniferous forest, its NO3-content is lower. (2) The thickness of soil layer has a significant effect on the accumulation and transformation of soil N. No matter in the evergreen-deciduous broad-leaved forest, coniferous or broad-leaved mixed forest or dark coniferous forest, the contents of total nitrogen, dissolved nitrogen and microbial biomass nitrogen in 0-5 cm soil layer were significantly higher than those in 5-15 cm soil layer. (3) The soil nitrogen mineralization in the subalpine ecosystem of Gongga Mountain is mainly ammoniated, but there are significant differences in the rates of ammoniation, nitrification and total mineralization between different forest types and different soil layers. Among the three forest types of evergreen-deciduous broad-leaved forest, coniferous-broad-leaved mixed forest and dark coniferous forest, the coniferous-broadleaf mixed forest had the highest soil ammoniation rate; the highest nitrification rate was dark coniferous forest, and the lowest was evergreen-deciduous broad-leaved forest. . (4) Surface cover type has a significant effect on soil nitrogen accumulation and transformation process, and different types of moss have the same effect on soil nitrogen transformation process. This study involved several types of coated patches. The contents of soil total nitrogen and dissolved nitrogen in the red stem and Jinsijing patches were comparable to or higher than that of herbaceous plants, both of which were significantly higher than those of bare soil. There was no significant difference in the content of total nitrogen, various components and barren soil between the pagoda patch soil and bare land. However, no matter what kind of cover, the contents of total nitrogen, dissolved nitrogen, ammonia nitrogen, and nitrate nitrogen in the 0-5 cm soil layer and soil nitrogen mineralization rate were significantly higher than those in the 5-15 cm soil layer. (5) Compared with bare land, the N2O emission rate of moss patch soil was significantly higher than that of bare land, but its variation with season was smaller than that of bare land, which proved the buffer effect of moss cover on soil N2O emission. There was a significant difference in soil net nitrogen mineralization rates under different cover types. This study involved several types of cover. The soil nitrogen mineralization rate was highest in the red stem and plaque, and was significantly higher than that in the herb patch. Both of them were significantly larger than those in the bare soil, Mao Deng and Xingta. There is no significant difference between the rate of change and bare ground. With the increase of soil depth, the net nitrogen mineralization rate of the five patched soils decreased. (6) Several dominant bryophytes of subalpine coniferous forests, nitrogen fixation activity was detected only in Jinsiella and pagodas, and the rate of nitrogen fixation of the two species was up to 0.572±0.045 mol N2 m-2 d-1 m from September to October. -2 d-1 and 0.393±0.049 mol N2 m-2 d-1. (7) The bryophytes of subalpine dark coniferous forests did not show significant trapping effect on atmospheric nitrogen deposition. On the contrary, the presence of bryophytes increased the N input of soil in dark coniferous forests. The input rates of NH4+-N and NO3--N in the bryophyte layer were 72.02 mg m-2 mon-1 and 5.04 mg m-2 mon-1, respectively. (8) Compared with the bare land, the soil patch species of the surface plants involved in this study had higher microbial biomass than the bare stem and herbaceous patches. In addition, the activities of nitrogen-related enzymes such as soil protease, urease, ammonia monooxygenase, and nitrate reductase were significantly higher in herbaceous and red stem plaques than in bare land, and in furrows and star towers. On bare ground, it implied the importance of moss and herbaceous plants in influencing the microbial pathways in soil nitrogen transformation.
Pages91
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24800
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
李安迪. 川西典型亚高山生态系统土壤N素转化特征及苔藓的影响[D]. 北京. 中国科学院大学,2018.
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