黄土丘陵区典型植被类型土壤微生物及异养呼吸特征

发布时间：2018-01-26 16:38

本文关键词： 植被类型土壤微生物生物量碳土壤微生物生物量氮土壤细菌群落土壤真菌群落土壤呼吸黄土丘陵区　出处：《中国科学院教育部水土保持与生态环境研究中心》2017年博士论文　论文类型：学位论文

【摘要】：自黄土高原地区大规模的实施了植被恢复以来,生态环境得到了大幅度的改善。植被恢复不仅可以保持水土,而且可通过土壤-植物之间的相互作用,改变土壤生态系统的生产力及改善土壤养分状况。研究植被恢复后不同植被类型下的土壤特点,是进一步认识生态系统结构和功能的基础,对于预测土壤生态系统功能对环境因子的响应规律、为黄土高原区植被类型优选有着重要的理论和现实意义。以陕西延安黄土丘陵区4种植被类型(人工刺槐林、天然侧柏林、天然辽东栎林、天然灌丛)为研究对象,以裸地作为对照,分析了土壤微生物生物量碳、氮含量、细菌和真菌的丰度及其与土壤基本化学性质的关系,探讨土壤微生物群落结构的主要影响因素和驱动力。结果表明:(1)4种植被类型的土壤质量较之裸地都有不同程度的改善;植被类型相似,土壤的化学性质也相似。本研究中天然辽东栎林在土壤养分的累积上优于人工刺槐林;与林地相比,裸地的土壤养分比较贫瘠。人工刺槐林的有机质、总氮和土壤碳氮比含量显著低于其他天然林地的含量(P0.05)。(2)不同植被类型,土壤养分状况不同,土壤微生物生物量也有较大差异。土壤养分的总体变化趋势为:天然林人工林裸地。土壤养分和微生物生物量表现出一致的趋势:天然林与灌丛最高,人工林次之,裸地最低。土壤微生物生物量碳、氮与土壤有机质、总氮和土壤有效磷呈显著正相关(P0.01)。(3)裸地土壤的细菌丰度最低,细菌丰度与土壤养分状况呈显著正相关(P0.05);人工刺槐林真菌含量显著低于天然辽东栎林,真菌与土壤养分无显著相关性,与土壤pH显著负相关(P0.05)。(4)细菌的优势门包括变形菌门(42.35%),放线菌(15.61%),酸杆菌(13.32%),拟杆菌(8.43%)和芽单胞菌(6.0%)。真菌优势门为子囊菌(40.39%),担子菌(38.01%)和接合菌(16.86%)。典范对应分析和冗余分析结果显示,土壤细菌和真菌群落都可以按照植被类型进行聚类。其中,细菌群落的主要驱动因子是土壤有机质,而真菌的主要驱动因子是土壤有效磷。该研究结果表明,植被类型不同可以导致土壤质量的差异,二者对土壤微生物群落组成具有控制作用,微生物的群落组成在一定程度上可以反映土壤质量状况。两典型林分(天然辽东栎林和人工刺槐林)的土壤呼吸强度在25oC时最大,且天然辽东栎林的土壤呼吸强度要高于人工刺槐林。天然辽东栎林土壤呼吸温度敏感性(1.630)略高于人工刺槐林(1.572)土壤呼吸强度均随着土壤湿度的升高先增强后降低,二者趋势均表现为60%时最高。
[Abstract]:Since the large-scale implementation of vegetation restoration in the Loess Plateau, the ecological environment has been greatly improved. Vegetation restoration can not only preserve soil and water, but also through the soil-plant interaction. To change the productivity of soil ecosystem and to improve soil nutrient status and to study the soil characteristics of different vegetation types after vegetation restoration is the basis of further understanding of ecosystem structure and function. To predict the response of soil ecosystem function to environmental factors. It is of great theoretical and practical significance to select vegetation types in Loess Plateau. The 4 planting cover types (artificial Robinia pseudoacacia, natural Platycladus orientalis, natural Liaodong oak forest) in Yan'an Loess Hilly area of Shaanxi Province are used. Natural scrub) as the study object, the relationship between soil microbial biomass carbon, nitrogen content, bacterial and fungal abundance and basic chemical properties of soil was analyzed with bare land as control. The main influencing factors and driving forces of soil microbial community structure were discussed. In this study, the accumulation of soil nutrients in natural oak forest was better than that in artificial Robinia pseudoacacia forest. Compared with the forest land, the soil nutrient of bare land was relatively poor. The contents of organic matter, total nitrogen and soil C / N ratio in artificial Robinia pseudoacacia forest were significantly lower than those in other natural forest land. Soil nutrient status is different. The total change trend of soil nutrient was: natural forest plantation bare land. Soil nutrient and microbial biomass showed the same trend: natural forest and shrub were the highest. Soil microbial biomass carbon, nitrogen and soil organic matter, total nitrogen and soil available phosphorus were significantly positively correlated with soil available phosphorus. There was a significant positive correlation between bacterial abundance and soil nutrient status (P0.05). The fungal content in artificial Robinia pseudoacacia forest was significantly lower than that in natural oak forest, and there was no significant correlation between fungi and soil nutrients. The dominant phylum of bacteria was 42.35 phylum, 15.61% actinomycetes and 13.32% actinomycetes. Bacteroides 8. 43) and B. spp. 6. 0. The dominant fungal phylum is ascomycetes 40.39). The results of canonical correspondence analysis and redundancy analysis showed that both soil bacterial and fungal communities could be clustered according to vegetation types. The main driving factor of bacterial community is soil organic matter, while the main driving factor of fungi is soil available phosphorus. The results show that different vegetation types can lead to the difference of soil quality. Both of them can control the composition of soil microbial community. The soil respiration intensity of two typical stands (natural oak forest and artificial Robinia pseudoacacia forest) was the highest at 25oC. The soil respiration intensity of the natural oak forest was higher than that of the artificial Robinia pseudoacacia forest, and the soil respiration temperature sensitivity of the natural oak forest was slightly higher than that of the artificial Robinia pseudoacacia forest. Soil respiration intensity increased first and then decreased with the increase of soil moisture. Both showed the highest trend at 60 hours.
【学位授予单位】：中国科学院教育部水土保持与生态环境研究中心
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S714

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