Knowledge Resource Center for Ecological Environment in Arid Area
| 青藏高原多年冻土区不同类型草地表层土壤碳氮时空分布特征 | |
| 其他题名 | Spatial and seasonal characteristics of surface soil organic carbon and total nitrogen under different vegetation types in permafrost regions of the central Qinghai-Tibet Plateau, China |
| 尚雯 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 赵林 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 本文以青藏高原中部典型多年冻土区为研究区域，应用野外采样和室内培养分析相结合的方法，围绕气候变化对多年冻土区土壤活性碳氮组分分布特征的影响这一主题，系统分析了四种不同植被类型下青藏高原典型多年冻土区土壤活性碳氮组分的时空变化动态及矿化特征。不同植被类型包括：高寒沼泽草甸，高寒草甸，高寒草原及高寒荒漠。高寒沼泽草甸植被盖度和地上生物量最高，高寒草甸和草原次之，高寒荒漠植被盖度和地上生物量最低。通过分析不同植被类型下土壤活性碳氮组分（溶解性碳、微生物量碳氮、轻组碳氮）的时空动态及土壤有机碳矿化特征，探讨了青藏高原多年冻土区土壤活性碳氮组分的时空变化特征及其影响因子。结果表明： （1） 植被类型显著影响土壤活性碳氮分布特征。土壤总有机碳和全氮含量在0-30 cm土层表现为高寒沼泽草甸＞高寒草甸＞高寒荒漠＞高寒草原，沼泽草甸和草甸土壤有机碳和全氮含量随土层加深降低；0-30 cm层土壤溶解性有机碳、微生物量碳氮和轻组碳氮含量则表现为高寒沼泽草甸最高，草甸和草原次之，荒漠最低。0-10 cm层的微生物量碳和轻组碳占土壤总有机碳的比例均表现为高寒沼泽草甸＞高寒草甸＞高寒草原＞高寒荒漠，但0-10 cm层溶解性有机碳占土壤总有机碳的比例则表现为高寒草原＞高寒沼泽草甸＞高寒草甸＞高寒荒漠。相关分析表明，土壤含水率、植被地上生物量、总有机碳和全氮含量与土壤各活性碳氮组分间呈极显著正相关关系。说明土壤活性碳氮各组分对土壤含水率、植被地上生物量、总有机碳和全氮含量响应敏感。气候变暖导致的植被和气象因子的改变可能会影响青藏高原多年冻土区土壤碳氮含量。 （2） 四种植被类型0-30 cm层土壤活性碳氮含量（溶解性碳、微生物量碳氮、轻组碳氮）存在明显的季节波动，这与土壤温度、水分、植被类型以及冻融循环特征有关。土壤活性碳氮在沼泽草甸和草甸土壤的季节波动幅度较大，在荒漠土壤中的季节波动幅度较小。沼泽草甸和草甸土壤活性碳氮的季节波动幅度随土层加深而下降。草原和荒漠土壤活性碳氮组分季节变化与土壤温湿度相关均不显著，草原土壤溶解性有机碳、微生物量碳和轻组碳含量与土壤总有机碳含量显著正相关；草甸土壤微生物量碳氮含量与土壤温度间存在极显著正相关关系，微生物量氮含量与土壤体积含水率呈极显著正相关关系；沼泽草甸土壤溶解性碳含量与土壤温度和体积含水率呈显著正相关关系。土壤活性碳氮各组分对气候变化的响应依赖于土壤温度、水分和植被类型，且植被盖度和土壤水分条件较好的沼泽草甸和草甸土壤溶解性碳、微生物量碳和微生物量氮对气候变化的响应更敏感。 （3） 经过25 °C 81天的室内恒温培养后，四种植被类型0-30 cm层的土壤有机碳矿化速率在0.12-211.29 μgCO2-C?g?d-1之间，0-20 cm层的土壤有机碳矿化速率在沼泽草甸最快，草甸和草原次之，荒漠最低。 各植被类型土壤有机碳矿化速率在培养的0-7天快速下降，7-11天缓慢下降，之后趋于稳定。四种植被类型0-30 cm层土壤有机碳矿化释放的CO2-C分配比例在1.06-4.43 % 之间，0-10 cm层草原土壤有机碳矿化释放的CO2-C分配比例分别是沼泽草甸、草甸和荒漠的3.96，2.33和0.96倍。草甸、草原和荒漠土壤有机碳矿化释放的CO2-C分配比例总体随土层加深降低。与其他三种植被类型相比，草原土壤固碳能力最弱，更易受到外界环境因素的影响，因此应加以保护。 |
| 英文摘要 | The study area was located in the permafrost regions of the central Qinghai-Tibet Plateau, China. Based on the methods of field investigation and laboratory incubation, this study evaluated the soil carbon (C) and nitrogen (N) concentrations in labile SOM fractions under different four vegetation types and analyzed their influencing factors in continuous permafrost regions of the central Qinghai-Tibet Plateau. Soil samples were collected in pits under four vegetation types — Alpine swamp meadow (ASM), Alpine meadow (AM), Alpine steppe (AS) and Alpine desert (AD) — at the depth of 0–30 cm. The vegetation coverage was the highest at ASM and AM, followed by AS and AD. The spatial and seasonal variations of labile soil organic carbon fractions (dissolved organic carbon, microbial biomass carbon and nitrogen, light fraction organic carbon and nitrogen) under four vegetayion types were analyzed. The mineralization rates of soil organic carbon at 0–30 cm depth under four vegetation types were also analyzed. In addition, we examined the relationship between environmental factors (such as aboveground biomass, soil moisture, pH, etc) and labile soil organic carbon fractions in permafrost regions of the central Qinghai-Tibet Plateau, China. Main conclusions can be drawn as follows: (1) The results indicated that the concentrations of dissolved organic carbon (DOC), microbial biomass carbon (MBC) and nitrogen (MBN), and light fraction carbon (LFC) and nitrogen (LFN) were significant differences among the four vegetation types. Soil organic carbon (SOC) and total nitrogen (TN) concentration was the highest in ASM soil, followed by AM and AD soils and the lowest in AS soil. SOC and TN concentrations in the ASM and AM soils were both deceased with increasing soil depth. The DOC, MBC, MBN, LFC and LFN concentrations in the 0-30 cm depth of the four vegetation types were in the order of ASM ＞ AM ＞ AS ＞ AD. The proportions of MBC/SOC, MBN/TN and LFC/SOC in the 0-10 cm depth were all highest in the ASM soil, followed by the AM and AS soils, with the lowest value in AD soil. However, the proportion of DOC/SOC in the 0-10 cm depth decreased as follows: AS > ASM > AM > AD. This suggests that the stability of dissolved organic carbon pool in the AS soils was more sensitive to the environment. Correlation analysis demonstrated that aboveground biomass, soil moisture content, SOC and TN concentrations significantly positively correlated to DOC, MBC, MBN, LFC and LFN, while pH significantly negatively correlated to DOC, MBC, MBN, LFC and LFN. There was no relationship between active layer thickness and SOC fractions. Results suggested that vegetation cover, soil moisture content, and SOC and TN concentrations were significantly correlated with the amount and availability of SOC fractions, while permafrost had less impact on SOC fractions in permafrost regions of the central Qinghai–Tibet Plateau. In a warmer world, the vegetation degradation will decline the labile SOM fractions in the Qinghai-Tibet Plateau. (2) The DOC, MBC, MBN, LFC, and LFN showed dramatic seasonal patterns in ASM and AM soils, but were relatively stable in AD soil. This difference resulted from a slower onset of the change in soil temperature and stronger nutrient dynamics in the ASM and AM soils. Soil DOC concentrations in the ASM, AM, and AD soils increased from April to May 2013, then increased again from July to August 2013 and from November to December 2013. The highest MBC and MBN concentrations in the ASM, AM, and AS soils all occurred in the summer (from June to August 2013), and the ASM soil showed a second peak in October or November 2013. The LFC and LFN concentrations in all four vegetation types were higher from June to August 2013. Seasonal changes in climatic conditions, substrate availability, and the permafrost features were great causes of labile SOM variations in this study. The labile soil organic carbon fractions were strongly affected by vegetation type. The ASM soil had the highest labile soil organic carbon fractions, followed by the AM, AS, and AD soils. These results suggest that ASM soil is the best system conserving soil nutrient (especially labile fractions) and microbial activity. Correlation analysis indicated that these fractions were not related to soil moisture and temperature in AS or AD soils, but soil temperature and moisture were significantly related to MBC and MBN in AM soils and DOC in ASM soil. Thus, the response of the labile SOM fractions to climate change is depended strongly on temperature, moisture, compositions of different labile SOM fractions, and vegetation type. Additionally, compared to the AD soils, the DOC, MBC and MBN in the ASM and AM soils were more sensitive to future climate change. (3) SOC mineralization carbon rates in the 0-30cm depth of the four vegetation types were estimated between 0.12-211.29 μgCO2-C?g?d-1 after 81 days incubation at 25 °C. The mineralization rate in the 0-20 cm depth was highest in the ASM soil, followed by AM and AS soils and the lowest in the AD soil. SOC mineralization carbon rates in the four vegetation types were quickly decreased in the initial 7 days, then decreased slowly in the 7-11 days and dinally stabilized after 11 days. The SOC mineralization rate in the 0-30 cm depth of the four vegetation types was between 1.06-4.43 %, and it was significant higher in the AS and AD soils than in the ASM soil. This suggests that soil carbon sequestration capacity in the AS soil was the lowest compared to the ASM soil and we should take protective measures to protect the carbon pools in the AS soil. |
| 中文关键词 | 青藏高原 ; 多年冻土 ; 溶解性有机碳 ; 微生物量碳氮 ; 轻组碳氮 ; 矿化碳 |
| 英文关键词 | Qinghai-Tibet Plateau Permafrost Dissolved organic carbon Microbial biomass carbon and nitrogen Light fraction carbon and nitrogen Mineralization carbon |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287534 |
| 推荐引用方式 GB/T 7714 | 尚雯. 青藏高原多年冻土区不同类型草地表层土壤碳氮时空分布特征[D]. 中国科学院大学,2015. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [尚雯]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [尚雯]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [尚雯]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
