Knowledge Resource Center for Ecological Environment in Arid Area
| 土地利用变化对伊犁河谷典型农牧交错区土壤碳氮磷的影响 | |
| 其他题名 | Effects of Land-use Change on Soil Carbon, Nitrogen and Phosphorus in a Typical Agro-pastoral Ecotone in the Ili River Valley |
| 刘翔 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 李兰海 ; 王权 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 草地生态系统约占陆地总面积的20%，其土壤碳、氮、磷动态在全球生物地球化学循环中扮演着重要的角色。我国拥有丰富的草地资源，总面积位居世界第二位。然而在开垦等人类活动的影响下，我国草地面积呈缩减趋势，并形成了大面积的农牧交错区。尽管种植业和畜牧业共存的发展模式使得该区域蕴含着巨大的生产潜力，但在全球气候变化和人类活动的影响下，该区域同时也成为了典型的生态脆弱区。因此，评估土地利用变化对农牧交错区土壤碳、氮、磷动态的影响对于保障国家粮食安全和区域可持续发展具有重要的意义。本研究以西北干旱区伊犁河谷的典型农牧交错区为研究对象，采用相邻样地比较法，选取了草地、农田、林地和果园4种该区域主要的土地利用方式，研究了草地开垦和农田退耕还林对土壤垂直方向上（0~60 cm）碳、氮、磷储量、化学计量比、有机碳组分以及Hedley磷形态的影响，对比了表层土（0~30 cm）和下层土（30~60 cm）碳、氮、磷对土地利用变化的响应特征，同时结合土壤物理、化学和生物学性质的变化特征，探讨了土地利用变化对干旱区农牧交错区土壤碳、氮、磷的影响机制。主要研究结果如下：研究区土壤呈碱性，属粉质壤土，缺乏碱解氮和速效磷，但富含速效钾。草地开垦为农田不仅导致了土壤盐碱化，还降低了表层土的微生物量。相比之下，农田退耕还林则有助于土壤盐碱化的缓解和土壤微生物量的提升，但农田转化为林地会增大部分土层的容重，使土体变得紧实，不利于植物根系的生长。草地开垦为农田引起了土壤碳、氮、磷的损耗，而农田退耕还林则促进了土壤碳、氮、磷的累积。在草地开垦为农田后，下层土碳、氮、磷储量的响应程度要大于表层土，表明仅评估土地利用变化对表层土碳、氮、磷储量的影响可能会低估土地利用变化的环境效应。土壤碳、氮、磷含量与pH和电导率显著的负相关关系预示着土壤盐碱化可能会对土壤碳、氮、磷的动态产生影响。草地开垦为农田以及农田退耕还林会对土壤碳氮比和氮磷比产生截然相反的影响，农田退耕还林对土壤碳磷比的影响则在不同土层有所差异。土壤惰性碳组分含量的变化特征表明土壤惰性碳库也会受到土地利用变化的影响，且该影响不仅仅局限在表层土。土壤有机碳稳定性在草地开垦为农田后有所降低，在农田转化为林地后有所提升，表明农田还林有利于研究区土壤的长久固碳。与土壤活性磷（H2O-Pi、NaHCO3-Pi和NaHCO3-Po）和中等活性磷（NaOH-Pi和NaOH-Po）相比，研究区土壤稳定性磷（HCl-Pi和残留-P）的含量更容易受到土地利用变化的影响。相关分析的结果表明，稳定性磷主要决定土壤磷的固定，而NaHCO3-Pi则影响着土壤磷库对植物的有效性。土壤质量综合指数（SQI）的变化特征表明草地开垦为农田后土壤有退化的趋势，而退耕还林则促进了土壤质量的恢复。土壤氮磷比与SQI极高的相关性预示着土壤氮磷比是反映研究区土壤质量变化情况的潜在指标。综上所述，草地开垦为农田和农田退耕还林会对干旱区农牧交错区土壤碳、氮、磷的储量、碳氮比、氮磷比及有机碳稳定性带来截然不同的影响，但对土壤磷的有效性影响较小。本研究不仅有助于了解土地利用变化对西北内陆干旱区土壤生物地球化学循环的影响，也为该区域农牧交错地带土地资源的科学管理和可持续利用提供理论依据。 |
| 英文摘要 | Grassland ecosystems cover approximately 20% of the total land area. Therefore, dynamics of soil carbon (C), nitrogen (N) and phosphorus (P) in grassland may play important roles in the global biogeochemical cycles. The grassland area in China is the second largest in the world, making an abundant grassland resources. However, grassland area in China showed a decreasing trend under the disturbance of human activities (e.g. cultivation) in recent decades. As a consequence, a large area of agro-pastoral ecotone has been established. Although such ecotones have tremendous potential for food production because the coexistence of planting industry and animal husbandry, these regions are fragile to global climate change and human activities. Hence, evaluating the effects of land-use change on dynamics of soil C, N and P in agro-pastoral ecotone are meaningful to guarantee the national food security and the regional sustainable development. In this study, a typical agro-pastoral ecotone in the Ili River Valley in northwest arid region was selected to: (1) study the effects of grassland reclamation and cropland afforestation on stocks and stoichiometric ratios of soil C, N and P, the stability of soil organic C (SOC) as well as the Hedley P forms along the 0~60 cm soil profile; (2) compare the response characteristics of C, N and P in topsoil (0~30 cm) and subsoil (30~60 cm) to land-use changes; (3) explore the mechanisms that how land-use changes affect soil C, N and P cycling based on the variation characteristics of soil physical, chemical and biological properties. Considering the main land-use types in the study area, four land-use types were selected using adjacent comparison method including a grassland (GL), a cropland (CL), a woodland (WL) and an orchard (OC). The main findings of this study can be drawn as the following:(1) Soils in the study area were alkaline with silt loamy texture. The soils were lack of alkali-hydrolyzable nitrogen and available phosphorus but were rich in available potassium. GL reclamation not only induced soil salinization, but also decreased topsoil microbial biomass. By contrast, CL afforestation contributed to suppress soil salinization and increase soil microbial biomass. However, soil compaction might be induced by converting CL into WL because bulk density in some soil layers significantly increased.(2) Depletion of SOC, total N (TN) and total P (TP) pools were observed after GL reclamation, whereas CL afforestation contributed to SOC, TN and TP accumulations. The responses of SOC, TN and TP stocks in subsoil to land-use change were stronger than those in topsoil, indicating that only evaluating the effects of land-use change on SOC, TN and TP stocks in topsoil may underestimate the environmental effects induced by land-use change. The significant relationships between SOC, TN and TP concentrations as well as pH and electrical conductivity suggested that soil salinization possibly influenced the dynamics of C, N and P.(3) GL reclamation and CL afforestation had opposite impacts on soil C to N ratio (RCN) and N to P ratio (RNP), while the impacts of CL afforestaion on soil C to P ratio (RCP) depended on soil depth.(4) Variation characteristics of recalcitrant SOC fraction indicated that recalcitrant SOC pool could also be influenced by land-use changes, and the influence was not restricted to topsoil. SOC stability decreased after GL reclamation, whereas increased after CL conversion into WL, implying that converting CL to WL contributed to long-term SOC sequestration.(5) Soil stable P (HCl-Pi and residual-P) were more sensitive to land-use changes compared with soil labile P (H2O-Pi、NaHCO3-Pi and NaHCO3-Po) and moderately labile P (NaOH-Pi and NaOH-Po). The results of correlation analysis suggested that stable P determined P fixation, whereas NaHCO3-Pi influenced the availability of soil P to plant.(6) Variation characteristic of soil quality index (SQI) demonstrated that GL reclamation induced soil degradation, whereas CL afforestation contributed to soil restoration. The significant relationship between soil RNP and SQI suggested that soil RNP was a potential indicator to predict the variation of soil quality in the study area.In conclusion, GL reclamation and CL afforestation had opposite impacts on SOC, TN and TP stocks, RCN, RNP and SOC stability, but had little impact on soil P availability. The present study not only contributes to better understand the influences of land-use changes on soil biogeochemical cycles in northwest inland arid region, but also provides theoretical basis for scientific management and sustainable utilization of land resources in agro-pastoral ectones in this region. |
| 中文关键词 | 土地利用变化 ; 农牧交错区 ; 土壤有机碳 ; 化学计量比 ; 干旱区 |
| 英文关键词 | Land-use Change Agro-pastoral Ectone Soil Organic Carbon Stoichiometric Ratio Arid Region |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288173 |
| 推荐引用方式 GB/T 7714 | 刘翔. 土地利用变化对伊犁河谷典型农牧交错区土壤碳氮磷的影响[D]. 中国科学院大学,2018. |
| 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 |
| [刘翔]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [刘翔]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [刘翔]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。
