Knowledge Resource Center for Ecological Environment in Arid Area
| 中国主要沙区植被恢复对土壤碳影响的研究 | |
| 其他题名 | Study on effects of vegetation restoration on soil carbon in the major sandy desert regions of China |
| 陈永乐 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 李新荣 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 在我国干旱、半干旱和部分半湿润地区的沙区，风沙危害长期威胁着当地的环境健康、社会生产和经济活动。近60年来，国家相继在以上地区实施了大规模以人工植被建设为主的植被恢复措施和工程。实践证明，这些地区的植被恢复有效遏制了沙漠化的发展，缓解了风沙危害，促进了局地生境的好转，同时也促进了生态系统中土壤碳的固定。在此过程中，实施了恢复措施的沙地（共和、毛乌素、浑善达克、科尔沁和呼伦贝尔沙地）和沙漠周边（塔克拉玛干、古尔班通古特、巴丹吉林、乌兰布和、腾格里和库布齐沙漠），形成了一批具有不同恢复年限、采用不同模式的人工植被区，使研究长时间序列上植被恢复对土壤碳变化的影响成为可能。分析沙区不同区域土壤碳变化的程特征和趋势及其影响因素，有助于我们更好的认识植被恢复对荒漠生态系统土壤环境的深刻影响。本文的研究从区域和局地两个方面展开。首先，以针对我国主要沙区植被恢复对土壤碳变化影响的个案研究为数据源，收集植被恢复前后土壤碳的数据，量化了我国主要沙区植被恢复后土壤有机碳变化的特征和趋势；分析了恢复年限、气候区、恢复前土地类型、恢复方式和恢复采用的物种类型的不同对土壤有机碳变化的不同影响，确定了土壤有机碳与恢复时间、降水、温度、土壤性质的数量关系。其次，以沙坡头不同年代固沙区为研究对象，探明了植被恢复过程中土壤有机碳、无机碳和根源碳各组分的变化，明确了植被恢复过程中与土壤中碳同步变化的主要植被和土壤特征。本文主要结果如下：（1）我国主要沙区植被恢复过程中土壤有机碳含量的平均变化量、年变化量和相对变化率分别为1.91 g kg-1，0.129 g kg-1 y-1和17.5 % y-1，其中，0-20 cm的分别为2.31 g kg-1，0.153 g kg-1 y-1和21.5 % y-1，>20 cm深度的分别为1.14 g kg-1，0.0832 g kg-1 y-1和9.82 % y-1。植被恢复对土壤有机碳积累具有明显的促进作用，且表层增速更大。（2）在所有深度，浑善达克沙地土壤有机碳含量的平均变化量最大，为4.58 g kg-1，科尔沁沙地的最小，为0.422 g kg-1；年变化量最大的是呼伦贝尔沙地的0.388 g kg-1 y-1，最小的是古尔班通古特沙漠的0.0335 g kg-1 y-1；呼伦贝尔沙地的相对变化率最大，为68.6 % y-1，最小的是库布齐沙漠的6.82 % y-1。（3）随着植被恢复年限的增加，土壤有机碳含量变化量逐渐增加，并在11-15年间达到一个较高的值；此后，0-20 cm的变化量小幅下降后回升到11-15年较高值的水平，而>20 cm的变化量表现为持续缓慢降低。在恢复年限大于40年后，所有深度的变化量均迅速增加。年变化量在恢复初期开始下降，在11-15年间回升到初期水平，随后持续下降，大于40年后增加。相对变化率总体表现为随恢复年限增加而下降的趋势。（4）半湿润区具有最大的有机碳含量变化量和年变化量，干旱区均最小；干旱区的相对变化率最大，半湿润区最小。恢复后，流动沙地与退化草地0-20 cm的变化量相当，>20 cm的小于后者；流动沙丘的年变化量低于退化草地，相对变化率高于退花草地。恢复后，人工措施的变化量和年变化量小于封育，但相对变化率二者相当。采用草本恢复后变化量和0-20 cm年变化量最大，灌木加草本组合的>20 cm年变化量和各深度相对变化率均最大。（5）随着沙坡头固沙区恢复年限的增加，浅层和深层土壤有机碳密度均增加，但浅层增速更大，导致浅层比例增加（流沙的14.3%到1964年固沙区的30.4%）而深层比例降低（流沙的64.8%到1964年固沙区的51.6%）；浅层和深层的无机碳密度有不显著的小幅增加，且深层增速较大，浅层和深层无机碳比例增加。浅层根系碳密度增加，深层根系碳密度先增加后减少。（6）植被特征中，灌木各属性对土壤碳和根系碳的影响最大，且随着恢复年限增加，对深层土壤的影响减弱；土壤粒径，氮、磷和土壤水分特征影响土壤碳和根系碳的分布。 |
| 英文摘要 | Wind-blown sand hazard has long been a threat to local environmental health, social production and economic activity of sandy desert regions in Chian’s arid, semi-arid and semi-humid areas. During past 60 years, the government has launched large-scale vegetation restoration projects featured as artificial vegetation in these areas. It has been found that vegetation restoration in these areas have effectively curtailed the development of sandy desertification, alleviated the wind-blown hazard, promoted the local environment and also facilitated carbon sequestration in the ecosystem. During all this process, there formed a series of artificial vegetation areas with different ages and employed different methods in different sandy desert and sandy land. Thus, it becomes possible to study the effects of vegetation restoration along long-term chronosequence scales. By analyzing the magnitude and direction of changes in soil carbon following vegetation restoration, it is helpful to us for understanding the profound impacts of vegetation restoration on soil environment of desert ecosystems.The present study is designed to perform at both regional scale and local scale. First, we extracted data involving changes in soil carbon following vegetation restoration, and qualified the magnitude and direction of soil carbon change following vegetation restoration in the major sandy desert areas. The effects of restoration time, climate zone, and land type before restoration, restoration method and species selected on soil carbon change were also compared. We also determined the relationships between soil organic carbon and restoration age, precipitation, temperature, soil nitrogen and other soil properties. Then, we explored the changes in soil organic carbon, inorganic carbon and roots derived carbon following restoration in Shapotou, and determined the main vegetation and soil properties related with changes in soil carbon.Main finds of the study are as follows:(1) The average change, yearly average change and relative yearly change in soil organic carbon of China’s sandy desert regions following vegetation restoration were 1.91 g kg-1, 0.129 g kg-1 y-1, and 17.5 % y-1, respectively. in which, the values of 0-20 cm depth were 2.31 g kg-1, 0.153 g kg-1 y-1, and 21.5 % y-1, and the values at depth more than 20 cm were 1.14 g kg-1, 0.0832 g kg-1 y-1, and 9.82 % y-1, respectively. On the whole, vegetation restoration could facilitate the carbon sequestration, especially in the topsoils.(2) In all the depths, the Onqin Daga Sandy Land has the maximum average value of change in soil organic carbon, 4.58 g kg-1, while the Horqin sandy land has the minimum value 0.422 g kg-1. The maximum value of yearly change of soil organic carbon is 0.388 g kg-1 y-1 from the Hulunbuir Sandy Land, while the minimum value is 0.0335 g kg-1 y-1 from the Gurbantunggut Desert. For relative change in soil organic carbon, the Hulunbuir Sandy Land has the maximum value of 68.6 % y-1, while the Hobq Desert has the minimum value 6.82 % y-1.(3) Along the restoration age, soil organic carbon content gradually increased and reached a relatively high value during 11-15 years. After that, the change in 0-20 cm first decreased and then returned to the value close to that during 11-15 years. However, the value of >20 cm depth continually decreased. When the restoration age were more than 40 years, the changes of all the depths increased rapidly. At the early stage of restoration, the yearly change decreased, but recovered to initial value in 11-15 years and continually decreased afterward, and didn’t until 40 years later. For the relative change, it decreased throughout the whole process of restoration.(4) Semi-humid regions have the maximum value of change and yearly change in soil organic carbon, while the minimum values of those were in arid regions. Arid regions have the maximum value of relative change, and semi-humid regions have the minimum value. Following restoration, the change of moving sand dunes at 0-20 cm had no differences with that of degraded grassland, while the value at >20 cm depth was less than that of degraded grassland. Moving sand dunes had lower value of yearly change and higher value of relative change than degraded grassland. The change and yearly change employing artificial method were less than those of employing enclosure method, but no differences were found between relative changes of two methods. By employing herbaceous species, it had the maximum value of change at 0-20 cm and the entire depth, while it had the maximum value of yearly change at depth of >20 cm and relative change by employing the combination of shrubs and herbaceous species.(5) At Shapotou, the soil organic carbon density of shallow layers increased faster than that of deep layers, resulting in increase in ratios of shallow layers (from 14.3% of moving sand dunes to 30.4% of 1964 sand-binding vegetation) and decrease in deep layers (from 68.4% of moving sand dunes to 51.6% of 1964 sand-binding vegetation).soil inorganic carbon density increased faster in deep layers than in shallow layers, but they were not significantly different, while the ratios of both layers increased. The roots derived carbon density of shallow layers increased, while those in deep layers increased firstly and then deceased.(6) The attributes of shrubs were main factors impacting soil carbon and roots derived carbon, however, its influence tended to be weaker in deep layers. Soil carbon and roots derived carbon were also influenced by soil texture, soil nitrogen, soil phosphorus, and soil water characteristics. |
| 中文关键词 | 沙区 ; 植被恢复 ; 有机碳 ; 无机碳 ; 根系碳 |
| 英文关键词 | Sandy desert regions vegetation restoration soil organic carbon soil inorganic carbon roots derived carbon |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 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/2XILL650/287951 |
| 推荐引用方式 GB/T 7714 | 陈永乐. 中国主要沙区植被恢复对土壤碳影响的研究[D]. 中国科学院大学,2017. |
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