Knowledge Resource Center for Ecological Environment in Arid Area
| 内蒙古草地生态系统对气候变化的响应研究 | |
| 其他题名 | Response of Grassland Ecosystem to Climate Change in Inner Mongolia |
| 郭灵辉 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 导师 | 吴绍洪 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 摘 要内蒙古自治区地处欧亚大陆草原带的中部，天然草地面积大，在我国畜牧业生产中占据非常重要的地位。该区自然条件严酷、气候波动大，是全球气候变化敏感区域之一。探讨气候变化对内蒙古草地生态系统的影响，对保障国家畜牧产品供给、维持区域生态安全和经济可持续发展至关重要。为此，本研究借助遥感反演产品、气候插值数据和空间化后的CENTURY模型模拟，从草地植被覆盖及生产功能两个角度探讨气候变化背景下内蒙古草地生态系统的响应特征，并预估典型浓度路径情景下未来内蒙古草地生态系统生产功能的变化趋势。主要结论如下：（1）在生长季尺度上，水分是内蒙古草原植被覆盖年际变化的主要驱动因素；从草甸草原、典型草原至荒漠草原，NDVI与降水、潜在蒸散的相关性逐渐增强，NDVI年际变异也逐渐增强；NDVI年际变异与降水的年际变异呈显著的正相关，而与温度的年际变异呈显著的负相关。在月尺度上，NDVI对气候变化的响应存在显著的月滞后效应，且降水的滞后效应在生长季中后期尤其明显；草甸草原和典型草原生长季初期NDVI增加显著，受升温影响大。（2）近30年来，内蒙古草原生态系统NPP与NEP呈显著下降趋势，草甸草原降速最大，荒漠草原最小。区域降水减少可能是内蒙古草原NPP下降的主要原因，温度升高也会导致草原NPP降低，但其作用程度远低于降水；随着干旱加剧，NPP的年际变异增强，荒漠草原NPP年际变异大于其它草原类型，且2000s年际变异较大，而草甸草原、典型草原在1990s年际变异较大。虽然总体上全区是个碳源，但年代际差异较大；在1980s呈现碳汇功能，而在1990s转变为一个微弱的碳源，进入2000s碳释放增强；降水减少可能是内蒙古草原NEP降低的主要因素，但增温对其影响也较大，在荒漠草原其作用可能超过降水的作用。（3）未来40年内蒙古草原NPP呈波动下降趋势，草甸草原NPP降速最大且显著，荒漠草原NPP降率最小。与基准时段相比，未来40年三大草原NPP均值均有所下降，荒漠草原降幅最大，典型草原降幅最小。各类草原各年代NPP均低于基准时段，且RCP8.5情景下的降幅大于RCP4.5情景。就NPP年际变异程度而言，在RCP8.5情景下未来40年内蒙古各类草原NPP年际变异加剧；而在RCP4.5情景下，仅典型草原NPP年际变异增强，荒漠草原和草甸草原NPP年际变异减弱。（4）未来40年内蒙古草原平均NEP低于基准时段，且在RCP8.5情景下降幅更明显；草甸草原NEP下降最为剧烈、碳释放最强，而荒漠草原NEP变化不大、碳释放最弱，且在RCP4.5情景下碳释放较基准时段减弱；未来40年各年代内蒙古草原均是碳源，NEP在2040s降幅最大，但草原类型间NEP年代际差异较大。 |
| 英文摘要 | AbstractInner Mongolia Autonomous Region (IMAR), is located in the middle of the Eurasia steppe zone, with most land covered by natural grassland, which plays an important role in the animal husbandry manufacture in our country. As a transition zone, it has a sharp rainfall-temperature gradient from the southwest to northeast, and is likely to be highly sensitive to climate change due to the fiercely fluctuant climate and the rigorous physical geography. Evaluating the impact of climate change on grassland ecosystem in this region, therefore, is essential for understanding of the underlying mechanisms controlling the relationship between climate change and grassland variability, and is also of fundamental importance to protecting national livestock products, as well as maintaining regional ecological security and the sustainable development of regional economy. In this study, based on the Normalized Difference Vegetation Index (NDVI) and interpolated climate data and the simulated data from a CENTURY-based modeling system, the responses of grassland ecosystem to climate change in IMAR were analyzed from the vegetation coverage perspective indicated by NDVI and the production function perspective indicated by Net Primary Productivity (NPP) and Net Ecosystem Productivity (NEP). Then, the possible changes in the production function of grassland ecosystems were further investigated by using the modeling system driven by the future climate scenario data (RCP4.5 and RCP8.5). The main conclusions include:（1）At the growing season scale, NDVI was positively linked with precipitation, but negatively correlated with potential evapotranspiration (ET), suggesting that water was the primary driver in vegetation change. In addition, from meadow steppe, typical steppe and desert steppe, the correlations between NDVI and the two climatic variables strengthened gradually, along with the increased coefficient of variation (CV) of NDVI. The CV of NDVI was negatively correlated with that of temperature for all steppes, whereas there was a significant positive correlation between the CV of NDVI and that of precipitation. At the monthly scale, the significant one-month lagged correlations between monthly NDVI and climate variables were found, and the hysteresis response of NDVI to rainfall was stronger at the middle and end of the growing season. Additionally, there was a significant increase in NDVI at the early stage of vegetation growth for meadow and typical steppe, which could be mainly associated with temperature change. （2）NPP and NEP of IMAR grassland ecosystem decreased significantly over the period of 1981-2010, with the largest decrease amount occurred in meadow steppe, and least in desert steppe. Precipitation may be the dominant factor in the decrease of annual NPP. Although the reduction of NPP also came from the effects of the recent warming, such impact was much weaker than that of precipitation. Coincide with the intensified drought, the CV of NPP increased. The inter-annual variability of NPP for desert steppe was larger than that for meadow and typical steppes. At the inter-decadal time scale, the largest CV of NPP occurred in 2000s for desert steppe, whereas in 1990s for the other biomes. Over the last three decades, the IMAR grasslands acted as small carbon source. However, a large inter-decadal variability was also found. In 1980s, it was carbon sink, and then shifted toward a carbon source for the periods of 1990s and 2000s, especially in 2000s. The primary driving force for the NEP trends was precipitation change, while recent warming effect also played a large role in accounting for the NEP decrease, especially in desert steppe, where the impact of temperature was much larger than that of precipitation.（3）Over the period of 2011-2050, the NPP is subject to a decline trend in IMAR steppe, with the maximum rate in meadow steppe and the minimum in desert steppe. Relative to the baseline value, all the three steppe types would i |
| 中文关键词 | 内蒙古 ; 草地生态系统 ; 气候变化 ; 响应 |
| 英文关键词 | Inner Mongolia Autonomous Region Grassland Ecosystem Climate Change Response |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院地理科学与资源研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287354 |
| 推荐引用方式 GB/T 7714 | 郭灵辉. 内蒙古草地生态系统对气候变化的响应研究[D]. 中国科学院大学,2014. |
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