Knowledge Resource Center for Ecological Environment in Arid Area
| 蒙古高原植被退化与恢复及其影响因素研究 | |
| 其他题名 | The Assessment and Influence Factors Analysis of Vegetation Degradation and Restoration in the Mongolian Plateau |
| 马文勇 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 王训明 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 植被退化是一个全球性问题，影响着发展中国家数十亿人，特别是农民和牧民的生计和粮食安全，是气候变化与人类活动综合作用的结果。明确典型区域植被退化与恢复状况，探讨其对人类活动和气候变化的响应，进而提出防治原理和对策是科学家长期关注的焦点和努力的方向。蒙古高原地处欧亚大陆腹地，面临着荒漠化和植被退化的问题，这不仅影响到该区域畜牧业生产的可持续发展，而且对东北亚地区的生态环境有着重要影响。近几十年来，由于气候变化及人类活动的加剧，对区域植被变化产生了一系列复杂的影响。将蒙古高原作为研究植被变化的典型区域，具有极其重要而迫切的现实意义。本研究针对蒙古高原及各气候分区的植被退化与恢复状况及其影响因素开展了系统性研究，主要包括以下四个方面的内容：1）根据植被指数NDVI和土地利用的变化，明确蒙古高原植被变化状况；2）分析气候要素（降水、温度和风速）的时空变化对植被变化的影响，探讨畜牧量表征的放牧强度及夜间灯光数据表征的社会经济发展对植被变化的影响；3）利用增强回归树法定量分析气候因子及人为因子对各气候区植被变化的相对影响，识别各区域植被变化主导因子；4）利用残差趋势法区分蒙古高原植被变化中气候及人为因子的贡献率，并分析蒙古高原边境线两侧植被变化影响因素的共性与差异性。本研究主要结果如下：（1）MODIS NDVI和土地覆被变化表明蒙古高原近16年来植被绿度呈现上升趋势，植被退化趋势趋于逆转。生长季NDVI以0.02/10a的速率增加，其中半干旱区和半湿润区以0.03/10a的速率显著上升；干旱区、半干旱区和半湿润区NDVI呈显著上升趋势区域分别占各区域25.73%、31.88%和51.52%；呈显著下降趋势的区域占比0.53%、0.33%和2.57%。土地覆被方面，干旱区裸地可能多转化为草地；半干旱区草地面积可能受耕地开垦影响严重、呈微弱增加的趋势；半湿润区草地可能大部分转化为森林，小部分转化为耕地。同时野外调查发现，在部分区域，适口性较好的植被被适口性很差甚至有毒的植被取代，这表明未来的研究中需要将遥感数据与植物群落组成的地面测量结合起来。（2）气候要素的时空变化对蒙古高原植被恢复的影响存在显著的区域差异。其中生长季降水呈现微弱增加的趋势，在蒙古高原干旱区和半干旱区的过渡地带、半干旱区的东部及大兴安岭南麓促进了植被恢复，分别占干旱区、半干旱区和半湿润区总面积的58.64%、63.20%和29.63%；同时降水在植被生长季各阶段均起到促进作用，尤其是6-8月份的降水。生长季温度呈现微弱降低的趋势，在蒙古高原的中部和西北部地区抑制了植被生长，分别占干旱区、半干旱区和半湿润区的28.87%、34.75%和15.27%；而且温度由生长初期的促进作用为主转为中后期的抑制作用为主。生长季风速呈现波动状态，对蒙古高原影响较小但区域差异明显，在锡林郭勒地区由初期的抑制植被生长转变为后期的促进植被生长，在鄂尔多斯高原表现出持续性抑制作用。（3）人类活动整体上促进了该区域植被状况的改善。干旱区、半干旱区和半湿润区的夜间灯光DN值均显著增加；相比较夜间灯光DN值为0的区域，DN值>0的区域内NDVI上升趋势更为明显，从干旱、半干旱到半湿润区分别是0.017/10a vs 0.007/10a，0.035/10a vs 0.027/10a和0.045/10a vs 0.019/10a，表明社会经济发展可能对区域地表植被恢复起到了一定的推动作用。近16年蒙古高原不同气候区的牲畜密度均显著增加，但各区域整体放牧强度处于合理水平，其中半干旱区和半湿润区牲畜密度与植被的长势密切相关。（4）从干旱区过渡到半湿润区，温度对植被的影响越来越显著。蒙古高原干旱区和半干旱区植被变化主导因子相差不大，但各因子对植被变化的影响程度存在差异。干旱区植被变化主要受降水和放牧强度的影响，其中6-8月降水量、牲畜密度和4-5月降水量的贡献率分别为35.15%、17.99%和12.44%，累计达到65.58%；半干旱区植被变化主要受降水、放牧强度和温度的综合影响，其中6-8月降水量、牲畜密度和4-5月温度的贡献率分别为41.61%、12.21%和11.79%，累计达到65.61%。半湿润区植被变化则主要受温度的影响，生长季各时期（6-8月、9-10月和4-5月）温度的贡献率分别为35.85%、26.54%和13.62%，三者累计达到76.01%。（5）蒙古高原沿中蒙边境线可以分为境内（中国）和境外（蒙古国）进行对比研究。境内地表植被状况及恢复状况均好于境外，尤其在干旱区和半湿润区。境内干旱区、半干旱区和半湿润区NDVI分别以0.01/10a、0.03/10a和0.03/10a速率增加，而境外仅在半干旱区以0.03/10a速率增加；境内干旱区和半湿润区的植被恢复和土地覆被变化有关，而半干旱区好转可能得益于草类植被的长势变好。气候要素对蒙古高原境内外植被恢复的促进作用相似，均占比41%左右；人为因子则存在一定的差异性，对境外植被破坏作用大于恢复作用（29.14% vs 10.60%），而对境内植被恢复作用大于破坏作用（21.62% vs 16.85%）。这和境内外城镇活动、工业活动、畜牧活动和政策差异密不可分，表明了人类活动对区域植被状况变化有着深远的影响。 |
| 英文摘要 | Vegetation degradation is a global problem affecting negatively the livelihoods and food security of billions of people, especially farmers and pastoralists in the developing countries. Vegetation degradation is determined by climatic factors and human activities, leading to decline of land quality, loss of vegetation productivity and intensified desertification. In recent years, there has been increasing research interests in exploring the causes and forms of vegetation degradation, as well as the means of managing and controlling it in drylands. Located in arid, semi-arid and semi-humid inland areas, the Mongolian Plateau is covered with natural grassland and desert. Desertification and vegetation degradation were two important ecological problems in this region, not only affecting the sustainable development of animal husbandry, but also impacting the ecological environment in Northeast Asia. In recent decades, the vegetation dynamics in Mongolian Plateau has produced a series of complex effects due to climate change and human activities. It is urgent to explore vegetation dynamics in this typical area. In this study, a systematic study on vegetation dynamics and its influencing factors were carried out from the perspective of the Mongolian Plateau and its individual climatic region. The objectives of this study were 1) to understand the condition of vegetation degradation and restoration based on MOD13A3 (MODIS vegetation index product) and MCD12Q1 (MODIS land cover product); and 2) to analyze the effects of spatial-temporal changes in climate factors including precipitation, temperature and wind speed, and of human activities including grazing intensity and light data (DMSP/OLS) on vegetation dynamics; and 3) to quantify the dominant factor of climatic factors and anthropogenic factors to vegetation dynamics in each climatic region using the BRT (Boosted Regression Trees) method; and 4) to identify the relative importance of climate factors and human activities in impacting vegetation dynamics using the RESTREND (Residual Trend Analysis) method and compare the differences between Mongolia and China. Main findings of this dissertation are as follows:（1）During the study period (2000-2015), the overall vegetation condition had improved in the Mongolian Plateau. The growing season (GS) NDVI had increased at the rate of 0.02/10a in the whole region, and 0.03/10a in the semi-arid and semi-humid region. The proportion of greening trend had occupied 25.73%, 31.88% and 51.52% of the three regions while the proportion of browning trend had occupied 0.53%, 0.33% and 2.57%, respectively. In addition, the bareland in arid area was transformed into grassland. The area of grassland in semi-arid area showed a slight increase trend, although it was seriously affected by land reclamation. Most of the grasslands in semi-humid area were converted into forest and a small part was converted into arable land. Further, the fact that the palatable grasses were replaced by poor or even poisonous weeds had been found in the field survey. This phenomenon highlighted the need to combine remote sensing with on-the-ground measurements of plant community composition.（2）The spatial-temporal changes of climatic factors on vegetation dynamics have regional differences in the Mongolian Plateau. The GS precipitation showed a slight increase trend, which promoted vegetation restoration during the whole growing season in the transitional areas from the arid area to semi-arid area, the eastern part of the semi-arid region and the southern part of the Daxing'anling, accounting for 58.64%, 63.20% and 29.63% of the individual climatic region, respectively. The GS temperature showed a slight decrease trend, which inhibited the growth of vegetation during the growing season especially from June to October in the middle and northwest of the Mongolian Plateau, accounting for 28.87%, 34.75% and 15.27% of the individual climatic region, respectively. Compared with precipitation and temperature, the effects of wind speed fluctuation turned out to be small with obvious regional differences. There had been promotion effect on vegetation restoration in the Ordos Plateau while variability effect in the XilinGol Plateau. （3）Significant positive effects are found in the Mongolian Plateau, suggesting that intensive human activity could accelerate the change in NDVI and vegetation. The DN value of the nighttime light in the arid, semi-arid and semi-humid areas had increased significantly. Compared with the area with DN value =0, the area with DN value >0 had a more obvious rising trend from arid, semi-arid area to semi-humid area, showing 0.017/10a vs 0.007/10a, 0.035/10a vs 0.027/10a and 0.045/10a vs 0.019/10a respectively. The livestock density in arid, semi-arid and semi-humid areas increased significantly with rational grazing intensities and it was closely related to the vegetation growth in semi-arid and semi-humid areas on the Mongolian Plateau.（4）The influence of temperature on vegetation dynamcis became more and more significant from the arid region to the semi-humid region. Although the dominant factors of vegetation dynamcis in arid and semi-arid area were similar, there were differences in the specific one. Land degradation was mainly determined by the precipitation and grazing in the arid area and semi-arid area. Specifically, the relative influences of precipitation (June to August), livestock density and precipitation (April to May) on vegetation dynamcis were 35.15%, 17.99% and 12.44%, respectively, in arid area. The relative influences of precipitation (June to August), livestock density and temperature (April to May) on vegetation dynamcis were 41.61%, 12.21% and 11.79%, respectively, in semi-arid area. Furthermore, GS temperature contributed to 76.01% (35.85%, 26.54% and 13.62% for each individual period) of vegetation dynamcis in semi-humid area.（5）The vegetation condition and its recovery within the borders of China were better than those of the Mongolia, especially in arid and semi-humid area. The NDVI of the arid, semi-arid and semi-humid areas had increased at the rate of 0.01/10a, 0.03/10a and 0.03/10a within the borders of China, while only the semi-arid area represented increasing trend at the rate of 0.03/10a in Mongolia. Vegetation restortation was correlated with land cover change in arid and semi-humid area of China and benefited from vegetation densification in the semi-arid area. The effect of natural factors on vegetation restoration was similar while the human facors showed obvious differences between Mongolia and Inner Mongolia Autonomous Region. The negative effect on vegetation condition was greater than positive effect in Mongolia (29.14% vs 10.60%), while it was exactly opposite in Inner Mongolia Autonomous Region (16.85%vs 21.62%). These differences were closely related to urban expansion, industrial activities, livestock activities and policy differences along the boundary line, indicating that the decision-making of the government had a profound impact on regional vegetation dynamcis. |
| 中文关键词 | 蒙古国 ; 内蒙古自治区 ; 植被变化 ; 气候变化 ; 人类活动 |
| 英文关键词 | Mongolia Inner Mongolia Autonomous Region vegetation dynamcis climate factors human factors |
| 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/2XILL650/288038 |
| 推荐引用方式 GB/T 7714 | 马文勇. 蒙古高原植被退化与恢复及其影响因素研究[D]. 中国科学院大学,2018. |
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