| 摘要: |
| 基于2001—2010年MODIS EVI时间序列数据反演了青海湖流域植被覆盖的空间格局和变化规律，并结合气象观测数据，在年际、月际等不同时间尺度上分析了植被变化及其对气候变化的响应以及驱动机制。结果表明：（1）2001—2010年青海湖流域总体植被变化趋于变好，EVI值10年共增长10.38%，其中春季和夏季植被增长率最大，10年增长率分别达到15.2%和18.63%；（2）植被对气候因子的响应具有明显的空间异质性。流域内植被覆盖增加的区域占全流域面积的70.68%，其中显著增加的区域占8.2%，主要分布在布哈河中游以及青海湖北部草场地区，植被覆盖下降的区域占总面积的29.32%，主要分布在西北高海拔地区以及青海湖湖滨沙地；（3）植被变化对气候因子的响应具有复杂性，在不同时间尺度上EVI和气候因子相关性不同。在年际尺度上，EVI和气温的相关系数是0.29，和降水无明显相关性；但比较10年中的生长季，即植被生长5—9月的EVI和气温、降水相关性为0.33和0.27，这里降水相关性显著增高，总体上说，气温是年际植被变化的主导因素。在月际尺度上，EVI和气温、降水强烈相关，相关系数分别为0.76、0.86（P<0.01）。青海湖地区地处高海拔地区，且雨热同季，某种程度上揭示了高原植被的生长策略和对气候的响应机制。 |
| 关键词: 青海湖流域 EVI 降水气温相关分析 |
| DOI：10.7515/JEE201304001 |
| CSTR： |
| 分类号:Q948.112 |
基金项目:国家科技支撑项目(2012BAH31B03)；国家自然科学基金(41301007，40901101)；中央高校科研支持计划(xjj2013079)
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| Spatial variations of vegetation change in Qinghai Lake Basin during 2001—2010 |
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NI Xiang-nan, GUO Wei
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Department of Earth and Environmental Sciences, Xi′an Jiaotong University, Xi′an 710049, China
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| Abstract: |
| Global warming has led to significant ecological landscape changes over the years, especially the vegetation change of alpine region has become a research focus in the Northern Hemisphere. This study is to discover the spatio-temporal variation of vegetation dynamics on the basis of MODIS-EVI time-series data from 2001 to 2010 in the Qinghai Lake Basin. Then we analyzed the responded mechanism of vegetation change to climate factors. The main conclusions are as follows: (1)The overall vegetation EVI in Qinghai Lake Basin was increasing at a rate of 10.38% from 2001 to 2010. The growing seasons include spring and summer exhibit very significant improving trend, accounted for 15.2% and 18.63% respectively. (2)In Qinghai Lake Basin, because of a variety of landscapes, vegetation′s responses to climate change showed obvious spatial heterogeneity. Overall, the vegetation coverage improved in most area since nearly 70.68% pixel of the whole basin showed increasing trend, while degraded slightly in a small part of the area only. The region with significant improving trend accounted for 8.2%, which is distributed over the middle reaches of Buha River Basin and North of Qinghai Lake. (3) The correlation coefficient between EVI and climate data was different on different time scale. On the interannual scale, the correlation coefficient between EVI and temperature was 0.29, and there is very weak even no correlation between EVI and precipitation. However, when we focused on growing season of the studying period, the correlation coefficient between EVI and temperature, precipitation was 0.33 and 0.27 respectively. The correlation coefficient of precipitation was significantly higher compared to the inter-annual scale. Generally, the temperature was the leading factor of vegetation change on the interannual scale. On inter-monthly time scale, EVI was strongly relative with temperature and precipitation, with the correlation coefficient was 0.76 and 0.86 respectively. |
| Key words: Qinghai Lake Basin Enhanced Vegetation Index (EVI) precipitation temperature correlation analysis |
