| 青藏高原植被NDVI对气候因子响应的格兰杰效应分析 |
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| 引用本文： | 周玉科.青藏高原植被NDVI对气候因子响应的格兰杰效应分析[J].地理科学进展,2019,38(5):718-730. |
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| 作者姓名： | 周玉科 |
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| 作者单位： | 中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京 100101 |
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| 基金项目： | 国家自然科学基金项目(41601478, 31700417);国家重点研发计划项目(2016YFC0500103);中国科学院STS项目(KFJ-SW-STS-167);资源与环境信息系统国家重点实验室开放基金(2016) |
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| 摘 要： | 多变的气候和复杂的地理环境使得青藏高原植被对气候变化响应敏感,因此分析高原植被与气候因子之间的动态关系对气候变化研究和生态系统管理具有重要意义。论文基于1982—2012年青藏高原气象数据(气温、降水)以及GIMMS NDVI3g遥感数据,在像素级别上运用格兰杰因果关系检验方法,在月尺度和季节尺度上分析了高原植被NDVI(主要是草原)与平均气温、降水量之间的响应情况及因果关系。研究表明：① 月尺度上NDVI与平均气温之间、NDVI与降水量之间的时序平稳性比例高于季节尺度,月尺度下达到平稳性的植被区域分别占99.13%和98.68%,季节尺度下分别占64.01%和71.97%;② 月尺度下高原平均气温和降水量对NDVI影响的滞后期都集中在第12~13个月,荒漠草原、典型草原和草甸3种植被类型的滞后期一致,季节尺度下平均气温和降水量对NDVI影响的滞后期主要分布在第3~4和第6个季度,3种植被类型的滞后期差异性较大;③ 月尺度下,青藏高原约98.95%的植被覆被区的平均气温是引起NDVI变化的格兰杰原因,反之,大部分地区(约89.05%,除高原东南区域)内NDVI也是引起平均气温变化的格兰杰原因;季节尺度下,青藏高原中部以外植被区域(约92.03%)内的平均气温是引起NDVI变化的格兰杰原因,而在东部和西部部分地区(约50.55%)中NDVI也是引起平均气温变化的格兰杰原因;④ 月尺度下,高原东北和西北地区(约72.05%)内的降水量是引起NDVI变化的格兰杰原因,大部分地区(约94.86%,除东南部少量区域)中NDVI是引起降水量变化的格兰杰原因;季节尺度下,高原东南部(约61.43%)地区内的降水量是引起NDVI变化的格兰杰原因,高原中东部地区(约48.98%)中NDVI是引起降水量变化的格兰杰原因。总之,高原植被NDVI与气温、降水的相互作用显著,彼此均可构成格兰杰因果效应,但总体上气候因子的影响程度大于植被的反馈作用,月尺度的效应区域大于季节尺度的效应区域。
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| 关 键 词： | 青藏高原 平稳性检验 格兰杰因果关系 多尺度分析 滞后阶 NDVI 气候变化 |
| 收稿时间： | 2018-09-11 |
| 修稿时间： | 2019-02-25 |
Detecting Granger effect of vegetation response to climatic factors on the Tibetan Plateau |
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| Yuke ZHOU.Detecting Granger effect of vegetation response to climatic factors on the Tibetan Plateau[J].Progress in Geography,2019,38(5):718-730. |
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| Authors: | Yuke ZHOU |
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| Institution: | Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Nature Resources Research, CAS, Beijing 100101, China |
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| Abstract: | Due to the complex plateau climate and unique geographical environment, the vegetation responds strongly to climatic shifts on the Tibetan Plateau. Therefore, it is of great significance to discuss the causality between vegetation and climate changes. Using the meteorological dataset including average temperature and precipitation and the GIMMS (Global Inventory Modeling and Mapping Studies) NDVI3g remote sensing data from 1982 to 2012 to analyze the causal relationship between NDVI and its influencing factors at the monthly and seasonal scales by the Granger causality test on the pixel level, this study examined the response of plateau vegetation (mainly grassland) to average temperature and precipitation change and causality. The results show that: 1) The stationarity proportion of vegetation NDVI and average temperature (99.13%), NDVI and precipitation (98.68%) at the monthly scale was higher than at the seasonal scale (64.01% and 71.97% respectively). 2) Lagging effects of average temperature on NDVI and precipitation on NDVI were around 12-13 months at the monthly scale and mainly 3, 4, and 6 quarters at the seasonal scale on the Tibetan Plateau. The three vegetation types—desert steppe, typical steppe, and meadow steppe—showed high similarities at the monthly scale, while greater heterogeneity was observed at the seasonal scale. 3) For 98.95% of the area covered by vegetation on the Tibetan Plateau, it is believed that average temperature change was the Granger cause of NDVI change, while for 89.05% of the region (except for the southeast), NDVI change was supposed to be the Granger cause of average temperature change at the monthly scale. At the seasonal scale, average temperature change was considered the Granger cause of NDVI change in 92.03% of the regsion (except for the central part of the Tibetan Plateau). Nevertheless, in the eastern and western parts of the plateau (about 50.55% of the region), NDVI change was interpreted as the Granger cause of average temperature change. 4) In the northeast and northwest of the region (about 98.95% of the area) precipitation change was believed to be the Granger cause of NDVI change, while in 94.86% of the region (except for a few areas in the southeast) NDVI change was supposed to be the Granger cause of precipitation change at the monthly scale. At the seasonal scale, precipitation change was considered the Granger cause of NDVI change in the southeastern part of the plateau (61.43% of the area). Nevertheless, in the central and eastern parts of the region (about 48.98% of the area), NDVI change was interpreted as the Granger cause of precipitation change. Overall, climatic factors on the Tibetan Plateau have an interactive relationship with vegetation and each can cause a Grainger effect to the other, with climatic factors having stronger Grainger effect on vegetation than the other way round. The Granger effect region on the Tibetan Plateau at the monthly scale is larger than the Granger effect region at the seasonal scale. |
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| Keywords: | Tibetan Plateau stationarity test Granger causality multi-scale analysis lag order NDVI climate change |
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