青藏高原典型植被生长季遥感模型提取分析
作者简介:常 清(1988-),女,硕士生,研究方向为植物物候与全球变化。E-mail: hellochangqing@126.com
收稿日期: 2013-10-11
要求修回日期: 2013-12-04
网络出版日期: 2014-09-04
基金资助
国家自然科学基金项目(41271426)
国家“973”计划项目(2011CB707100)
The Remote Sensing Monitoring Model of the Typical Vegegtation Phenology in the Qinghai-Tibetan Plateau
Received date: 2013-10-11
Request revised date: 2013-12-04
Online published: 2014-09-04
Copyright
物候变化是衡量全球气候变化最直接、敏感的指示器,针对青藏高原这个独特地域单元上特殊的高寒植被进行关键物候期遥感提取模型及植被物候时空变化的研究具有重要的意义。本文首先以反距离加权空间插值算法与Savitzky-Golay滤波算法相结合的数据重建模型获得高质量2003-2012年青藏高原MODIS归一化植被指数(NDVI)数据。在此数据基础上,分别利用动态阈值法、最大变化斜率法、logistic曲线拟合法3种遥感植被生长季提取模型,对青藏高原地区两种典型植被的生长季(SOS生长季开始期,EOS生长季结束期,LOS生长季长度)进行提取。通过对3种模型提取结果的对比分析,并结合日均温模型对提取结果的验证发现,动态阈值法为青藏高原地区典型植被生长季的最优遥感提取模型。该模型对近10 a的高分辨率典型高寒植被物候参量的反演及时空变化特征分析表明,受青藏高原水热及海拔梯度的影响,青藏高原植被物候变化呈现出从东南向西北的空间分异规律,随春季温度的升高,近10 a来青藏高原高寒草地总体呈现生长季开始期(SOS)提前(0.248 d/a)的趋势。
常清 , 王思远 , 孙云晓 , 殷慧 , 尹航 . 青藏高原典型植被生长季遥感模型提取分析[J]. 地球信息科学学报, 2014 , 16(5) : 823 -816 . DOI: 10.3724/SP.J.1047.2014.00815
Vegetation phenology changes is one of the most direct and sensitive indicators of global climate change and it has become the focus problem of the word studies. The Qinghai-Tibetan Plateau is a unique geographical unit covered by alpine vegetation types so that it is very important to study the remote sensing monitoring model of these vegetation types’ phenology. Firstly, Based on MODIS Normalized Difference Vegetation Index (NDVI) data from 2003 to 2012, we reconstructed the long-term time-series datasets through the combination of Inverse Distance Weighted Interpolation and Savitzky-Golay fitting method. After filtering, the obvious noise is removed but the detail information of vegetation growth is kept well so that the time-series curve is definitely suitable for the extraction of phenology paramethers. Then, we studied the extraction models of the typical vegetation phenology in the Qinghai-Tibetan Plteau with dynamic threshold value method, biggest change slope method and logistic curve fitting method. We compared and analyzed the monitoring results based on the nearly ten years NDVI dataset using the relationship between vegetation growing characteristics and daily mean temperature and then selected the dynamic threshold value method as the best model for typical vegetation phenology extraction in the Qinghai-Tibetan Plateau. Finally, we extracted the phenology information of grassland in the plateau with dynamic threshold value model. After the analysis of nearly ten years vegetation phenology, the results showed that the alpine grassland in the plateau experienced the trend of start of season (SOS) advancing (the ratio is 0.248d/a) as the end of season (EOS) following a more complex rule. The andvanced SOS manily caused by the rise of spring temperature and the influence of precipation is not significant. What’s more, the vegetation phenology and variation trends in the plateau showed obvious spatial distribution rule from the southeast to the northwest.
Fig.1 Vegetation types of the Qinghai-Tibetan Plateau图1 青藏高原植被分布图(数据来源于中国科学院地理科学与资源研究所2000年1:100万植被类型图) |
Fig.2 Flowchart of the NDVI time-series resconstruction method图2 NDVI时序数据重建流程 |
Fig.3 Results of NDVI time-series reconstructing图3 长时间序列数据重构结果 |
Fig.4 Monitoring results of the typical vegetation phenology in the Qinghai-Tibetan Plateau based on three different models图4 基于3种模型的青藏高原典型植被物候期遥感提取结果 |
Fig.5 The start data when mean daily temperature of alpine meadow exceed 0℃ (2003-2012)图5 高寒草甸日均温≥0℃的初始日期(2003-2012年) |
Fig.6 Spatial distribution and temporal trends of start of season (SOS), end of season (EOS) and length of season (LOS) for the period of 2003-2012; ten years averaged SOS(a), EOS(b) and LOS(c); ten years trends of SOS(d), EOS(e) and LOS(f)图6 2003-2012年间青藏高原典型高寒植被生长季时空动态变化 |
Tab.1 The correlational analysis between the SOS in Qinghai-Tibetan Plateau and meteorological data表1 青藏高原植被SOS与气象数据的相关性 |
春季温度(℃) | 春季降水(mm) | 秋季温度(℃) | 秋季降水(mm) | ||
---|---|---|---|---|---|
高寒草原的SOS | -0.32 | –0.32 | 高寒草原的EOS | 0.19 | 0.11 |
高寒草甸和苔原的SOS | -0.67 | –0.11 | 高寒草甸和苔原的EOS | 0.24 | -0.02 |
高寒草地的SOS | -0.66 | –0.24 | 高寒草地的EOS | 0.37 | 0.28 |
Fig.7 The response of phenological phases (SOS, EOS) to temperature and precipitation changes in the Qinghai-Tibetan Plateau图7 青藏高原典型植被物候期(SOS、EOS)对温度、降水变化的响应 |
The authors have declared that no competing interests exist.
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