中国地理科学 ›› 2016, Vol. 26 ›› Issue (3): 352-365.doi: 10.1007/s11769-016-0805-2

• 论文 • 上一篇    下一篇

Mapping Deciduous Broad-leaved Forested Swamps Using ALOS/Palsar Data

BIAN Hongfeng1, YAN Tingting1, ZHANG Zhengxiang2, HE Chunguang1, SHENG Lianxi1   

  1. 1. State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 131117, China;
    2. School of Geographical Sciences, Northeast Normal University, Changchun 130024, China
  • 收稿日期:2015-07-02 修回日期:2015-10-13 出版日期:2016-06-27 发布日期:2016-05-09
  • 通讯作者: SHENG Lianxi, YAN Tingting E-mail:shenglx@nenu.edu.cn;yantt1121@outlook.com
  • 基金资助:

    Under the auspices of Special Funds of State Environmental Protection Public Welfare Industry (No. 2011467032)

Mapping Deciduous Broad-leaved Forested Swamps Using ALOS/Palsar Data

BIAN Hongfeng1, YAN Tingting1, ZHANG Zhengxiang2, HE Chunguang1, SHENG Lianxi1   

  1. 1. State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 131117, China;
    2. School of Geographical Sciences, Northeast Normal University, Changchun 130024, China
  • Received:2015-07-02 Revised:2015-10-13 Online:2016-06-27 Published:2016-05-09
  • Contact: SHENG Lianxi, YAN Tingting E-mail:shenglx@nenu.edu.cn;yantt1121@outlook.com
  • Supported by:

    Under the auspices of Special Funds of State Environmental Protection Public Welfare Industry (No. 2011467032)

摘要:

Accurate, updated information on the distribution of wetlands is essential for estimating net fluxes of greenhouse gases and for effectively protecting and managing wetlands. Because of their complex community structure and rich surface vegetation, deciduous broad-leaved forested swamps are considered to be one of the most difficult types of wetland to classify. In this research, with the support of remote sensing and geographic information system, multi-temporal radar images L-Palsar were used initially to extract the forest hydrological layer and phenology phase change layer as two variables through image analysis. Second, based on the environmental characteristics of forested swamps, three decision tree classifiers derived from the two variables were constructed to explore effective methods to identify deciduous broad-leaved forested swamps. Third, this study focused on analyzing the classification process between flat-forests, which are the most severely disturbed elements, and forested swamps. Finally, the application of the decision tree model will be discussed. The results showed that: 1) L-HH band (a L band with wavelength of 0-235 m in HH polarization mode; HH means Synthetic Aperture Radars transmit pulses in horizontal polarization and receive in horizontal polarization) in the leaf-off season is shown to be capable of detecting hydrologic conditions beneath the forest; 2) the accuracy of the classification (forested swamp and forest plat) was 81.5% based on hydrologic features, and 83.5% was achieved by combining hydrologic features and phenology response features, which indicated that hydrological characteristics under the forest played a key role. The HHOJ (refers to the band created by the subtraction with HH band in October and HH band in July) achieved by multi-temporal radar images did improve the classification accuracy, but not significantly, and more leaf-off radar images may be more efficient than multi-seasonal radar images for inland forested swamp mapping; 3) the lower separability between forested swamps dominated by vegetated surfaces and forest plat covered with litter was the main cause of the uncertainty in classification, which led to misleading interpretations of the pixel-based classification. Finally, through the analysis with kappa coefficients, it was shown that the value of the intersection point was an ideal choice for the variable.

关键词: forested swamp, Palsar radar images, forest hydrological characteristics, multi-temporal technique, decision tree classifier

Abstract:

Accurate, updated information on the distribution of wetlands is essential for estimating net fluxes of greenhouse gases and for effectively protecting and managing wetlands. Because of their complex community structure and rich surface vegetation, deciduous broad-leaved forested swamps are considered to be one of the most difficult types of wetland to classify. In this research, with the support of remote sensing and geographic information system, multi-temporal radar images L-Palsar were used initially to extract the forest hydrological layer and phenology phase change layer as two variables through image analysis. Second, based on the environmental characteristics of forested swamps, three decision tree classifiers derived from the two variables were constructed to explore effective methods to identify deciduous broad-leaved forested swamps. Third, this study focused on analyzing the classification process between flat-forests, which are the most severely disturbed elements, and forested swamps. Finally, the application of the decision tree model will be discussed. The results showed that: 1) L-HH band (a L band with wavelength of 0-235 m in HH polarization mode; HH means Synthetic Aperture Radars transmit pulses in horizontal polarization and receive in horizontal polarization) in the leaf-off season is shown to be capable of detecting hydrologic conditions beneath the forest; 2) the accuracy of the classification (forested swamp and forest plat) was 81.5% based on hydrologic features, and 83.5% was achieved by combining hydrologic features and phenology response features, which indicated that hydrological characteristics under the forest played a key role. The HHOJ (refers to the band created by the subtraction with HH band in October and HH band in July) achieved by multi-temporal radar images did improve the classification accuracy, but not significantly, and more leaf-off radar images may be more efficient than multi-seasonal radar images for inland forested swamp mapping; 3) the lower separability between forested swamps dominated by vegetated surfaces and forest plat covered with litter was the main cause of the uncertainty in classification, which led to misleading interpretations of the pixel-based classification. Finally, through the analysis with kappa coefficients, it was shown that the value of the intersection point was an ideal choice for the variable.

Key words: forested swamp, Palsar radar images, forest hydrological characteristics, multi-temporal technique, decision tree classifier