Journal of Geo-information Science >
The Progress of Forest Understory Retrieval from Remote Sensing
Received date: 2014-02-26
Request revised date: 2014-04-04
Online published: 2014-07-10
Copyright
:Forest understory contributes significantly to cycles and accumulation of carbon, water and nutritional elements in the ecosystem. Remote sensing with multi-angular, hyperspectral or Lidar systems is very sensitive to the stratification of forest, which allows us to quantify understory. In this paper, the progress of forest understory retrieval from remote sensing is reviewed. The definition of understory is firstly discussed. Then, a systematical analysis is presented. The review focuses on forest background reflectivity, understory leaf area index, and understory height and coverage that are retrieved respectively from multi-angular, hyperspectral and Lidar data. Based on the different contributions of forest canopy and background with respect to different observation angles, multi-angle observations make it possible to retrieve forest background reflectivity. The retrieved forest background reflectivity could further be used to estimate understory leaf area index through various retrieval algorithms. In addition, as Lidar systems are capable of directly observing understory through forest canopy, understory height and coverage could be retrieved from Lidar cloud points and waveform information. Finally, the shortcoming of current research and possible improvements in future research are discussed. There are mainly three facets where future understory retrieval could emphasize, including the using of spectral, phonological and angular differences between understory and overstory, the simulation of multi-angular observations by bidirectional reflectance function, and the fusion of multi-source data from radar, Lidar and hyperspectral remote sensing systems.
Key words: understory; remote sensing retrieval; reflectivity; Lidar
JIAO Tong , LIU Ronggao , LIU Yang , CHEN Jingming . The Progress of Forest Understory Retrieval from Remote Sensing[J]. Journal of Geo-information Science, 2014 , 16(4) : 602 -608 . DOI: 10.3724/SP.J.1047.2014.00602
The authors have declared that no competing interests exist.
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