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Remote Sens. 2017, 9(1), 52; doi:10.3390/rs9010052

Estimating Savanna Clumping Index Using Hemispherical Photographs Integrated with High Resolution Remote Sensing Images

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1,2,* , 1,2
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1
Institute of Remote Sensing and Geographic Information System, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
2
The Beijing Key Laboratory of Spatial Information Integration and 3S Application, Beijing 100871, China
3
Department of Geography, Minjiang University, Fuzhou 350108, China
*
Author to whom correspondence should be addressed.
Academic Editors: Jose Moreno and Prasad S. Thenkabail
Received: 16 September 2016 / Revised: 13 December 2016 / Accepted: 5 January 2017 / Published: 8 January 2017
View Full-Text   |   Download PDF [6684 KB, uploaded 11 January 2017]   |  

Abstract

In contrast to herbaceous canopies and forests, savannas are grassland ecosystems with sparsely distributed individual trees, so the canopy is spatially heterogeneous and open, whereas the woody cover in savannas, e.g., tree cover, adversely affects ecosystem structures and functions. Studies have shown that the dynamics of canopy structure are related to available water, climate, and human activities in the form of porosity, leaf area index (LAI), and clumping index (CI). Therefore, it is important to identify the biophysical parameters of savanna ecosystems, and undertake practical actions for savanna conservation and management. The canopy openness presents a challenge for evaluating canopy LAI and other biophysical parameters, as most remotely sensed methods were developed for homogeneous and closed canopies. Clumping index is a key variable that can represent the clumping effect from spatial distribution patterns of components within a canopy. However, it is a difficult task to measure the clumping index of the moderate resolution savanna pixels directly using optical instruments, such as the Tracing Radiation and Architecture of Canopies, LAI-2000 Canopy Analyzer, or digital hemispherical photography. This paper proposed a new method using hemispherical photographs combined with high resolution remote sensing images to estimate the clumping index of savanna canopies. The effects of single tree LAI, crown density, and herbaceous layer on the clumping index of savanna pixels were also evaluated. The proposed method effectively calculated the clumping index of moderate resolution pixels. The clumping indices of two study regions located in Ejina Banner and Weichang were compared with the clumping index product over China’s landmass. View Full-Text
Keywords: clumping index; leaf area index; moderate resolution pixel; hemispherical photograph; high resolution images clumping index; leaf area index; moderate resolution pixel; hemispherical photograph; high resolution images
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Li, J.; Fan, W.; Liu, Y.; Zhu, G.; Peng, J.; Xu, X. Estimating Savanna Clumping Index Using Hemispherical Photographs Integrated with High Resolution Remote Sensing Images. Remote Sens. 2017, 9, 52.

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