Arid
DOI10.1016/j.isprsjprs.2018.02.010
Mapping fractional woody cover in semi-arid savannahs using multi-seasonal composites from Landsat data
Higginbottom, Thomas P.1; Symeonakis, Elias1; Meyer, Hanna2; van der Linden, Sebastian3
通讯作者Higginbottom, Thomas P.
来源期刊ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING
ISSN0924-2716
EISSN1872-8235
出版年2018
卷号139页码:88-102
英文摘要

Increasing attention is being directed at mapping the fractional woody cover of savannahs using Earth observation data. In this study, we test the utility of Landsat TM/ETM-based spectral-temporal variability metrics for mapping regional-scale woody cover in the Limpopo Province of South Africa, for 2010. We employ a machine learning framework to compare the accuracies of Random Forest models derived using metrics calculated from different seasons. We compare these results to those from fused Landsat-PALSAR data to establish if seasonal metrics can compensate for structural information from the PALSAR signal. Furthermore, we test the applicability of a statistical variable selection method, the recursive feature elimination (RFE), in the automation of the model building process in order to reduce model complexity and processing time. All of our tests were repeated at four scales (30, 60, 90, and 120 m-pixels) to investigate the role of spatial resolution on modelled accuracies.


Our results show that multi-seasonal composites combining imagery from both the dry and wet seasons produced the highest accuracies (R-2 = 0.77, RMSE = 9.4, at the 120 m scale). When using a single season of observations, dry season imagery performed best (R-2 = 0.74, RMSE = 9.9, at the 120 m resolution). Combining Landsat and radar imagery was only marginally beneficial, offering a mean relative improvement of 1% in accuracy at the 120 m scale. However, this improvement was concentrated in areas with lower densities of woody coverage (<30%), which are areas of concern for environmental monitoring. At finer spatial resolutions, the inclusion of SAR data actually reduced accuracies. Overall, the RFE was able to produce the most accurate model (R-2 = 0.8, RMSE = 8.9, at the 120 m pixel scale). For mapping savannah woody cover at the 30 m pixel scale, we suggest that monitoring methodologies continue to exploit the Landsat archive, but should aim to use multi-seasonal derived information. When the coarser 120 m pixel scale is adequate, integration of Landsat and SAR data should be considered, especially in areas with lower woody cover densities. The use of multiple seasonal compositing periods offers promise for large-area mapping of savannahs, even in regions with a limited historical Landsat coverage. Crown Copyright (C) 2018 Published by Elsevier B.V. on behalf of International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). All rights reserved.


英文关键词Landsat-metrics Optical-radar fusion Woody cover mapping Savannahs Large-area mapping
类型Article
语种英语
国家England ; Germany
收录类别SCI-E
WOS记录号WOS:000431160100007
WOS关键词TIME-SERIES ; VEGETATION ; FOREST ; CLASSIFICATION ; SAR ; ECOSYSTEMS ; PATTERNS ; REGION ; PALSAR ; MAP
WOS类目Geography, Physical ; Geosciences, Multidisciplinary ; Remote Sensing ; Imaging Science & Photographic Technology
WOS研究方向Physical Geography ; Geology ; Remote Sensing ; Imaging Science & Photographic Technology
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/210335
作者单位1.Manchester Metropolitan Univ, Sch Sci & Environm, John Dalton Bldg, Manchester M1 5GD, Lancs, England;
2.Philipps Univ Marburg, Fac Geog, Environm Informat, Marburg, Germany;
3.Humboldt Univ, Geog Dept, Berlin, Germany
推荐引用方式
GB/T 7714
Higginbottom, Thomas P.,Symeonakis, Elias,Meyer, Hanna,et al. Mapping fractional woody cover in semi-arid savannahs using multi-seasonal composites from Landsat data[J],2018,139:88-102.
APA Higginbottom, Thomas P.,Symeonakis, Elias,Meyer, Hanna,&van der Linden, Sebastian.(2018).Mapping fractional woody cover in semi-arid savannahs using multi-seasonal composites from Landsat data.ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING,139,88-102.
MLA Higginbottom, Thomas P.,et al."Mapping fractional woody cover in semi-arid savannahs using multi-seasonal composites from Landsat data".ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING 139(2018):88-102.
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