Mapping the dynamics of eastern redcedar encroachment into grasslands during 1984-2010 through PALSAR and time series Landsat images

REMOTE SENSING OF ENVIRONMENT

卷:190

Article

Wang, Jie¹  Xiao, Xiangming^1,2  Qin, Yuanwei¹  Dong, Jinwei¹  Geissler, George³  Zhang, Geli¹  Cejda, Nicholas¹  Alikhani, Brian¹  Doughty, Russell B.¹ 

[1] Univ Oklahoma, Ctr Spatial Anal, Dept Microbiol & Plant Biol, Norman, OK 73019 USA

[2] Fudan Univ, Inst Biodivers Sci, Shanghai 200433, Peoples R China

[3] Oklahoma Dept Agr Food & Forestry, Oklahoma Forestry Serv, Oklahoma City, OK 73105 USA

关键词: Juniperus virginiana;    Woody encroachment;    Land cover;    Phenology;    Vegetation indices;   

DOI  :  10.1016/j.rse.2016.12.025

来源: Elsevier

【 摘 要 】

Woody plant encroachment of eastern redcedar Juniperus virginiana L, hereafter referred to as red cedar) into native grasslands in the U.S. Southern Great Plains has significantly affected the production of forage and livestock, wildlife habitats, as well as water, carbon, nutrient and biogeochemical cycles. However, time series of red cedar maps are still not available to document the continuously spatio-temporal dynamics of red cedar encroachment across landscape, watershed and regional scales. In this study, we developed a pixel and phenology-based mapping algorithm, and used it to analyze PALSAR mosaic data in 2010 and all the available Landsat 5/7 data during 1984-2010 with the Google Earth Engine (GEE) platform. This pilot study analyzed 4233 images covering >10 counties in the central region of Oklahoma, and generated red cedar forest maps for 2010 and five historical time periods: the late 1980s (1984-1989), early 1990s (1990-1994), late 1990s (1995-1999), early 2000s (2000-2004), and late 2000s (2005-2010). The resultant maps for 2010, the late 2000s, early 2000s, and late 1990s were evaluated using validation samples collected from Google Earth's high-resolution images and geo-referenced field photos. The overall (producer and user) accuracy of these maps ranged from 88% to 96% (88%-93%, and 96%-99%). The resultant maps clearly illustrated an increase in red cedar encroachment within the study area at an annual rate of similar to 8% during 1984-2010. These maps can be used to support additional studies on the driving factors and consequences of red cedar encroachment. This study also demonstrated the potential to trace the historical encroachment of red cedar into grasslands using time series Landsat images and PALSAR data. (C) 2017 Elsevier Inc. All rights reserved.

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