Mapping Deciduous Rubber Plantation Areas and Stand Ages with PALSAR and Landsat Images

Weili Kou,Li Li,Yuanwei Qin,Deli Zhai,Geli Zhang,Xiangming Xiao,Shu Gan,Jinwei Dong

doi:10.3390/rs70101048

Abstract

Accurate and updated finer resolution maps of rubber plantations and stand ages are needed to understand and assess the impacts of rubber plantations on regional ecosystem processes. This study presented a simple method for mapping rubber plantation areas and their stand ages by integration of PALSAR 50-m mosaic images and multi-temporal Landsat TM/ETM+ images. The L-band PALSAR 50-m mosaic images were used to map forests (including both natural forests and rubber trees) and non-forests. For those PALSAR-based forest pixels, we analyzed the multi-temporal Landsat TM/ETM+ images from 2000 to 2009. We first studied phenological signatures of deciduous rubber plantations (defoliation and foliation) and natural forests through analysis of surface reflectance, Normal Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Land Surface Water Index (LSWI) and generated a map of rubber plantations in 2009. We then analyzed phenological signatures of rubber plantations with different stand ages and generated a map, in 2009, of rubber plantation stand ages (≤5, 6–10, >10 years-old) based on multi-temporal Landsat images. The resultant maps clearly illustrated how rubber plantations have expanded into the mountains in the study area over the years. The results in this study demonstrate the potential of integrating microwave (e.g., PALSAR) and optical remote sensing in the characterization of rubber plantations and their expansion over time.

Highlights

As economies and industries develop, the need for natural rubber products has been increasing over time, which has led to substantial and continuous expansions of rubber plantations around the world.The Food and Agriculture Organization of the United Nations (FAO) reported a twenty percent expansion of global rubber plantations in the past two decades, and 90% of the expansion is in Asia [1], mainly distributed in Indonesia, Thailand, Malaysia, and China
We have developed a novel, simple and robust procedure that combines Phased Array type L-band Synthetic Aperture Radar (PALSAR) 50-m orthorectified images and multi-temporal
Land Surface Water Index (LSWI) data derived from Landsat images

Summary

Introduction

The Food and Agriculture Organization of the United Nations (FAO) reported a twenty percent expansion of global rubber plantations in the past two decades, and 90% of the expansion is in Asia [1], mainly distributed in Indonesia, Thailand, Malaysia, and China. The expansion mainly occurred at the expense of natural forests and shifting agriculture [3,4]. Southern China has been a hotspot for northward-expansion of rubber plantations. The dramatic expansion may negatively impact forest carbon stocks and biodiversity [3,4,5,6]. Accurate and updated maps of rubber plantation cover areas and their stand ages are needed to quantify Land Use Land Cover Changes (LULCC) and assess its impacts on biodiversity, carbon sinks, and water cycles in the tropical forest areas

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Conclusion