Classification of Tropical Forest Tree Species Using Meter-Scale Image Data

Matthew Cross,Wesley Marshall,Orlando Vargas-Ramirez,Fabio Pacifici,Rafael Moreno-Sanchez,Ted Scambos

doi:10.3390/rs11121411

Abstract

Accurate classification of tropical tree species is critical for understanding forest habitat, biodiversity, forest composition, biomass, and the role of trees in climate variability through carbon uptake. The aim of this study is to establish an accurate classification procedure for tropical tree species, specifically testing the feasibility of WorldView-3 (WV-3) multispectral imagery for this task. The specific study site is a defined arboretum within a well-known tropical forest research location in Costa Rica (La Selva Biological Station). An object-based classification is the basis for the analysis to classify six selected tree species. A combination of pre-processed WV-3 bands were inputs to the classification, and an edge segmentation process defined multi-pixel-scale tree canopies. WorldView-3 bands in the Green, Red, Red Edge, and Near-Infrared 2, particularly when incorporated in two specialized vegetation indices, provide high discrimination among the selected species. Classification results yield an accuracy of 85.37%, with minimal errors of commission (7.89%) and omission (14.63%). Shadowing in the satellite imagery had a significant effect on segmentation accuracy (identifying single-species canopy tops) and on classification. The methodology presented provides a path to better characterization of tropical forest species distribution and overall composition for improving biomass studies in a tropical environment.

Highlights

Accurate identification of tropical forest species would support a more accurate measure of several important species-dependent environmental variables, such as above-ground biomass and carbon uptake [1]
Most pixel-based tropical forest studies generated accuracies ranging from 42–74%, depending on the forest assemblage and environments studied [8,9,10]
Because of the off-nadir image collection and the inherent displacement error due to overall tree canopy height, a georectification process was performed to improve the locational accuracy of trees within the study area

Summary

Introduction

Accurate identification of tropical forest species would support a more accurate measure of several important species-dependent environmental variables, such as above-ground biomass and carbon uptake [1]. Many studies have attempted to use remotely sensed imagery for tree type identification in complex tropical forest assemblages [4,7]. Most pixel-based tropical forest studies generated accuracies ranging from 42–74%, depending on the forest assemblage and environments studied [8,9,10]. Some features, such as tree canopies, are typically not homogeneous, which can lead to a reduction of separability between other features [9]. This can lead to poor feature definition and low classification accuracies [11]

Objectives

Methods

Results

Conclusion