Early Monitoring of Health Status of Plantation-Grown Eucalyptus pellita at Large Spatial Scale via Visible Spectrum Imaging of Canopy Foliage Using Unmanned Aerial Vehicles

Megat Najib Megat Mohamed Nazir,Roger Meder,Ahmad R Norhisham,Razak Terhem,Sheriza Mohd Razali

doi:10.3390/f12101393

Megat Najib Megat Mohamed Nazir, Roger Meder + Show 3 more

Open Access

https://doi.org/10.3390/f12101393

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Abstract

Eucalyptus is a diverse genus from which several species are often deployed for commercial industrial tree plantation due to their desirable wood properties for utilization in both solid wood and fiber products, as well as their growth and productivity in many environments. In this study, a method for monitoring the health status of a 22.78 ha Eucalyptus pellita plantation stand was developed using the red-green-blue channels captured using an unmanned aerial vehicle. The ortho-image was generated, and visual atmospheric resistance index (VARI) indices were developed. Herein, four classification levels of pest and disease were generated using the VARI-green algorithm. The range of normalized VARI-green indices was between −2.0 and 2.0. The results identified seven dead trees (VARI-green index −2 to 0), five trees that were severely infected (VARI-green index 0 to 0.05), 967 trees that were mildly infected (VARI-green index 0.06 to 0.16), and 10,090 trees that were considered healthy (VARI-green index 0.17 to 2.00). The VARI-green indices were verified by manual ground-truthing and by comparison with normalized difference vegetation index which showed a mean correlation of 0.73. This study has shown practical application of aerial survey of a large-scale operational area of industrial tree plantation via low-cost UAV and RGB camera, to analyze VARI-green images in the detection of pest and disease.

Highlights

Plantations of genus Eucalyptus L’Hér amount to more than 20 million hectares globally [1] and are the second largest global forest plantation species behind Pinus L. [2].Their capability for fast growth, ability to grow in a range of site conditions, ease of propagation, and their desirable wood qualities have led to widespread establishment of large Eucalyptus plantations in many countries of Southeast Asia which has over 2.5 million planted ha [3]
The visual atmospheric resistance index (VARI)-green analysis undertaken in the 6-month-old stand (Block 42G) was, unsuccessful due to the size of the tree crowns being too small for detection
1065 trees were recorded as living during the early inventory measurement (EIM), and 754 trees were recorded as living after VARI-green analysis

Summary

Introduction

Plantations of genus Eucalyptus L’Hér amount to more than 20 million hectares globally [1] and are the second largest global forest plantation species behind Pinus L. [2].Their capability for fast growth, ability to grow in a range of site conditions, ease of propagation, and their desirable wood qualities have led to widespread establishment of large Eucalyptus plantations in many countries of Southeast Asia which has over 2.5 million planted ha [3]. Plantations of genus Eucalyptus L’Hér amount to more than 20 million hectares globally [1] and are the second largest global forest plantation species behind Pinus L. Their capability for fast growth, ability to grow in a range of site conditions, ease of propagation, and their desirable wood qualities have led to widespread establishment of large Eucalyptus plantations in many countries of Southeast Asia which has over 2.5 million planted ha [3]. In the Malaysian state of Sabah on Borneo Island, Eucalyptus species and hybrids have been shown to have high productivity and have a variety of end use potentials [4,5,6,7].

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