Canopy chlorophyll content retrieved from time series remote sensing data as a proxy for detecting bark beetle infestation

Abebe Mohammed Ali,Haidi Abdullah,Roshanak Darvishzadeh,Andrew K Skidmore,Marco Heurich,Claudia Roeoesli,Marc Paganini,Uta Heiden,David Marshall

doi:10.1016/j.rsase.2021.100524

Abstract

The European spruce bark beetle (Ips typographus, L.) is an invasive species resulting in a high degree of fragmentation, forest productivity, and phenology. Understanding its biology and its early detection based on its behaviour is essential for its successful management and eradication. This study demonstrates the potential of the canopy chlorophyll content (CCC) product retrieved from remote sensing datasets to detect early bark beetle infestations in the Bavarian Forest National Park. Time series CCC maps were generated through radiative transfer model inversion of images from RapidEye and Sentinel-2 (2011–2018). The CCC products were then classified into stressed and healthy classes using calculated CCC mean and variance values obtained for infected and healthy Norway spruce trees in 2016. The location of infected plots obtained from the interoperation of resolution (0.1 m) aerial photographs was used as reference data to validate the accuracy of the infestation maps generated from CCC. Validation of the infestation maps indicated a classification accuracy of up to 78%. Our results demonstrated that CCC products derived from satellite remote sensing data were a rigorous proxy for early detection of bark beetle infestation. Hence, CCC products may play a significant role in understanding the dynamics of the Infestation and improving the management of bark beetle outbreaks in forest ecosystems. Inclusion of other remotely sensed plant traits as additional parameters in the model, such as dry matter and nitrogen, may further improve the accuracy of early detection of bark beetle infestation using satellite remote sensing.

Highlights

The spruce bark beetle (Ips typographus, L.) is considered the most critical disturbance agent in European forest ecosystems (Ohrn et al, 2014)
We aim to demonstrate the role of canopy chlorophyll content (CCC) derived from satellite remote sensing data through radi ative transfer model (RTM) inversion to detect the stress and changes caused by European spruce bark beetles
None theless, it is apparent that CCC products derived from RapidEye data

Summary

Introduction

The spruce bark beetle (Ips typographus, L.) is considered the most critical disturbance agent in European forest ecosystems (Ohrn et al, 2014). The swarming of bark beetles usually starts mid-April when the air temperature reaches the threshold of 16.5 ◦C (Ohrn et al, 2014; Wermelinger, 2004). After being infested forest stands (trees) exhibit three distinct stages: green, red, and grey attack (Wermelinger, 2004). During the early stage (green attack), the foliage is still alive and visually green. In this stage, the newly hatched gener ation of beetles is developing within the inner bark of the infested trees. The infested tree will stay green until late July, when the foliage colour changes (to red) become apparent. While at the grey attack stage, the tree is dead and totally defoliated

Objectives

Methods

Results

Conclusion