Remote Sensing Assessment of the Expansion of Ips typographus Attacks in the Chuprene Reserve, Western Balkan Range

Abstract

The Chuprene Reserve was created in 1973 to preserve the natural coniferous forests in the Western Balkan Range in Bulgaria. The first infestations by European spruce bark beetle (Ips typographus) were registered in Norway spruce (Picea abies) stands in the mid-1980s. The aim of this study is to assess the damages caused by I. typographus in the Chuprene Reserve using remote sensing techniques – unmanned aerial vehicle (UAV) images, airborne images, and satellite images of European Space Imaging (EUSI), combined with terrestrial verification. High-resolution images in four bands of the electromagnetic spectrum and in a standard RGB channel were taken in 2017 via a multispectral camera ‘Parrot Sequoia’, integrated with a specialized professional UAV system eBee ‘Flying Wing’. The health status of Norway spruce stands in the reserve was assessed with the normalized difference vegetation index, based on the digital mixing of imagery captured in the red and near infrared range. The dynamic of bark beetle attacks was studied in GIS on the basis of maps generated from photographic surveys, airborne images taken in 2011 and 2015, and satellite images from 2020. In the UAV-captured area (314.0 ha), the size of Norway spruce stands attacked by I. typographus increased from 7.6 ha (2.4%) in 2011 to 44.9 ha (14.3%) in 2020. The satellite images showed that on the entire territory of the Chuprene Reserve (1451.9 ha), I. typographus killed spruce trees on 137.4 ha, which is 9.6% of the total area.

Study on the Coupled Human – Natural System in Velingrad municipality, Bulgaria: a resilience perspective

“…Intensive succession processes have begun in the direction of restoration of the natural deciduous vegetation (Popov et al, 2018). The gradual change in climate conditions reduces the resistance of forest stands and makes them susceptible to pest attacks (Georgiev et al, 2022). Given the fact that most of the mature plantations are located at a higher altitude, the rise in temperatures will shift the isotherm lines in height, which will create conditions for insects to affect new forest areas.…”

Individual Tree-Level Monitoring of Pest Infestation Combining Airborne Thermal Imagery and Light Detection and Ranging

“…The fast-spread characteristic of pest infestation severely threatens forest health status, thereby decreasing their vitality and carbon sequestration over large areas. Moreover, changes in climatic conditions, which have decreased forest resistance, have intensified outbreak opportunities for pest infestation [5,6]. The commonly used artificial ground survey exhibits great limitations and high costs for detecting pest infestation in a large region [7].…”