Challenges for the operational detection of mountain pine beetle green attack with remote sensing

Abstract

Mountain pine beetle infestations are spatially correlated; current (green) attack is often located near previous (red) attack. This spatial correlation between the green and red attack stages enables operational survey methods, as detection of red attack trees-typically from an airborne survey such as a helicopter GPS survey or aerial photography-guides the location of subsequent ground surveys for green attack trees. Forest managers, in an attempt to understand beetle movement and infestation patterns, hope to utilize remotely sensed data to detect and map green attack trees, with the expectation that the spatial extent, accuracy, and timeliness afforded by remotely sensed data will greatly improve the efficacy of beetle treatment and control. In this communication, we present the biological, logistical, and technological factors that limit the operational utility of remotely sensed data for green attack detection and mapping. To provide context for these limitations, we identify the operational information needs associated with green attack and discuss how these requirements dictate the characteristics of any potential remotely sensed data source (e.g., spatial, spectral, and temporal characteristics). Based upon our assessment, we conclude that the remote detection of green attack is not operationally viable, and is unlikely to become so unless the limiting factors we have identified are altered substantially or removed.Key words: green attack, remote sensing, operational, insect survey, high spatial resolution, high spectral resolution RÉSUMÉ Les infestations de dendroctones du pin ponderosa démontrent une corrélation spatiale : l'attaque courante (verte) est souvent localisée à proximité de l'attaque précédente (rouge). Cette corrélation spatiale entre les périodes vertes et rouges permet l'utilisation de méthodes de relevé opérationnelles, compte tenu que la détection d'arbres rouges attaqués-habituellement à partir d'un relevé par voie aérienne par exemple effectué au moyen d'un GPS monté à bord d'un hélicoptère ou par photos aériennes-indique la localisation des relevés terrestres à venir des arbres verts attaqués. Les aménagistes forestiers, cherchant à comprendre le déplacement des dendroctones et les patrons d'infestation, souhaitent utiliser les données obtenues par télédétection afin d'identifier et de cartographier les arbres verts attaqués, avec l' espoir que la distribution et la précision dans le temps et l' espace permises par les données de télédétection permettront de grandement améliorer l' efficacité du traitement et du contrôle du dendroctone. Nous présentons dans ce texte les facteurs biologiques, logistiques et technologiques qui limitent l'utilité opérationnelle des données de télédétection dans le cas de la détection et la cartographie des attaques vertes. Afin d'illustrer le contexte de ces limites, nous identifions les besoins requis en matière d'information opérationnelle associée à une attaque verte et nous discutons comment ces besoins dictent les caractéristiques de tout...

Early Detection of Bark Beetle Green Attack Using TerraSAR-X and RapidEye Data

“…Although Wulder et al [75] found the use of remotely sensed data for detection of bark beetle green attack at endemic level not viable in Canada, results from the current study are promising for the region in which the study was conducted. However, as indicated by other researchers (e.g., [13,68,76]), the spectral reflectance of the bark beetle green attack is too generic to identify this specific stressor.…”

Remote sensing of forest pest damage: a review and lessons learned from a Canadian perspective

“…As a result, there is interest in developing the capability to detect green attack with remotely sensed data. Wulder et al (2009b) detailed the many factors that preclude the operational detection of green attack, most of which were actually unrelated to the ability of remotely sensed instruments to detect the subtle spectral response associated with green attack. In an operational context, field-based green attack surveys are often undertaken to identify infested trees that may be felled and destroyed, hence preventing the development adult beetles .…”

Monitoring the impacts of mountain pine beetle mitigation

“…Research has indicated the importance of accurately detecting and mitigating the greatest proportion of green attack trees possible each year (Carroll et al, 2006a;Coggins et al, 2008); however, there are many challenges to the operational detection of green attack using remotely sensed data (Wulder et al, 2009). Failure to mitigate effectively in the context of environmental conditions favourable to the expansion of mountain pine beetle will result in rapidly increasing beetle populations with concomitant negative impacts on pine forests.…”

“…Direct control programs generally target green attack trees, with the objective of destroying the host tree before the beetles contained therein have the opportunity to emerge and disperse. Infested trees in the red attack stage are detected during annual airborne forest health surveys conducted throughout the province and green attack trees are then detected by way of their spatial association with these surveyed red attack trees (Mitchell and Preisler, 1991;Wulder et al, 2009). Since emergence typically occurs in late July to mid-August, mitigation of green attack trees should be planned for winter and spring, and subsequent ground surveys to assess population levels would then be conducted in late summer or early fall.…”