Abstract
The recent and intense outbreak (first decade of 2000s) of the mountain pine beetle in the Black Hills of South Dakota and Wyoming, which impacted over 33% of the 1.2 million acre (486,000 ha) Black Hills National Forest, illustrates what can occur when forest management practices intersect with natural climatic oscillations and climate change to create the “perfect storm” in a region where the physical environment sets the stage for a plethora of economic activities ranging from extractive industries to tourism. This study evaluates the potential of WorldView-2 satellite imagery for green-attacked tree detection in the ponderosa pine forest of the Black Hills, USA. It also discusses the consequences of long term fire policy and climate change, and the use of remote sensing technology to enhance mitigation. It was found that the near-infrared one (band 7) of WorldView-2 imagery had the highest influence on the green-attack classification. The Random Forest classification produced the best results when transferred to the independent dataset, whereas the Logistic Regression models consistently yielded the highest accuracies when cross-validated with the training data. Lessons learned include: (1) utilizing recent advances in remote sensing technologies, most notably the use of WorldView-2 data, to assist in more effectively implementing mitigation measures during an epidemic, and (2) implementing pre-emptive thinning strategies; both of which can be applied elsewhere in the American West to more effectively blunt or preclude the consequences of a mountain pine beetle outbreak on an existing ponderosa pine forest.
Highlights
The recent and intense outbreak of the mountain pine beetle in the Black Hills of South Dakota and Wyoming, which impacted over 33% of the 1.2 million acre (486,000 ha) Black Hills National Forest, illustrates what can occur when forest management practices intersect with natural climatic oscillations and climate change to create the “perfect storm” in a region where the physical environment sets the stage for a plethora of economic activities ranging from extractive industries to tourism
There is a reduction in the number of refractory surfaces within the spongy mesophyll caused by a reduction in intercellular cavities and air-to-water interfaces (Ceccato et al, 2001); the Near Infrared (NIR) spectral reflectance is suppressed
Our research indicates that the NIR1 band of the WorldView-2 imagery is a key dataset for green-attack detection
Summary
Native to the Black Hills, the mountain pine beetle (Dendroctonus ponderosae), commonly referred to as the bark beetle, ranges from Mexico to British Columbia. Mountain pine beetles take flight in July and August and subsequently bore into trees and construct vertical egg galleries (Safranik and Carroll 2006). The larvae feed on nutrients in the phloem where they construct feeding tunnels perpendicular to the egg galleries. Ponderosa pines respond to a beetle attack by transporting sap to beetle entry points to “pitch” beetles out of the tree, which results in a light-colored circular plug manifesting on the surface of the darker bark (Figure 1).
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