My spatial problem:

Under what forest and climatic conditions do endemic mountain pine beetle populations switch to epidemic populations?

The null hypothesis is that conditions are random and alternative hypotheses include: 1) population eruptions are simply cyclic or periodic; 2) there are specific environmental condition triggers; 3) some combination of alternative hypotheses 1 and 2.

Mountain pine beetle survival is dependent on availability of susceptible hosts and suitable temperature range, with the primary limitation being minimum temperature.  In an endemic state, mountain pine beetles may kill several trees in a dispersed pattern, while in an epidemic state, nearly continuous, widespread host tree mortality is observed.  Population eruptions exhibit both temporal and spatial patterns over the landscape making spatial statistics a useful analysis tool.

There are two parts to the study: 1) outbreak detection and monitoring using 40 years of Landsat satellite imagery and 2) analysis of relationships between outbreak initiation and spread and forest and climate conditions

Independent variables include:

Host availability at time of outbreak:

Host density

Host age

Topography:

Elevation

Slope

Aspect

Climate at and prior to time of outbreak:

Min and max temperature for various time periods

Precipitation for various time periods

Forest structure:

Composition

Management

Disturbance history

Each of these variables could potentially be related to outbreak timing and position through geographically weighted regression.