Digital photography for detecting change in lodgepole pine forests

Digital photography for detecting change in lodgepole pine forests

Forests, and the ecosystem services that they provide, are impacted by changes that occur on relatively fast and slow timescales. These include seasonal variations such as snowmelt, rapid events including fire, slow processes like forest succession, and disturbances with complex patterns in space and time like insect outbreaks. Notable to the ponderosa, lodgpole, and whitebark pine forests of western North America is the recent outbreak of the mountain pine beetle (MPB, Dendroctonus ponderosae). MPB-impacted forest canopies turn from green but dying, to red, to grey over a period of a few years often in a complex pattern across the landscape. Tracking such forest changes over time is a fundamental challenge in ecological science. Here, we apply digital repeat photography to track changes in lodgepole pine ecosystems at high frequency (30 minutes) over seasonal time scales in the Tenderfoot Creek Experimental Forest in the Little Belt Mountains of west-central Monana. Extracting information from the red, green and blue channels of the .jpeg images allows initial inference into MPB spread and matches well with a remote-sensing analyses. Camera observations in the visible also correspond with a reasonable degree of accuracy with radiometer observations of shortwave albedo. Combined with additional camera observations from the U.S. National Phenology Network, our ability to quantify ecological processes of importance to forest ecology is improving.