Northwest Boreal Landscape Conservation Cooperative

Globally, forest distribution is influenced by bioclimatic variables and humidity gradients (Krishnaswamy et al. 2009). Climate has a significant influence on vegetation, and feedbacks of vegetation on local climate may be important (Mack et al. 2005). This relationship may be particularly relevant in the boreal region, where large intact forests are still primarily influenced by natural processes such as climate and disturbance. CMI is a simple index for assessing moisture variation and drought severity in remote forested regions where long-term climate data are typically limited to temperature and precipitation (Hogg 1994, 1997). The index is calculated from weather data, including the input of moisture from rain and snow, and the losses from evaporation and transpiration i.e., water vapour released from the leaves of trees and other vegetation: