Using structural equation models (SEM) to link climate change, forest composition, deer, and outdoor recreation

Climate change will likely cause changes in the composition of forests worldwide, with consequent impacts on forest ecosystems and the ecosystem services they provide. In northeastern Minnesota, climate change will likely cause a shift from boreal to temperate forest by the end of the century. Such a shift will affect species populations such as deer and outdoor recreation, a valuable ecosystem service with over $4 billion in annual expenditures in hunting, fishing, and wildlife viewing. In this paper, a structural equation modeling (SEM) framework is used to model four key variables, climate change, deer, forest composition, and outdoor recreation, as an interactive system with data from the Laurentian Mixed Forest (LMF) region of Minnesota. A series of SEM models of increasing complexity are used to draw out the individual and system level effects. The results show: a strong empirical relationship between forest composition and recreation; climate affects both forest composition and recreation, mainly through temperature effects; deer affects both forest composition and recreation. A systems modeling approach like SEM is needed because there are important complex interactions, such as the effect of deer on forest composition and of forest composition on deer.