Incorporating Carbon Storage into Forest Management in Michigan: A Modeling Based Scenario Analysis

Abstract

Forest ecosystems play an important role in the global carbon (C) cycle, as they can be both a sink for and a source of atmospheric CO2. State owned forests in Michigan are dominated by early successional Aspen trees and are frequently managed to maintain Aspen dominance. Here, I developed a model that allows a user to assess the impacts of forest management decisions on forest composition, tree species and size diversity, stand economic value, and C storage. The model, MITRIX, pairs an empirical growth model with a C accounting model and was specifically designed to be useful to forest managers in Michigan to assess the tradeoffs encountered in meeting diverse management goals while incorporating the relatively recent goal of stabilizing or increasing C storage. Inventory and sale data from the Michigan DNR and field data from the University of Michigan Biological Station were obtained for model development and validation. Validation showed that the model accurately simulates forest stand growth and succession. Model simulations suggested that C storage is maximized when an Aspen dominated stand is allowed to succeed to a later successional species cover. If an Aspen stand is to be maintained, increasing the rotation period results in a greater overall C storage. When a landscape-based management approach is taken, timber profits, species diversity, and stand C storage are all stabilized. With a 200 year frame of analysis, the price of C necessary to balance opportunity costs was $22-26 per metric ton. However, when the time frame of analysis was shortened, this price was considerably higher. The 2008 Michigan state forest plan includes C storage in forest management objectives. The results suggest that considering C storage in Michigan forests will affect stand management decisions and the model described here is a useful tool to assess the impact of altered management strategies.