Effects of Stand-Replacing Wildfire on Ecosystem Carbon Pools in Lake States Jack Pine Forests

A key barrier to resolving uncertainty about the effects of fire on ecosystem C balance is the fact that fire effects on ecosystem C budgets are manifested over decadal time scales, meaning that we are largely forced to draw inferences using space-for-time substitution, or chronosequence, studies. Whereas chronosequences allow us to study processes occurring over long time scales, they are almost never re-sampled to verify the temporal trajectory of response variables, raising questions about the validity of chronosequence estimates of post-fire C dynamics. We re-sampled a well-studied fire chronosequence of jack pine (Pinus banksiana) forests in Michigan, providing a unique opportunity to both determine the accuracy of chronosequence estimates of post-fire C fluxes for this forest type, as well as elucidate variability in rates of C loss and recovery following wildfire. In addition, we conducted stable-isotope analysis of deep soil C profiles to gain a better understanding of the response of mineral soil C to stand-replacing wildfire and used retrospective, tree-ring analysis to identify potential changes in tree growth over the past 50 years. Finally, we integrated these results into a spatial modeling framework to estimate the effects of alternative management practices and changing disturbances regimes on landscape carbon balance. We are currently in the process of preparing manuscripts for peer-reviewed publications addressing chronosequence C budgets and deep-soil C response to disturbance. We are also developing a Technical Report for land managers addressing the implications of changing rotation length and disturbance regimes on landscape C balance