Carbon storage and stand conversion in a pine-dominated boreal forest landscape

Abstract

Although climate change is expected to have wide-ranging effects on the distribution and character of forest biomes, major changes to forest cover are enacted as part of normal forest management. In this paper, I compared ecosystem carbon storage in a chronosequence of forest stands dominated by two common pine species – jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) growing on homogeneous beach ridge sands in Sandilands Provincial Forest (SPF), Manitoba. In SPF, there has been a history of converting stands formerly dominated by jack pine to regularly spaced red pine plantations. Ecosystem carbon (C) storage was dominated by soil and live tree ecosystem components. However, while there were no interspecific differences in soil storage, the red pine stored a larger proportion of ecosystem C in live trees than jack pine, a difference that appeared to grow greater with age. Differences in C storage appeared to be driven by divergent patterns of longevity and vulnerability to senescence and disturbance (e.g. windthrow) in jack pine and red pine. These differences in life history traits also appeared to be responsible for contrasting accumulation patterns of woody debris and litter with stand age. Consistently higher canopy cover in red pine stands may also have been responsible for age-related reductions in C storage in the herbs and short shrubs (those <1.5m tall) in red pine. These results indicate that changing the character of forest cover, even when closely related species are substituted for each other, can produce large differences in overall C storage, as well as in the distribution of C among ecosystem compartments.