Abstract
Modeling of carbon dynamics at the landscape, regional, and continental scales is currently limited by few empirical studies of biomass and carbon accumulation after some types of disturbances. For temperate forests of North America, only three previous studies described biomass and carbon accumulation after wind disturbances, and those were limited by either coarse temporal resolution of the first several decades, or limited time span. Here, 25 years of aboveground biomass and carbon accumulation following severe wind disturbance of an old-growth hemlock-northern hardwoods forest of northwestern Pennsylvania are documented to characterize the temporal trends with fine temporal resolution and extend into the third decade post-disturbance. Mature undisturbed forest at the site supported roughly 296 Mg ha−1 live aboveground biomass and 148 Mg ha−1 of carbon. The disturbance reduced the aboveground woody biomass to ~7 Mg ha−1, and carbon to ~3.5 Mg ha−1. During regrowth, biomass and carbon accumulated slowly at first (e.g., 2–4 Mg ha−1 year−1 for biomass and 1–2 Mg ha−1 year−1 for carbon), but at increasing rates up through approximately 17 years post-disturbance, after which accumulation slowed somewhat to roughly 3.4 Mg ha−1 year−1 of biomass and 1.7 Mg ha−1 year−1 of carbon. It appears that the rates reported here are similar to rates observed after wind disturbance of other temperate forests, but slower than accumulation in some tropical systems. Notably, in tropical forests, post-windthrow accumulation is often very rapid in the first decade followed by decreases, while in the results reported here, there was slow accumulation in the first several years that increased in the second decade and then subsequently slowed.
Highlights
Forests of North America have recently been a carbon sink, with a net uptake of 217 Tg carbon (C) per year [1]
One year after the disturbance, surviving trees >5 cm dbh made up 7.11 Mg ha−1 of biomass and
Regeneration biomass increased from 1.84 Mg ha−1 in 1987 (2 years post-disturbance) to 25.9 Mg ha−1 in 1993 (8 years post-disturbance); it reached 70.3 Mg ha−1 in 1999
Summary
Forests of North America have recently been a carbon sink, with a net uptake of 217 Tg (teragrams) carbon (C) per year [1]. Shorter intervals between disturbances would cause a greater fraction of a forested landscape to be in early recovery, or equivalently, a greater fraction of centennial or millennial time scales to be spent in the first decades after disturbance. Under such a scenario, the rate of post-disturbance increase in net primary productivity (NPP) will strongly influence short term C storage in the recovering forest. An abundance of post-wind recovery research reports trends in Forests 2019, 10, 289; doi:10.3390/f10030289 www.mdpi.com/journal/forests
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