Boreal black spruce forests contribute to climate change mitigation by accumulating large amounts of carbon (C) in moss-derived peat. When left undisturbed, a thick peat layer can inhibit tree growth, and this trade-off between peat and tree biomass can have implications on the forest C dynamics. Similarly, wildfire severity and frequency can modify C accumulation patterns, but this impact remains poorly documented. We used the Carbon Budget Model of the Canadian Forest Sector version 3 (CBM-CFS3) to explore over a 400-year simulation period, the effects of high-severity fire (HSF) and low-severity fire (LSF) on C dynamics of two forest types (black spruce?Sphagnum (BSSP) and black spruce?feathermoss (BSFM)). We found that total C stocks increased to higher levels after LSF than after HSF in BSSP due to peat accumulation. Conversely, in BSFM, HSF resulted in greater C storage than LSF due to tree biomass. The tree component is key to the rapid recovery of C pools in both BSSP and BSFM forests specifically after HSF, while mosses maintain C sinks over the long term. This study suggests that a good characterization of forest type is key to better predictions of the effects of a change in fire regime on ecosystem C dynamics.

There are ongoing debates among different stakeholders about which forest and ungulate management strategies will sustain high levels of timber and animal harvest and maintain important ecosystem functions under climate change. Ungulate-forest interactions are complex, including periods where forest regeneration is sensitive to browsing pressure, making it difficult to predict the consequences of a given strategy over time. To aid decision-making, we simulated the impacts of moose browsing on forest succession under 18 different combinations of moose (Alces alces) harvest rate levels and forest management scenarios in a boreal forest landscape in southern Sweden given projected changes in forest growth due to climate change. We found that the current management practices are important for sustaining a moose-forest system. Increasing moose harvest rates led to slightly smaller moose populations, larger estimates of landscape carrying capacity, and less biomass removal of Scots pine (Pinus sylvestris), a commercially valuable species. However, minor changes in the moose harvest were hardly affecting timber production. Increasing the timber harvest rotation time led to the highest estimates of Scots pine biomass, while thinning younger cohorts lead to the highest estimates of Norway spruce (Picea abies) biomass. These changes came without much effect to moose population dynamics. However, the increased broadleaf production scenario had a very large positive effect on total aboveground live biomass of deciduous species and on landscape carrying capacity and moose density. This scenario subsequently resulted in the greatest estimates of biomass removal of Scots pine, highlighting the tradeoffs associated with increased moose production.