Global climate change is at the forefront of issues in forest management. Forest managers are now faced with the challenge of incorporating climate change into their forest management values and objectives, as existing paradigms may be invalidated by the changing climate. The exploration of climate change impacts and formulation of potential management strategies will be necessary to reduce the vulnerability of forests. Halifax Water manages forest watersheds for the purpose of supplying clean water to much of the Halifax Regional Municipality. The purpose of this study is to characterize the future forest structure of the two principal watersheds supplying the Halifax Regional Municipality and to evaluate different adaptations incorporated into forest management using a modelling approach. The landscape disturbance model LANDIS-II and ecosystem process model PnET-II were used to simulate the forest response to climate change and adaptive measures in timber harvesting. Several impacts of climate change were examined in the study area. The most drastic effect of climate change in the watersheds was considerable change in forest composition, with a sharp decline in the abundance of boreal species, such as balsam fir and black spruce, and an aggressive increase in some temperate and pioneer species, such as red maple and aspens. Incorporating climate change adaptation into timber harvesting scenarios was found to be effective in minimizing trade-offs between timber supply and forest ecosystem integrity in the face of climate change. The watersheds managed by Halifax Water represent a situation where the principal objective is the maintenance of water quality as opposed to timber production, and therefore offer a unique opportunity to implement cutting-edge practices and adaptive forest management focused on climate change resilience and resistance while also facilitating transition to the changing climate.

Global environmental change represents one of the greatest challenges facing forest resource managers today. The uncertainty and variability of potential future impacts related to shifting climatic and disturbance regimes on forest systems has led resource managers to seek out alternative management approaches to sustain the long-term delivery of forest ecosystem services. To this end, forest managers have begun incorporating adaptation strategies into resource planning and are increasingly utilizing the outcomes of forest landscape simulation and climate envelope models to guide decisions regarding potential strategies to employ. These tools can be used alongside traditional methods to assist managers in understanding the potential long-term effects of management and climate on future forest composition and productivity. This study used a spatially explicit forest landscape simulation model, Landis-II, to examine and evaluate a range of long-term effects of current and alternative forest management under three projected climate scenarios within a 50,000-hectare forested landscape in southeastern Vermont, USA. Multiple scenarios were examined within this mixed ownership landscape, allowing for an evaluation of the influence of management and climate on future forest conditions in the region. These simulations indicate that land-use legacies and the inertia associated with long-term forest successional trajectories are projected to be an important driver of future forest composition and biomass conditions for the next 100 years. Nevertheless, climate is projected to have a greater influence on species composition and aboveground biomass over the next two centuries, with forests containing a greater abundance of species from more southerly regions and lower levels of aboveground biomass, resulting in shifts in the future provisioning of ecosystem services. Key words: Vermont, USA; climate change; forests; LANDIS-II; forest adaptation; forest management; above ground biomass; landscape inertia; land use recovery; forest composition