Making the case for cumulative impacts assessment: Modelling the potential impacts of climate change, harvesting, oil and gas, and fire

Abstract

The cumulative impacts of human and natural activity on forest landscapes in Alberta are clear. Human activity, such as forestry and oil and gas development, and natural processes such as wildfire leave distinctive marks on the composition, age class structure and spatial configuration of the forest. Also, other processes such as climate change may be slowly and subtly modifying forest dynamics and may lead to important changes over time. Given the importance and ubiquitous nature of these cumulative impacts, a forest management plan that does not adequately take such impacts into account cannot be expected to adequately manage the forest, neither its components nor its processes. In order to address the question of cumulative impacts in the context of forestry, a landscape model was designed and built in order to simulate forestry, oil and gas, climate change, wildfire, and demographic change for the Whitecourt forest management area over a long time horizon. This paper presents the model and the forest landscape states it forecasted with cumulative impacts, and evaluates the fate of some key indicators of biodiversity and forest productivity. Simulations of harvesting as the only disturbance, the nearest analogue to the current approach to forest management planning, yield results that differ greatly, in every respect, from the results of simulations of harvesting combined with other disturbance agents. The simulation of multiple disturbance agents together allows for the detection of interactions among disturbance agents, and indeed, there are important interactions between the processes of fire and oil and gas. Results also show that climate and demographic change will intensify the impact of fire on the supply of timber and other values. Also, the continued development of petroleum resources will lead to an important erosion of the forest landbase. Overall, this paper makes a strong case for cumulative impacts assessment and the use of spatial and temporal stochastic modelling in forest management. Key words: cumulative impacts, forest management, climate change, landscape modelling, APLM