Future climate affects management strategies for maintaining forest restoration treatments

Forests adapted to frequent-fire regimes are being treated to reduce fuel hazards and restore ecosystem processes. The maintenance of treatment effects under future climates is a critical issue. We modelled forest change under different climate scenarios for 100 years on ponderosa pine landscapes in the south-western USA, comparing management regimes that included prescribed burning, tree cutting, and no-management. We applied the Forest Vegetation Simulator (1) in its standard form, and (2) with modifications of reduced tree growth and increased mortality to simulate the effects of two levels of climate change. Without climate change effects, several management regimes, including the use of frequent burning similar to the historical fire frequency (similar to 5 year), maintained future forest structure within a target range of variability. In contrast, simulations that accounted for climate change effects indicated that burning intervals should be lengthened (similar to 20 year) and future tree thinning should be avoided to minimise forest decline. Although it has been widely predicted that future climate conditions will support more burning (warmer, drier fuels, longer fire season), our modelling suggests that the production of fuels will decline, so there will eventually be a trade-off between increased fire, driven by climate, v. reduced fuel, also driven by climate.