Our climate is changing. The natural cycles of the forest – which are already compromised from a century of commercially-driven management – are becoming unpredictable. Climate changes will likely exacerbate existing trends in ecosystem degradation by affecting key processes such as stream temperature, surface flows, groundwater and floodplain connectivity, landslide rates, fuels, fire, invasive species, and post-disturbance human responses, to name but a few. However, wise management choices could increase the forest's natural ability to pull CO2 out of the atmosphere and potentially mitigate some of the worst impacts of climate change.
Climate change will adversely impact water, wildlife and the natural disturbance regimes in the forest.
Water: Many models suggest precipitation and temperature patterns will change in the Pacific Northwest in coming decades. The timing and type of precipitation is also likely to change, leading to more rainfall instead of snowfall and more rain-on-snow events, which are the leading cause of flooding in the area. Snowmelt could occur at earlier times and in higher volumes over shorter periods of time, altering peak and low-flow patterns for streams.
Fish & Wildlife: As Oregon streams experience higher winter flow and reduced summer flows, and temperature rises and the variability of precipitation increases, the impacts on populations of threatened salmon could be disastrous. Warmer air temperatures combined with lower summer stream flows will increase water temperatures and cause thermal stress and possibly death to adult & juvenile salmon. Threatened Northern Spotted Owls are also adversely impacted by a changing climate, as are numerous other species with specialized habitat needs.
Fire: Ecologists predict that climate change may alter the fire season to begin earlier and last longer. While there are many ecosystem benefits from wildland fire, the current approach to wildland fire on Mt. Hood National Forest is to fully suppress any ignition outside designated Wilderness. This means that the ecological benefits of fire will not be realized, though all the detrimental impacts of industrial firefighting will be.
Changes in forest management can be part of the climate solution, or lead to increased carbon pollution
Carbon sequestration, the process where CO2 is pulled from the atmosphere and stored for a long period of time, may be one way to slow or reverse the accumulation of CO2 in the earth’s atmosphere. The amount of carbon sequestered by forest ecosystems – in plants, soils and rocks – plays an important role in regulating atmospheric levels of carbon dioxide. All living forests both absorb and release CO2 and the relative balance between the two processes determines whether a forest is a source or sink of CO2.
The potential to store additional carbon in Paciﬁc Northwest forests is among the highest in the world because much of the area has forests that are long-lived and maintain relatively high productivity and biomass for decades to centuries. Nine of the top ten carbon sequestering National Forests, including Mt. Hood National Forest, are in the Pacific Northwest.
A recent study found that forests in Oregon are at 54% of their maximum carbon storage levels. Total carbon stocks could theoretically double if forests were managed for maximum carbon sequestration. This could be achieved by maintaining mature and old forests that already store large amounts of carbon, and by increasing the commercial logging rotation age by 30–50 years. Another study calculated that if all timber harvest ceased on national forests, the rate of carbon storage on those lands could be increased by an average of about 30% percent over the next five decades, compared to a “business as usual” scenario.
In direct contrast, commercially-driven forest management can release huge amounts of carbon into the atmosphere with logging as the primary source of land-use related carbon emissions. Typically, carbon emissions from the decay of dead plant material in logged forests exceeds the carbon sequestered from the growth of new vegetation. Not only does logging emit CO2, most forms of logging reduce the carbon sequestration capacity of a
given site simply because trees that once captured and stored carbon are no longer present. Lost carbon sequestration capacity is a form of indirect emissions because CO2 that was once being removed from the atmosphere now remains thus contributing to increasing CO2 concentrations.
Fuel-reduction treatments aimed at preventing future high-severity wildfires emit more carbon into the atmosphere than they ultimately save from combustion. For example, simulations of conifer forests in Oregon indicate that removing three units of carbon in treatment will protect one unit of carbon from wildfire combustion. Also, they do not have a major impact on total wildfire carbon emissions because high severity fires release only moderately more carbon (~30%) than low-severity fires.