This is the fourth in a series of columns addressing various issues surrounding climate disruption in the West Kootenay. Greg Utzig is a local conservation ecologist who has been working on climate change issues for two decades.
Forests are one of the things that make the West Kootenay (WK) such a wonderful place to live, whether it be the majestic old growth cedars, the lichen-laden Engelmann spruce-subalpine fir stands or the brilliant golden larches in the fall. For anyone who spends even a few minutes outside of their house, be it at Gyro Park or the back country, the interior temperate rainforests are the essence of the WK.
In a recent project for the B.C. Ministry of Forests. a team of local scientists explored what climate disruption will mean for WK forest ecosystems. As with most things around ecology, the answer was not simple.
Using the results of available climate projections and modeling by researchers at the University of Alberta, the team examined what WK forests might look like in the 2080s. They chose this long time frame because trees planted today will likely not be harvested for 100 years, and therefore they have to be suitable for good growth many decades into the future.
The models didn’t actually predict what future vegetation would be, but rather identified what vegetation is currently associated with projected climates. The models did this by searching all over Western North America for climates similar to those projected for the future in the WK.
Due to variation in climate models, there is some uncertainty about what our future climate may look like. Some of that uncertainty stems from not knowing whether we will reduce our GHG emissions or, if so, by how much.
The team therefore chose to look in detail at three unique scenarios of the more than 40 available. They purposely chose three recommended by climate scientists to explore the range of possibilities. Although the results of no single scenario is likely correct, the answer was probably somewhere between the three outcomes.
The results of the three scenarios differed in some factors but there was significant agreement in others. They all agreed that temperatures would increase in the future, particularly in the summer, but differed by how much. They also all agreed that annual precipitation would also increase, but that summer precipitation would either decrease or remain roughly unchanged. In short, they all agreed the summer growing season will become more arid.
Previous articles in this series:
One key agreement among the scenarios concerned changes projected for the valley bottoms where we mostly live. All the scenarios agreed that the increasing aridity would result in a shift from climates that support closed forests to climates more conducive to open Ponderosa pine stands or grasslands. Imagine Castlegar resembling Boise, Idaho, or Kaslo looking like Grand Forks. The difference between the three models was how far north the grassland climates extended, or how soon the change occurred.
Another point of agreement was that the high elevation forests of majestic spruce and subalpine fir will no longer find the climate suitable. What the models didn’t agree on was what they would be replaced with. The projected “bioclimates” of the future ranged from climates similar to today’s WK low elevation forests, today’s Alaskan coastal forests, or forests similar to low elevation forests in the East Kootenay. This uncertainty will prove very difficult for foresters trying to decide which trees to plant following logging.
Another question explored by the research team was how our forests will make the change from today’s ecosystems to tomorrow’s. The optimistic view would be that they would slowly transition over time. Unfortunately what is more likely is an abrupt change following a catastrophic disturbance, such as wildfire, windstorm, killing frost, landslide or pest infestation.
The lack of cold winters contributed to the recent mountain pine beetle epidemic. The ongoing mortality of birch in the WK is the result of interplay between warm springs, late frosts, leaf miners, and attacks by the bronze birch borer. Recent droughts resulted in the death of tree seedlings on shallow soils and the increased incidence of Douglas-fir beetle. What kind of forests will develop following last summer’s wildfires?
Unfortunately the climate is changing too rapidly for many species to adjust their ranges. Many plant species can only expand their ranges by a few metres or kilometres per decade, and some of the predicted changes will require species to move hundreds of kilometres in a few decades. What may result following these disturbances are ecosystems full of opportunistic weeds, rather than species that supply us with the ecosystem services we have come to expect.
To avoid the worst of these projections, we have to reduce our GHG emissions immediately. Simultaneously we also have to build resiliency into our forest ecosystems for the changes that are already locked in. In contrast to what the forest industry is calling for, conservation measures have to be strengthened, not weakened. Current forest management practices have to change.