A guest post from Kevin Matthews:
A substantial body of science shows a general pattern, that when the ecological integrity of a natural ecosystem is degraded, its response curve is non-linear. The state that occurs when the response curve becomes non-linear, such that small additional impacts result in large losses of ecosystem integrity, is sometimes referred to as ecosystem collapse.
One of the scientific bases for why ecosystem collapse tends to catch humans by surprise is pretty interesting with regard to the O&C checkerboard forest lands of western Oregon.
Natural ecosystems tend to be very resilient, accommodating heavy damage and still recovering, up to typically somewhere between 50% and 90% damage. This lulls humans into complacency, to the sense that they can keep taking, and the ecosystem will keep recovering.
Then, somewhere in the range of substantial alteration of from 50% and 90% of habitat area, ecosystem resiliency breaks down. A threshold gets crossed, where things fall apart fast and hard. And in a relatively short time frame, the habitat is changed (loss of soil, hydrology, key species, whatever) so the ecosystem no longer has a viable path to recovery.
The point of collapse is hard to predict because the system responses go rapidly non-linear. Past rates of recovery, however well-researched, become almost instantly irrelevant.
A rough, understated estimate would be that the overall O&C checkerboard is already at 75-80% substantial impact, based on close to 100% impact to the industrial part, and optimistically 60% impact to the BLM part. (Looking just at old growth remnants, 90% or more impacted would be defensible.)
Add in the ongoing impacts due to climate change, and there’s a strong basis to believe the checkerboard forests are hanging on the edge of serious collapse.
Interestingly, much same thing is true for ecosystems overall, viewed at the global scale:
Habitats incorporating giant trees were endemic across the well-watered areas of what is now the U.S., from the Appalachians to the Great Plains, from the Carolinas to Maine to Minnesota. After a few centuries of western expansion, all that remains of those great tree forests is a thin fringe along the western edge of the continent. And this thin fringe is critically endangered.
Time to change our ways.
If we were ecologically realistic, given the heavy impacts on western Oregon forests to date, in order to avoid collapse we might want to plan for significant disturbance to not more than 25% of the checkerboard lands, and that, only in lands heavily disturbed already.
Key questions then would be, how could we make a sustainable level of harvest, contained by that threshold, work for the economics of rural communities? Could we continue needed building construction with the resulting output of sawlogs? Could we maintain a timber culture that we would all be proud of?
Recent calls by Senators and other politicians to increase logging, without addressing these broader and deeper issues, are fundamentally misinformed.
I’d like to see all sides work together in seeking a true balance, based on clear evidence, for forest policy in this new century.