Environmental Insight With a Touch of Real Science
by Don Flora (a real scientist)
Last month I mentioned planners’ enthusiasm for restoring shorelines to their “pre-settlement” condition. Not they, nor you, nor I know what that really means on the ground. Here’s why. Our Puget Sound lowlands have been in constant flux since the glaciers left. Picking a point in time to emulate precludes mimicking all other occasions.
The water has moved up or down hill with sea level changes. Long-ago levels can only be guessed, because old maps are vague and the underlying geologic changes can be gauged with only limited accuracy. Not only do we not know quite where sea level was at any particular time, we can’t put it back there.
Beaches have moved landward at various rates. Nobody has been able to predict rates at which beaches erode their way into the upshore, based on rain torrents (bluff saturation), ice events (weathering of bluffs), wind storm intensity and duration (wave dynamics), and all the other relevant factors. And even if a shore attrition ‘model’ could be developed, the historic occurrence of all those driving factors is largely unknown.
In fact, the contours, textures, and habitat character of specific shores long ago are veiled in history. As are the kinds and densities of shore dwelling plants and animals. They vary widely today and presumably did in the past. It is doubtful that, even if we knew the right mix, we could re-create it.
The upland was likewise diverse and impossible to create. Less than 10 fir-tree generations ago the Puget Sound lowland wasn’t conifer-covered at all. The dominant vegetation was oak trees and grass, a savanna of which we still have patches. Habitats revolved around the grass seed and acorns. Do we want this again?
Perhaps we want land cover like that of a couple of millennia later. We probably can’t have it. The climate regime that existed at the time that our current oldest forests began is quite different from the climate of the last century.
In the early 1800’s we had malaria, the ague (fever) that settlers came west to escape. We may not want to replicate the malarial swamps of that time. If the climate warms more we can have that plus yellow fever and the West Nile disease.
Advocates for restoration portray an array of vegetation overhanging tidewater banks to shade and nourish passing fish. They imply that ancient forests worked that way. But around half of the old-growth woodlands were burns, and perhaps half of the unburned trees were dead.
Many ecologists now caution that trying to restore forests to their pre-European condition is chimera.
Many Puget Sound rivers have been so altered …that it is difficult to envision their historic appearance, let alone quantitatively reconstruct those conditions.
These statements in the research literature are made by scientists after decades of examining forest and river restoration respectively. Wrenching tidewater shores back to historic conditions is a route we cannot follow.
Given the problems with guessing historic conditions, discovering whether they were really desirable, and then returning to them may not be feasible. We can’t get there from here. Rather, we can decide what “functions” and “values” we want from shores in the future, including benefits to the people, then head that way.