Carl Wernicke: Restorative Ecological Change Must Be Holistic
A valuable lesson I learned over years as a reporter in writing about the environment is that to see is not always to understand. Crystal clear water can be severely polluted, and verdant woods can be a tree farm that bears little comparison to a healthy, diverse forest.
To understand what’s really happening, you need research. And what such research reveals can be spectacular. Especially when you realize that because of nature’s amazing resiliency, great damage done to ecological systems can sometimes be undone through relatively simple steps.
For example, today it’s well know that simply mimicking the natural cycle of fire in the longleaf pine ecosystem has huge benefits.
One of my favorite stories is how the red-cockaded woodpecker benefits from fire. Gallberry grows profusely in our pine woods, and without fire to control it, it goes crazy. Gallberry also absorbs calcium from the soil, and holds it. Fire releases that calcium back into the ground, where ants consume it. These ants are one of the woodpecker’s favorite meals, and more calcium in the ants means stronger eggs for the woodpecker, which means higher reproduction and a healthier pecker population. Our well-intended fire suppression policies created a calcium deficiency in the woodpeckers; fixing it merely required restoring fire to the ecosystem.
Recently a friend sent me a fascinating video about the impact of reintroducing wolves to Yellowstone National Park in 1995, after an absence of 70 years. It was a controversial move then, and probably still is. But research now shows that the benefits go far beyond what anyone could have imagined.
The major impact the wolves have had is to reduce the overpopulation of deer, which flourished in the absence of predators like wolves, and despite human efforts at population control. The wolves also drove the herds away from places like open valleys and hillsides where they are easy prey.
With the voracious deer gone, trees like aspen, willow and cottonwood returned, which brought back the birds that had left. The trees also drew beavers, which created pond habitats that attracted fish, ducks, otters and amphibians.
The wolves also killed coyotes, which allowed rabbits and field mice to multiply, which drew hawks, foxes and weasels. Badgers and eagles returned to feast on carrion from wolf kills.
So did bears, drawn by berries on the rebounding vegetation. The bears also reinforced the wolves’ impact by preying on deer calves.
Meanwhile, the return of trees and plants to stream banks and hillsides reduced and slowed stormwater runoff, which reduced erosion and improved water quality. This also stabilized stream banks, slowing the flow of water, and the streams began to meander more, creating new habitats.
So simply reintroducing wolves created what scientists refer to as a trophic cascade, which is a wide-ranging ecological change started by a change at the top of the food chain.
For me it’s another lesson about the vast, interconnected web that is nature. Without understanding these connections it is impossible to understand how mindlessly we can devastate an ecosystem, or how we can restore it with the right actions. That’s an important lesson to remember as we debate how to use the money from the BP oil spill to restore water quality along the Gulf of Mexico.