IS THERE A BALANCE OF NATURE?

IS THERE A BALANCE OF NATURE? Matt Ridley had a review in the Wall Street Journal (March 23) of THE RAMBUNCTIOUS GARDEN by Emma Marris, which summarized her challenge to the idea of a balance in nature. Ridley begins by stating “a paradox that is increasingly vexing the science of ecology, namely that the only way to have a pristine wilderness is to manage it intensively.” Until recently ecologists have believed in a tendency of nature to reach a stable equilibrium (economists have had a similar belief in economic systems tending to reach a stable equilibrium.) Ridley points out examples of equilibrium states that are unstable. In African forests, elephants sometimes have to be controlled to prevent deforestation. Oak forests are unstable because oak seedlings don’t do well under mature oaks. The mature oaks rain caterpillars on the seedlings. Without management, some species become dominant. “To let aspen, willow and beaver return to Yellowstone, it was necessary to reintroduce the wolf, which reduced elk numbers.”