To the Editor:

Arthur Middleton, in “Is the Wolf a Real American Hero?” (Op-Ed, March 10), disputes the widely accepted view that the reintroduction of wolves into Yellowstone 19 years ago is primarily responsible for the “cascade” of largely positive ecological effects now witnessed in the park.

This view holds that wolves are reducing overpopulation in wapiti (elk) and that excessive cropping pressure on tree species is being relaxed, encouraging recovery of devastated landscapes and allowing displaced species to recolonize.

Mr. Middleton argues that measurable effects of wolf restoration are mostly negligible and that the “cascade” is attributable to a linkage of effects of many kinds. His article suggests that the American Museum of Natural History has not adequately noted this in its Bernard Hall of North American Mammals.

But the significance of top predators for restoration efforts is itself a subject of intense debate among ecologists, and these cannot be properly conveyed in a brief diorama label. Large carnivores clearly do cause trophic cascades in many parts of the world, and their preservation is important for the maintenance of healthy ecosystems, Yellowstone’s included.