Forest in a Looking Glass
they respond differently to the different types of cutting?Cutting down a portion of the mature forest caused the densities of all five mature-forest birds to drop somewhat after the cutting. They have since rebounded. The responses of these birds to the different treatments varied. Wood thrushes seemed to be attracted more to the forest stands near openings in the even-aged sites than to the openings created by uneven-aged management. Ovenbirds and worm-eating warblers, on the other hand, seemed to be more negatively affected by even aged management than by uneven-aged management. Kentucky warblers were positively influenced by both types of cutting, and Acadian flycatchers did not seem to favor one or the other.
The densities of four of the six early successional species increased dramatically within the newly-created habitat. Clawson and Faaborg found that yellow-breasted chats and prairie warblers responded more positively to even-aged treatments than to uneven-aged treatments. Indigo buntings and hooded warblers seemed to respond positively and equally to both treatment types. Blue-winged warbler and white-eyed vireo densities have remained low throughout the study to this point.
The scientists found no significant change in nest success rates between pre-harvest and post-harvest monitoring. Faaborg and Clawson concluded that, within this forest-dominated landscape, forest management does not create edge effects that are a problem for birds.
In addition to attracting the early-successional birds to nest and rear their young, the brushy habitat created in the openings, especially from even-aged treatment, is very attractive to broods of mature-forest species. Rick Clawson suggests that the dense vegetation provides both good foraging habitat and cover from predators for the adults and their young.
The understory, the plant and animal communities that live below the level of the tree canopy, is an important part of the forest. Conservation Department botanist Jenny Grabner and her team looked at the ground layer of vegetation, gathering pre-treatment ground flora data during the summers of 1994 and 1995 and post-treatment data in 1999 and 2000. They looked at the numbers of different species, how much area each species covered and what types of plants dominated the sites. As expected, Grabner observed increases in the number of species and how much ground they covered on cut areas. An unexpected result was a noticeable decline in species richness on uncut areas, possibly due to dry weather over the past three to four years. Annual species, such as horseweed