Community-Level Effects of Clearcutting and Wildfire on Shrews, Grasshoppers, and Ground-Dwelling Beetles
Timber harvesting is often proposed as a substitute for stand-replacing wildfire; many feel such a controlled disturbance plays a similar ecological role to the natural disturbance of fire. In order to gain more insight into the soundness of this management approach, ground-dwelling beetles (Coleoptera), grasshoppers, crickets, and allies (Orthoptera), and shrews (Insectivora: Soricidae) were sampled by pitfall trap in recently burned, clearcut, and undisturbed forested plots (controls) near Logan, Utah. Over 200 beetle species from 39 families were included in the study. Nine orthopteran and two shrew species were included as well.
Beetle abundance was reduced after burning and clearcutting, but neither type of disturbance resulted in a total loss of biomass. Beetle species richness increased after burning but did not change after clearcutting. Orthopteran abundance and richness strongly increased after burning and clearcutting, but did not differ between clearcuts and burns. The response by shrews was species dependent; more S. cinereus were collected in undisturbed forest than in clearcuts or burns. Slightly more S. monticolus were trapped in clearcuts, but too few were captured to show a clear preference for any habitat type.
Burns, clearcuts, and mature forests all supported their own characteristic beetle species assemblage; most interestingly, the species compositions from clearcut and burned plots were different from one another. Orthopteran species assemblages also differed among burns, clearcuts, and controls. Band-winged grasshoppers (Acrididae: Oedopodinae) were most prevalent in clearcuts, but burns provided greater numbers of the camel cricket Ceuthophilus fusiformis (Scud der) (Gryllacrididae: Rhaphidophorinae) and Steiroxys pallidipalpus (Thomas) (Tettigoniidae: Decticinae).
Rank-abundance curves for carabid beetles in disturbed plots were less steep than those from undisturbed plots. Small carabids species were better represented in both clearcuts and burns. A higher percentage of flightless carabid species was found in control plots but a variety of flightless carabid species recolonized the disturbed plots as well.
Although the effects of clearcutting and burning on ground-dwelling beetle, orthopteran, and shrew assemblages showed similarities, important short-term differences were also manifest. If maintaining animal diversity is deemed important, clearcutting should not be viewed as an adequate substitute for all forest fires.
Clayton, J.C. (2002). Community-level effects of clearcutting and wildfire on shrews, grasshoppers, and ground-dwelling beetles. Diss. 160p.