SEARCH

SEARCH BY CITATION

Keywords:

  • Accipiter gentilis;
  • desired conditions;
  • food webs;
  • forests;
  • habitat;
  • landscape;
  • management;
  • northern goshawk;
  • ponderosa pine

Abstract

Ecosystem-based forest management requires long planning horizons to incorporate forest dynamics — changes resulting from vegetation growth and succession and the periodic resetting of these by natural and anthropogenic disturbances such as fire, wind, insects, and timber harvests. Given these dynamics, ecosystem-based forest management plans should specify desired conditions such as tree species composition, age class, tree density and structure, size and density of snags and course woody debris, and the size, shape, and juxtaposition of trees, groups of trees, and stands in order to create and sustain habitats for wildlife. The management recommendations for the northern goshawk (Accipiter gentilis) in the southwestern United States (hereafter, recommendations; Reynolds et al. 1992) is a management plan designed to conserve this top predator by accounting for factors thought to limit their populations: vegetation structures, foods, predators, and competitors. The recommendations combined coarse- and fine-filter approaches to develop desired habitats for goshawks and their prey in landscapes whose compositions, structures, and patterns were conditioned on the aut- and synecologies of over- and understory plant species in forest ecosystems. Management plans that address all stages of a species' life history, the physical and biological factors limiting its populations, the habitats of other members of its ecological community, and the spatial and temporal dynamics of forests it occupies should be robust to failure (Reynolds et al. 2006a, b). The recommendations have been implemented in National Forests in the southwestern United States since 1996 (USDA Forest Service 1996), but their efficacy at conserving goshawk reproduction and survival has yet to be demonstrated. Recently, Beier et al. (2008) conducted a test of the recommendations and concluded that reproduction of goshawks declined as forest structures in their breeding areas became increasingly similar to those described in the recommendations. Here we show that methods they used to determine similarity to the structural conditions described in the recommendations resulted in inappropriate measures of similarity. We also show that their monitoring of goshawk reproduction on the 13 breeding areas used in their study was insufficient, and show how their insufficient monitoring introduced a systematic bias that reduced the precision of their test even if they had correctly measured similarity. We end by suggesting approaches for determining structural similarity to the goshawk recommendations in ponderosa pine and how to achieve adequate sampling for reproduction on breeding areas. © 2012 The Wildlife Society.