Although species with large area requirements are sometimes used as umbrella species, their general utility as conservation tools is uncertain. We surveyed the species diversity of birds, butterflies, carabids, and forest-floor plants in forest sites across an area (1,600 km2) in which we delineated large breeding home ranges of Northern Goshawk (Accipiter gentilis). We tested whether protection of the home ranges could serve as an effective umbrella to protect sympatric species of the four taxa. We also used an empirical habitat model of occupancy of home range to examine mechanisms by which the Northern Goshawk acts as an umbrella species. Among species richness, abundance, and species composition of the four taxa, only abundance and species composition of birds differed between sites located inside and outside home ranges, which was due to greater abundance of bird species that were prey of Northern Goshawks inside the home ranges. Thus, although home range indicated areas with high abundance of certain bird prey species, it was not effective as an indicator of the species diversity of all four taxa. We also did not find any difference in species richness, abundance, and species composition between sites predicted as occupied and unoccupied using the habitat model. In contrast, when we selected sites on the basis of each habitat variable in the model, habitat variables that selected sites either in agricultural or forested landscapes encompassed sites with high species richness or particular species composition. This result suggests that the low performance of the Northern Goshawk as an umbrella species is due to this species' preference for habitat in both agricultural and forested landscapes. Species that can adjust to changes in habitat conditions may not act as effective umbrella species despite having large home ranges.

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As planted forests expand in area, they are beginning to dominate landscapes as a matrix and cause the fragmentation of remaining natural forests. To understand and predict the responses of biological assemblages to maturing planted landscapes, examining the effects of forest type (natural vs planted) and forest age on such assemblages is particularly important. Therefore, to document the effects of forest type and age on longhorned beetle assemblages, in 2008 we collected beetles in broad-leaved natural and cedar planted forests where beetles had also been collected in 1989. Beetle species composition differed greatly between the two forest types in 1989, whereas this difference was less pronounced in 2008. Species richness and total abundance were higher in natural forests than in planted forests in 1989. In 2008, species richness had decreased in both forest types, but the difference between the two forest types had been maintained. Total abundance was also markedly lower in 2008, and the difference between forest types was much smaller. Although larval host plants were not associated with the responses of species to year (forest age or maturation), beetle species whose larvae fed on either broad-leaved or coniferous trees (or both) exhibited slight preferences for natural forests. These results suggest that longhorned beetle assemblages become impoverished in planted landscapes as the planted matrix matures. Changes in species composition with forest maturation may be difficult to predict based on larval host plants. However, consideration of larval host plants may enable the prediction of changes in species composition caused by the replacement of natural forests by planted forests.

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