RESPONSES OF FOREST SQUIRRELS TO GROUP-SELECTION TIMBER HARVESTING IN THE CENTRAL SIERRA NEVADA

摘要

Responses of Douglas' squirrels, Tamiasciurus douglasii, and western gray squirrels. Sciurus griseus, to group-selection timber harvesting were studied between 1995-2002 using point counts at four 21 2-ha stands in the central Sierra Nevada, California Each stand had paired and adjacent 10.6-ha treatment and control plots, and four 0 6-ha group-selection harvest units were randomly placed and harvested in each treatment plot in 1998 and 1999. Effects were assessed using the Before-After/Control-lmpact - Pairs (BACIP) design The harvest reduced (P < 0.05) tree basal area (m~2/ha) and density (#/ha) by approximately 30% and snag density by approximately 45% within treatment stands Douglas' squirrel populations differed among stands (P < 0.001) and among treatment and control plots nested within stands (P < 0.079) Douglas' squirrel populations were variously affected in the treatment plots during the post-treatment period because there was interaction (P < 0.065) between the stands and treatment period. Between-plot differences in Douglas' squirrel abundance varied among stands (P = 0.002) and there were greater post-treatment population declines (P = 0.095) in the control plots than treatment plots.