. Bark beetle and wood borer infestation in the Greater Yellowstone Area during four postfire years. Bark beetles Yellowstone National Park; Wood borers Yellowstone National Park; Trees Diseases and pests Yellowstone National Park; Forest fires Yellowstone National Park. 1-20 21-40 41-60 61-80 81-100 Percent Basal Circumference Killed Figure 8—Relationship of pine engraver infes- tation to basal fire injury of lodgepole pine. Total Lodgepole pine mortality 1991 versus 1992 Weighted Regression Analysis 1991 Y = + ** R"2 = a 1991 V1992 1992 V= + ** fl**2 = 20 40
. Bark beetle and wood borer infestation in the Greater Yellowstone Area during four postfire years. Bark beetles Yellowstone National Park; Wood borers Yellowstone National Park; Trees Diseases and pests Yellowstone National Park; Forest fires Yellowstone National Park. 1-20 21-40 41-60 61-80 81-100 Percent Basal Circumference Killed Figure 8—Relationship of pine engraver infes- tation to basal fire injury of lodgepole pine. Total Lodgepole pine mortality 1991 versus 1992 Weighted Regression Analysis 1991 Y = + ** R"2 = a 1991 V1992 1992 V= + ** fl**2 = 20 40 60 Percent Basal Fire Injury Figure 10—Relationship of insect infestation to basal fire injury of lodgepole pine, 1991 versus 1992. Mountain pine beetle infested only a small number of lodgepole pine and did not show much preference for any fire-injury class. Infestation ranged between percent of the trees in the 61 to 80 percent basal injury class to percent of the uninjured tree class (fig. 11), which is consistent with previous measure- ments in the Greater Yellowstone Area (Amman and Ryan 1991) and other studies (Blackman 1931; Hopkins 1905). Mountain pine beetle appears not to respond to trees stressed by fire or drought, since both were present in the Greater Yellowstone Area during this study. An alternative hypothesis is that beetles respond to stressed trees but are unable to build up populations in them. Schmitz (1988) observed mountain pine beetle infesting diseased lodgepole pine when beetle populations were at an endemic level, but brood production was low which prevented buildup of the beetle population. Not until mountain pine beetles infest better quality lodgepole pine (those growing faster and having thicker phloem, which is the food of developing larvae) does the population build to a potential outbreak. Our sample of Douglas-fir (1991 and 1992 surveys combined) showed that percent of all fire-injured trees were infested by insects. Infestat
Size: 2554px × 979px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
