Incidence and Effects of Endemic Populations of Forest Pests in Young Mixed-Conifer Forests of the Sierra Nevada

摘要

Approximately 3,200 trees in young mixed-conifer stands were examined for pestactivity and human-caused or mechanical injuries, and approximately 25 percent of these trees were randomly selected for stem analyses. The examination of trees felled for stem analyses showed that 409 (47 percent) were free of pests and 466 (53 percent) had one or more pest categories. Incense-cedar contained the fewest number of pests with 133 out of 193 trees (69 percent) free of pests, and 60 trees or .31 percent with one or more pests. White fir and ponderosa pine trees had the highest percentage of pests and mechanical injuries: 64 percent (252 trees out of 395), and 62 percent (93 trees out of 151), respectively. Top injury and disease were the two most frequent pest/damage categories recorded among all tree species. White fir blister rust and cedar rust were the most frequent disease recorded on sugar pine and incense-cedar. Bark beetles were an important pest category for white fir, ponderosa pine, and incense-cedars.