登入選單
返回Google圖書搜尋
Six-year Beechnut Production in New Hampshire
William B. Leak
出版U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station, 1993
URLhttp://books.google.com.hk/books?id=ioJ_i-cYsugC&hl=&source=gbs_api
EBookFULL_PUBLIC_DOMAIN
註釋Beechnut production and losses were studied over a 6-year period in 41 northern hardwood stands ranging in age from 10 to 140 years. Production increased consistently with stand age or d.b.h. of dominant trees and with percentage of basal area composed of beech. Losses to insects, rodents, and birds before the seed reached the ground ranged from 24 to 100 percent; insects caused the greatest losses. A good seed year occurred about every third year.