Download Free Decay In Tops Killed By Douglas Fir Tussock Moth In The Blue Mountains Book in PDF and EPUB Free Download. You can read online Decay In Tops Killed By Douglas Fir Tussock Moth In The Blue Mountains and write the review.

Insects multiply. Destruction reigns. There is dismay, followed by outcry, and demands to Authority. Authority remembers its experts or appoints some: they ought to know. The experts advise a Cure. The Cure can be almost anything: holy water from Mecca, a Government Commis sion, a culture of bacteria, poison, prayers denunciatory or tactful, a new god, a trap, a Pied Piper. The Cures have only one thing in common: with a little patience they always work. They have never been known entirely to fail. Likewise they have never been known to prevent the next outbreak. For the cycle of abundance and scarcity has a rhythm of its own, and the Cures are applied just when the plague of insects is going to abate through its own loss of momentum. -Abridged, with insects in place of voles, from C. Elton, 1924, Voles, Mice and Lemmings, with permission of Oxford University Press This book is an enquiry into the "natural rhythms" of insect abundance in forested ecosystems and into the forces that give rise to these rhythms. Forests form unique environ ments for such studies because one can find them growing under relatively natural (pri meval) conditions as well as under the domination of human actions. Also, the slow growth and turnover rates of forested ecosystems enable us to investigate insect popula tion dynamics in a plant environment that remains relatively constant or changes only slowly, this in contrast to agricultural systems, where change is often drastic and frequent.
Mature grand firs (Abies grandis [Dougl. ex D. Don] Lindl.) were sampled in two stands, one cutover and one virgin, in the Little Salmon River drainage in west-central Idaho, to estimate stem volume losses associated with topkilling. Damage to the stands resulted from three outbreaks of western spruce budworm (Choristoneura occidentalis Freeman) in 1922-30, 1952-55, and 1969-78. Stems of the firs were dissected and examined for reductions in height and radial growth, stem deformities, and decay associated with topkills. Merchantable volume losses (to a minimum 4-inch diameter top) were calculated for each outbreak. Greatest volume loss was associated with tops killed by the 1922-30 outbreak. Loss varied widely among the trees and stands sampled. In the cutover stand, which received a sanitation cutting in the late 1960's, firs topkilled by the 1922-30 outbreak averaged losses of 9.5 ft3 (0.3 m3), amounting to 11.1 percent of merchantable stem volume. In the vigin stand, losses averaged 26.3 ft3 (0.3 m3) or 20.5 percent of stem volume. Topkill-associated decays, caused mainly by Indian paint fungus (Echinodontium tinctorium Ell. and Ev.) were responsible for most of this loss. Smaller volume losses were recorded in firs topkilled by the 1952-55 outbreak. Losses per tree averaged 3.3 ft3 (0.1 m3) or 5.4 percent in the cutover stand, and 0.5 ft3 (0.02 m3) or 0.3 percent in the virgin stand. These losses resulted mainly from height growth reductions rather than decay. No merchantable volume losses were recorded for the 1969-78 outbreak.