Occurrence of Shrubs and Herbaceous Vegetation After Clear Cutting Old-Growth Douglas-Fir in the Oregon Cascades (Classic Reprint)

Occurrence of Shrubs and Herbaceous Vegetation After Clear Cutting Old-Growth Douglas-Fir in the Oregon Cascades (Classic Reprint)
Author: Vern P. Yerkes
Publisher: Forgotten Books
Total Pages: 22
Release: 2018-09-09
Genre: Science
ISBN: 9781396041587

Excerpt from Occurrence of Shrubs and Herbaceous Vegetation After Clear Cutting Old-Growth Douglas-Fir in the Oregon Cascades Little consistent difference in Species frequency was evident between various elevation classes. However, only one clear - cut unit was located above 3, 000 feet, and it is believed that with more data from higher elevations a difference may be evident. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Natural Regeneration of Douglas-Fir and Associated Species Using Modified Clear-Cutting Systems in the Oregon Cascades (Classic Reprint)

Natural Regeneration of Douglas-Fir and Associated Species Using Modified Clear-Cutting Systems in the Oregon Cascades (Classic Reprint)
Author: Jerry F. Franklin
Publisher: Forgotten Books
Total Pages: 28
Release: 2017-10-28
Genre: Business & Economics
ISBN: 9781527918481

Excerpt from Natural Regeneration of Douglas-Fir and Associated Species Using Modified Clear-Cutting Systems in the Oregon Cascades The staggered-setting clear cut had only 407 Douglas-fir seedlings per acre and 28 percent of the plots stocked with any Species. Poor stocking is typical of many large clear cuts in this general area. For example, twelve 3 to 5-year-old clear cuts on the experimental forest surveyed in 1956 had an average of only 301 (range 81 to 525) Douglas-fir seed lings per acre. Total plots stocked with any Species averaged 28 (range 11 to 48) percent and plots stocked with Douglas-fir averaged only 24 (range 9 to 36) percent, even though both 1 and 2-year-old seedlings were included in the tally. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Vegetation-environmental Relationships on Two Clearcuts on the Western Slopes of the Oregon Cascades

Vegetation-environmental Relationships on Two Clearcuts on the Western Slopes of the Oregon Cascades
Author: Dawn M. Egeland
Publisher:
Total Pages: 222
Release: 1985
Genre: Douglas fir
ISBN:

Douglas-fir and western hemlock growth and stocking were examined on two neighboring clear-cut watersheds in the Western Cascades of Oregon and related to the intensity of burning and logging disturbance, habitat type, soil type, aspect and the influence of percent cover of both invading Ceanothus species and residual Acer circinatum. The nitrogen content of the surface soil, both total and mineralizable nitrogen, and current and year old Douglas-fir foliar nitrogen contents as percent dry weight were determined. Total nitrogen content was determined by micro-kjeldahl techniques. Mineralizable nitrogen was obtained through anaerobic incubation at 40 C for seven days. Douglas-fir establishment and growth were not limited on severely burned or compacted sites. A strong preference for unburned sites was shown by western hemlock, however. Appreciable Douglas-fir stocking, basal diameters, basal areas and relative densities were supported by Rhma/Gash, Acci/Gash and Cola habitat types. Cola communities also contained the greatest western hemlock stocking and basal area values. Soil type influenced Douglas-fir but not western hemlock. Largest Douglas-fir basal diameters, basal areas and relative densities were found on lateritic soil types. Both Douglas-fir and western hemlock stocking were favored on northerly exposures, though the basal diameters of Douglas-fir were maximized on level and westerly aspects. The percent cover of snowbrush (Ceanothus velutinus), redstem ceanothus (C. sanguineus), deerbrush (C. integerrimus) and vine maple (Acer circinatum) was also examined in relation to site factors. Cover values of all Ceanothus species were highest on disturbed and! or burned sites. For the most part, the three Ceanothus species had varying preferences in terms of habitat type, soil type and aspect expressed as degrees of cover. Percent vine maple cover was only influenced by burning and habitat type, preferring sites undisturbed by burning and Rhma/Gash, Acci/Gash and Acci/Bene communities in which it was also an important component before logging. Nultiple regressions indicated that no site factor, shrub cover or nitrogen variable accounted for more than sixteen percent of the total explained variation in conifer growth or stocking. Site factors could explain the most variation. greater Douglas-fir basal diameters occurred on plots with snowbrush cover, while the presenee of redstem ceanothus was associated with lower Douglas-fir basal diameters, basal areas and relative densities. The presence of Ceanothus species was generally not associated with increased soil or foliar nitrogen content, though Douglas-fir year old needles showed slightly higher mean values on sites with redstem ceanothus. Plots containing vine maple, however, contained greater quantities of mineralizable nitrogen. Nitrogen data indicates that though total soil nitrogen levels appear adequate for Douglas-fir nutrition, mineralizable and foliar nitrogen may be limiting at least during the growing season. While partially ameliorated, results suggest that the effects from harvesting and slash burning have yet to subside, though factors including habitat type, soil type and aspect are becoming increasingly- important in determining the distribution of shrub cover as well as the growth and establishment of Douglas-fir and western hemlock.

Understory Herb and Shrub Responses to Root Trenching, Pre-commercial Thinning, and Canopy Closure in Douglas-fir Forest of the Western Cascades, Oregon

Understory Herb and Shrub Responses to Root Trenching, Pre-commercial Thinning, and Canopy Closure in Douglas-fir Forest of the Western Cascades, Oregon
Author: Briana C. Lindh
Publisher:
Total Pages: 238
Release: 2003
Genre: Forest ecology
ISBN:

This thesis examines factors limiting understory herb presence and flowering in young second-growth Douglas-fir (Pseudotsuga menziesii) forests on the west side of the Cascade Mountains, Oregon, USA. I studied the belowground effects of canopy trees on understory herbs and shrubs in old-growth forests using trenched plots from which tree roots were excluded. Effects of tree density and stand age were tested by comparing the understory community composition of old-growth stands and pre-commercially thinned and unthinned young second-growth stands. I also examined the effect of conifer basal area on understory herb presence and flowering within one young second-growth watershed. In young stands, I focused on three groups of understory herb species: disturbance-responsive (release), forest generalist and old-growth associated. The effects of root trenching on vegetation and soil moisture were tested in closed-canopy and gap locations in two old-growth Douglas-fir (Pseudotsuga menziesii) forests. Ten years after installation, trenched plots averaged 92% total understory cover while untrenched plots averaged 47% cover. Trenched plots under closed canopies were moister than control plots throughout the growing season; the trenching effect on soil moisture became apparent in the generally wetter gaps only at the end of the growing season. Vegetation responses to trenching were concomitantly larger under closed canopies than in gaps. Stands that had been pre-commercially thinned 20 years earlier exhibited understory composition more similar to old growth than did unthinned stands. Thinned stands exhibited higher frequencies, abundances and density of flowering of old-growth associated herbs than did unthinned stands, but lower than did old-growth stands. Forest generalist and release species showed mixed responses to thinning. I used both general linear models and classification and regression tree models to explore the association of herb species presence and flowering with conifer basal area and abiotic variables. Both modeling approaches yielded similar biological insights. Flowering was more sensitive than presence to current stand basal area. Flowering of old-growth associated and release species was negatively correlated with conifer basal area. Linear models allowed clearer hypothesis tests, while tree-based models had greater explanatory power and provided information about interactions between variables.