نتایج جستجو برای: timber trees
تعداد نتایج: 97259 فیلتر نتایج به سال:
The development of the profession and practice of forestry in the United States can be linked to urgent concerns regarding timber shortages in the late 19th century (Williams 1989). These were based largely on perceived failures of forest landowners to protect or invest enough in the productive capacity of their forests (Manthy 1977). The South, as the only major timberproducing region of the U...
BACKGROUND A large proportion of the tropical rain forests of central Africa undergo periodic selective logging for timber harvesting. The REDD+ mechanism could promote less intensive logging if revenue from the additional carbon stored in the forest compensates financially for the reduced timber yield. RESULTS Carbon stocks, and timber yields, and their associated values, were predicted at t...
Improper forest harvesting can potentially degrade forest ecosystem functions and services. Human-assisted regeneration (e.g., planting) is often used to increase the rate of forest recovery and thereby reduce regeneration failure. Seed dispersal is a fundamental ecological process that can also influence spatio-temporal patterns of forest regeneration. In this study, we investigated the relati...
A dramatic increase in railway car axle loads has occurred over the past 50 years. This paper presents the results of an experimental program undertaken at the University of Manitoba to evaluate the structural performance and durability of treated timber bridge ties under different load levels. A portion of a prototype bridge deck, consisting of eight prototype timber ties, was tested under var...
I compared physical, chemical and biological characteristics of nine rivers running through three timber harvest regimes to investigate the effects of land use on river ecosystems, to determine whether these corresponded to changes linked with downstream location, and to compare the response of different types of indicator variables. Physical variables changed with downstream location, but vari...
Questions: Is the introduced timber species Fraxinus uhdei invasive in Hawai‘i? Has logging disturbance facilitated the spread of Fraxinus and other alien species? Location: Windward Mauna Kea, island of Hawai‘i. Methods: We surveyed 29 plots which were established before selective logging of the native tree Acacia koa in 1971 to determine if Fraxinus spread beyond the borders of an existing pl...
In the 1990s the federal forests in the Pacific Northwest underwent the largest shift in management focus since their creation, from providing a sustained yield of timber to conserving biodiversity, with an emphasis on endangered species. Triggered by a legal challenge to the federal protection strategy for the Northern Spotted Owl (Strix occidentalis caurina), this shift was facilitated by a s...
Amazonian várzea forests are characterized by a high diversity of species and adaptations against extended flooding. Waterlogging and submergence can last up to 210 days per year, with a water column of up to 6-7 m. The present paper gives an insight into the current knowledge of morpho-anatomical, phenological and physiological responses to flooding in várzea trees, into patterns of regenerati...
Timber price forecasts are important components of timberland investment analysis. Two techniques are widely used in forecasting. Econometric models use one or more independent variables to predict a dependent variable. Time series analysis or autoregression techniques use the prior observations of a variable, and only those prior observations, to make predictions of that variable. Either techn...
Previous studies in Eucalyptus nitens have revealed favourable genetic correlations exist between acoustic wave velocity (AWV) in standing trees and modulus of elasticity (MOE), which can determine the suitability of trees for structural timber and/or engineered wood products. This study investigates the strength and stability of genetic variation in standing tree AWV across a range of environm...
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