نتایج جستجو برای: timber

تعداد نتایج: 8181  

2001
David Pearce Francis E. Putz Jerome K. Vanclay

12 The profitability of uncontrolled logging can be a significant obstacle to sustainable forest 13 management, especially in the tropics. Rice et al. (1997) have argued that not only does 14 traditional selective logging provide higher returns but also incurs less damage to forests than 15 sustainable forest management systems that involve harvesting of many species and the creation 16 of larg...

2001
Pekka Leskinen Jyrki Kangas

Timber prices belong to the most important variables affecting the optimality of forest management. On the other hand, forecasting of timber prices is very uncertain. One difficulty when using past time series data in forecasting future timber price development is the possibility of changes in the markets and in the society at large. Expert knowledge can be applied in forecasting of timber pric...

2005
David N. Wear Jeffrey P. Prestemon

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...

2014
Michel Ndjondo Sylvie Gourlet-Fleury Raphaël J Manlay Nestor Laurier Engone Obiang Alfred Ngomanda Claudia Romero Florian Claeys Nicolas Picard

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...

2003
S. H. Rizkalla

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...

2012
J. Timothy Wootton

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...

1998
Jack Lutz

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...

2005
Matthew H. Pelkki

Timber stumpage prices exhibit considerable volatility, which has a tremendous effect on the long-term returns associated with growing timber. Predicting trends in the market occupies a great deal of effort in forest economics research and practice. But what are the possible gains from having the ability to predict the future of timber stumpage markets? On the stand-level, forward-recursive dyn...

2010
Luca Caneparo

The paper presents the computer-aided design and construction of a large glued laminated timber structure in Aosta, Italy. The structure was completely computer modelled with in-house developed software, which considers both torsion and curvature constraints of timber. Further proprietary software was used to develop, on a plane, the shape of each timber layer without torsion and curvature . Th...

2005
D. Li T. Hong J. Yang

In this paper, Chi Lin Nunnery, the imitation of early Tang-Dynasty timber-structure building in Hong Kong, is used as an example to perform 3D model reconstruction and demonstrate the assembling process, as well as make a digital database of buildings. This paper gives an introduction to the features of ancient Chinese timber-structure buildings and also the workflow of 3D reconstruction of an...

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