Articles containing the keyword 'mathematical models'

Linear programming was used to analyse the land use alternatives in the Debre Birhan Fuelwood Plantation area, in the central highlands of Ethiopia. The region represents a rural, high-altitude area, where the main land uses are grazing and cultivation of barley, wheat and pulses. To alleviate fuelwood shortage, large plantations of Eucalyptus globulus Labill. have been established. Livestock has traditionally used the major part of the production capacity of the sites. A decrease in the number of cattle would facilitate a considerable increase in the production of cereals, pulses, fuelwood and construction timber. The optimal share of the land for arable crops, grazing and tree plantations would be about 40, 45 and 15% respectively.

The PDF includes an abstract in Finnish.

• Pukkala, E-mail: tp@mm.unknown
• Pohjonen, E-mail: vp@mm.unknown

In the original set of equations derived by regression analysis, relative-height diameters (endogenous variables) are presented as nonlinear functions of the other relative-height diameters and of the height of the tree (an exogenous variable). Any of the original equations can be replaced by an interpolation formula which links a measured diameter to the four closest relative-height diameters. The solution of the simultaneous equation model yields 10 relative-height diameters. Intermediate values are obtained to avoid biases due to the nonlinearity of the simultaneous model equations.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown
• Varmola, E-mail: mv@mm.unknown

A simultaneous equation model to determine taper curve for Scots pine is presented. The diameters at relative heights are endogenous variables and height an exogenous variable. Any equations may be substituted by the measured value of diameter. Solution of the system of equations yields 11 diameters at relative heights. Intermediate values are obtained by interpolation. Interpolation allows the use of diameters measured at absolute heights, too.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown
• Saramäki, E-mail: ms@mm.unknown
• Varmola, E-mail: mv@mm.unknown

• Dzierzon, Institut für Forstliche Biometrie und Informatik, Universität Göttingen, Büsgenweg 4, D-37077 Göttingen, Germany E-mail: hdzierz@gwdg.de
• Sievänen, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: rs@nn.fi
• Kurth, Institut für Informatik, Brandenburgische Technische Universität Cottbus, P.O. Box 101344, D-03013 Cottbus, Germany E-mail: wk@nn.de
• Perttunen, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: jp@nn.fi
• Sloboda, Institut für Forstliche Biometrie und Informatik, Universität Göttingen, Büsgenweg 4, D-37077 Göttingen, Germany E-mail: bs@nn.de