Department of Forest and Soil Sciences, Institute of Forest Growth, BOKU University of Natural Resources and Life Sciences, Peter-Jordan-Straße 82, 1190 Vienna, Austria.
Prof. Dr. Hubert Sterba
Department of Forest and Soil Sciences, Institute of Forest Growth, BOKU University of Natural Resources and Life Sciences, Peter-Jordan-Straße 82, 1190 Vienna, Austria.
▶ We examined four individual tree models in Europe: BWIN, Moses, Silva and Prognaus. ▶ We simulated growth of open-grown trees and on research plots for 15 or 30 years. ▶ Height:diameter ratios were correctly predicted by all four models. ▶ Height:diameter ratios were within the bounds of open grown trees and dense stands. ▶ They decreased with age and density; dominant trees had lower ratios than mean trees.
25 April 2008 in Forestry: An International Journal of Forest Research
Sampling procedures within stands for species and diversity indices have been widely discussed. However, little attention has been paid to the assessment of such indices within the framework of forest inventories on the management district level. This study deals with such an inventory comprising 245 angle counts in a 750-ha forest management district at the northern fringe of the Austrian Alps. To calculate spatially explicit indices, the nearest neighbours of the angle count in-trees have to be assessed. The distributions of the indices, their correlations and their ability to discriminate between different stand classes are discussed. It is concluded that these indices are meaningful, because they describe the species composition and the structure of the forest district in the expected way and differ significantly and meaningfully among stand classes which have been classified for silvicultural purposes.
Stem number distributions in uneven-aged forests are assumed to be stable, if they follow special functions, e.g. de Liocourtâs reverse J-shaped breast height diameter distribution. These distributions therefore are frequently regarded as a target in all-aged forests. Intending to convert an even-aged forest or any other forest, not yet exhibiting this sort of equilibrium, towards a steady state forest, the question rises, how to choose an appropriate equilibrium curve and how to achieve this stem number distribution by an appropriate thinning and harvesting schedule. Two stands are investigated: One dominated by Norway spruce (Picea abies), having developed from a 120 year old even-aged stand 25 years ago, after several âtarget diameter thinningsâ. The other one is a mixed species stand of Norway spruce, white fir (Abies alba), larch (Larix europea), common beech (Fagus silvatica), and Scots pine (Pinus sylvestris), having lost its typical uneven-aged structure 20 years ago. These stands were used, together with the distance independent individual tree growth model PrognAus, to reveal that 1) there are more than only one equilibrium curve per stand, 2) not every hypothesised equilibrium can be reached with any stand, 3) an equilibrium in stem number does not necessarily mean a stable species distribution, and 4) growth models provide an excellent help to decide between several equilibrium curves and harvesting schedules to reach them.
9 January 2008 in European Journal of Forest Research
▶ Determination of individual tree leaf area usually is only possible destructively. ▶ Surrogates which can be assessed non-destructively are investigated. ▶ From about 150 trees leaf area is estimated by 3P-branch sampling. ▶ These estimates are best correlated with crown surface area. ▶ Equations to determine individual tree leaf area non-destructively are presented.