BFW-Berichte 142/2008 Vergrößern

BFW-Berichte 142/2008

Gabler K., Schadauer K.: Methods of the Austrian Forest Inventory 2000/02: Origins, approaches, design, sampling, data models, evaluation and calculation of standard error.




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Abstract
This publication of the Department Forest Inventory concentrates on substantial elements regarding the origins of the Austrian Forest Inventories with emphasis on terrestrial data survey and computational interpretation including evaluation and standard error calculation. Historical examples and ancient sampling methods setting the basis for the currently used design of the Austrian Forest Inventory are described. Most of the used volume and form factor functions as well as height increment and D03H models with approaches and regression coefficients developed for each inventory period are presented. The figures for data collection describe the sampling grid of clusters with the sample plots and lines, stand and site characteristics including data on sample trees and measuring tools and units used. Special surveys on regeneration, dead wood and forest infrastructure are described in more detail as they have been surveyed under new aspects only from 1992 onwards and the methods have not yet been completed. Data interpretation includes formulae for the calculation of forest area as well as for values per hectare and for total values of growing stock, increment, harvesting and number of stems. The evaluation of the forest road network is based on the approach by Matérn (1964). To evaluate regeneration data (including browsing damage) a special calculation scheme is used. For lying dead wood (stumps and logs) the calculation is relatively simple. This scheme is susceptible to refinement in the future. Volume calculation of standing dead trees is done in the same way as for the other sample trees. In addition, a few special features of Austrian Forest Inventories such as the "Nullteilung" of areas as well as the "Braun'sche Ansatz" (approach by Braun) is discussed in detail.

Keywords: Forest, forest inventory, cluster sampling, subdivision of plots, line survey, height increment, volume and form factor functions of trees, evaluation and calculation of standard error


Contents


Abbreviations and Symbols
Abstract
Introduction, overview and acknowledgement
Data collection
The sampling unit: the cluster
Sampling grids
Sample plot data survey
Regeneration survey
Dead wood survey
Unusually shaped trees
Assessment of sample trees
Line survey and forest road inventory
Special surveys
Basics of the Austrian Forest Inventory
Main principles of the Austrian Forest Inventory
The Austrian "Waldstandsaufnahme" 1952/56 and the Swedish National Forest Inventory
Some pilot studies and assessments in Austria from 1953 to 1960
The ¿Funktionsstämme¿ and first approaches to get new form factor functions
Data models
Volume and form factor functions for trees in the angle count sampling
Volume and form factor functions for trees in the small circular sampling plot
Regression functions for the upper diameter D03H
Regression functions for the height increment
Calculation of estimates
Forest land cover
Per hectare values and totals
The approach by Braun
Growing stock, increment, harvesting and number of stems
Evaluation of line survey and forest road inventory
Evaluation of regeneration survey
Evaluation of dead wood survey
Remarks to applied methods
Calculation of standard error
Subdivision of sample plots at forest edges and stand boundaries
Possible uncertainties due to too long time differences between successive surveys
Summary
References
A short description of assessed stand and site characteristics
Annex