THEORETICAL-ANALYSIS OF THE FOREST DISEAS E INVENTORY IN LOWER SAXONY

It was shown clearly that the results of the forest disease inventory in Lower Saxony can be interpreted approximately as proportions of for est area covered with trees (leading social classes) of certain diseas e classes. They cannot be interpreted as percentages of trees belongin g to a disease class, ii evaluation is done for a larger range of age classes. Less biased, alternative sampling techniques exist, but they require a larger amount of time for data collection and one of them wo uld even lead to a new sample tree population finishing the existing t ime series of sample trees. It is possible to save costs by reducing t he actual sample grids to a common 4 km x 4 km grid without a remarkab le increase of sampling errors. In spite of the obvious homogeneity of satellite clusters at a sample point, a reduction of the number of sa tellites is not economic because of the time consuming movements betwe en sample points in comparison with the relatively short time spent pe r satellite. Halving the grid for sample points younger than 60 years might be an additional way for saving inventory costs, which needs fur ther discussion.