Ableitung des Sturmwurfrisikos aus Luftbildzeitreihen : Workshop Sturmwurfforschung

1999

S. 18-29

6 Lit. Ang.

Unselbständiges Werk

200058905

For the survey of the extent and the distribution of spruce stands in the northern Alpine foreland satellite photographs were analysed. On the base of this investigation two small areas in upper Austria (near Vöcklabruck and Lambach) were selected for the investigation of stand history by analysis aerial photograph time series. The target of this investigation is to get information about stands during the last 40 years regarding its stage of development and tree species composition as well as its topology. In this region color infrared aerial photograph are available from the year 1994 as well as black and white aerial photograph of 1969 1954. Stands were defined and the data were determined by visual interpretation from these pictures. Altogether a surface of 2125 hectars (Vöcklabruck 1290 hectars and Lambach 835 hectars) were processed. The stand development of the last 40 years was reconstructed by the fusion of the stand structure. During the observation period only small areas were damaged by storms, snown or insects, although the surrounding area was affected by wind fall in this period several times. This is a remarkable result, because in this area for more than 40 years wide pure spruce stand of timber and old stands occur, which must have a high stand risk. In the area Lambach occured 1994 wide young-growth and thicket, which came out from disasters. The analysis of the stand history resulted in that pure stands and mixed stands were affected by the disasters in same type. The method of the analysis of historical aerial photographs for the reconstruction of the individual stand history worked well in the recent project.