501.
The watersheds of the rivers Enns and Steyer border the Reichraminger Hintergebirge. This area has a long tradition in the iron processing industry. Because mineral coal was not available, charcoal has been produced for the iron industry for the past 500 years, leading to a heavy exploitation of the vast forests (180 km
2).
From the logging sites in the mountains the timber had to be transported up to 12 km to the forges in the lowland. Most of the small rivers had insufficient water to drift logs efficiently. Therefore, at gorges or at places where there were narrow steep sided valleys wooden dams (klausen) were built to block the water, using the first cut trees of a newly targeted harvesting area. By abruptly opening the dams, the rapid flow of the raised water level carried the logs to the next klausen. Up to seven klausen were built in a valley before the rechen (rake-like grids within the river to collect the logs) of the Enns and Steyer were reached.
To reconstruct the history of log drifting in the Reichraminger Hintergebirge, 33 klausen and rechen were visited and dendrochronologically sampled. The remaining wood of the dam constructions showed progressive stages of degradation, and in some cases only a few logs remained preserved under the water. With cores from living trees added to the dataset, master chronologies were established for spruce (576 years), fir (569 years) and larch (342 years). The construction history of the klausen can be sequentially traced back to 1563 AD. The time spans of the individual chronologies varied between 40 and 392 years. All available conifer species were utilized to build the dams, except during the 19th century, when the most suitable species - larch - was used to a higher degree. 相似文献