Vorkommen des Weissrückenspechts Dendrocopos leucotos und Waldnutzung in Nordbünden.
(von 1994 bis 2006 vergeben)
Bestandsentwicklung, Reviere, Dichte, Winter, Lebensraum, Habitatqualität, Höhenverbreitung, Waldzustand, Forstwirtschaft, Altholz, Totholz, Waldbewirtschaftung, Schutzwald, Naturwaldreservate, Altholzinseln, Biotopbäume
Prättigau, Churer Rheintal, Graubünden, Schweiz
Occurrence of White-backed Woodpecker Dendrocopos leucotos and forest use in northern Grisons. From 1997 to 2019, a systematic investigation for White-backed Woodpecker occurrences was carried out in a 254 km2 study area in the Prättigau and Rhine Valley near Chur. The area is limited to the colline to upper-montane altitudinal range between 490 and 1550 m a.s.l. and contains 54 % forest. The investigation concentrated on 37 potentially suitable areas characterised by a large supply of deadwood and old trees with a structurally rich habitus, covering 21.98 km2. White-backed Woodpeckers have been recorded in 21 of these areas. However, many areas were irregularly occupied. A maximum of 9 simultaneously occupied areas were verified in one year. Apparently, there were also roving White-backed Woodpeckers. The total population is estimated at a maximum of 11–14 pairs, which is obviously subject to considerable fluctuations. The observation series indicates a slight increase during the survey, but only to the extent of one newly populated area per 6–15 years. The species was also found in winter in the breeding areas.
Statistics on wood logging and data from the regional forest inventory show that only about one third of the timber growth in the presently occupied forests has been used for 60 years, resulting in significantly higher deadwood stocks than in the surrounding forests. The occupied forests can be characterized as being in the mature optimum phase with the beginning of decay. Considered at large scale, the supply of deadwood at the end of the study period was, however, obviously still too small to maintain a stable population. Presumably there are small-scale deadwood accumulations that ensure the survival of the species in the northern Grisons. However, it is also possible that the deadwood, which has only emerged in recent decades, is still too sparsely populated by arthropods.
The example of the North Grisons shows that the application of the principles of near-natural forestry alone is not enough to secure White-backed Woodpecker habitats. More far-reaching measures are needed to ensure that a sufficient amount of deadwood is continuously being created in managed forests. The establishment of a network of natural forest reserves, old-growth patches and habitat trees, as is currently happening in the canton of Grisons, will make a significant contribution to this. The White-backed Woodpecker is only one of many species that depend on a high deadwood supply.
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