The role of forest structural elements in determining the occurrence of two specialist woodpecker species in the Carpathians, Poland

Abstract

The White-backed Woodpecker (WbW) and the Three-toed Woodpecker (TtW) are rare woodpecker species that inhabit natural old-growth forests with abundant dead wood in Eurasia. We studied stand-related environmental factors subject to forest management (stand structure, tree-species composition, accessibility by humans) in determining the distribution of these two species in mountainous forests of the Polish Carpathians. Data were collected during 2007-2009 at the Beskid Wyspowy Mountains. WbWs preferred multispecies deciduous over pure beech forests, whereas TtWs were most frequently found in spruce-dominated forests. The thresholds of dead and dying wood for WbW presence in managed forests were approximately 50 m3ha 1 and35m3ha respectively, and for TtW were approximately 30 m ha and 115 m ha , respectively. These were 5-8 times higher than in randomly-selected control plots with no woodpeckers. In both cases, lower logging intensity on difficult-to-access slopes and higher amount of dead and dying wood correlated with increasing occupancy probability of the woodpeckers. These results help develop classification criteria for the monitoring of woodpecker habitats over the Natura 2000 network and improve the ecological soundness of forest management guidelines.