Spruce regeneration on woody microsites in a subalpine forest in the Western Carpathians

Abstract

The density of Picea abies [L.] Karst. regeneration on different microsites, the quantity and quality of woody microsites, and seedling occurrence probability on stumps and fallen deadwood were studied in a subalpine forest in the Gorce Mountains, part of the western Carpathians, which has been under protection for approximately 30–40 years. Thirty percent of seedlings and 29% of saplings grew on stumps and fallen deadwood, while the remaining regeneration occurred on the forest floor and mounds created by uprooted trees. The occurrence probability of Picea seedlings on fallen deadwood increased with deadwood diameter and decay stage and with the volume of living trees, and decreased with increased density of living trees, sapling density, and land slope. Furthermore, seedlings were more likely to grow on stumps with a greater diameter and in plots with higher sapling density, but less likely to grow on higher stumps. Stumps and fallen deadwood covered about 408 m2/ha of the forest floor, but strongly decomposed logs and those of a diameter exceeding 30 cm, which are the most important for promoting regeneration, took up only about 22 m2/ha. In the studied subalpine forest, which has been protected for 30–40 years, tree regeneration takes place mostly on the forest floor and on stumps. The role of fallen deadwood increases over time as a greater number of suitable logs of sufficient size and decay stage become available.