Dead trees and protected polypores in unmanaged north-temperate forest stands of Lithuania

The availability of coarse woody debris (CWD) and distribution of dead trees into categories of mortality (dead standing, broken and uprooted) were investigated in north-temperate forests of central Europe (Lithuania). The studied area comprised 188.7 ha and included 18 different stands 40-130 years of age with a variety of tree species (spruce (Picea abies (L.) Karst.), pine (Pinus sylvestris L.), alder (Alnus glutinosa (L.) Gaertn.), birch (Betula pendula Roth and B. pubescens Ehrh.), aspen (Populus tremula L.), oak (Quercus robur L.), forest types (caricus-sphagnum, vaccinium-myrtillus, oxalis, myrtillus-oxalis, caricus-calamagrostis) and edaphic conditions (peaty, sandy, loamy soils of different moisture). The stands were excluded from wood 3 harvesting for at least 30 years. A total of 11 365 dead trees (over 10 cm in DBH) or 6160.7 m(3) of dead wood was found (60.2 trees/ha and 32.6 m(3) /ha). The volume of CWD per hectare was larger in older stands (r(S) = 0.78, P < 0.01). Tree mortality 3 during the last 2 years consisted of 482 trees and 381 m(3), or 1.28 trees/ha x year and 1.01 m(3) /ha x year. In 25-33% of cases it was wind-related. Uprooted and broken trees were of larger DBH than dead standing. The distribution into the categories of mortality was strongly dependent on tree species (chi-square test, d.f. = 10, P = 0). Dead standing dominated in CWD of pine and alder. Broken trees comprised almost a half in CWD of aspen, and about one-third in birch, alder and oak. Uprooting most often occurred in spruce, aspen and birch. Edaphic conditions and stand age had a pronounced impact on distribution into mortality categories for spruce (chi-square test, d.f. = 20, P < 0.00001) and pine (d.f. = 8, P less than or equal to 0.0003). On peat soil, only a minority of trees of both pine and spruce was uprooted, and standing dead prevailed. In CWD of spruce and pine, the proportions of both dead standing and broken decreased and that of uprooted trees increased on mineral soils of higher moisture and bulk density in older stands. By contrast, uprooting in birch and alder occurred less often on more wet sites, where the proportions of standing snags were higher. A total of 41 species of wood-decomposing polypores were found in the study area. Among those, 10 (24%) were of conservation value. (C) 2004 Elsevier B.V. All rights reserved.