Effects of Norway spruce monocultures on the structure of bird communities in a submontane-montane forested landscape of Central Germany

Abstract

The present study investigates the effects of Norway spruce plantations on the structure of breeding bird communities in a former beech dominated forested landscape in submontane to montane elevation in Northern Hesse, Germany. Three plots of 16.5 - 19.8 ha were established in each of the following settings: (i) structurally-rich spruce stands with a mosaic of young and old patches, (ii) homogeneously structured mature spruce stands (,monocultures, and (iii) old-growth beech stands which may resemble the potential natural vegetation of the region. Based on a survey of bird territories in summer 1997, 37 species were identified in total as breeding birds in the 9 plots; 17 species occurred in both spruce and beech forests, 6 species were restricted to spruce stands and 12 to beech stands only. Strucrurally-rich spruce stands showed a substantially higher number of bird species per plot area (19 on average) and a higher density of bird territories (30.4 per 10 ha) than either spruce monocultures (11 species, 23.8 territories per lip ha) or beech stands (17 and 21.2, respectively). The breeding bird community of spruce monocultures showed a low species evenness and lacked species that nest in hollows or near the ground. In general, distinct differences exist in the species composition of spruce and beech stands. A number of apical deciduous forest birds are missing in coniferous stands. The pygmy owl (Glaucidium passerinum) mac serve as a good indicator of species-rich bird communities in spruce-dominated landscapes as this species depends on high vertical and horizontal forest heterogeneity. It is concluded that spruce plantations may represent valuable habitats with respect to biodiversity conservation in temperate forests if forest management maintains a small-scale mosaic consisting of patches of different age.