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Abstract:
1. For managed temperate forests, conservationists and policymakers favour fine-grained uneven-aged
management over more traditional coarse-grained even-aged management, based on the assumption that
within-stand habitat heterogeneity enhances biodiversity. There is, however, little empirical evidence to
support this assumption. We investigated for the first time how differently grained forest management
systems affect the biodiversity of multiple above- and below-ground taxa across spatial scales.
2. We sampled 15 taxa of animals, plants, fungi and bacteria within the largest contiguous beech forest
landscape of Germany and classified them into functional groups. Selected forest stands have been
managed for more than a century at different spatial grains. The even-aged (coarse-grained management)
and uneven-aged (fine-grained) forests are comparable in spatial arrangement, climate and soil
conditions. These were compared to forests of a nearby national park that have been unmanaged for at
least 20 years. We used diversity accumulation curves to compare γ-diversity for Hill-numbers 0D (species
richness), 1D (Shannon diversity) and 2D (Simpson diversity) between the management systems. Beta
diversity was quantified as multiple-site dissimilarity.
3. Gamma diversity was higher in even-aged than in uneven-aged forests for at least one of the three Hillnumbers
for six taxa (up to 77%), while eight showed no difference. Only bacteria showed the opposite
pattern. Higher γ-diversity in even-aged forests was also found for forest specialists and saproxylic beetles. 4. Between-stand β-diversity was higher in even-aged than in uneven-aged forests for one third (all species)
and half (forest specialists) of all taxa, driven by environmental heterogeneity between age-classes, while
α-diversity showed no directional response across taxa or for forest specialists.
5. Synthesis and applications. Comparing even-aged and uneven-aged forest management in Central
European beech forests, our results show that a mosaic of different age-classes is more important for
regional biodiversity than high within-stand heterogeneity. We suggest reconsidering the current trend of
replacing even-aged management in temperate forests. Instead, the variability of stages and stand structures should be increased to promote landscape scale biodiversity.
