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Abstract:
Forest management not only affects biodiversity but also might alter ecosystem processes mediated by the organisms, i.e.
herbivory the removal of plant biomass by plant-eating insects and other arthropod groups. Aiming at revealing general
relationships between forest management and herbivory we investigated aboveground arthropod herbivory in 105 plots
dominated by European beech in three different regions in Germany in the sun-exposed canopy of mature beech trees and
on beech saplings in the understorey. We separately assessed damage by different guilds of herbivores, i.e. chewing,
sucking and scraping herbivores, gall-forming insects and mites, and leaf-mining insects. We asked whether herbivory
differs among different forest management regimes (unmanaged, uneven-aged managed, even-aged managed) and
among age-classes within even-aged forests. We further tested for consistency of relationships between regions, strata and
herbivore guilds. On average, almost 80% of beech leaves showed herbivory damage, and about 6% of leaf area was
consumed. Chewing damage was most common, whereas leaf sucking and scraping damage were very rare. Damage was
generally greater in the canopy than in the understorey, in particular for chewing and scraping damage, and the occurrence
of mines. There was little difference in herbivory among differently managed forests and the effects of management on
damage differed among regions, strata and damage types. Covariates such as wood volume, tree density and plant diversity
weakly influenced herbivory, and effects differed between herbivory types. We conclude that despite of the relatively low
number of species attacking beech; arthropod herbivory on beech is generally high. We further conclude that responses of
herbivory to forest management are multifaceted and environmental factors such as forest structure variables affecting in particular microclimatic conditions are more likely to explain the variability in herbivory among beech forest plots.
