Plasticity of beech (Fagus sylvatica L.) in advance regeneration on soils with chronic nitrogen deposition and low magnesium availability

Quelle: Forstarchiv 85; 5, 155-162 (2014)
Autor(en): BOUMAN O T

Abstract: In central Europe, forest policies aim increasingly at reducing operational canopy disturbances to conserve forests dominated by European beech (Fagus sylvatica L.) and their multiple functions to society. The feasibility of low-disturbance forest management relies on the capacity of ecosystems to sustain advance regeneration of beech. In a non-destructive field experiment, advance regeneration was tested for morphological parameters, total chlorophyll concentration, and foliar nutrients in southern Saarland, Germany. Three sapling height classes were sampled beneath tall deciduous canopy of three stands on Triassic sandstone with strongly acidified soils and chronic N deposition. A fourth stand on Triassic limestone was included for contrasting biogeochemical site conditions. Within a limited size range of beech saplings growing as advance regeneration in deep to moderate shade, saplings showed allometric ontogeny gradually changing shoot morphology; significant effects of crown position on leaf traits; linear relationship between structural and chemical determinants of photosynthetic capacity; differences in the plasticity between morphological and physiological leaf traits; linear relationship between the content of total chlorophyll and N in foliage; and, no discernible effects of a distinct biogeochemical contrast on foliar concentration of nitrogen and magnesium irrespective of sapling size. Advance regeneration for managing beech forests close to the climax stage of natural forest succession appears feasible albeit strong anthropogenic changes of the chemical environment. Rapid optical determination of canopy closure and leaf chlorophyll index should become part of forest ecosystem monitoring for quantitative assessments of sapling photosynthetic capacity and functional analyses of stand dynamics. Future research needs to determine sustainable levels of sapling density in advance regeneration of beech across differing site conditions.

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