Management regimes in a coastal heathland –effects on vegetation, nutrient balance, biodiversity and gain of bioenergy

Little is known about nutrient balances and the effect of different management measures on coastal heathlands, which differ in habitat structure and nutrient deposition from the more well-investigated inland heaths. This investigation aims at documenting management effects in a coastal heathland on the island of Hiddensee, northeastern Germany, and to recommend suitable management measures for this heathland type. Soil and vegetation samples were taken, and the development of vegetation was monitored after a number of restoration measures such as sod-cutting, choppering, Heirieten (= manual removal of over-aged Calluna vulgaris) and mowing. Effects from grazing were estimated based on own and literature data, and the possible effect of burning was calculated. Finally, the potential gain of renewable energy was considered. A positive correlation between mineral soil nutrient concentrations and share of grasses in the vegetation indicates increasing grass-encroachment due to eutrophication. Areas with heavily grass-encroached, overaged Calluna developed a vegetation poor in grass cover and with dense, healthy Calluna after sod-cutting, choppering, mowing and Heirieten. Nutrient balance calculations indicate that high-intensity measures (sod-cutting, choppering, Heirieten) counteract 450, 250 and 90 years of nutrient deposition, respectively. A combination of low-intensity measures such as mowing, sheep grazing, burning and regular shrub clearance is recommended to preserve a high biodiversity, to rejuvenate Calluna vegetation and to achieve a balanced nutrient budget in Baltic coastal heathlands, where atmospheric nutrient deposition is far lower than in western Europe. Contrary to inland heathlands, mowing seems to be sufficient even for an initial restoration of heavily grass-encroached areas.