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Question: Can prescribed winter burning compensate atmospheric nutrient loads for dry heathlands? What effects does prescribed burning have on nutrient balances, particularly as regards the limiting nutrients N and P? Location: Lueneburg Heath, NW Germany. Methods: In two burning experiments (in 10/15 year old Calluna-stands) nutrient balances (for N, Ca, K, Mg, P) were calculated by analysing nutrient inputs (atmospheric deposition, ash deposition), nutrient stores (above-ground biomass, organic horizon) and nutrient outputs (biomass combustion, leaching). Results: Atmospheric nutrient deposition amounted to 22.8 kg.ha -1 .a -1 for N and < 0.5 kg.ha -1 .a -1 for P. Nutrient stores in the above-ground biomass were 95/197 kg.ha -1 for N and 5/13 kg.ha -1 for P (first/second experiment, respectively). From these stores 90/53% (for N) and 25/14% (for P) were removed by burning. Effects of leaching on nutrient balances were low. In the first two years after burning, leaching rates of N increased by about 4/6 kg.ha -1 , whereas leaching rates of P did not change significantly. Input/output-ratios showed that prescribed burning leads to positive nutrient balances for N, Ca and Mg in the long term. For example, the amounts of N removed by prescribed burning are equivalent to ca. five years of atmospheric inputs. Applied in ten-year cycles, this measure alone cannot prevent N accumulation in the long term. Conclusion: Regarding 10/15 year old Calluna-heaths, we assume that prescribed burning cannot compensate for atmospheric N inputs, thus making long-term changes in the nutritional state inevitable. Therefore, prescribed burning should be applied in combination with high-intensity management measures.

Heathland management is an important tool with which to modify ecosystem impacts caused by atmospheric nutrient deposition. Since changes in nutrient availability as a result of management measures affect the outcomes of heathland succession and species competition, studies on this issue are important from both a nature conservation and management point of view. This study reports the effects of prescribed burning on nutrient availability in dry heathland soils and the nutrient content of the two competing heathland species Calluna vulgaris and Deschampsia flexuosa, with particular reference to N and P. We hypothesise that winter prescribed burning leads to additional N availability, which enhances the importance of P in the context of nutrient limitation in heathland ecosystems. In the nature reserve ''Lueneburg Heath'' (NW Germany) we examined the availability of nutrients in the humus horizons and in the leachate as well as the relevant C:element ratios in Calluna and Deschampsia before and after a burning experiment. Our results show that prescribed burning resulted in drastically increased NH 4 + availability in the O-horizon. We observed only short-term effects (for NO 3 -, PO 4 3-, Mg) and insignificant effects on the availability of other nutrients (K, Ca). As a consequence of an increased nutrient availability in the humus horizons and a limited nutrient uptake by plants after burning, leaching increased significantly for N, Ca, K, and Mg after burning treatment. No significant changes were found in the foliar C:N ratios for either species after prescribed burning, although Deschampsia showed an increased deficiency for all the other nutrients, particularly for P, as expressed by increased foliar C:P and N:P ratios. By contrast, the nutrient content of Calluna did not change significantly, suggesting that prescribed burning favours the competitive capacity of Calluna as against Deschampsia. We assume that water shortage as a result of changes in the microclimate was mainly responsible for the deterioration of the nutrient content of Deschampsia. This gives Calluna a competitive advantage, enabling it to out-compete Deschampsia on burned heathlands, with respect to the key factor P-limitation.

Question: Can prescribed winter burning compensate atmospheric nutrient loads for dry heathlands? What effects does prescribed burning have on nutrient balances, particularly as regards the limiting nutrients N and P? Location: Lueneburg Heath, NW Germany. Methods: In two burning experiments (in 10/15 year old Calluna‐stands) nutrient balances (for N, Ca, K, Mg, P) were calculated by analysing nutrient inputs (atmospheric deposition, ash deposition), nutrient stores (above‐ground biomass, organic horizon) and nutrient outputs (biomass combustion, leaching). Results: Atmospheric nutrient deposition amounted to 22.8 kg.ha‐1.a‐1 for N and < 0.5 kg.ha‐1.a‐1 for P. Nutrient stores in the above‐ground biomass were 95/197 kg.ha‐1 for N and 5/13 kg.ha‐1 for P (first/second experiment, respectively). From these stores 90/53% (for N) and 25/14% (for P) were removed by burning. Effects of leaching on nutrient balances were low. In the first two years after burning, leaching rates of N increased by about 4/6 kg.ha‐1, whereas leaching rates of P did not change significantly. Input/output‐ratios showed that prescribed burning leads to positive nutrient balances for N, Ca and Mg in the long term. For example, the amounts of N removed by prescribed burning are equivalent to ca. five years of atmospheric inputs. Applied in ten‐year cycles, this measure alone cannot prevent N accumulation in the long term. Conclusion: Regarding 10/15 year old Calluna‐heaths, we assume that prescribed burning cannot compensate for atmospheric N inputs, thus making long‐term changes in the nutritional state inevitable. Therefore, prescribed burning should be applied in combination with high‐intensity management measures.