Effects of prescribed burning on plant available nutrients in dry heathland ecosystems

Abstract

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.

Genetic erosion in a stenotopic heathland ground beetle (Coleoptera: Carabidae): a matter of habitat size?

“…The high levels of atmospheric nitrogen deposition require considerable habitat management efforts. Management measures such as grazing, prescribed burning, or sod-cutting, may partly compensate for atmospheric N loads, but are expensive, particularly for large habitat patches Mohamed et al 2006;Müller and Schaltegger 2004;Niemeyer et al 2005).…”

Nutrient leaching in dry heathland ecosystems: effects of atmospheric deposition and management

“…Although one would expect the deposition of basic ash to have raised pH values in the subplots subjected to burning (Forgeard 1990), increased nitrification rates and, thus, liberation of protons may in fact have compensated for a pH increase (Brady and Weil 2002;Mohamed et al 2006). In our experiment, soil pH proved to be an inappropriate indicator of internal turnover processes.…”

“…The significant increase in Ca and Mg leaching in the burned subplots can be attributed to the deposition of ash containing high amounts of Ca and Mg (Niemeyer et al 2005). Since plant uptake was limited and amounts of seepage water increased after burning, post-management leaching of these cations significantly increased (Mohamed et al 2006). The high leaching rates for Ca found for the choppering controls were probably due to slightly higher loam contents at these sites.…”

Response of soil microbial communities to management strategies for enhancing Scots pine (Pinus sylvestris) establishment on heather (Calluna vulgaris) moorland

“…In addition to its successful use at Abernethy Forest for the promotion of Scots pine establishment, the management of heather moorland vegetation by prescribed burning is practiced widely in the UK (Yallop et al 2006). Such burning can influence nutrient availability (Niemeyer et al 2005;Mohamed et al 2007) and has been shown to alter patterns of fungal fruiting at Abernethy Forest, with mycorrhizal taxa observed to fruit more abundantly in the year following burning (Amphlett et al 2006). Until now, however, analysis of the effects of burning on below-ground communities of fungi and microbial activities has been lacking.…”