A comparison of regeneration dynamics following gap creation at two geographically contrasting heathland sites

Abstract

Summary1. Lowland Calluna-dominated heathlands are a high priority for conservation in Europe. As an anthropogenic subclimax community they require regular management intervention to maintain their conservation interest. 2. Increasingly, Calluna is disappearing from lowland heathlands and being replaced by grasses, especially in the Netherlands and more recently in south-east England. While Calluna is highly competitive over much of its life cycle, its competitive ability is reduced during the regeneration phase that follows the death of stands or results from management activity. 3. We examined the in¯uence of ®ve factors on regeneration of vegetation in gaps in two broadly similar lowland dry heaths over a 3-year period. These were: geographical location (combining a variety of environmental contrasts); dominant species (Calluna or grasses); management techniques; gap size; and seed source availability. 4. Site location had the greatest eect on patterns of regeneration. Regeneration on the Wirral (north-west England) was faster and more dominated by Calluna than regeneration in Breckland (south-east England), which was dominated by other species including grasses and annual plants. Addition of Calluna seed at the Breckland site failed to increase Calluna cover. It was concluded that climatic or other environmental factors were the most probable cause of poor regeneration. 5. Cover of grasses in regenerating areas was greatest in Breckland, where Deschampsia was able to establish in all gaps where there was a seed source (either in the surrounding vegetation or applied as a treatment). On the Wirral, Deschampsia establishment was limited, even in gaps where a seed source was applied. 6. This work has implications for the conservation management of heathlands, which currently follows a standard prescription throughout the UK. It is suggested that management regimes should be tailored to suit the conditions prevailing at individual sites as regeneration dynamics may be extremely variable.

Long‐term nitrogen additions increase likelihood of climate stress and affect recovery from wildfire in a lowland heath

“…C. introflexus poses a threat to local flora, due to its tendency to form monotonous, dense carpets (Biermann & Daniels, 1997;Vanderpoorten & Goffinet, 2009) which impede germination and establishment of Calluna (Equihua & Usher, 1993). Considered in conjunction with observed negative effects of N deposition on Calluna seedling establishment (Helsper et al, 1983;Britton et al, 2000) and postfire re-establishment of U. minor (this study), increases in abundance of C. introflexus could have important consequences for heathland composition and integrity in areas of high N deposition, particularly as summer fires are predicted to become a more frequent phenomenon in the future (IPCC, 2007).…”

The age of Calluna stands moderates post‐fire regeneration rate and trends in northern Calluna heathlands

“…These species are not a threat in our study area; in fact Pteridium aquilinum is not present at all in the archipelago, encouraging and simplifying the use of burning as part of the management regime here. This illustrates that site-specific considerations are important in deciding the prescription of management and conservation, as emphasized by others (Britton et al 2000;Oberndorfer & Lundholm 2009).…”

Estimating Foliar Nitrogen Concentration of Heather (Calluna vulgaris) from Field and Laboratory Spectra

“…Heathlands, being typically nutrient poor ecosystems, are potentially affected by increased abundance of various forms of nitrogen (Lee and Caporn 1998). Having adapted to low nitrogen supply over the years, the increased availability of nitrogen disrupts competition with other species, such as grasses (Baker et al 2004;Britton et al 2000). In addition, nitrogen directly affects the growth and productivity of heathland lower and higher plants, as well as their ability to cope with stress factors, such as changing climatic conditions (Carroll et al 1999;Power et al 1998).…”