Fire intensity, fire severity and ecosystem response in heathlands: factors affecting the regeneration ofCalluna vulgaris

Abstract

Summary1. Upland heaths in the UK are of significant conservation importance. Large areas are managed through prescribed burning to improve habitat and grazing for red grouse Lagopus lagopus scoticus, deer Cervus elaphus and sheep Ovis aries. Previous research has identified trends in vegetation development following burning, but has not linked this to variation in fire behaviour and severity. 2. We burned 15 experimental fires on an area of Calluna vulgaris-dominated moorland, and recorded pre-and post-fire vegetation structure and composition, fire behaviour characteristics, and several 'proxy measures' of fire severity. 3. We distinguished measures of fire severity, describing the immediate physical effects of burning, from the long-term ecosystem responses of substrate development and Calluna regeneration. Proxy measures of fire severity did not relate strongly to fire behaviour or ecosystem response. 4. Post-fire regeneration was strongly linked to stand age and post-fire substrate type. Fire behaviour and severity had little effect, though fire-induced ground-surface heating may promote Calluna seedling establishment. Vegetative regeneration of Calluna was extremely poor in older stands, as was seedling establishment in areas where the post-fire substrate was dominated by live or dead pleurocarpous moss mats. 5. Synthesis and applications. Significant nonlinearities exist in fire severity on heathlands, with step changes related to the depth and moisture content of moss ⁄ litter layers and peat. Younger stands, less than c. 30 cm tall, should be the focus of management if the objective is to maximize Calluna regeneration. Burning older and uneven-aged stands is discouraged except for the purposes of fire hazard management. Managers should develop landscape-level burn plans to target burning effectively and create diverse fire regimes.

Burned Area Detection and Burn Severity Assessment of a Heathland Fire in Belgium Using Airborne Imaging Spectroscopy (APEX)

“…Heathlands in Europe are highly valued as habitats for biodiversity conservation, as relict landscapes of European heritage and as prime leisure areas [1][2][3][4][5]. Most remaining heathlands are now protected under the European Habitats Directive (92/43/EEC), the European Birds Directive (2009/147/EC), or under national legislation.…”

“…Most remaining heathlands are now protected under the European Habitats Directive (92/43/EEC), the European Birds Directive (2009/147/EC), or under national legislation. Although prescribed burning is used as a management tool in many heathlands [4,[6][7][8][9][10], uncontrolled wildfires are a major threat to heathland habitats (e.g., [1,11,12]), with potentially devastating effects. In the short-term, heath fires partially or completely remove the vegetation layer and litter [5,11], thereby destroying the typical habitats and associated fauna.…”

Procesindicatoren PAS : rapportage 2016

“…Er kan kort na het branden een versnelling van de mineralisatie plaatsvinden, waardoor er tijdelijk een verhoogde nutriëntenbeschikbaarheid kan ontstaan (Kemmers et al 2005a, Davies et al 2010. Analyses en veldbeschrijving dienen voor en na de ingreep plaats te vinden en eventueel na vijf jaar herhaald worden.…”

Sphagnum abundance and photosynthetic capacity show rapid short-term recovery following managed burning

“…To measure moss consumption, we assessed changes in moss layer depth using five metal "duff spikes" (Davies et al 2010) per plot. A visual estimation of the cover of individual Sphagnum species (to the nearest 1%, using a 1 m × 1 m quadrat placed centrally in each plot) was estimated on September 2015.…”

“…In bogs with high Sphagnum cover, low severity fires, where surface moisture content (top 2 cm) of the moss and litter layer is >200-300% (Grau-Andrés et al In Press), could help maintain high Sphagnum abundance. At low fire severities, consumption of the bryophyte layer is minimal, and Calluna regeneration, especially in old stands where resprouting capacity is low (Hobbs and Gimingham 1984), may be slow given the limited establishment of Calluna seedlings on moss substrates (Davies et al 2010). Furthermore, burning in spring rather than in autumn could result in faster post-fire Sphagnum recovery due to warmer temperatures and improved light quality (Taylor et al 2017).…”