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

Abstract

Questions: Does stand age influence the direction and rate of post‐fire successional dynamics in coastal Calluna heaths and can old degraded heath vegetation be restored through reintroduction of fire? Location: Coastal heaths in the Tarva archipelago, central Norway. Methods: We investigated revegetation dynamics after experimental fires set in young (8 years since last fire) and old (>50 years since last fire) grazed heath stands. A repeated measures design was used, with floristic data recorded in permanent plots in the post‐fire successions (n=12) over a 7‐year period. The data were analysed using multivariate ordination techniques (PCA, RDA and PRC) and mixed effects models. Results: The age of Calluna stands strongly influenced post‐fire succession, different trends due to age explained 10.4% of variation in floristic data. Young heath showed faster succession towards pre‐fire community composition than old heath, and this could partially be explained by succession‐related factors: young heath had lower cover of mosses and lichens in the pre‐burned vegetation, and lower cover of litter early in succession. Young heath had a less pronounced overall community response to fire than old heath. Vegetative regeneration of C. vulgaris was absent in both old and young heath, but Calluna still re‐established as the dominant species within 5–7 years in both young and old stands. Regeneration dynamics were also affected by habitat conditions, different trends due to habitat explained 6% of variation. Conclusions: Our study demonstrates that old stands do develop characteristic heathland vegetation and structure after fire, and while potential invasives into the system such as trees and rhizomatous species are present, they do not impair Calluna regeneration or vegetation development towards the target heathland community composition and structure. Further, as our young stands are only in their second fire rotation after restoration, we suggest that characteristic dynamics of managed heathlands can re‐establish relatively rapidly, even in severely degenerated sites (>50 years since last fire). Site‐specific factors also need to be considered. We conclude that there is restoration potential in old heaths, despite slow dynamics in the first rotation.

Matrix modelling of prescribed burning in Calluna vulgaris‐dominated moorland: short burning rotations minimize carbon loss at increased wildfire frequencies

“…) or 5–7 years where regeneration is from seed. Furthermore, regeneration characteristics of young heather can be re‐established after only two rotations following restoration from degenerate condition (Velle, Nilsen & Vandvik ). While conditions are different at the site considered here to those in Velle's study, the vegetation is productive with active layering and is likely to show rapid regeneration.…”

“…Calluna is a fire-adapted species and shows increased regeneration from seed in response to regular fire, provided that temperatures and exposure times do not exceed lethal values (e.g. Nilsen, Johansen & Velle 2005;M aren et al 2010;Velle, Nilsen & Vandvik 2012). Following burning, Calluna can also regenerate by vegetative means, which may be more rapid than seed regeneration, but is reduced when plants older than 15-20 years are burned (e.g.…”

“…Following burning, Calluna can also regenerate by vegetative means, which may be more rapid than seed regeneration, but is reduced when plants older than 15-20 years are burned (e.g. Miller & Miles 1970;Hobbs & Gimingham 1984b;Davies et al 2010) and may be absent in some regions, for example northern European heathlands (Nilsen, Johansen & Velle 2005;Velle, Nilsen & Vandvik 2012) and parts of lowland Britain (Marrs 1986). Where vegetative regeneration is suppressed, regeneration from seed may result in a lag period of little or no growth before germination and establishment (Grant 1968), although other studies have observed seed regeneration within a year of burning (e.g.…”

Experimental evidence from Cantabrian mountain heathlands suggests new recommendations for management of Vaccinium myrtillus L

“…In recent decades, the area covered by these habitats has decreased considerably, mainly due to changes in management (Diemont et al 1996;Webb 1998), grazing pressures (Iason and Hester 1993;Pakeman et al 2003) and probably also due to increased atmospheric nitrogen deposition (de Smidt 1995;Strandberg and Johansson 1999). Given the strong influence of human activities on European heathlands, there is great interest in developing management actions to preserve the characteristic species of these habitats and their structural vegetation (Calvo et al 2007;Fottner et al 2007;Celaya et al 2010;Velle et al 2012).…”

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

“…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.…”