Marrs, Robert 
ORCID: 0000-0002-0664-9420, Velle, Luv Guri, Egelkraut, Dagmar, Davies, G Matt, Kaland, Peter Emil and Vandvik, Vigdis
(2021)
The Calluna heathland management cycle.
Figshare.
Abstract
Calluna vulgaris (L.) Hull- dominated heathlands are widespread along the west coast of Europe, from Portugal in the south, to the north of Norway. These habitats emerged millenia ago, and are maintained, through low-intensity management regimes involving prescribed burning, grazing and/or mowing. This figure shows the core Calluna management cycle (black arrows), as well as drivers, outcomes and mitigation measures associated with intensification, or extensification abandonment, of the management regime (grey dashed arrows). After heathland burning, the core Calluna heathland cycle progresses through a pioneer phase, a building phase, and a mature phase. (i) The pioneer phase is characterised by a low-growing and open Calluna canopy, a sparse and shallow bryophyte layer, and relatively high abundance of graminoids and forbs. (ii) In the building phase, Calluna cover is continuous and dominates the vegetation whilst canopy height increases. Bryophytes increase, whilst graminoids and forbs decrease. (iii) In the mature phase, Calluna reaches maximum canopy cover, height, and dominance. Bryophyte cover is dense and often relatively deep. The maximum Calluna canopy height and standing above-ground biomass decreases along the latitudinal bioclimatic gradient, being taller in the warmer south and shorter in the colder north. The duration of each of the phases increases along the same latitudinal gradient, so that the cycling rate is faster in the south compared to the north. The rate of heathland cycling is further affected by the management regime; grazing and/or mowing will generally prolong the duration of each phase and slow down the cycle. However, local variation in land-use exists. For example, building phase heathlands can be maintained by grazing and/or mowing, without burning (top, grey arrows). In more humid settings, horizontal growth, layering and adventitious root formation may also prolong Calluna vigour. Species richness of graminoids and forbs is highly variable, and generally higher in heathlands on relatively calcareous bedrock. Heathlands are threatened both by intensification and extensification of the land-use regime. If management is too intensive, either through overgrazing, too frequent burning, and/or nutrient pollution, heathlands may transform into semi-natural grasslands. Management options to recreate heathlands from such grasslands include biomass or topsoil removal, and adaptation of the grazing and fire regimes. If management intensity is too low, i.e., too low a grazing pressure and/or abandonment of prescribed fire, Calluna will enter the degenerate phase, where the canopy opens, gaps form, bryophytes and lichens reach maximum abundance, and later-successional (tree/woody) species can colonize. Management options to counteract this process includes tree felling, clearing, and the re-introduction of fire. Other threats include heather beetle attacks, spread of invasive alien species, and habitat loss. Acknowledgements: The core heathland cycle is adapted from Watt and Jones (1948), Gimingham (1972), and the figure by Kaland and Isdal as published in Kaland (2014). Heathland status and trends in Europe are summarised in the IPBES-ECA report (IPBES 2018). Translation to Norwegian by Liv Guri Velle and Vigdis Vandvik.
| Item Type: | Article |
|---|---|
| Divisions: | Faculty of Science and Engineering > School of Environmental Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 10 May 2021 10:31 |
| Last Modified: | 18 Apr 2023 12:56 |
| DOI: | 10.6084/m9.figshare.14207354.v1 |
| Open Access URL: | https://doi.org/10.6084/m9.figshare.14207354.v1 |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3121625 |
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