Managing heterogeneity: the importance of grazing and environmental variation on post‐fire succession in heathlands

Abstract

Summary1. Semi-natural habitats have been shaped by human disturbance regimes for centuries. Spatially and temporally heterogeneous land-use practices, such as cutting, burning, grazing and turf-cutting, have resulted in complex mosaic landscapes that are of high priority for conservation in Europe. Contemporary conservation subjects these systems to management regimes that are generally less diverse, in terms of disturbances and finescale temporal and spatial variability, than traditional land use, but the ecological consequences of these simplifications are unclear. 2. We investigated the interactive effects of fire and grazing on plant species composition and diversity along local environmental (moisture) gradients in coastal heathlands. A replicated series of post-fire successions ( n = 12) was initiated in three heathland habitats and the areas subjected to two grazing regimes. Floristic and environmental data were recorded in permanent plots over a 5-year period. Community data were analysed using multivariate ordination techniques (principal components analysis, partial redundancy analyses, and principal response curves) and generalized linear models. 3. Fire induced strong successional trends in the species composition of the heathlands. These trends differed among heathland habitats, and with grazing. Strong interactions between fire, habitat and grazing implied that the effect of grazing on the successional dynamics differed among habitats. Species diversity decreased in the first year after fire but increased beyond the pre-fire levels during succession. This trend was not affected by local environment or grazing, although there were main effect differences in diversity between environments and grazing regimes. 4. Synthesis and applications . Our results demonstrate that the two management practices do not have simple additive effects within the semi-natural system studied, as grazing created ecological opportunities for additional sets of species, increased variability among habitats, and added complexity to the post-fire successional dynamics. In order to preserve diversity, conservation management should thus aim to preserve the level of complexity of the traditional management regimes, both in terms of the actual disturbances (e.g. fire and grazing) as well as the spatial scales at which they are applied. Further, the considerable change in these effects along the local environmental gradient brings into question the efficiency of general management prescriptions, and indicates that local environmental variability should be taken into account in the conservation of semi-natural habitats.

Conserving idealized landscapes: past history, public perception and future management in the New Forest (UK)

“…Such practices are used, for example, in the maintenance of chalk downlands in the UK and for northwest European heathlands (e.g. DEFRA 2002;UKBAP 1994;Vandvik et al 2005;Webb 1998). In the New Forest, human intervention is probably required for any attempt to maintain A&O woodlands in a state similar to that of today.…”

The future of fire management in the British uplands

“…Traditional management techniques can be appropriate for managing threatened species such as hen harriers (Circus cyaneus) (Thirgood et al 2000), and the mosaic of heather habitats produced results in greater diversity at the landscape scale, thus helping to ensure ecosystem robustness to environmental change. In a number of countries with declining areas of heathland, prescribed fire is being researched or re-introduced as an important tool to prevent habitat loss (Sedláková and Chytrý 1999;Vandvik et al 2005, Ascoli et al 2006. While much burning is well-managed by experienced gamekeepers, there is rightly concern that there may also be some extremely poor burning practice.…”

Wall Vegetation in Old Royal Mining Towns in Central Slovakia

“…The use of controlled fire is recognized to be one of the most effective tools for the conservation management of this type of vegetation (Sedláková & Chytrý 1999, Mohamed et al 2006, Klein et al 2009, Davies et al 2010, Måren et al 2010, Harris et al 2011. Nevertheless, Calluna regeneration after fire may be modified by the local environment (Vandvik et al 2005) and also by interactions with encroaching woody species (Manning et al 2004). Several studies have noted that fire provides sites for aspen and birch seed germination (Chantal et al 2005, Borghesio et al 2009) and depletes allelopathic soil compounds (Mugion 1996).…”