Initial ecological change in plant and arthropod community composition after wildfires in designated areas of upland peatlands

Wildfires are an increasing concern due to rising temperatures and incidence of droughts associated with changing climate, poor land management, and direct human interference. Most studies of the impact of fire on temperate heathland and bog examined the consequences of controlled or prescribed burning. Less is known about the impacts of uncontrolled wildfires on sites designated for their conservation value. We examined the initial impact and short-term trajectory (3.5 years) of cool temperate peatland plant and arthropod communities on designated upland sites in Northern Ireland following wildfires, that is, unplanned with respect to where and when they occur, severity, and duration. These near simultaneous wildfires were often due to a failure to control prescribed burns. Wildfires were associated with a loss of blanket bog and heath indicator species. Broad vegetation groups showed initial recovery characterized by a decrease in bare ground and increasing cover of shrub species and bryophytes. However, at a species level, Sphagnum spp and bryophyte communities, which are central to peatland ecosystem functioning, showed no sign of recovery to prefire composition. Rather, bryophyte communities became more divergent over the course of the study and were mainly characterized by increased abundance of the alien pioneer acrocarp Campylopus introflexus. Similarly, composition of arthropod communities (ground beetles and spiders) differed between burnt and unburnt areas and showed no evidence of a return to species composition in unburnt areas. The nationally rare beetle Carabus nitens was more common in the aftermath of wildfire. Synthesis. Whilst, long-term recovery was not investigated, these short-term changes suggest enduring detrimental impacts on the distinctive communities associated with peatlands, primarily through the loss of Sphagnum spp., affecting ecosystem services such as carbon sequestration and water and soil retention. It may not be possible to restore exact prefire species composition of plant and animal communities. We suggest a precautionary approach involving management of upland vegetation, public education, and vigilance, to prevent further wildfires and protect these key upland habitats.

The Response of Spore Germination of Sphagnum Mosses to Single and Combined Fire-Related Cues

Plants in flammable ecosystems have different response strategies to fire, such as increasing germination after exposure to smoke and break of dormancy through heat shock. Peatlands are ecosystems that are more likely to be disturbed by fire with increasing temperatures, but it is not clear how fire affects spore germination of Sphagnum, the dominant plants in peatlands. Here, we hypothesize that Sphagnum spores respond positively to single and combined treatments of moderate heat and smoke (by increased germinability), while spore germinability decreases in response to high temperature. We exposed the Sphagnum spores of four selected species (S. angustifolium, S. fuscum, S. magellanicum and S. squarrosum) collected from peatlands in the Changbai Mountains to heat (40, 60 and 100 °C), on its own and combined with smoke-water treatments. Our results showed that a heat of 100 °C inhibited the spore germination or even killed spores of all species, while spore germination of three (Sphagnumangustifolium, S. fuscum and S. squarrosum) of the four species was promoted by 40 and 60 °C heat compared to the control (20 °C). Hollow species (S. angustifolium and S. squarrosum) showed a stronger positive responsive to heat than hummock species (S. fuscum and S. magellanicum). Sphagnumfuscum spores responded positively to the combined heat and smoke treatment while the other species did not. For the first time, we demonstrate the positive effects of heat on its own and in combination with smoke on spore germination in wetland mosses, which may be important for the establishment and persistence of peatmoss populations after fire.