The Ecological Significance of Fire in Limestone Grassland Communities of the Derbyshire Dales

• Published in: The Journal of ecology 1968-11, Vol.56 (3), p.811-826
• Main Author: Lloyd, P. S.
• Format: Article
• Language: English
• Subjects: Forest fires; Grasses; Grassland fires; Grassland soils; Herbs; Limestone grasslands; Orchard soils; Seedlings; Soil erosion; Vegetation
• ISSN: 0022-0477; 1365-2745
• DOI: 10.2307/2258108

Fire in limestone grassland communities in the Peak district of Derbyshire is shown to occur widely within the area, predominantly in communities which are not or are only slightly grazed. Three such communities are distinguished and are described in outline: Festuca ovina-Helictotrichon pratense grassland, Agrostis tenuis-Anthoxanthum odoratum grassland and Agrostis tenuis-Holcus lanatus grassland. Most of the observations and experiments reported have been made on the first of these communities, but in outline the conclusions reached can be applied to the other communities. In these communities spring fires occur sporadically and destroy most of the above-ground vegetation. The proportion of bare ground is thus greatly increased and it gradually decreases over a period of 3-4 years after the fire. The heat of the fire does not penetrate deeply into the soil although surface temperatures have been recorded of up to 400° C. Subsequent to the fire, water relations of the vegetation do not appear to be significantly affected, but surface soil temperatures are a few degrees higher than in unburned vegetation. As the community regenerates after fire there is increased representation of short-lived species and the relative proportions of the more frequent species may be altered. Invading woody plants are severely checked though rarely killed outright. Soil erosion is normally slight but on occasion may be severe and the nature of the vegetation is then radically changed. Annually burned tall herb communities appear to be in balance with a spring burning regime as the fires occur before growth resumes in the spring, at a time when the bulk of the reserves of the plants are underground. In the absence of grazing periodic spring fires in grassland communities have the effect of maintaining the floristic diversity of the communities and checking scrub invasion. Only rarely do fires appear to be detrimental to the communities in which they occur.