Effects of Fire on the Chemical Status of Herbaceous Communities of the Derbyshire Dales

Abstract

It has previously been demonstrated that sporadic burning is an important influence in determining the nature of some types of limestone grassland in the Derbyshire Dales (Lloyd 1968). There are both short-term effects (seen in the transient abundance of annual and biennial species) and long-term effects (seen in changes in abundance of the dominant grasses and in control of scrub invasion). When a plant community is burned, in addition to the damage to plants and alterations to the physical environment, there are considerable changes in the chemical status of the community. There may be a substantial loss of nutrients in the smoke or in windblown ash and there may also be a release of readily soluble nutrients in the deposited ash. The significance of such chemical changes in herbaceous communities on limestone soils is assessed in this paper. Forest fires usually result in a clear increase in the availability of mineral nutrients (Ahlgren & Ahlgren 1960), but grassland fires are not reported to have so marked an effect, possibly because of the smaller standing crop (Daubenmire 1968). In Britain Allen (1964) and Allen, Evans & Grimshaw (1969) have investigated the chemical aspects of fire in Callunetum, an ericaceous community of acidic, peaty soils. The present study provides a contrast in that the grassland and tall herb communities examined all occur on soils containing free calcium carbonate. Changes in the nutrient status of the plant-soil system after fire have been studied by estimating losses in the smoke, deposition in the ash, retention of soluble nutrients in the soil and by monitoring the nutrient content of vegetation at intervals after a fire.