A study of the changes in plant and soil nutrients associated with moorburning and grazing

Abstract

From the Summary: "The work has consisted of the measurement of processes connected with the normal management of grouse moors in the Glen Clova area of Angus. The problems associated with burning have been summarised together with the remits of previous work. The geology and topography of Glen Clova have been described briefly, and the vegetation of the Rottal area of the glen has been described in detail with respect to the particular parts under consideration. A method of ring counts has been used to define the age of Calluna stands. The methods used for analysis of mineral nutrients have been described. One method, Atomic Absorption Spectroscopy, has required extensive calibration and has been described in more detail. It has been shown that the temperature and duration of heath fires depends upon the age of the vegetation. The temperature and duration of a fire determined the loss of nitrogen in the form of smoke.

The temperature of a fire has been shown to affect the solubility of nutrients in ash. Increase in temperature caused a greater release of soluble potassium and calcium, but a decrease in soluble phosphate, The release of mineral nutrients from Calluna leaf litter has been compared with that from ash.

Experiments were instigated to measure the effect of grazing upon the yield and mineral content of Calluna, the greatest effect being found 5 - 10 years after burning. The addition of mixed fertiliser to some of the stands was found to increase the yield and nutrient content of the leaven of Calluna.

Soil samples from 22 stands of Calluna were analysed in November each year, for three years, and the total content of nitrogen, phosphate, potassium, magnesium, calcium and iron estimated. In the first instance other analyses including pH, conductivity, organic carbon and mechanical analysis were performed in order to distinguish between the two soil types present. Significant changes in the nutrient content of the soils have been discussed. A balance sheet of the losses and gains to the ecosystem was prepared to indicate the changes in mineral nutrients. it has been calculated that the potential losses of individual nutrients by leaching, ignition and grazing could be replaced over a period of 15 years from rainwater, with the exception of phosphate which is only present in small quantities in rainwater. The implications of the results have been discussed."