FLORISTIC DIVERSITY IN RELATION TO SOIL CHARACTERISTICS IN A LEAD MINING COMPLEX IN THE PENNINES, ENGLAND.

Adjacent species-rich and species-poor areas of a limestone outcrop were investigated in a heavy metal mining complex on Grassington Moor, Yorkshire, England, to determine reasons for the differences in their floras. Levels of soil lead, zinc, nitrogen, phosphorus and potassium were determined and the activities of the enzymes urease, acid phosphatase and dehydrogenase in the soil were measured. Soil respiration rates were also determined. The percentages of the variation in species-density accounted for by each factor were determined using a step-wise multiple regression technique. Binding of lead in organic forms resulting in low levels of available lead, together with higher levels of the major plant nutrients, were probably the main factors enabling a species-rich community to occur on one part of the outcrop. Possible ways in which the differences in habitat became established are discussed. [ABSTRACT FROM AUTHOR]