A COMPARATIVE-STUDY OF LEAF NUTRIENT CONCENTRATIONS IN A REGIONAL HERBACEOUS FLORA

Mineral nutrient concentrations were determined in leaves of 83 mostly herbaceous species collected from central England. Most samples were analysed for N, P, K, Ca, Mg, Na, Fe, Al, Mn, Cu and Zn. Concentration s of K, N and P showed similar levels of interspecific variability, wi th the highest concentrations being 6-9 times the lowest. Mg and (espe cially) Ca were much more variable, with the highest concentrations be ing 24 and 49 times the lowest respectively. Only in the case of P con centration was the majority of the variance in the data found at or be low the species level. Most of the Variance in Ca and Mg concentration s was between monocots and dicots. Concentrations of N and P were stro ngly positively correlated with each other. Only Ca and Mn were consis tently associated with soil pH, positively and negatively respectively . Dicots tended to accumulate more Ca and Mn from high soil concentrat ions than did monocots. Concentration of P was significantly positivel y correlated with maximum potential relative growth rate. Plants of wo odland and arable habitats contained high concentrations of P, and tho se of pasture and skeletal habitats contained low concentrations of P. The P:N ratio was higher in plants of arable habitats. Species with P -rich leaves tended to be currently increasing in abundance. The resul ts suggest that plants with nutrient-rich foliage grow quickly, domina te nutrient-rich ecosystems and are generally increasing as a result o f the eutrophication and disturbance arising from human exploitation.