A Scandinavian perspective on ecological gradients in north‐west European mires: reply to Wheeler and Proctor

Abstract

In their recent review of gradient relationships in mires, Wheeler & Proctor (2000) question the central paradigm in Scandinavian mire ecology that there are three major gradients in mires, which relate to nutrient richness, water-table depth and proximity to the mire margin (see Sjors 1948; Malmer 1962; 0kland 1989a). Wheeler & Proctor (2000) propose that the simple 'poor-rich' gradient should be replaced by a dual system considering '... [first] variation in pH and concentrations of metallic cations [and, second] variation in the availability of limiting nutrients, primarily phosphorus (P) and nitrogen (N)'. They further suggest that the current practice of using the mineral soil water limit that distinguishes between ombrotrophic and minerotrophically influenced sites 'as a general main division within mires' should be discontinued because this limit 'is not sharp, and cannot be related to consistent differences in either