The relationship between density and mean frond weight in monospecific seaweed stands

Abstract

The equation w = Kd^−3/2 (log₁₀ w = log₁₀ K − 1.5 log₁₀ d) (1) defines a boundary condition known as the −3/2 power law¹, above which combinations of mean plant weight and density may not occur. In this equation w is mean above-ground plant dry weight, d is plant density and K is a constant. For developing cohorts of plants combinations of mean weight and density approach and then move parallel to this boundary along lines for which log₁₀ K is typically between 3.5 and 4.3². Annual shoot populations produced by clonal perennial herbs approach, but do not cross the line where log₁₀ K = 4.3 (refs 3, 4). Dense, natural stands of many species with a wide range of growth forms and age distributions lie close to, but below the same line^2,5. Virtually all plant populations for which data are available, therefore, fall below the line given by log₁₀ w = 4.3 − 1.5 log₁₀ d (2) We present here evidence suggesting that this line also defines a boundary condition for mean weight and density combinations in monospecific seaweed stands.