Nutrients and autotrophs: variable internal nutrient levels

Abstract

The mathematical formulations of nutrient-limited autotrophic growth used in Chapter 3, the Monod-type growth function and its variations, are based on the assumption that the growth rate depends directly on the pool of available limiting nutrient in solution external to the autotroph. This assumption is not always a good one, at least on short time scales, over which growth may depend directly on the level of nutrient stored internally in the autotroph. Another assumption of Chapter 3 was that a nutrient occurs as a fixed proportion of autotroph biomass. While this assumption makes model analysis easier, it ignores such facts as the widely different nutrient requirements of different species, the different nutrient storage levels between different individuals of the same species in different environments, and the allocations of nutrients to different components of the same plant.