ABSTRACT
In ecology, the term growth of an organism or population of organisms refers to the chain of metabolic processes resulting in the increase of organism weight or number of individuals. If x is a variable representing the concentration of organic material (biomass) of a given type, the speed of growth is expressed by x td d (see, e.g., Section 6.4). Unlimited unconstrained growth, with constant growth rate μ, may be described by a linear growth model as
x t
d d
= µ
Of course, such an oversimplified model has little ecological meaning. Indeed, growth depends on several species-specific characteristics and environmental factors, such as age, temperature of the environment, ration of the food ingested, and body size (see Figure 14.1). In general, μ includes several of these factors, for example,
µ µ= …( , , , )T L S
with T the temperature, L the light, and S the substrate (e.g., nutrients). This function is usually expressed as a composition of various limiting factors (see Chapter 15).
