Over a Barrel: Nutrient Co-Limitation and Liebig's Law of the Minimum.

Liebig’s Law of the Minimum posits that plant growth is controlled not by the total   resources available, but by the scarcest resource ( the limiting factor), and is portrayed as a barrel with staves of differing heights. When thinking about availability of soil nutrients, only by increasing the amount of the limiting nutrient (the one most scarce in relation to "need") is the growth of a plant (in our case trees or stand of trees) improved. We have demonstrated this repeatedly with short-lived plants, and dramatic examples exist in plantation forestry.  The diagnosis for nutrient limitation in mixed species forests is less straightforward.   Examples are presented of traditional nutrient limitation studies in forests, using information from plantation forests, and the relatively rare information from mixed species natural forests.  The concept of co-limiting nutrients is discussed in light of these examples.