Biology 2290F/G—Team Project (Krajnyk Unit, Rm. 331 NCB)
Effect of density on plant growth
Competition is an interaction between two or more organisms when both or all individuals
are negatively affected by the interaction.
That is, individuals perform less well in the
company of a competitor than they would do in its absence.
The consequences of
competition for an individual can be slower growth, lowered or delayed reproduction, less
efficient care of young, serious injury or even death.
The results for a population often
involve lower values for rate of increase and/or decrease in total population size.
Two ‘kinds’ of competition are recognized.
When the interacting organisms belong to the
same species, the interaction is termed intraspecific competition; when they are of different
species, it is referred to as interspecific competition. Interspecific competition, then, is an
interaction between organisms of two species in which both are detrimentally affected.
There are other types of species interactions such as mutualism (both species beneficially
affected), exploitation (one species beneficially affected and the other detrimentally
affected) and amensalism (one species detrimentally affected and the other unaffected).
Competition between plants may be for (1) water, wherever soil moisture is sub-optimal for
even part of the year, (2) nutrients, wherever the concentration of one or more nutrients is
sub-optimal, (3) light, wherever luminous energy is sub-optimal for one plant as a result of
shading by another, (4) heat, wherever in cold environments radiant energy is intercepted
by the canopy of one plant to the detriment of another, (5) CO
, at times in dense
vegetation when photosynthesis is vigorous, (6) oxygen, as with organisms in ponds or
roots in soil, (7) space, as with algae requiring surfaces to attach holdfasts.