(ii) Identify and describe TWO resources that may have been limited. (2 points)
The maximum biomass was achieved at 10 seeds per pot. After that, as
population density increased, biomass decreased. Factors that may have
limited biomass might have included: 1. Competition for soil nutrients. As
root density increased, less nutrients would have been available for growth.
- Competition for light. As the density increased, less light would have been
available for smaller seedlings. - Competition for water. Given a fixed amount of water provided, as plant
density increased, less water would have been available for additional
seedlings.
(iii) Discuss the results obtained from the class for Part I in terms of two
biological laws or principles. (2 points) The effect of intraspecific
competition in plant populations is usually examined by planting the species
over a range of densities. The most common result is that a point is reached
where the mean weight per plant decreases as density increases, so that the
maximum yield approaches some constant value. This result is called the law
of constant yield. The maximum plant productivity of a particular
environment is called the carrying capacity. In this case, the carrying capacity
was reached when the biomass reached 7.0 grams for the size of the pot.
Environmental variables (nutrients, space, water, and light) that restrict the
realized niche are called limiting factors. Liebig’s law of the minimum states
that an organism is most limited by the essential factor that is in least supply.
In terms of survivorship, the radish seeds represent Type III characteristics
that include large amounts of seeds being produced with few surviving, small
size invaders of disturbed environments, and rapid growth.
(b) 5 points maximum (i) Which plant was most affected by the competition