One way in which organisms interact with their surroundings is through competition with other organisms for limited resources in the environment. Ecologists have long considered competition to be one of the most important factors that determines the distribution and abundance of organisms. For these experiments, you will be investigating competitive interactions between seedling plants. We are using plants for practical reasons, most especially because plant growth can be very plastic – that is, the size and shape of a growing plant is strongly determined by its environment, within the confines of genetic growth characteristics. For instance, a pea plant cannot grow into a mighty oak tree, but a pea plant with access to an ideal balance of resources will grow to be much larger and more productive than a pea plant that only has access to very limited resources.