Write an ecological hypothesis that can be tested using this field experiment as a basis. Request that the students write their hypothesis in the lab manual before they begin to collect data. Talk about the importance of statistical replication. The field is not the same throughout the site. It is important to know what happens if you dont do anything.
Controls provide a comparison to evaluate the significance of the results of the treatments.
Look at the block to be sampled with the students before you begin. In most of the blocks, there are obvious differences in size and color in fertilized versus unfertilized, cut and uncut plots. People cut and fertilize their lawns to encourage grasses. Trees will come in to uncut plots. It is more likely to find statistical significance among treatments with more statistical replicates.