Use a field guide and try to identify the various plants. Try ant tracking - place the crumbs of a chocolate chip cookie on the forest floor and wait for ants to come. See how long before the ant returns with helpers. Try to follow the ants back to their nest. Ants lay chemical trails that help them find their way back to the nest.
Many plants depend on insects for pollination.
Try sitting near a plant and watch to see what types of animals come to it. Look for signs of insect damage on the leaves of plants. Some plants spread by sending out underground roots that develop into new stems. Typically plants that spread in this way grow in clumps. Look for clumps as you explore the pasture.