Student Observation of the Marl Prairie Ecosystems/ Marl Prairie/ Student Observation Marl Prairie 3/17/02    Photographed by: Kelly McWilliams

Descriptive Information Time: early afternoon Weather: hot and sunny Observations Scattered throughout the marl prairie there were groups of trees ands shrubs called hammocks. These trees form domes, with the shortest trees growing on the edges and the tallest trees growing in the middle. Hammocks are formed on limestone outcroppongs, which are higher than the surrounding area and therefore not as wet. The hammock was surrounded by sawgrass. There was also a ring of deeper water around the taller saw grass. The hammock we observed had a road cutting through the center of it. It consisted of taller slash pine trees with shorter mahogony trees growing underneath. This type of hammock depends on fire to keep the undergrowth of mahogony trees at bay. If there is no fire, the mahogony trees gradually choke out the slash pines and take over. Grasses Several species of grasses, trees and shrubs grow thickly in the hanmmock. These are a few of the species we observed: Saw grass: The grass here is much taller (aprox. 4 ft) near the hammock than out in the open prairie. This is the normal height for this grass. It grows in a tall ring around the hammock, and also inside it. However, inside, it is sparse and short. Trees Slash Pine (Pinus elliottii): The highest tree we observed was 40-50 feet tall and located in the middle of the hammock. The slash pines has tall, relatively thin trunks. Their bark was in large rectangular pieces. All the branches and leaves were located at the top third of the tree. Needles were about 8 inches long and in groups of three. The egg-shaped cones were and about 6 in. long. The slash pines didnÕt cluster thickly in this hammock, but had an average of about 10 feet between trees. These trees were closer together towards the center of the hammock. Saw Palmetto (Serenoa repens): These trees were clustrered between pine trees. They were 5-6 feet tall with leaves about 3 feet long. The leaves were arranged in a fan-shape and deeply palmated (Audubon 107). The truncks grow sprawled along the ground. The saw palmetto has small barbs on its stems and trunck. These barbs are larger and sharper on older growth. These plants were scattered all throughout the hammock. Mahogany (Swietenia mahagoni): These trees grew thickly between the slash pine. Their leaves are 7 inches long and pinnately compound with 8-20 2 1/2 in. pointed leaves. They have star-shaped, yellow flowers from June to August, and 4 in., pear-shaped brown fruit (Audubon 124). The tallest mahogany we observed was about 15-20 ft. tall, which is relatively short considering that mahoganies can grow to be 40 ft. tall. These trees were beginning to take over the hammock since there hasnÕt been a fire for several years.