On March 26, my peers and I visited Fort Tilden, the first of two ecosystems we were to observe.
At this specific site we were interested in the interaction of living and nonliving things in this environmental ecosystem. On April 2, we visited Plumb Beach, our second ecosystem we observed. Both beaches are part of Gateway National Recreation Area. During these lab periods we attentively examined and inspected several sand danes. There are several different kinds of ecosystems. An ecosystem is an area where the living community interacts with the nonliving world.
The two ecosystems I visited were the sand dunes. The sand dunes are mounds of sand that are piled up by the wind. Sand dunes are on coastal or inland areas(Encyclopedia of Plants,1988). The conditions of the sand dunes are quiet harsh due to the high speed winds and intense heat from the sun. There is also very little water available. In fact the main source of water is from the rain(Encyclopedia of Plant,1988).
Because of this, the primary plant is grass. Grass has the flexibility and adaptability which permits it to live in many different situations. Grass have long roots enabling it to get water and nutrients(Scientific American,1974). There are certain adaptations that different plants adopt to, like grass accumulation on the sand dunes. These plants may have similar leaf structures because there they share the common hazard of losing water by evaporation process of transpiration(Scientific American, 1974). Sand dunes like other types of ecosystems are very complex.
The different components such as biotic and abiotic surroundings, greatly effect the population and status of the particular place. Besides this, man plays a major role. If people pollute the environment, no matter how much water and nutrients the organisms receive, they will still be unable to survive. MATERIALS and METHODSAt the two Sand dune ecosystems, my group and I were to investigate the difference in abundance and distribution of plant life within the two ecosystems.
The first one “Fort Tilden”, is an undisturbed sand dune ecosystem. It has been protected from human disturbance by an extensive fence system. The second sand dune “Plumb Beach”, is a disturbed sand dune ecosystem. We also had to compare the abundance of plants in the front and back of the sand dunes and the interdunes.
They may all have a difference abundance of vegetation. We walked across the dunes at both beaches and gazed at the vegetation and species. Our focus at hand was on four particular plants. They were grasses, herbs, shrubs, and trees. My general hypothesis was that the disturbed ecosystem should have a lot less vegetation then that of the undisturbed ecosystem.
When people step on and litter on the sand dunes, they destroy the plants and vegetation. As to the difference of the front and back of dunes, my hypothesis is based on the direction of the wind. The wind causes that there should be less vegetation. DISCUSSION Comparison of the two sand dunesBased on the data I collected in both sand dunes, I did not see a significant difference in plants between the disturbs and undisturbed sand dunes. There were however, a few blow outs which were caused on people stepping on the sand dunes and by all the litter that is found all over the beach. The reason for the fairly large abundance of plants at Plumb Beach ecosystem, must be caused by some other factor then that of Fort Tilden which is undisturbed.
As we know, peoples behavior makes a noticeable affect on plants, e. g. the blow outs. Therefore, it might be the difference in distance of the sand dunes.
The primary sand dune in Plumb Beach is closer to the water, therefore, causes more vegetation or equal to Fort Tilden, even though it is known to be disturbed. Sand Dunes at Fort TildenPrimary dune: The Front of the dune had 15% grass, 5% herbs, 0% shrubs and 0% trees. The back had 45% grass, 15% herbs, 0% shrubs and 0% trees. The difference between front and back must be caused by the water. The water has a lot of salt in it. This makes the front primary dune weaker to grow plants.
Inter dune: This is between the first and second dune. It had 50% grass, 10% herbs, 15% shrubs, 0% trees. The inter dune is more shallow than the actual dune. This means that it is closer to the water under the sand, therefore, it is richer in plants. Second dune: Here we found more of the plants in the front rather than the back.
This would support my hypothesis that if the wind blows on one side there would be less vegetation on that side. In this case the wind is blowing on back of the dune. Inter dune: There is only 5% of grass and herbs, 50% shrubs and 15% trees. This can be compared to the first inter dune just with an abundance of trees and shrubs. Third dune: In general there is more plants in the front then the back. This again would prove my hypothesis that the wind makes it harder for vegetation to grow.
Inter dune: There were 25% grass, 10% herbs, 15% shrubs, and 0% trees. This would again indicate the shallowness of the area. Fort dune: This is a man-made dune. This might be the cause in the difference between this and the previous dunes.
In this dune we find more vegetation in the back than in the front. The man-made dune is structured differently, therefore it is not the same as the other dunes. There was a fresh water pond at Fort Tilden near the fourth dune. Many species come and drink from the water. The water does not evaporate because it is in the shallow area and rain water falls in the pond from the surrounding areas. CONCLUSIONThe above gives numerous reasons and explanation as to why certain vegetation grows and does not grow in certain parts or types of sand dunes.
The main factor however, is caused by human destruction. These activities affect the organisms and life in or on the sand dunes. Although the difference in the abundance between the two sand dunes were not significant, nevertheless, the factor of human destruction is the over righting cause of the difference in plants. This is a major factor that each and every one of us have to remember: “in an environment we are all codependent on each other. “EXTRA CREDITQUESTIONS1) Is there significant difference between the amount of grass on the front and back of the primary dune?2) Is there a significant difference between the amount of grass on the front of dunes numbers 1 and 4?3) Is there a significant difference of amounts of shrubs and trees between interdunes 1 and 2?ANSWERS1) Based on my own data I would hypothesis that there is a significant difference.
Based on my statistical analysis which compared the two groups as follows: The calculated T-value equals . 1542014. The critical value for a level of significant is 2. 23. I therefore accept the null hypothesis, which tells me there is no significant difference. 2) My general hypothesis based on my data would make me conclude that there is no significant difference.
Based on the statistical hypothesis the calculated T-value was . 4432906, and the critical T-value was 2. 23. Based on the T-test rule, I accept the null hypothesis that there is no significant difference in these two front dunes, as my hypothesis indicated. 3) My general hypothesis would be that there is no significant difference.
Based on the statistical analysis we do see a difference. The calculated T-value is 5. 0527 and the critical value is 2. 23. Because the calculated value is larger then the critical T-value we accept the alternate hypothesis and I would conclude that there is a significant difference.
LITERATURE CITED1) Prof. David M. Moor, 1988. Encyclopedia of Plant and Animals. 2) Amos, William H.
, 1974. The Life of a Sand Dune, Scientific American 32:287-293. 3) Gemmell, D. J. Ph. D.
1997. Personal Communication. EXPLANATION OF TABLESThe first four tables show the abundance of four plants in the front and back of the dunes at Fort Tilden. The fifth table demonstrates the percentage of these plants in the inter dunes of Fort Tilden. The sixth table demonstrates the abundance of plants at Plumb Beach.
