The Effects of Maple Seed Design on Seed Dispersal
The purpose of this lab is to find out how variations in maple seed's structure affects their dispersal. We believe that seeds with the larger samara wings, and a wide angle between them will increase dispersal distance. We hypothesize that the tree disperses its seeds when they are at minimal water weight. Too heavy a seed will plummet straight to the ground. Too light a seed will drift and not be spun.
This lab idea has gone through many revisions. It has been narrowed down from general seed dispersal to concentrating on one prominent tree species in the area. We chose the maple tree for it's accessible and easily identifiable seeds. The two joined seeds are commonly known as "helicopters" for their wings that propel them into a spiraling motion. Samara is the scientific term for the entire seed structure. We were interested if the samaras design differed amongst the species of maples according to the geographic location (edge of forest vs. open field). Samples were collected and drastic differences in seed structure prompted us to further investigate.
Our specific questions incorporate seed dispersal variables such as the structure of the seed and the strength of the wind affecting the distance that the seed is carried. By collecting the seeds and reenacting the moment of seed release, we hope to gain greater knowledge of seed dispersal, not only for the maple but also for other types of trees as well.
Relevance of your research question:
While researching our topic we found a previous Miami University group study with a completed project similar to our own. They focused on the maple tree and its various modes of dispersal- wind, water, and animals. Seed traps were set up around the tree to measure the distances traveled.
Through research, it was also discovered that the maple population is diminishing. Studying the tree's mechanism of reproduction (the seed) could provide clues as to why this is happening. The maple tree produces an abundance of the seeds to increase the chance of reproduction, but is this enough? Does the maple tree need to adapt its seeds according to its surroundings in order to maximize this chance? We maintain that it does. Through our experiment we hope to discover which structural designs are most advantageous. The maple tree is an example of how adaptive features in nature attempt to ensure reproductive success, therefore ensuring the survival of the species.
Materials and Methods:
To carry out this experiment we will need a fan, a permanent marker, a large white cloth, tape measure, 10-foot ladder, and numerous samples of seeds from different maple trees.
To begin our experiment, we have designated the maple tree on the sidewalk near Peabody as our constant. We have designed an experiment with three components that will be performed on our constant and then repeated on our various other selected maple trees.
The first of these components will test the distance that the seed falls from the trunk of the tree. A white sheet will be placed beneath the tree, spanning from the trunk of the tree outward to approximately 20 feet past the furthest branch. The seed dispersal will be monitored daily for one week. At the end of the week, the number of seeds on the sheet will be counted in increments of 5 feet from the trunk of the tree. This experiment will be repeated for five other trees and the results will be compared to the results of the constant.
The next component of the experiment is a simulation of the seed dispersal due to wind. In preparation, the seeds will need to be dried in a microwave (set on low; time yet to be determined) to remove excess water. We do this based on the assumption that the tree releases the seed when most of the water is removed. The seed will be suspended from a fixed point ten feet above the ground. The fan will be placed on the ladder at this height as well. Turn the fan on to it's medium setting (this will represent an average wind current). The seed will be dropped and carried by the wind current. Measure the displacement of the dropped seed from the midpoint of the base of the ladder and record. Repeat five times for each seed, from each of the five trees.
The third and final component of the experiment will be to observe the samara design of each of the tested trees. The weight of the seeds, the angle between the two wings, the length of the wingspan, and wing shape, will be compared and contrasted to each other. We will use these observations as criterion for analyzing the results of the two previous components of the experiment.
We believe our design is significantly sound because we incorporate a field study as well as a model. The two tests decrease data discrepancies (human error) by supporting one another. We researched the Internet, proposed our idea to our peers, and consulted faculty for further experimental design assistance. A large sampling pool will ensure unbiased results.
We will provide our class with sampling packets. Each packet will contain 5 seeds from each of the 5 maple trees. They will asked to perform the second component of our experiment; simulated seed dispersal. Then the class will be asked to observe and record the various components of seed structure; wing length, span, shape, and the angle between the wings. Equipped with this newfound knowledge they can deduce which seed design is most advantageous for dispersal.
A data sheet with three tables have been supplemented; one for each component of the experiment.
Our experiment will require approximately a week and a half to carry out and may be repeated to increase research accuracy.
Results (Methods for Interpretation):
Utilizing the Stat View program a t-test will be conducted between components one and two of the experiment. The p-value that will be obtained will determine whether the differences in the results are due to chance alone (not significantly different). If the p-value is greater than .05 we will conclude that the differences in the results are not statistically significant. If the p-value is less than .05 then the differences in the results are statistically significant. We will also use histograms to chart the frequency of the seed counts in the first two components of the experiment. We will collate our results with those of the students.
Our results will be displayed in our data table and graphs that will be determine based upon our results. At this point we think that the seed with the longest wing span and the greatest angle will be dispersed farthest from the tree. Diagrams of both experiments will be included.
Discussion and Conclusion:
After we have analyzed our result we expect that we will be faced with additional questions having to with seed dispersal. If we were to investigate this topic further we could also include the various heights of the seeds on the differing maple trees.
Sugar Maple seed production and dissemination.
Maple tree seed dispersal and seed trapping
3. Annual Review of Ecology and Systematic, Vol. 25 (1994) pp.263-292
A Day in the Life of a Seed: Movements and Fates of Seeds and their implications for natural and managed systems
We are still in the process of researching what others have done on this topic. We found a great deal of information in general on sugar and silver maple trees. We will continue to probe scientific journals for more pertinent information.
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