All the Leaves are Brown... or aren't They?
This topic submitted by Zack Hausrath, Erika Merrell, Sarah Price, Molly Thomas (
thomasm8@muohio.edu ) on 10/10/03 .
Introduction:The purpose of this experiment is to determine the cause of leaf color change, and the different factors that affect the rate at which leaves change. The factors that we are testing include the treeÕs environment (whether it be in a forest environment or in the open), as well as the species of the tree. We will be testing five different species of trees: Black Oak, Redbud, Sugar Maple, Honeysuckle, and Ginkgo.
Our hypothesis is that Black Oak trees in the open will change more rapidly than the other species, because their height as compared to the other trees allows them to be more susceptible to sunlight. Drawing from this reasoning, we predict that all trees in the open will change more
quickly than trees in the wooded areas. We also predict that the Sugar Maple will change to a flame red or orange color, and that the Black Oak will change to a tan or brown color. Since we have no previous knowledge of the Redbud, Ginkgo, and Honeysuckle trees, we cannot make predictions
as to what colors they may change to.
Through this experiment, we plan to gain a greater knowledge of the different aspects that affect leaf color change, and in turn to learn more about the trees that we see every day walking around Oxford. This subject is interesting to us because we have always enjoyed the beautiful
colors of the trees during the fall in Southern Ohio, but we have never examined them this closely before. It will be very interesting to find out what causes the trees to transform into such stunning colors, and also what colors each individual species that we test is most likely to change to.
RelevanceIn the spring and summer months, leaves are perpetual cooking machines, creating more and more pigment on a daily basis in order to preserve the color of a certain leaf. The amount of chlorophyll in a leaf masks the other yellow and orange colors that are evident in the leaf. However, as the temperature becomes cooler and light becomes less frequent, the kitchen slows down the production of the green pigment- chlorophyll- and the lesser seen carotenoids, which give the leaves their brighter shades in the fall, emerge for a few short weeks. That's what you see in the fall! It sure is beautiful isn't t?
The change in leaf colors is dependent on many factors, such as precipitation, height, temperature variance, and exposure to light and wind elements. We will be exploring the element of light exposure.
We made a logical decision that the leaves could possibly change quicker if they were out in the open- more exposed to light and wind- with the idea of weathering in mind. We thought of the examples of rocks. If there were two of the same kind of rock placed in different habitats; one under a log, and the other on the edge of a riverbank, which one would be more effected by the elements of light and wind? The river rock, of course! We assume that our selected "in the open" trees- being more exposed to the elements- will change color at a faster rate than the "in forest" trees. We hope to prove this as true!!!!
In relation to the world, we found that leaf color change may become extinct with the distant removal of winter due to global warming, so this phenomenon should be researched and recorded now- while we still can! We would also like to capture the beauty that is found by looking at these trees using photography. We hope that people will be encouraged to spend more time outside, pondering all that nature has to offer us.
We found that Kenji Seiwa's article relates to our project in that the subject being studied- deciduous forests, is also the subject of our project. The information provided on color change within various levels of the vertical structure of the forest is very valuable to our project because of the in-depth research on trees that are not only under, but within the canopy.
Adriana Takahasi's article is important to our project in that there is an intense examintaion of different types of forests. We were able to gain a greater sense of understanding of our forest type while also comparing it to other enviroments.
Shogo Kato's article is important to us because of the research on the effect of leaf color phenology in the canopy and its effect on the phenology of the other levels of the vertical structure. The article also suggests the major impact of canopy phenology on the formation of the forests as whole, and we are very interested in that topic because we have already noticed a difference in leaf change with regards to canopy interaction.
We found J. Cavender-Bares article interesting because the research involves the Oak tree, which is one of the species that we selected for our project. The article focuses also on carbon dioxide levels, but we are mostly interested in how the light levels affected phenology, specifically leaf color changes, among the Oak species.
Michael White's article was very informative in that we found a piece of evidence in varying phenologies between urban and rural environments. Although Miami is basically rural, we thought we could extrapolate our data from say, our local forest vs walkway of busy street, to the region of "country" vs "city".
Marco Archetti's article provided our group with an evolutional perspective on leaf change- the signaling to insects that the trees' leaves will be dying, thus providing the insects with a chance to move their eggs to another habitat in order to hatch before winter.
J. Cavender-Bares' article enhanced our knowledge of leaf color in response to temperature change. A short-term drop in temperature can result in a fifty percent deficit in the photosynthetic rate. Our ability to understand the correlation between temperature and color change was very beneficial to our project.
Pilar Huante's article was very helpful for us because it provided information on tree response to color change under the canopy. There was also an extensive amount of data on light tolerance among smaller trees and how the light affects these trees when the canopy loses its leaves, therefore exposing the subcanopy and herbaceous layer to much light. The trees proved to be much more sensitive to light because of their obvious lack of light throughout the summer season.
Philippe Matile's article was excellent in providing a wider knowledge of why leaves change in a chemical sense. The loss of chlorophyll along with the absorption of carotene contributes to the change in color in the fall season.
Hamilton's article provided our group with even more understanding of tree color changes being used as a defense mechanism towards invasive insects. The bright color warns the insect of leaf, and therefore habitat loss.
Cornelissen's research gave our group a vast amount of knowledge as to the decomposition rate of deciduous trees. The study shows that there seems to be a connection between the rate in coloration and the kind of decomposition in Autumn.
Sparks' article emphasizes the pattern of global warming and how that is shortening the length of leaf color change and also the season of winter. This information is useful to our group because we are testing the time of leaf change from species to species, and the span of time that leaves take to change color seems short enough as it is, let alone if it becomes shorter with the warming of the earth.
** We were unable to post our data sheet on this page as of Thursday, October 9, 2003!!**
Web Resources
Leaf Color Breakdown
-This particular site was extremely useful in describing the process of color change in terms of chemical reactions within the leaf. Good diagram!
Physical Leaf Change
-This site is very interesting in that it not only discusses color change but also changes in height and width during the autumnal months.
Leaf Science Page
-This site is helpful in describing the role of chorophyll in leaf color and how masks certain colors from the naked eye. Very easy to read diagrams!
Simple Leaf Facts
-This site provides information on not only the change in leaf color but the change in the actual tree that contributes to the color appearance.
Leaf Color Variance in Canopy
-This site acknowledges the time difference in leaf change among different parts of a forest's vertical structure.
Specific Research DesignIn this experiment we are observing the color change patterns of 20 trees in the Western Campus area. The twenty trees will consist of five different species: Sugar Maple, Black Oak, Honeysuckle, Redbud, and Gingko. We have located four trees of each species. Two trees of each species are out in the open, and the other two are in the forest. On Sunday, Tuesday, and Thursday of every week until mid November we will go to each tree and photograph its leaves to see if they have changed in any way. We will also use a color wheel to put a name to each leaf color. We will speak more on our methods in the next section.
Materials and MethodologyIn analyzing the color change patterns in several trees, many methods will be applied. To restate, our group will locate four of each of five species of trees (Black Oak, Redbud, Sugar Maple, Honeysuckle, and Gingko). We will find two of each of these species in the open and two in the forest. After we find all 20 trees, we will pinpoint them all on a campus map so they will be easier to locate in the future. On Tuesday, October 7th, we will begin our study. We will visit each tree, determine the present color of each treeÕs leaves on a color wheel, and write the information in a journal. We will also take a picture of each tree with a digital camera to further visualize the color change over time. The pictures will then also go into the journal. We will continue observing the color changes with a color wheel, while we will also take pictures each Tuesday, Thursday, and Sunday, until no leaves remain or until the allotted time runs out. After we finish our study, we will look over the data to determine which species and location of trees lost its leaves the fastest. Based on our results, we will formulate a conclusion.
We will involve the class in a brief hike around our tree observing area and will allow them to observe the difference in leaf color (hopefully we may still have some leaves on the trees by then!)-not only from species to species but from forest and open locations.
Research TimelineSunday, October 5th and Monday, October 6th, 2003ÑBegin looking for five different species of trees. Two of each species must be found in the open and two must be found in a forested area.
Tuesday, October 7thÑDeadline for finding all trees, observing initial colors, and taking first pictures.
Tuesday, Thursday, and Sunday of each week (until all trees are bare or allotted time runs out)ÑContinue observing colors and taking pictures.
Results and ConclusionWe will post our findings as soon as the last leaf falls! We will be there when it happens!
Works CitedSeiwa, Kenji. 1999. "Changes in Leaf Phenology are dependent on Tree Height in Acer mono, a Deciduous Broad-Leaved Tree."Annals of Botany, 83(4): 355-361
Takahasi, Adriana. 2000. "Phenology of Atlantic Rainforest Trees: A Comparative Study." Biotropica, 32(4):811-823
Kato, Shogo. 2002. "Spatial and Seasonal Heterogeneity in Understory Light Conditions Caused by Different Leaf Flushing of Deciduous Overstory Trees." Ecological Research, 17(6): 687-693
Cavender-Bares, J. 2000. "Consequences of Carbon Dioxide and Light Interactions for Leaf Phenology, Growth, and Senescence in Quercus rubra." Global Change Biology, 6(8): 877-887
White, Michael A. 2002. "Satellite Evidence of Phenological Differences Between Urbanized and Rural Areas of Eastern United States Deciduous Broadleaf Forest." Ecosystems, 5(3): 260-273
Archetti, Marco. 2000. "The Origin of Autumn Colours by Coevolution." Journal of Theoretical Biology, 205(4): 625-630
Cavender-Bares, J. 1999. "Chilling-Induced Photoinhibition in Two Oak Species: Are Evergreen Leaves Inherently Better Protected Than Deciduous Trees?" Photosynthetica, 36(4): 587-596
Huante, Pilar. 1997. "Responses to Light Changes in Tropical Deciduous Woody Seedlings with Contrasting Growth Rates." Oecologia, 113(1): 53-66
Matile, Philippe. "Biochemistry of Indian Summer: Physiology of autumnal leaf coloration." Experimental Gerontology, 35(2): 145-158
Hamilton, W.D. 2001. "Autumn Tree colors as a handicap signal." Proceedings: Biological Sciences, 268(1475): 1489-1493
Cornelissen, J.H.C. 2000. "Autumn Leaf Colours as indicators of decomposition rate in Sycamore." Plant and Soil, 225(1/2):33-38
Sparks, T.H. 2002. "Observed Changes in seasons: An overview." International Journal of Climatology, 22(14): 1715-1725
Have fun enjoying the beautiful changes in seasons! We KNOW that we will!! Happy Autumn!
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