Rate of Color Change in Leaves
By Karla Lockhart, Lauren Matus, Corinne Schwager, and Stasia Czech
In studying the color change of leaves on trees, we will be comparing the rate in which the leaves change color in four different species of trees: maples, oaks, ashes, and sweet gums. The purpose of this lab is to determine the rate at which the tree begins in the color changing process and to compare how long it takes the four species of trees to fully change from green, through the color spectrum (red, yellow, brown), until they fall- assuming they fall within a two month period of time. We predicted that the species of trees will change a variety of colors at different rates. Specifically, the maple trees may turn to a deep reddish-purple, while the oaks could possibly turn red or brown. Ashes may turn from green directly to brown, and drop. Finally, we predict that the sweet gum trees will beautifully go through the color spectrum. We made these predictions based on research and our own experiences in nature.
There are three factors that influence leaf color. They are: leaf pigment, length of night and weather ( Lanner 3 ). The length of night is an important factor in deciding the timing of leaf color change. As nights grow longer and cooler, biochemical processes in the leaf cause it to change color. Chlorophyll gives leaves their green color. This enables the plants to use sunlight through photosynthesis and produce sugar (Lanner 3). Carotenoids, another pigment, has many colors in it such as yellow, orange, and brown. These colors are found in certain types of plants such as bananas and corn ( Lanner 4 ). The third pigment that is important for the color changing process is anthocyanins. It is water soluble and is shown through the leaf cell. Some things that have anthocyanins are cranberries, grapes and cherries ( Lanner 3 ). All of these pigments are very important for the leaf changing process. Both chlorophyll and carotenoids are in the leaf's cell throughout the growing season ( Lanner 4 ). During the autumn season anthocyanin is predominant because there is more bright light and excess plant sugar in the cells ( Marten 2 ). Through the growing season the chlorophyll is being produced and then broken down, so the leaf continues to stay green. During the autumn season as the nights get longer the plant has a harder time producing chlorophyll. Eventually, all of the chlorophyll is stored in the tree and the changing of the colors begins ( Marten 2).
Weather may also have an affect on the color change. Temperature and moisture are the main influences in the appearance of the leaf ( Lanner 2 ). To bring about the most vivid array of color, the best times to witness this change is during a continual pattern of warm, sunny days and cool, crisp but not freezing nights (Bell and Lindsey 4 ). During the days when it is hot there is a lot of sugar produced, but at night when it is cold the sugar stays in the veins of the leaf and can not go anywhere. Therefore, because the sugar is still in the leaf it produces a brilliant spectrum of colors ( Marten 3 ).
The soil can also be another variable because the moisture can vary from year to year drastically. When there is a severe drought the leaf color can change and be behind by a few weeks ( Bell and Lindsey 3). When there is a warm period it lowers the intensity of the color in the leaves (Ringel 1 ). The best type of temperature is warm wet spring, good summer weather, sunny fall days with cool nights show the best color in the leaf (Bell and Lindsey 4 ).
Our study of leaf change will take place over a two month period of time. We have four people in our group, therefore we each took a different species of tree, picked four different trees within that species and are making observations. Lauren is observing maples, Cory chose sweet gums, Stasia has ashes, and Karla is selected oaks. Every Sunday and Wednesday we will be using a camera to take pictures of our trees. Each day we will take the picture from the same spot and around the same time of day. After developing the pictures, the "second phase" begins. We are going to determine the percentage of each color in the picture of the tree. In order to come to a general agreement on the percentage we made a color wheel which is our constant, and we can refer to this to understand the number. The picture will be divided into four sections and we will refer to our color wheel for the number. This will help us determine what percentage of the tree has changed color the most For example, if half the tree in the picture is one color and other half another color, then, we would say 50% of the tree is yellow and the other 50% of the tree is green. We are going to do this for the sixty-four pictures of four different species of trees. We will be comparing the sections and the whole tree to our spectrum of color. This will help show where our tree is in the color changing process.
We will quantify the change of color by using a color spectrum that we have made. In order to maintain uniformity we will use our spectrum as a standard with which to compare all the trees. The spectrum ranges from dark green through the yellows, oranges, reds and finally ends in brown. This is our standard, but after we have analyzed our trees, we are going to make separate spectrums specifically designed for each tree. This will help show how each tree was different in going through the changing process. We have split our spectrum into 28 different segments and have assigned each segment a number. We will use these numbered segments to compare and relate the leaves to each other. This way each tree will be organized and it will be easier to refer back to data when we need it
Depending on the project, materials can either be scarce or abundant. For our lab, we used only the bare necessities. Considering our project was based on taking pictures, we needed four cameras and film. We also used a color spectrum chart, a ruler, and Microsoft Excel Spreadsheet. The color spectrum chart was a constant in our project, it was used to determine the color to which the leaves are changing. We used a ruler to divide each picture into four sections so we could determine the colors to which the fourths have changed. Finally, we used Microsoft Excel to make a spreadsheet which included all of our final data and calculations. From the spreadsheet, we were able to produce our final results and graphs. We did this so we could easily compare the sections to the color wheel. Also, we dated all of the pictures so we could easily organize them by week.
Sept. 23- we began the lab by take pictures and writing our lab proposal
Sept. 27- take pictures
Sept. 30- take pictures
Oct. 4- take pictures
Oct. 7- take pictures (expect slight change)
Oct 9 - developed some pictures
Oct. 11- take pictures
Oct 12 - researched color spectrums and leave change
Oct.14- take pictures (should be changing more rapidly)
Oct.18- take pictures
Oct 20 - made color spectrum
Oct. 21- we wrote our lab teaching packet and took pictures
Oct 24 - made class participation and presentation finalized
Oct. 25- take pictures
Oct. 28- take pictures, and reseach the data collected. We will be numbering the pictures, to decide the right color that it is.
Nov. 1- take pictures (leaves should be almost fully changed)
Nov. 4- take pictures
Nov. 8- take pictures (leaves should be completely changed)
Nov. 11- take pictures (leaves better have changed!! Ha! Ha!)
Nov. 15-Analyze results
Nov 16-29 - Prepare presentation, calculate results, and finalize project
Nov. 30 Final Class Presentation
Dec. 6 The best group got pick to present at media night (Ha Ha!!)
Dec. 7 Presented at Media night
Dec. 10 Completed final semester generated lab write-up (Thank God)
Red Oak Trees
In experimenting on the color rate of the leaves on red oak trees , I predicted on September 23rd, that the leaves on the red oaks would turn a brilliant blood red color during the second and third week of October. According to my results that was not the case. The leaves on trees one and two turned from green to a dirty yellow to a dark reddish brown color. Trees three and four seem to change from a bright green to a bright orange-yellow to finally a brilliant red-orange color before the leaves dropped. Factors associated with these two cases could be for trees one and two, those trees were older and more mature with fuller branches of leaves compared to trees three and four. Trees three and four seemed to be less mature with fewer branches of leaves. Also, the rate at which it took the red oaks to start changing colors was slower than I expected. They started changing colors during the transition days of October to November and the first week of November. Once the leaves on the red oaks started changing colors, the rate at which they were changing colors was rapid. It probably took the red oaks to change from a leafy green tree to a tree with no leaves about two weeks to complete this process of leaf fall compared to the ash, the maple, and the sweet gum trees.
September 23rd was the first day I started taking pictures of four red oak trees until November 15th. I used an Olympus Zoom 211 Camera with Kodak film exp. 24 and 200 speed. Tree one was located in between Clawson and McKee Halls. Tree two was located in front of Boyd Hall while tree three was located next to Peabody Hall. As for tree four, it was located in front of Kumler Chapel.
According to my graph, tree four seem to start changing its colors at the fastest rate while tree two started to change colors at the slowest rate, possibly due to the age factor of tree two. Trees one and two are towards the bottom of the graph while trees three and four are the younger trees. As a final result on the red oak graph, tree three and four had the highest color value meaning they had some of the brighest colors compared with tree one and two. The colors, according to the graph, were close in value on the color scale, though.
In conclusion, my expectations of the results on the red oaks would be somewhat correct. I knew that the colors on the leaves of the red oaks had deep reds and browns before they dropped, but I did not know that they would take a long to begin to change colors, but once they started changing colors those rates were rapid. By the time you were done admiring the color of the leaves on the red oaks, they had already dropped and were dead.
When I began this lab I went out to find four different Ash trees to take pictures of. My first tree it was located before the McKee bridge. It is a fairly tall tree and only half of the tree receives sun light. This tree changed from the color green to yellowish-orange and finally ended in the color brown. Tree number one was ranked third on my final result chart. The rate at which it changed was very gradual until October 19 the color changed dramatically from green to orange. Some of the factors that may be considered is that t4ree number one is a fairly old tree and part of it is in the shade, which may have slowed the changing process down.
For my second Ash tree it was located right behind McKee Hall . Out of all four trees this tree was the tallest and was also old. In the beginning, I had predicted that this tree would lose it’s it leaves first because it was so tall. I was wrong it came in second on the graph showing the rate of color change. It went from the color dark green to green for a long period of time. It then suddenly burst into a dark shade of brown. My second tree made the sudden change around the same time as my first tree. Some of the main factors that may be considered is that McKee Hall blocks sunlight from half of the tree. It may have been that the tree is dying because it is so old.
For my third Ash Tree it was located across the street from Boyd Hall. This tree was the youngest out of all four. This tree was the first one to change dramatically on the graph. On October 4 it changed from yellow to a deep reddish color. Then again on October 14 it made another dramatic change to orange and then brown. Some of the factors that made this tree change could have been that it was young and in an open atmosphere and it received full sunlight.
For my fourth Ash Tree it was located on the corner of Boyd Hall. This tree was the oldest out of the four trees. This tree stayed steady at green for a while. Then it slowly made a changing process from yellow, orange and then to brown. My fourth tree was last on my Ash graph. Some reasons for this color change would be because the tree was so old so the process was slower. The area that it was located was very cluttered and so that may have effected the tree also.
For this lab I took pictures of my four trees around 6 o’clock every Sunday and Wednesday with a Minolta Explorer camera on 200 speed film, and got my film developed at Shriver. In conclusion, through working on this lab for the past two months I have learned that many things have to be considered in the leaf changing process. I thought that the leaves on the bigger trees would fall faster but I was wrong and it was the opposite, the younger trees leaves ended up dropping first.
When we began this project I set out to find four trees of the same species around the Western Campus area. I never took into consideration factors such as the location of the trees, what can effect the color change, or what makes the leaves change colors. I went out on a search for a tree that would change colors beautifully to learn about. Sweet Gum tree were chosen because the leaves are shaped in a star-like form which interested me. When we began research, we found that the Sweet Gum trees’ leaves have a lot of sugar it them, which in turn, during the autumn season, will turn red or scarlet. Throughout the project I did conclude that my trees were turning more red and purple compared to the other trees’ results. My results, in some ways, were similar and different at the same time to my expectation.
I began taking pictures on 9-23-98 and every Sunday and Wednesday for the next two months and ended 11-15-98. The type of camera used was Kodak Max with 200 speed film. Each picture was taken at approximately 6:00p.m. Each rolls of film was developed at Krogers into 4’x6’ prints. My first tree was located in front of Boyd Hall. It is an estimated ten feet away from the road, and about fifty feet tall and thirty feet wide, full of leaves with two trees surrounding it. In the beginning, tree one was light green on the color spectrum. It gradually turned light yellow, orange, finally a orange-brown until it dropped.
My second tree is located next to Alexander Hall. This tree is one of the smallest, healthiest, and youngest compared to my other three trees. It is the furthest away from the road with no trees surrounding it. The second tree changed the brightest reds and purples out of the four. When I first began, tree two was a dark green and gradually changed directly to oranges, reds and purples, and finally turned a beautiful bright reddish-orange.
My third tree was located in front of the church, estimated about twelve feet away from the road. It is the oldest, tallest and skinniest tree out of the four. In the beginning, the tree was green and gradually turned light green and yellow and ended up dark orange.
My fourth tree is located next to Peabody. It’s between two other trees by the road. Large and tall, tree four was green, gradually turning light green, yellow and orange. It finally ended with the leaves being orangish-brown.
The final comparison between my four Sweet Gum trees resulted in all of the trees’ leaves dropping at the same rate on November 13. Trees one, three and four all gradually climbed the color spectrum together stating that they turned the same colors, somewhat. Tree two went through the color spectrum faster than the other three trees.
The four trees I chose were located on Western Campus near the buildings of Boyd and Peabody. I chose these trees based on location and convenience. My first two trees were between Boyd Hall and Peabody Hall. My third tree was located in front of Boyd Hall. Finally, my fourth tree was found directly next to Boyd Hall on the north side of the building.
Data collection began on September 23. I used an Olympus camera with 200 speed film. To develop the pictures, I took the film to Wal-Mart. My last pictures were taken on Oct. 29, much earlier than the other three species. This shows that my tree changed the fastest in comparison to the other species. As explained in the method section of our paper, we assigned each color on our spectrum a color value. But sometimes, when assigning a value to our tree, the color we assigned it wasn't the correct color because of different factors such as light, developing and difference of opinions. This caused some odd patterns to appear in my graph, but, in the end, my graph showed the predicted colors.
I predicted that all three of my trees would change different colors (compared to each other) before falling. I made these predictions based on what my research told me about the affects of environment on the trees. Another factor that I had no way of accounting for, was the different proportions of the three pigments that cause leaf color change, chlorophyll, cartenoids, and anthocyanins.
Tree number one was located approximately 7 feet from the road, and 4 feet from the sidewalk. I believe it was a young tree because it was fairly small. The size and age of the tree could both be factors in how fast the leaves changed. But, the fact that the tree was located so close to the road, where exhaust fumes and salt from winterization could inhibit the growth, is also a factor in how fast the leaves changed. It took until October 19 before any dramatic difference was noticeable in tree number one. After October 19, a quick change was clearly visible. Tree number one went from a light green to a bright red in a span of three days. Within the next two weeks, the leaves changed to a vibrant orange and fell. This sudden change can be due to the factors I discussed earlier.
The data for tree number two, found between Peabody and Boyd, was incomplete, so this tree was thrown out of the final analysis.
Tree number three was the largest of my trees. It was also found near the road. This tree changed at a slightly faster pace than tree number one. But these two trees' results were the most similar. Tree number three began to turn on October 11th. It reached a deeper shade of orange than tree number one, then surpassed it on the color chart until it reached a deep crimson. Again, by October 29, all of the leaves had dropped. The size and health of the tree, and it's proximity to the road could have affected the rate of change.
My fourth tree, right next to Boyd, was a small tree, but I believe it was either old or sick because the leaves did not look healthy. This could have been due to the tree being so close the building; the roots' growth could have been inhibited by the building's foundation. It's rate of change was very steady, and it never turned past a yellow-orange hue. The variance of color was slight, but their was no difference, compared to the other two trees, in the time when the leaves eventually fell. To reiterate, I believe the strange results I got for this tree were due to the close proximity to the building.
Results of Species Comparison:
In contrast to our presentation, we have decided to compare all four species (previously, we had omitted maples from the final analysis). We calculated the color value of each tree to determine an average color for each species. Through our results we are showing the rate of color change, the average color value, and which trees lost their leaves first.
The largest change in color was visible in the ash trees. They changed to the high color value of 24. Following close behind were the oaks, at 22, then maples and sweet gums at 15 and 14, respectively.
On average, the first trees to die were the ashes, on the 26th of October. Shortly thereafter, came the maple trees, on October 27th. Then the sweet gums, which changed around November 6th, and the oaks which held onto their leaves until November 15th. In conclusion, we were very surprised to see that ash trees turned so early in the fall season and that maples held on the longest. And that sweet gums and oaks maintained their color the longest.
In the beginning, we were a little hesitant on how this experiment would turn out. But it ended very successfully and was a wonderful learning experience. Not only did we come to appreciate what’s involved in the color changing process, we learned to work well with others. We all now have a much greater appreciation for the beauty of the autumn leaves on Western Campus.
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