digital camera

At each school we studied two different kinds of trees. One is a Silver Maple and the other is a Crab Apple.

Silver Maple Acer saccharinum: Silver Maple is part of the Maple family. The Silver Maple grows from the Midwest to the eastern of the United States except Florida and some parts of Maine. They have palm-shaped, simple and opposite leaves. The height of the tree tends to be around 80 to 100 ft. The leaves are green above and whitish below, but they will eventually become dull yellow in the fall. The bark of the Silver Maple is grayish and is smooth. Birds, squirrels, and other small animals eat the winged fruit from the Silver Maple.
[Zim 1956]

Crab Apple Pyrus coronaria: Crab Apple is part of the Rosaceae family and is a deciduous tree. The Crab Apple grows in the temperate region of Northern Hemisphere. The height of the tree tends to be around 8 to 50ft. The leaves have an oval shape and are colored green above and lighter on the bottom. The leaves can become reddish. The color of the flowers ranges from white to purplish-red. The apples grow on Crab Apple and have the color of red or yellow but are tiny. Crab Apples require fertile, moist soil, full sun, and the protection from late frost. [Simon and Schuster 1978]

In general all of our four trees seemed to be in good health. A few of the branches and the leaves on both trees at MSSD were dead and fell off, and we think it was because of drought and insects. The MSSD students talked with Trudy Haselhuhn, a horticultural expert from our campus, and she said 2006 was a very dry year in D.C. and many trees on campus are showing stress. In Indiana the Crab Apple tree is in pretty good health right now, but they have been attacked by Japanese beetles in past summers, according to our teacher. Our Silver Maple tree trunk is split and has a hole that has been used as a home by Northern Flickers. At MSSD, Mrs. Haselhuhn also told us that the trees we are studying are not watered or fertilized except by nature. At ISD, we also investigated and found out that our trees are not watered or fertilized during the year too. That is important because for our research, it is important that the trees are responding to the natural environment and not to man-made conditions.

At MSSD, we went to Hall Memorial Building (HMB) to learn about the automated weather station. The weather station is on the roof of the HMB. Dr. David Snyder explained to us that every 5 minutes the weather station measures 11 different things. We wanted to know about temperature, humidity and precipitation, so we learned how to get that data from the Internet. (The weather station is connected to a special web page so we could get the data). We checked on Google Maps and found out the weather station is 120 yards from the MSSD Silver Maple tree.

Outside:

Inside:

At MSSD:

At ISD:

A Sunny Winter Day, March 11:

At MSSD, when we checked on the Silver Maple, we found out that the buds had pollen on tiny anthers.

Above: The buds had pollen falling from the anthers like this.

At ISD, we were puzzled with comparing our Silver Maple tree with MSSD’s Silver Maple tree. Our tree was very different! We thought something was wrong. Our tree did not have pollen, and grew seeds before the leaves appeared. We looked at the flowers with a microscope and made drawings. We found out that MSSD’s tree is a male tree and ours is a female tree! [Trees of Wisconsin 2007]

The female flowers and seeds from ISD’s Silver Maple tree

At MSSD, our Crab Apple buds burst on March 17, 2007. They were blooming with pink flowers on the branch with the leaves at the same time. The Silver Maple’s leaf buds had not burst like the Crab Apple’s buds, which we were trying to figure out why this happened to both trees as they were side by side trees.

At ISD, our Crab Apple buds burst on March 24, 2007, but ours were blooming with white flowers.

MSSD	ISD (photo by Ian Britton)

On 3/28, at MSSD all those Silver Maple flower buds that burst for a few days were dead now and fell to the ground.

Early in April, at both of our schools, we had freezing temperatures. On April 7, at MSSD it was snowing outside so our trees were covered by the late snow. The buds on our Crab Apple survived through the cold, snowy days. At ISD, we had below freezing temperatures. The cold weather damaged the flowers and leaves on our Crab Apple tree.

Snow on our Crab Apple at MSSD

Damaged leaves and blossoms at ISD

At both schools, we continued checking our buds on our trees. We decided to measure the leaves to see how fast they grew. In the picture below, the leaf measures about 4 cm. As we watched these leaves on the Silver Maple each week, they grew greener and bigger. When we recalled that we measured these leaves, we found out that they grew by 1 cm per day. At MSSD, the silver maple leaves continued to grow until the first of May, when they were full grown (about 180 mm). They ure grew faster than we them expected to. At ISD, our silver maple leaves grew to an average length of 140 mm and our crab apple leaves had an average length of 72 mm.

Calculations

At each school, we did the calculations of the G.D.S, P.E.T., and water difference for the Silver Maple and Crab Apple trees. We calculated GDS and Water Difference so we could see how the timing of budburst is related to the climate. We learned how to do these calculations from the GLOBE Program budburst learning activity. [GLOBE 2007]

Growth Degree Summary (GDS)

GDS is the sum of the average positive temperatures before budburst. Starting with January 1, we added the numbers of degrees each day to see the total of it. But there’s another thing we should not do, we don’t need to include temperatures at or below zero, so we have to ignore it each day that the average temperature was below zero. We stopped adding on the day the buds burst.

To calculate GDS we only needed to add up the Tavg above 0°C and not below 0°C. We did not add up the Tavg below 0°C because the trees are not able to grow when temperatures are below zero. This was set up as a standard for the international GLOBE to find the estimation of the plant’s GDS. We learned that different plants have different degree limits as they would not able to grow below a certain temperature. Since we do not actually know the exact number of temperature that the Crab Apple or the Silver Maple stops growing, we just followed the GLOBE protocol and used zero degrees Celsius. GDS is one way to estimate how much warming a plant requires before it can have budburst.

Potential Evapotranspiration (P.E.T) and Water Difference

This will tell you how much water had been lost or evaporated. For the inputs, we summed up the daily precipitation for the 29 days before the budburst till the day of budburst. Precipitation includes rainfall and the snow that had melted into water. Then, for the outputs we used the daily temperature average (Tavg) 30 days prior to the budburst, till the day of the budburst. After we had the Tavg we used the table that will showed the P.E.T. in mm per day. Then, we totaled up the PET for 30 days. We found the water differences (WD) by the following equation: input – output = WD. This is saying that we subtracted the P.E.T. from the precipitation to find the WD. The WD told us how much water was available to the trees. If the WD is negative the plants are in a dry condition while if the WD is positive the plants are in the wet condition.

Collaborations

At the end of our measurements, we had videoconferences between our two schools. We compared the locations of our two schools and pictures of our trees. We talked about how we did our measurements for bud burst. We shared our graphs and discussed the data. It was fun talking about our trees, what we learned, what our data showed, whether our hypothesis was right or wrong, and how we could improve our research. Our teachers helped us make a plan for writing our report as a team.