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RESEARCH RESULTS

Does the Age of a Tree Effect Carbon Storage?

Introduction

"The greenhouse effect has been detected and it is changing our climate now," stated James Hansen in a 1988 edition of The Washington Post. The greenhouse effect is caused by anthropogenic acts such as dramatic increased use of fossil fuels. Remains of organisms produced fossil fuels three hundred million years ago. Today, fossil fuels such as coal, oil, and gases are used in cars, factories, and other machineries. Even though fossil fuels make millions of lives easier, burning them is making the earth an unsafe place to live in due to the chemicals released by these greenhouse gases. When these tiny particles of greenhouse gases are released into the atmosphere they trap solar heat within the atmosphere. When the atmosphere has too much greenhouse gases, it behaves like a one way valve. It allows energy (in the form of solar energy) to pass through from the sun into the earth but does not allow the heat energy to escape back out. More solar radiation is trapped within the earth, making it warmer.

Carbon plays a major role in keeping the earth stable. It has allowed life to exist and flourish on earth. However, if carbon dioxide is being produced by the combustion of fossil fuels the earth will begin to go through many negative changes. Making carbon dioxide a greenhouse gas. When coal is burned the carbon that is produced and released into the atmosphere eventually reacts with oxygen, generating CO2. The amount of carbon dioxide stored in the atmosphere contributes to about 50% of the greenhouse effect. As time passes there is an increase in the amount of CO2, which may produce environmental changes, such as an increase in atmospheric temperature.

Over much of the last century, the East Coast land has changed from basic agricultural use to forestland. Because there is an increase in the amount of forests, more trees are taking in carbon dioxide and reducing the amount of CO2 in the atmosphere. When plants allow CO2 to flow into the leaves, tiny amounts of water vapor being released which cools the land surface. However, when the concentration in the amount of carbon dioxide increases, plants aren't able to release as much water vapor, causing a decrease in ability to keep the land cool. If this continues to happen, our climate will change. There will be an increase in temperature, which may cause droughts affecting vegetation growth. This will cause further complications to the earth because the earth will not be able to adapt to the changed environment as quickly as needed.

Ecosystems play a major role in keeping the earth stable. An ecosystem consists of biotic and abiotic factors that keep the environment in equilibrium. Our study focuses on how the Black Rock Forest stores carbon. According to William Schuster, director of Black Rock Forest, over a past 72 years above ground carbon storage has increased in the Black Rock Forest. The Black Rock Forest has had a six-fold increase in biomass over the 70-year period, while thinned plots have taken an extra 40-50 years to reach the same amount of biomass. The tree that stores the most carbon in the Black Rock Forest is the Red Oak, which has a growth rate of approximately 600 kg/H. Carbon in trees make up approximately 1/3 of carbon stores and the remaining 2/3 of carbon storage is below ground. The Black Rock Forest is still trying to recover from past settlers that broke down the forest into various types of ecosystems. Over the past 15 years there have been 3 forest fires from West Point Military Academy, each causing stored carbon levels to decrease in amount.

In order to understand the difference in carbon storage between young and old forests we have been collecting various types of data, such as temperature change, sun intensity, the population of animals, and human impact on the environment. By looking at these variables one is able to observe and hypothesize about the tree growth, giving us an idea of the amount of carbon that may be stored in the trees. Since the older trees have been living longer, they have had more time to store carbon than of the younger forest. I believe that older forests would have more carbon storage than the younger forests, but since there are more trees in the younger site there would be more carbon storage in the younger site due to quantity as well as variety of trees. The younger trees are also storing carbon in a faster rate because they're producing food more quickly than the older forest.

Methods

The way we are researching our question is by using a variety of techniques to help us understand and look further into the amount of carbon storage in old and young forests. Throughout our two-week period in Black Rock Forest we have collected and recorded tremendous amount of data, which has helped us understand the importance as well as the amount of carbon storage in plants. We have mapped out two different sites, one site that consists of old trees which are 150 years old, and the another site consisting of young tree, which are approximately 35 years old. Each site was an area covering 42.5 square meters. After the forest was divided into two parts, we mapped out each part into four quadrants in which all the trees were counted. Afterwards, we described the canopy of the trees, the circumference, and the types of trees. This was done so future researchers would be able to locate our sites and do further research in the years to come.

After mapping our sites, we used a GPS (Global Positioning System) device to record longitude, latitude, and elevation of the two sites. We sketched maps of the sites, determining site orientation, with using a compass. For the topography we observed, recorded, and then drew a sketch of what we saw for both sites. The vertical survey (above ground), and landscape survey (above ground) were drawn, including the name of the species, and the biotic and abiotic factors. To find out the percentage of the tree root coverage we just observed the ground carefully and estimated a percentage. To check soil composition we dug about a meter down and observed the soil pit then sketched the layers of sediments in the pit, for both sites. Using a dowel we checked the soil depth for each corner and the center (for both sites).

For about two weeks everyday we would check the air temperature, floor temperature, and soil temperature in the center of both sites, using a thermometer. We measured sun intensity on the floor, as well as a meter above the ground, on each of the four corners of the two sites, using a voltmeter. To measure wind speed, we stood in the center of the site holding the wind speed device 1.5 meters above ground. We also identified whether cloud coverage was complete, moderate, light, or non-existent. Every other day we would take out samples of soil on the forest floor, 10 centimeters, and 15 centimeters below ground. The samples were taken to the lab, where soil pH moisture was measured. To measure the percentage of moisture in the soil, we weighed of the soil before and after putting the soil samples in a 100ºC oven that evaporated the moisture from the soil. The percentage moisture in the soil was the mass of the soil before putting it in the oven subtracted by the mass of the soil after putting the soil sample in the oven. Once we obtained percentage of soil moisture, we divided the sample value by the mass of the original soil and then multiplied by 100 to get the percentage of soil then multiplied by 100 to get the percentage of the moisture. We also adjusted our masses to account for the tin cans that we used to hold the soil. Subsequently soil was burned in a 500ºC oven to determine the amount of carbon stored within the soil sample.

Results

Figure 1

The chart above shows the amount of total tree carbon in the young and the old forest. The chart describes the carbon storage within each plot in one area for both young and old. The horizontal axis describes the site and the vertical axis shows the carbon storage in kilograms. The young site had more carbon storage then the old, because there were half as many trees and there was less species variety in the old site. The chart above shows the amount of total tree carbon in the young and the old forest. The chart describes the carbon storage within each plot in one area for both young and old. The horizontal axis describes the site and the vertical axis shows the carbon storage in kilograms. The young site had more carbon storage then the old, because there were half as many trees and there was less species variety in the old site.

Figure 2

The bar graph above shows the diversity of tree species. The horizontal axis shows the tree species and the vertical axis shows the number of trees in each species. For the young site there are more red maples then any other tree species, and for the old site there are more chestnut oak then any other tree species. There is a bigger number as well as a larger variety of trees in the young site then there is in the old site.

Figure 3

The graph above displays the strata of the trees in both the young and the old site. The horizontal axis illustrates the site’s tree species and the vertical axis illustrates the number of each tree species. The diameter was taken from breast height for each tree. Most of the red maples in the young site are one to five inches in diameter and the chestnut oak from the old site is mostly five to ten inches in diameter

Figure 4

The graph above displays the height of the trees. The horizontal axis shows the tree species and the vertical axis shows the height of the trees in centimeters. The red maple is the tallest in the old site and the chestnut oak is the tallest in the young site.

Discussion

Our main objective was to compare the amount of carbon storage in old and young ecosystems Site 1 was the young deciduous forest; it is 35 years old. There were many different species found as well as different (canopy) heights. The tree species found in the young site were red maple, red oak, witch hazel, chestnut oak, and yellow birch. Site 2 was the old deciduous forest, which is 150 years old. Most of the trees were in a dominant (canopy) height. Every type of tree is present from site 1 except the red oak. The most abundant tree species in site 2 was chestnut oak.

Overall the carbon team has measured the amount of carbon stored at Black Rock Forest both under natural and impacted conditions. Carbon is vital for life on earth but there haven’t been many studies focusing on this issue. Carbon storage in the forest is influencing atmospheric carbon levels by helping to keep the level of carbon in balance. This will help keep an ecosystem in a homeostasis, in which animals will be able to adapt to the changes that are happening at a rapid rate. However, in the years to come carbon rates will increase dramatically making it nearly impossible for plants to store such a high amount of carbon in a small amount of time.

All of the aforementioned variables listed in the methods help to determine the amount of carbon storage in the forest. They may have an influence on climate, which determines how the trees will grow. The trees are the mean through which carbon is stored in the forest. Additional research is necessary to substantiate our results; we look forward to comparing next year’s research results with this year’s results. The carbon team is still in the process of figuring out how an addition amount of carbon dioxide will affect different types of ecosystems. This can only be determined if further research is done in the years to come.

Future Questions Specific to sites with varying age:

  1. How does carbon storage in 90-year-old forest compare to that of forests that is 35 and 100 years old?
  2. What predictions can we make regarding the amount of carbon storage in 20, 50, and 100 years to come?
  3. How do carbon storage rates vary with forests of different ages?

Bibliography

  1. Michael Weisskopf (The Washington Post) Greenhouse effect fuels policymakers August 15, 1988
  2. Carl Sagan (Ballantine Books, New York) June 1998
  3. Michael Weisskopf (The Washington Post) Scientists Says Greenhouse Effect Is Setting In June 25, 1988