2002: Black Rock Forest Carbon Initiative: Examining Forest Carbon Sequestration: Is More Stored in the Trees or Soils?

Why is Carbon Important?

Carbon is the key element in the biogeochemical cycle on Earth that enables living organisms to exist and flourish. From blanketing the Earth to keep it warm, to being an elemental building block of molecules that make up all organisms on Earth, carbon is important for the very life that exists on our planet. Forest ecosystems both store and emit carbon back to the atmosphere as they constantly recycle carbon (photosynthesis and respiration). But how can we measure net carbon storage in vegetation and soils? What are the carbon sinks today in our regional forest ecosystem? How do the sinks vary in uplands, wetlands, and in different types of trees and different types of soils? What is meant by the "missing sink" of northeastern North America? These and other questions will be considered throughout the Carbon Initiative Program.

Humans alter Earth's land surface through various activities, impacting the forests, soils, and wetlands where carbon is stored. These carbon reservoirs have an influence on changing atmospheric composition and can even contribute to climate warming or cooling. Exciting results of the last five years have placed a fundamental science question concerning carbon storage squarely in the lap of terrestrial ecologists. How much carbon is being stored in the terrestrial part of the earth? How much is in the trees in a forest versus the soils? How much is in the wetland soils versus the upland soils? How much does this carbon sequestering vary over time? At GISS, we have a chance to make a real contribution to this question by using our combined carbon and paleoclimate research in Black Rock Forest, NY.

Black Rock Forest is a regional representative oak forest where current scientific research involves carbon sequestration measurements in the trees as well as in the soils. We will target Cascade Brook Watershed, where our research on carbon in upland soils can complement existing carbon research on trees. We also have some carbon data on wetland soils in this region of the forest. Our measurements on carbon in Black Rock Forest will aid researchers Bill Schuster (studying carbon in trees) and Dee Pederson (studying carbon in upland soils) as well as D. Peteet's research on wetland soils. Our ultimate goal is to make estimates of the carbon content of particular type forests at present, and then estimate future carbon content of these ecosystems as the climate changes. Together we can begin to answer questions about the "missing sink" of carbon in the northeastern US, which has been proposed to be in our growing forests.

More carbon is being released into the atmosphere today than is absorbed by sinks. As carbon dioxide levels in Earth's atmosphere rise, (atmospheric carbon dioxide has risen by 30% since the 1800s) many scientists believe that subtle environmental changes occur. One such change may be an increase in the global average temperature by about 0.6°C. The addition of carbon dioxide and other greenhouse gases to the atmosphere may be contributing to this global temperature increase. But the weakness in our understanding the carbon cycle is demonstrated by the difficulty in trying to balance the carbon budget. Although forest timber inventories have been rising in the last few decades, other estimates suggest that these forests are in carbon balance, or possibly a source to the atmosphere. This difference in forest carbon estimates leads to the need for further careful research.

As the carbon dioxide levels in the past hundred years have risen, the land use on the East Coast of the United States has also changed. Since the beginning of the 1900's East Coast land use has changed from agriculture to forestland. This change in land use has returned much of the old agricultural fields to forest. As the forests grow and mature, the amount of carbon stored in the trees increases.

The carbon initiative team will quantify the amount of carbon being stored in a representative East Coast oak forest. The team will study different parts of the forest, which represent various ecosystems in the forest, to understand which ecosystems are storing the largest amounts of carbon. Although carbon is vital for life on Earth, few studies have been undertaken to quantify the relationship between the amount of carbon in soils in a particular area with the amount of carbon in trees. Even fewer studies have attempted to estimate the soil carbon content in uplands versus lowlands (wetlands). The team will quantify the amount of carbon stored in a particular watershed, Glycerine Hollow to the Cascade Brook Watershed, in Black Rock Forest, looking carefully at different spatial scales.

Black Rock Forest, a research forest site in upstate New York, gives the Carbon Initiative team an unique study setting. As mentioned above, Black Rock Forest and the entire East Coast of the United States is currently being reforested after years of intense farming practices. This reforestation provides an excellent opportunity to conduct research on the types of carbon sequestration changes that forests undergo as they age and are impacted by both natural and manmade events. The research being conducted this summer is a pilot for more in-depth studies to be conducted during the next few years.

Project Plan

The participants will study at least 3 different sites within Black Rock Forest. Each study site has different environmental factors affecting the site. Participants will study both Upland and Lowland sites by using the provided protocols to:

• Identify the ecosystem's physical characteristics. This will involve taking and recording measurements such as temperature with a thermometer, altitude with a GPS device, estimating slope, and measuring soil depth.
• Determine the amount of carbon stored within the plant's tissues using allometric methods. These methods involve measuring plant circumference, indirectly measuring the height of the individual trees and identifying tree species. With the use of excel spread sheets students will calculate the amount of stored carbon.
• Calculate the amount of carbon sequestered in soil layers by digging soil pits and burning the soil samples.
• Determine the mass of live roots in each soil type by screening the soil samples (and with the use of the allometric methods).
• Compare the amounts of carbon stored in each study site with the physical features of each site.
• Use the data obtained from this study as evidence of carbon dioxide emissions and carbon sequestration to critically discuss environmental change and impacts.
• Through these discussions the team members will develop their perspectives and practice informed decision making.

Learning Objectives

Science Understandings

Through photosynthesis plants sequester carbon by taking carbon dioxide in and synthesizing organic molecules.

Through combustion and respiration sequestered carbon can be released into the atmosphere.

Carbon can be stored in a forest in organic matter found both above ground and below ground.

Environmental factors, both abiotic and biotic, play a role in the rate at which an ecosystem can store or release carbon.

Carbon dioxide and other greenhouse gases contribute to the temperature of Earth's surface and changes in these gases can contribute to climate warming or cooling.

Human impacts to ecosystems can influence those ecosystems on a local scale as well as influence the global biosphere.

Increased dependence on technology has lead to an increase in fossil fuel combustion and an increase in the release of carbon into the atmosphere.

Mathematical Understandings

Allometric equations can be used to calculate the amount of carbon sequestered above the ground in deciduous forest trees.

Trigonometry can be used as an indirect method to calculate and estimate tree height.

With the knowledge of soil mass before and after burning the amount of soil organic matter can be calculated.

Different species of plant store differing amounts of carbon.

A comparison of two different methods of quantifying carbon can be used to determine precision in data collection.

The use of data tables and graphs can help researchers discover and document real life trends in Earth systems.

Technology Understandings

Computers can be used to simplify mathematical calculations to produce estimates of forest carbon storage through spreadsheets and programs such as MSExcel.

Excel is used to produce comparative graphical analysis of the percentage of carbon stored in different tree species and soil samples.

Computers can be used as a presentation medium through the use of Power Point software.

Digital camera can be used to obtain site-specific data of ecosystem characteristics.

GPS devices utilized to precisely describe locations.

A variety of measuring devices will be used to obtain information about the study area, e.g. thermometer, measuring tape, clinometer, compass, anometer.

Research Questions

Guiding Science Questions

How does carbon sequestration in trees compare to carbon sequestration in soils in Black Rock Forest?

How is carbon storage in a forest ecosystem influencing atmospheric carbon levels?

What ramifications does this carbon storage have on future land management issues?

Basic Science Questions

What is atmospheric carbon?

What is a carbon sink?

What is the carbon cycle?

What is an ecosystem?

How do we measure carbon that is stored in a forest ecosystem? In trees? In soils?

Discussion Papers:

• Wofsy, S. C. 2001. Where Has All the Carbon Gone? Science 292: 2261-2262
• NASA FACTS. 1999. Changing Global Land Surface. http://www.gsfc.nasa.gov: June.
• Dixon, R.K., Brown, S., Houghton, R.A., Solomon, A.M., Trexler, M.C., and Wisneiwski, J. l994. Carbon pools and flux of global forest ecosystems. Science 263: 185-190.
• Post, W.M., Emanuel, W.R., Zinke, P.J., and Stangenberger, A.G. l982. Soil carbon pools and world life zones. Nature 298: 156-
• Sedjo, Roger. 1992. Temperate forest ecosystems in the global carbon cycle. Ambio 21(4): 274-277.