What’s a Forest Without Trees?

This is a special guest post by an undergraduate student in Samantha Smith’s Spring 2018 “Current Topics and Methods in Environmental Science” course at Thomas More College (Crestview Hills, KY).  This course is designed to provide a broad overview of current and ongoing issues in environmental science through discussions and field/laboratory exercises.  Students were assigned to write blog posts to strengthen their ability to convey scientific research to a wider audience. 

About the Author: Katie Laine

I am currently in the process of earning my bachelor’s degree in Environmental Science with a concentration in Ecology at Thomas More College. At Thomas More I am involved in the Women’s NCAA Division III Bowling team, as well as being a member of the biology and environmental science clubs. After graduating, my dream job would have something to do with water quality, either working in the field or in the laboratory. Outside of school, I enjoy hiking, fishing, and spending quality time with my friends and family.

Article: Pearson, Timothy R. H., et al. “Greenhouse Gas Emissions from Tropical Forest Degradation: an Underestimated Source.” Carbon Balance and Management, vol. 12, no. 1, 2017, doi:10.1186/s13021-017-0072-2.

Deforestation vs. Forest Degradation

Many people confuse the concepts of forest degradation and deforestation. Deforestation is the complete clearance of trees within a certain area. This is a strictly anthropogenic activity related to logging and the increasing demand for space to raise livestock or grow crops. Forest degradation is when a forest community changes in a negative way but retains at least 10% tree cover, so it’s therefore still categorized as a forest.

“Forest degradation is broadly defined as a reduction in the capacity of a forest to produce ecosystem services such as carbon storage and wood products as a result of anthropogenic and environmental changes” (Thompson et al.,2013).

Forest degradation has human and natural causes, including overgrazing, extreme amounts of logging, pests, storms, and fires. The two concepts, deforestation and forest degradation, are connected by the role that humans play.

How are greenhouse gases tied to forest degradation?

One of the most prominent greenhouse gases (GHGs) is carbon dioxide (CO2). Anthropogenic emissions tied to vehicle exhaust are a significant source of this greenhouse gas. In forested, rural areas, activities such as logging or mining contribute to regional CO2 emissions. Timothy Pearson and colleagues highlighted that forest degradation from anthropogenic activities, such as excessive logging and mining for coal, are a source of CO2 emissions that is often unaccounted for. Both industries require large machinery to meet the demands of the consumers. With large machinery comes significant emission of CO2 in their exhaust. The main link, however, is that when trees are removed or burned the stored carbon from their biomass gets released into the atmosphere as CO2.  All of the above contribute to the “greenhouse effect”: the warming of the Earth’s surface and lower atmosphere caused by atmospheric gases trapping outgoing radiation.  The overabundance of CO(which can harm trees) combined with the increase in logging activity has created an unsustainable environment for trees to grow, leading to a heavy decline of tree populations throughout the world.  

Read more… To make matters worse, as we lose trees we lose out on their ability to convert CO2 into oxygen which acts as a “carbon sink.”  This means that the reduction in tree biomass by forest degradation and deforestation can have a compounding effect on the amount of greenhouse gases in our atmosphere.  Learn more about forests as carbon sinks here, and find other related Envirobites posts here.

How are the amounts of GHGs being regulated and accounted for?

Until now, it has been difficult to measure forest degradation because it’s not detected by the methods normally used to monitor deforestation.  Pearson and colleagues measured CO2 emissions from forest degradation in 74 countries using three techniques: 1) actual carbon lost in the form of tree wood due to logging, 2) carbon lost in the form of tree wood from dead trees surrounding the logging activity, and 3) carbon lost in the form of tree wood from dead trees in the timber harvesting area. The authors assumed that the harvested wood would be turned into fuel or otherwise emitted back into the atmosphere through burning. By combining the three estimates of carbon, Pearson and colleagues obtained an estimate of emitted carbon from timber harvest.

The results showed that for 28 of the 74 countries, more than half of the total emissions were derived from forest degradation. The most emissions given off were found in the more arid areas, like South Asia and North and East Africa. It was shown that logging was the largest contributor to emissions release.

The table shows that deforestation gives off the most emissions as a whole, but when looking at only degradation, the timber industry gives off the most by a margin of 0.47 Gt CO2e year-1 (or 23%).  The unit “Gt CO2e year-1” means “billions of tons of CO2 equivalents per year” and can be used to describe the emissions of different greenhouse gases in terms of CO2 for direct comparison of their global warming effects.

Graph 1: Proportion of total forest emissions from forest degradation for the 74 countries included in this study (Pearson et al., 2017).

During this study, emissions data were taken from 74 developing countries located mainly in tropical areas. In total, 2.2 billion hectares of forested land were assessed. Most emissions came from either Africa or Asia, the more arid locations. Burkina Faso, Sudan, Pakistan, and Senegal produced almost 100% of their total CO2 emissions from forest degradation. This shows the impacts of the timber and wood fuel industries, which emit large quantities of CO2 into the atmosphere and degrade the environment around them.

What can be done?

This study found that the emissions equivalents from forest degradation are significant: globally they exceed the total emissions in the US for both highway vehicles (1.7 Gt CO2e/year) and power generation (1.9 Gt CO2e/year)! Unfortunately, the impact of forest degradation is overlooked and unaccounted for in current greenhouse gas regulations.  Now that we know more about this source of CO2 emissions, we can start creating strategies to reduce them in the global effort against climate change.


“Greenhouse Gas (GHG) Emissions.” EPA, Environmental Protection Agency, 14 Feb. 2017, www.epa.gov/ghgemissions.

Pearson, Timothy R. H., et al. “Greenhouse Gas Emissions from Tropical Forest Degradation: an Underestimated Source.” Carbon Balance and Management, vol. 12, no. 1, 2017, doi:10.1186/s13021-017-0072-2.

Thompson, I. D., et al. “An operational framework for defining and monitoring forest degradation.” Ecology and Society, vol. 18, no. 2, art. 20, 2013, https://www.ecologyandsociety.org/vol18/iss2/art20/.

(Image) http://www.irishenvironment.com/iepedia/reducing-emissions-deforestation-forest-degradation-redd/

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Samantha Smith

Samantha Smith

I completed my MS in Environmental Science from the University of Cincinnati in 2015 and have been a research contractor at US EPA since long before that. My recent projects have focused on drinking water treatment technologies to address ongoing issues like cyanobacteria (which form Harmful Algal Blooms) or the removal of PFAS (think non-stick, stain-resistant, or waterproofing-type chemicals). While it's fun being a scientist, I also love dragging my husband to new places near and far, exploring the outdoors, and nerding over books/music. Twitter: @SamSmithCinci

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