Deforestations affect on climate

This topic submitted by Christian Ratterman, Joe Johnson, Sarah Hewitt, John-Thomas Crockett (, at 7:07 pm on 12/8/00. Additions were last made on Wednesday, May 7, 2014. Section: Cummins

Natural Systems I
Final Lab Report
Professor: Dr. Hays Cummins

Joe Johnson Sarah Hewitt
John-Thomas Crockett Christian Ratterman
December 8, 2000


What are the effects of

Deforestation on the Local Climate and what

are the Global Implications of this question


With this laboratory experiment we hope to establish a link between evaporation (relative to plant density), evaporative transpiration, deforestation, and climate change. A rudimentary interpretation of our thesis suggests there is a connection between the four phenomena: the rise in the rate of deforestation has had a detrimental affect on the rate of evaporation in deforested areas. These lowered rates of evaporation (as a result of deforestation) affect the levels of precipitation and ultimately climate in deforested areas by lowering the rate of evaporative transpiration. (Note: Evaporative transpiration is the process by which water is evaporated from within the leaves of plants.) We will use separate experiments to test the evaporative transpiration and rate of evaporation relative to plant density.


This Discovery Lab Packet contains an Abstract, Table of Contents, Introduction, Relevance/ Summary section, Materials-Equipment/ Methods section, Discussion of Data section, Conclusion, and Bibliography.


Deforestation as a geologic phenomenon affects many countries all over the world. This laboratory exercise will examine whether or not deforestation affects climate changes. It incorporates research from written sources and data gained from two laboratory experiments.


Deforestation has an affect on local climate by affecting biotic factors such as precipitation, the levels of sunlight, and the quality and quantity of soil.


Deforestation Evaporation

Evaporative Transpiration (Evapotranspiration) Climate

Xylem Phloem


This lab is designed to familiarize its participants with deforestation, evaporation, evaporative transpiration (evapotranspiration), and climate. It also aims to familiarize its participants with textual research, data collection and interpretation, and the scientific method.

Summary/ Relevance

Setting the Scene

The study of climate can tell a great deal about the Earth. It can help explain natural phenomena such as hurricanes and tornados, and we can make inferences about plant and animal adaptation and evolution over Earth’s history.

By studying climatological trends, we can better understand both the Earth’s history and its current state. We can understand how oceans and deserts were formed, how animals came to inhabit specific areas and how certain species finally came to be extinct. We can come to understand how winds and water sculpted the mountain ranges over periods of millions of years and how those same winds and waters have affected all life on Earth. Through these studies we can even make predictions about our planet’s future.

The Tie that Binds

We believe that plant density directly affects the rate of evaporation within a specific area. As a corollary to that the rate of evaporation is connected to the rate of precipitation, thus, affecting the climate in that defined area. This hypothesis examines four main criteria: the rate of evaporation relative to plant density, the rate off evaporative transpiration due to plant density, climate change relative to plant density, and deforestation’s effect on the other criteria. Previous studies and experiments have examined each criterion and have provided data that suggests that our hypothesis will be substantiated by the results of our combined studies.

The underlying principles for this study come mainly from biology and chemistry. The first is that water (H2O) is a molecule that can be heated to the point of evaporation. Furthermore, the rate of water’s evaporation is affected by heat directly. The second principle fundamental to this experiment is the understanding the plant density affects surface temperature. From this, it can be ascertained that the rate of evaporation, which is affected by temperature, is also affected by plant density (which has an affect on surface temperature). The third principle is related to a function of plants called evaporative transpiration. It is this process that accounts for much of the increased precipitation in densely forested areas. Simply put, evaporative transpiration is the process by which water is evaporated from the leaves of plants. This illustrates the strong correlation between plant density and rates of precipitation (a key factor in climate). Deforestation, therefore, not only affects plant density, it also can affect climate.

The purpose of our laboratory exercise is to understand deforestation’s global effect on climate by studying the relationships between plant density and evaporation, and to understand if there is any significant difference in the levels of transpiration and evaporation due t deforestation. Simply put, what are the affects (if any) of deforestation on the water cycle (on a local scale) and climate (on a larger scale)? By better understanding this relationship, we aim to discover any detrimental effects deforestation may have on the Earth, and assuming that there is a negative correlation, we intend to postulate ways to counteract any further destruction.

The Big Picture

Not all deforestation is preventable, and not all deforestation is naturally occurring. There are some instances in the Earth’s history where natural processes changed forest to desert and oceans to plains. However, today, millions of acres of forest are destroyed by humans for commercial exploitation. It is important for humans to understand the impact their actions today have on the world tomorrow.


Why Study Deforestation?

The effect climate has on Earth appeals to scientist who specialize in different areas of study. Climatoligists, meteorologists, archeologists, biologists, and botanists all have vested interest in better understanding the ways in which climate is affected and how it affects life on Earth. Studying the relationship between plant density and evaporation, as well as the relationship between local evaporation and climate has importance to many scientific disciplines.

Scientist who study climate, climatologists, study the global trends of climate over extended periods of time. They look at the factors that affect climate such as temperature, geologic phenomena (i.e., earthquakes, and volcanoes), population ecology, and even extinction level events (ELEs). They would be very interested in the relationship deforestation would have on local and global climate.

Meteorologists use climate as a reference tool. By understanding an areas climate, they are able to interpret and explain weather patterns and predict the weather with remarkable accuracy. Understanding what affects climate would allow them to better predict the weather.

Archeologist can use information about what the Earth’s historic climate was as a tool identifying where certain species lived, how they adapted and evolved to fit their individual environments, and where certain species may be found. If deforestation has an affect on climate, this knowledge would ad them in their uncovering of fossils, and their interpretations of what they discover.

Biologist and botanist would like to understand the mechanics of and interactions between living things and plants, respectfully. To understand better the relationship between evaporation rates and climate would allow them to better understand how plants work and how they interact with their environments.

Who Cares?

The aspects, factors, and effects of deforestation on local and global climate have been the subject of many articles and journalistic letters. Likewise, the study of evaporation rates relative to climates and plant “ evaporation mechanics” has also been done. It is the goal of this study to incorporate all of these aspects (climate, evaporation, deforestation, and plant biology) with the goal of understanding them all better.

The variety of scientists who want to know more about deforestation is wide. There are thousands of studies and texts pertaining to climate change, evaporation, and deforestation. These studies have focused on regional deforestation ( in the Amazon tropical rain forests and throughout South America, Western and Central Africa, Continental Asia, the Pacific Islands, and North America). There have been studies concentrating on the global effects of deforestation that both cite the Earth’s history as evidence, and attempt to predict its future (climatologically) relative to the rate of global deforestation. There are controlled and observational studies and experiments to better understand the process of evaporative transpiration and the factors that limit it. Many of these experiments develop, reiterate, or establish the principles on which this experiment is based. By synthesizing some of the main ideas in these previous works, we hope to firmly establish a base upon which we can study more closely the links between evaporation, evaporative transpiration, plant density/ deforestation, and climate (change).

With human deforestation occurring on a larger and larger scale every year, it is important to better understand the long-lasting effects this action will have on the world around us. Perhaps, there are methods of counter-acting any harmful effects deforestation has on local or global climates and this study will lend evidence to theories that propose this. Perhaps, there is nothing that can be done to rectify the changes in evaporation levels due to deforestation and this exercise will reiterate this reality. However, since climate is an issue of global importance, this study is relevant to all the world's inhabitants.

Materials- Equipment/ Methods

1) 50 circular pie pans (standard pie size)
2) Water from western pond (we did not want treated water)
3) 2 Buckets to carry the water
4) 4 small pitchers
5) 4 100ml graduated cylinders
6) 4 computerized temperature recorder and computer link equipment (tidbits)
7) Many sunny days
8) 3 fans
9) Camera (for cool data collecting shots)
10) A number of plants
11) 2 large window fans


Experiment 1

The purpose of our first experiment was to determine whether plant density has an effect on the rate of evaporation in a given area. We established five testing locations: four of varying plant density and one control area. The locations were as follows:

1) Wooded area on east side of the Earnest Theater stage. Our location was about 50 feet deep, in a well-covered section of the woods.

2)The edge of the woods near the wooded experiment. We have the cove east of the Earnest Theater.

3)A sidewalk in the sun. We used a section back by the parking lot between Peabody and Boyd.

4)A Grassy spot in the sun. We used the field between Peabody and Boyd.

5)The Weather Center. We placed a set on the roof of Boyd in the weather center. This gave us a connection to the data we pull down off the weather site and the data at each site.

At each of these testing locations we set up ten pie pans each filled with 200ml of water from the Western Swan Pond. In the middle of each pie pan formation we placed a “tidbit” temperature recorder.

This “tidbit” took a temperature reading every fifteen minutes so we could determine whether temperature was a deciding factor in the amount of evaporation that took place. We also used the weather center at Boyd to record temperature and humidity levels from a more controlled location. We set this experiment up in the mornings. In the late afternoons, we measured the amount of water that had evaporated from each individual pie pan at all five locations. The test was run at approximately 10:00am until 6:00pm on five occasions. Unfortunately, due to circumstances of weather and human error, we were only able to analyze and use the data from three of these days. After all the data had been collected, we used StatView to analyze the data and ANOVA to compare each of the test sites on each day. All of these results may be seen below.

Thanks to all the people that helped us!

Experiment 2

The purpose of our second experiment was to determine whether varying amounts of wind have an effect on the rate of evaporation. Based on the first experiment alone, we would have been unsure of whether the evaporation was only dependant on the amount of direct sunlight on that area, or if wind had an effect as well. This is important because both are issues in deforested areas. Because of the loss of trees, there is a much higher exposure to sunlight, and the area is more open to the force of wind. For this experiment we set up three stations of ten pie pans each in the same formation as the first experiment. However, all three were placed in a laboratory in Boyd hall, each with equal exposure to sunlight through the windows. In front of one set, we placed a fan on its highest setting. In front of the second, we placed a fan on its medium setting. We left the last set with no fan. This experiment was given the same amount of time as experiment one. At the end of the day we tested each pie pan for water loss and recorded the results. Again we analyzed the data using StatView and we compared the results using ANOVA tests.


All of our data can be found by downloading the document below. You can also see the quick view of some of our data in the graph below.

PDF Document of data: Evapdata.pdf

Discussion of Data

These data fields examine the results of both experiments in a quantitative fashion. The data collected was put through several statistical analyses. The purpose of these tests was to determine if the data indicated a significant difference in the mean levels of water evaporated in each respective experiment. For the experiment that compared evaporation levels in areas of varying plant densities, the statistical tests proved that there was a significant difference in the mean levels of water collected in the five different locations. It also demonstrated that there was a large disparity between the areas with the least plant density and the areas with the most plant density.

Given that wind and temperature can also affect temperature, these factors needed to be examined. Only by discounting wind and temperature as factors that will affect the validity of the data, is the data and its interpretation applicable. Measurements of the temperature at each unique location were taken. After analyzing the data, it was determined that temperature did not significantly affect the levels of evaporation at the unique locations.

A second experiment tested the effects of wind on evaporation. After recording and analyzing the data, it was determined that wind affects the level of evaporation directly (i.e., the more wind the higher the levels of evaporation).

Irregularities in the data were not uncommon and even resulted in the negation of several large sections of data. Many of the errors were a result of human error. Human error was a result of errors in measurement, calculation, and experimental design.


As a result of the integration of (textual) research and field data, several key assumptions as well as the hypothesis were substantiated.

The primary assumptions that were substantiated were assumptions vital to the hypothesis. The first is that deforestation is the process of forest destruction and that deforestation affects climate. The change manifest themselves in changes in the levels of precipitation among other things.

Precipitation is vital to forested areas. Precipitation is reabsorbed (thus fueled by) two main processes: evaporation and evapotranspiration. Some estimates state that more than 70% of water reabsorbed in forested areas is done so through evapotranspiration. Deforested areas lose this capacity for evapotranspiration; thus, most of water re-absorption in these areas is a product of evaporation. This change in the means of water re-absorption affects precipitation, soil, and ultimately sunlight levels – three factors of climate.

Using field data, it can be said that deforestation does affect the levels of evaporation in unique areas. This , with the data collected through texts suggest that the initial hypothesis is substantiated. Deforestation does affect climate.



"permit.html" Shukla, J., C. Nobre, and P. Sellers. 1990. Amazon deforestation and climate change. Science 247: 1322-25.


Scientific American

CLIMATE CHANGE IN THE HEAT OF THE NIGHT Warmer nights may be slowing tropical forest growth and raising carbon dioxide levels

Earth Science DESERTING THE SAHARA Dying plants harvest harsh surprises from climate change


FROM THE EDITORS If You Can't Stand the Heat ...

Earth Observatory

Tropical Deforestation


Global Deforestation and the Nineteenth-Century World Economy

Edited by Richard P. Tucker and J. F. Richards

Duke Press Policy Studies

Durham, N. C. 1983

Potential Impacts of Climate Change on Tropical Forest Ecosystems

Edited by Adam Markham

Kluwer Academic Publishers

P.O. Box 17, 3300 AA Dordrecht, The Netherlands 1998

Tropical Deforestation: A Socio-Economic Approach

C. J. Jepma

The Tropenbos Foundation/CJ Jepma, 1995

Climate-Biosphere Interactions: Biogenic Emissions and Environmental Effects of Climate Change

Edited by Richard G. Zepp

John Wiley & Sons, Inc. 1994

Amazonian Deforestation and Climate

Edited by J. H. C. Gash, C. A. Nobre J. M. Roberts and R. L. Victoria

John Wiley & Sons Ltd. Institute of Hydrology 1996

Blowing in the Wind: Deforestation and Long-Range Implications

Editors at Studies of Third World Societies

Department of Anthropology, College of William and Mary. 1981

World Deforestation in the Twentieth Century

Edited by John F. Richards and Richard P. Tucker

Duke University Press, 1988

The Social Dynamics of Deforestation: A case study from Nepal

J. Soussan, B. K. Shrestha and L. P. Uprety

Parthenon Publishing Group Ltd. 1995

Evapotranpiration from Successional Vegetation in a Deforested Area of the Lake Wales Ridge, Florida

By D. M. Sumner

Tallahassee, Florida 1996

Cut & Run: Saying Goodbye to the Last Forests in the West

By Grace Herndon

Western Eye Press, 1991

Reframing Deforestation: Global Analyses and Local Realities: Studies in West Africa

By James Fairhead and Melissa Leach

Routledge, 1998

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