Deforestation effects on Climate

This topic submitted by Christian Ratterman, Joe Johnson, John Crockett, Sarah Hewitt (, at 12:01 pm on 10/20/00. Additions were last made on Saturday, March 2, 2002. Section: Cummins


Natural Systems I

Lab Packet

Professor: Dr. Hays Cummins

Joe Johnson
Sarah Hewitt

John-Thomas Crockett

Christian Ratterman

October 20, 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.


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 and Methods

Required Materials

Materials that may be added

Experiment I

This experiment is to test the differences in evaporation in areas with varied plant density. We have five test sites planned (see below) and we will place 10 pans of water in each one. We will have 200ml of water per pan and in each location we will place a temperature recorder in a spot not shaded by the pie pans or other things we place on the site. The temperature recorder will automatically give us temperature readings once every second, we plan on using one every 15 minutes. The weather center is also a key tool for us. We are compiling data taken from the roof of Boyd every 15 minutes as well. We are looking into using another device to check the relative humidity at each site periodically. This reading can be used to make some references to the differences in dew points from the main dew point reader on Boyd?s roof and each of the other sites

Test Sites

1)Wooded area on east side of the Earnest Theater stage. Our location is 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 are planning of using a section back by the parking lot between Peabody and Boyd.

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

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

We will be running our experiment mainly on Tuesdays, Thursdays, Saturdays and Sundays. On the days we run the tests the sky must be fairly clear, there can be no rain. The tests will be run from about 10:00am until 6:00, These are the prime hours of the day, it is when the sun is out in full force. We will place the pans out in the layout below, fill them with water and later measure the amount of water left in each pan. We will also place a temperature recorder at each location. (To avoid theft or damage the field and sidewalk temperatures will be taken by one recorder left in the field.)

Pan layout

Our Group will split up into 2 teams. (Group 1- Joe Johnson & Christian Ratterman, Group 2- Sarah Hewitt & John-Thomas Crockett) Each team will set up the experiment and watch and check the results in the layout below. Times and groups are variable. We try to stick with this as much as possible however we must make adjustments if there are absent group members or if there is problem we must over come. We use this schedule as a basis for our layout. Our goal is to stay as close to it as possible.

Experimental Timing

  • How did the experiments go? (11/19/00) [ Contributor: hot spots-Section: cummins ]
  • Stuff for the class to read (10/30/00) [ Contributor: Christian Ratterman-Section: cummins ]

    9:30am Groups mark off the test sites and place the empty pie pans out.

    10:00am Group 1 puts 200ml of water into each pan in the woods.

    10:00am Group 2 puts 200ml of water into each pan on sidewalk.

    10:10am Group 1 puts 200ml of water into each pan on edge of woods.

    10:10am Group 2 puts 200ml of water into each pan in open grassy field.

    10:20am Group 1 & 2 Meet at Boyd and fill the pans in weather center with 250ml of water.

    Every half hour starting at 11 the groups will take turns checking the sites. We also keep an eye on the Boyd weather site to make sure that the online data is coming through well. In the end we use the data of the daily compiled sheet. (

    5:30pm Group 1 empties, measures and records data for each pan in the woods.

    5:30pm Group 2 empties, measures and records data from each pan on sidewalk.

    5:40pm Group 1 empties, measures and records data from each pan on edge of woods

    5:40pm Group 2 empties, measures and records data from each pan in field.

    5:50pm Groups 1 & 2 empty, measure and records data from each pan on the roof of Boyd.

    5:00pm Groups 1 & 2 Clean Up all sites.

Data for this experiment will be formed into a single StatView file that will be used to analyze the all the data. We plan on using an ANOVA test to compare each of the test sites on the different days. We are still working on the exact layout of the StatView document. There are a lot of different types of data in our experiments and we need to find the right way to work all of it in. I have included however the layouts for the temporary data charts that we will be using to make sure that our data is safe. These charts let us easily judge the data from each individual experiment separately and that way we can find the problems that need to be worked out.

Experiment II

This Experiment is our control test. We plan to set up pans of water in the lab and place fans running at different speeds in front of the sets. Each set will have a the same design layout and the same climate, however the wind level will be different. This will let us know what effect the wind had on evaporation. We also hope to include a number of checks on the temperature in each control set and the humidity. The plan so far is to get 3 fans and set up four sets of 9 pans. One set will not have a fan blowing on it, one set will have the fan on low and the 2 other sets will be medium and high fan settings. Below is a diagram of the layout we hope to use.

Experiment III

This experiment is still in the works. We are looking into the equipment required and if it is worth running. The idea is simple. We would like to test the level of Transpiration in different climate variables. We are looking into running an experiment like number 2 except we will change the pie pans to plants so that we can get an idea of how much water is evaporated off of plants. This will allow us to have a better idea of what actually gets evaporated off a Forrest. We are now looking for a way to test h

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