The Forest Ecology Activity

Handout for the Forest Ecology Activity

Developed by Dr. Greg Perrier, NOVA

Introduction

NOVA has a campus in a virtual world called Second Life (SL).  On this virtual campus there is a forest very similar to the forests you would see on the real NOVA campuses.   Because of the high tick population with the corresponding risk on Lyme’s disease we have stopped taking students into the real forest, but we can still conduct interactive forest ecology activities in the forest on NOVA’s Second Life campus.  In this activity you will collect data on the number of trees by species in three different plots and from this data will be able to determine relative frequency, relative density, and relative basal area for the different tree species.  For Bio 102 classes, you will be provided with an Excel Program that does these calculations for you and you need only interpret the results.  For an Ecology class, you will be asked to do these calculations.

This handout assumes you are at the Main Landing site on the NOVA campus in Second Life (SL) (see image below).  Your professor should have provided a handout on how to get started in Second Life which tells you how to get to the Main Landing Site.  Whenever you wish to exit SL, simply left click on the white X in the red box on the top right of your screen.

Security

SL is like a large city.  At any time there are about 50,000 people logged in.  Most of those people are nice and respectful, but like any city, there are people who might bother you.  As long as you stay on the NOVA Island, it is unlikely anyone will bother you.  Most the avatars you will see at NOVA are other students or professors, so feel free to chat with them. Be aware that on the campus nudity as well as abuse or harassment of other students will not be tolerated and anyone doing this will be banned from the campus. If someone ???

How to Find the Forest

At the landing site you will see an old fashion telephone booth on the lawn between the sidewalk and the building.  The sign over the door to the booth says “Telephone.”
 
Left click on this telephone booth.  Your avatar will now be inside the booth and you will see a list of the different locations on campus.  You can click on cancel if you want to leave the booth. 

There are three menus of locations.  Click next to see the next menu if needed.  Find the location named Activity 11 and left click on it.   You should now be at that correct location for the forest ecology activity. 

There you will see a sign that says Station 11 - Forest Ecology (see image below).  The coordinates found in the middle of the top toolbar should read around (50, 50, 23).

Whenever you wish to exit Second Life, left click on the white X in the red box on the top right of your screen.  When you return to Second Life, your avatar will appear at the same location it was when you logged off.

Activity Handout for the Forest Ecology Activity

Introduction

In this activity you will collect data on the number of trees by species in three plots in a virtual Eastern hardwood forest, similar to the forests on the real NOVA campuses.

From this data you can determine relative frequency, density, and basal area of the trees species in this forest as well as determine a species importance value index and a biodiversity index.  These are all ecological parameters used to describe the structure of a plant community.  For BIO 102 students and Excel sheet is provided that once you enter the data you collected, completes all the calculations for you.  USE THE EXCEL.

The Forest

The forest is a mixture of 11 different species of trees and is a rough approximation of the Eastern hardwood forest.  Under the trees there are wildflowers, grasses, ferns, and mushrooms.  Wildlife is also found in the forest, keep your eyes open for things that move. 

Common names, scientific names, and the diameter in centimeters for each tree species are listed in table 1.

Table 1: Trees of the forest.

Common Name	Scientific Name	Diameter cm
White Birch	Betula papyrifera Marshall	32
Red Cedar	Juniperus virginiana L.	3
American Chestnut	Castanea dentata (Marshall) Borkh.	84
Shagbark Hickory	Carya ovata	20
American Elm	Ulmus americana L.	135
Red Maple	Acer rubrum L.	274
Black Oak	Quercus velutina Lam.	190
Red Oak	Quercus rubra L.	155
Virginia Pine	Pinus virginiana Mill.	74
White Pine	Pinus strobus L.	68
Red Spruce	Picea rubens Sarg.	160

Locating the Forest Plots

You will collect your data from three rectangular plots, each 20 meters by 40 meters (800m2) (see image on the page below).

The plots have red stakes at the corners and a yellow “rope” is stretched between the posts.  Facing the forest, two plots are on your right – the one you can see and another at the far end of the forest – and one plot on your left – located between the two plots on your right.

You can collect data from the 3 plots in any order.  Make the first plot you collect data from Plot 1, the second plot then is Plot 2 and the last plot is then Plot 3.

Now walk into the forest.  Note that the trees just inside the forest are labeled with the common name for the tree.  Take a little time to see the differences between the different tree species so you can better identify them later. 

If you forget their names you can find the name of a tree by right clicking above your head level on the tree and in the menu that appears, select edit.  Under the general information tab in edit you can see the tree name. 
Now go to the first plot and begin data collection.  The data you are collecting is the number of trees in each plot by species (e.g. how many red oaks in the plot).

Collecting Tree Data

Once in the plot, walk all the way through the plot and then turn around so that the mountain is on your left. 

You will notice that all the trees have a red or green square on them (see image on page below).  This will help you keep track on the trees you have counted.  You simple left click on the front of this square and in a few seconds it should change from red to green or green to red. 

When you start make sure the squares are all the same color, either red or green.  Left click on each square as you enter the tree in your datasheet. 

If the square does not change color, then right click on it and select “touch.”   The change in color indicates that you counted that tree.  In a real forest, you would mark the tree with chalk. 

You want to count the trees in plot 1 by species and enter the data into Table 2 below.  Note that the plots only have 9 of the 11 species.  None of the red cedars or red spruce fell within the 3 plots.

Table 2: Tree numbers by species and plot.

Common Name	Plot 1	Plot 2	Plot 3	Total
White Birch
American Chestnut
Shagbark Hickory
American Elm
Maple Tree
Black Oak
Red Oak
Virginia Pine
White Pine
Total

Now move on to your second plot (Plot 2) and repeat the steps you did for plot 1 and enter the data for plot 2 in table 2.  Move on to your final plot (Plot 3) and repeat the steps you followed for plots 1 and 2 and enter the data under plot 3 in table 2.  Calculate the total number of trees for each species and the total number of trees in each plot and enter these numbers in the appropriate column and row in table 2.

If you are in a general biology class (e.g. Bio 102 at NOVA) your professor should have provided you with an Excel file for this activity.  Open the Excel file now and transfer your data in Table 2 on this Word document to complete Table 2 in the Excel file.  This Excel program will then complete the calculations for tables 3 to 6.  You do not need to complete tables 3 to 6 in this Word document, but the explanations provided for each table will help you answer the worksheet questions.

Use the information on tables 3 to 6 in the Excel file to answer the questions at the end of this handout.

If you are in a more advanced Biology class, your professor probably did not provide the Excel file and you must complete tables 3 to 6 yourself and then answer the questions at the end of the handout.

Calculation of Relative Frequency and Relative Density

First transfer the total number of trees of each species from Table 2 into column one of Table 3.

Relative frequency is simply the proportion of all trees in the three plots for each tree species.  For example, if there are 100 trees in all three plots, and 10 of these trees are red maple, the relative frequency for red maple is 10/100 or 0.10. 

Relative density is similar to relative frequency but considers also the area of the plots.  Each plot is 20 meter by 40 meters or 800 m2.   The total area of the three plots is 2,400 m2.  Density is given in terms of trees per 1,000 m2, so simply divide the tree density for 2,400m2 by 2.4 to get the density per 1000 m2. 

To get the relative density per tree species, divide each species density by the total tree density.

Table 3: Relative Frequency and Relative Density.

Common Name	Total	Relative Frequency	Density Per 2400 m2	Density Per 1000 m2	Relative Density
White Birch
American Chestnut
Shagbark Hickory
American Elm
Maple Tree
Black Oak
Red Oak
Virginia Pine
White Pine
Total

Calculation of Relative Basal Area 

To calculate relative basal area, first you need to calculate the basal area per tree for each species.  To do that, you take the tree diameter from Table 1 and divide it by 2 and multiply by 3.14 (pi).  The equation is basal area = (diameter / 2) * 3.14.  Enter that number into the “Tree Basal Area” column in Table 4.

Transfer the total number of trees for each species from total column of Table 1 to the “Number of Trees” column of Table 4. 

To calculate the species basal area, multiply the basal area per tree by the number of trees for each species.   To calculate the relative basal area, you divide the total basal area for each species by the total basal area for all trees in the three plots (found at the bottom of column 3 –“Species Basal Area”) in Table 4.

Table 4: Relative Frequency, Density, and Basal Area.

Common Name	Tree Basal Area	Number Of Trees	Species Basal Area	Relative Basal Area
White Birch
American Chestnut
Shagbark Hickory
American Elm
Red Maple
Black Oak
Red Oak
Virginia Pine
White Pine
Total

Importance Value Index (IVI)

The IVI is an approximation of the biomass (weight) of all the trees for a given species in the forest.  The greater the biomass associated with a tree species, the more dominant that species is within the forest ecosystem.  IVI is calculated by adding the relative basal area, relative density, and relative frequency (see equation).

IVI = Relative Basal Area + Relative Density + Relative Frequency.

Transfer the data from tables 3 and 4 to the appropriate columns in table 5 and then calculate the IVI for each species.

Table 5: Importance Value Index (IVI)

Common Name	Relative Basal Area	Relative Density	Relative Frequency	IVI
White Birch
American Chestnut
Shagbark Hickory
American Elm
Red Maple
Black Oak
Red Oak
Virginia Pine
White Pine

Calculating Simpson’s Biodiversity Index

Biodiversity is a measure of species richness (the number of species) plus species relative abundance (relative frequency).   There are several different indices for biodiversity.  We will use the Simpson Biodiversity Index, developed in 1949 by Edward Simpson.  The equation for the Simpson index is shown below.  The index first requires that for each species you multiply the total number of trees (n_i) by the total number of trees minus 1 (n_i – 1).  Then you sum the result for all nine species found in the three plots.  Next you take the total number of trees in all three plots (N) and multiply that by the total number of all trees minus 1 (N-1).  Now you divide the number you calculated from summing the number for all nine tree species by the number you obtained using the total number of trees.   The result is the Simpson Index of Biodiversity.   Use Table 3 to help make these calculations.
. 
Simpson Index of Biodiversity Equation

Table 6: Simpson Index of Biodiversity Calculations

Common Name	# Trees	# Trees -1	# Trees x # Trees - 1
White Birch
American Chestnut
Shagbark Hickory
American Elm
Red Maple
Black Oak
Red Oak
Virginia Pine
White Pine
*Total  - ni * (ni-1)
**Total  - N * (N-1)
Simpson Index of Biodiversity *Total / **Total

Final Steps

The next step is to take a photo of your avatar in the forest and email it to your professor so he or she knows you were there.  To do this, left click on the camera icon in the bottom toolbar.  The image you will see in the box it your photo.  If you do not like the photo, cancel the box and click on the camera again.  Once you have a photo you like, click on the email option for your photo, enter your professors email address, and send the photo to your professor.  For Dr. Perrier, send it to gperrier@nvcc.edu.  In the message box that goes with the photo email be sure to give your real name so your professor can give you credit for this activity.

Now go to the next page and complete the questions.  Once you have answered the questions, email the answers plus tables 2 through 6 to your professor.  You can copy and paste into the email or copy the tables and questions into a Word file and attach that word file to your email. 

I hope you enjoyed your stay in the forest and learned a bit about forest community structure and how forests are studied.

Question Page                                                        

Student name ________________

Avatar name ________________ 

Conifers grow where there is a lot of sunlight.  The conifer trees in this forest were established before the hardwood trees were tall and shaded the forest floor.  Note there are no young conifer trees in the middle of the forest. 

1. What are the four conifer species in this forest?

1.
2.
3.
4.

2. Where are the young red cedars located and why are they located there?

3. The dominant tree in a forest is usually the most abundant tree.  It has the most biomass (weight) for any species.    Forest are usually named for the two most abundance tree species.

What are the two most abundant tree species (highest frequency) in your plots?

1.
2.

4. What would the name of this forest type be?
 A _______________________ and ____________________ forest

5. Each plot is 40m x 20m (800m2).   What is the density of trees in the forest given as trees per 1000m2? Note: the total area for the 3 plots in 2,400m2.

6. Compare relative density and relative frequency.  Why are they the same?

7. The size of the forest is 65m x 150m or 9,750m2.   Estimate the total number of trees in the forest.

8. Which tree species has the largest basal area for an individual tree?

9. Which tree species has the largest relative basal area in the plots?

10. Which two species have the highest IVI and which two species have the lowest IVI? 

11. How do the species with the highest and lowest IVI in question 10 compare to the species with the highest and lowest density?

12. What two factors go into determining the biodiversity of a forest?   Read the section on Calculating Biodiversity above to answer this question.