Department of Land Resources and Environmental Sciences
Montana State University-Bozeman
LRES 110, Land Resources and Environmental Science
Field Trip to "M"
September 15, 2000: 4-7 pm
Introduction
The "M" recreation area is on Gallatin National Forest Land on the south end of the Bridger Mountain Range (see map). This area is typical of many urban fringe trail heads, because it receives intense recreational use. Many trails were created on the steep slopes and thus erosion has been excessive. The combination of erosion and intense humane use has been accompanied by invasion of several weed species that continue to spread. A citizens group, along with State and Federal Agencies have been developing a management strategy for the "M" area.
The purpose of this field trip is to acquaint you with some of the management objectives associated with the "M" area, identify some research questions that will bring supportive objective information to the management planning process, identify testable hypotheses, and actually make some measurements and do some preliminary analysis to demonstrate the use of data to help answer the research questions.
Station 1:
Issue: The presence of the invading weed leafy spurge is degrading the ecosystem on the slopes below the "M".
Research Question: Does leafy spurge cause a degradation of the ecosystem below the "M"?
Identify Dependent Variable: Plant community species diversity.
Identify Independent Variable: Presence or amount of leafy spurge:
Testable Hypotheses: Plant community species diversity is lower in leafy spurge patches.
Plant community species diversity is negatively correlated with amount (density or cover) of leafy spurge.
[Note that the hypotheses state nothing about the cause of differences in the dependent variable. Think about why that is appropriate?]
Measurements: 9 flags have been placed in leafy spurge patches on the slope below the "M". Form a two person team. Each team will go to a different flag and place one 0.25 m2 circular frame in the leafy spurge patch near the flag and one frame outside (within 5 m) the leafy spurge patch. Record the information for each frame on the data sheet provided. One side of the data sheet for each frame. Each student must place their name on a data sheet to get credit for attending the field trip. If you cannot identify a plant species then ask one of the TA's or simply record each unknown species with a different number (e.g. unknown #1, unknown #2, etc.). Record your plant species under the correct category (grass, forb, shrub or tree) even if it is an unknown. Try to record the density (number of plants of a given species per unit area, in this case 0.25 m2), and estimate the percent canopy cover in the frame for each species by looking down on the frame. In your mind you must group each species to make this estimate. Your total cover may not add up to 100% because of non-vegetation surface. Place the total number of species for your frame at the bottom of the "Presence" column.
Data: The plant species data will be compiled in a Microsoft Excel spreadsheet and be available on September 25, 2000 at 5:00 pm. Before that time you will be able to look at the 1999 data.
Data file download (click on the desired format):
Microsoft Excel or Word Format
ASCII Data Format (should go into any program)
If you have trouble downloading the data, you can cut and paste back into Excel from the data table below:
2000 Data: Treatment: 0 = outside of leafy spurge patch and 1 = inside leafy spurge patch.
|
LRES 110 Field Trip to "M" Compiled Data |
|
09/15/00 |
|||
|
|
|
|
Leafy Spurge |
Endemic |
Exotic spp |
|
Flag No. |
Treatment |
Total spp |
Density |
spp No. |
No. |
|
7 |
0 |
6 |
9 |
5 |
1 |
|
7 |
1 |
2 |
60 |
1 |
1 |
|
6 |
1 |
5 |
11 |
4 |
2 |
|
6 |
0 |
4 |
3 |
3 |
1 |
|
5 |
1 |
7 |
25 |
4 |
3 |
|
5 |
0 |
5 |
2 |
3 |
2 |
|
9 |
1 |
5 |
43 |
2 |
3 |
|
9 |
0 |
5 |
5 |
2 |
3 |
|
4 |
0 |
4 |
36 |
3 |
1 |
|
4 |
1 |
2 |
15 |
1 |
1 |
|
9 |
1 |
5 |
20 |
1 |
4 |
|
9 |
0 |
6 |
10 |
3 |
3 |
|
3 |
0 |
5 |
1 |
3 |
2 |
|
3 |
1 |
5 |
104 |
3 |
2 |
|
8 |
0 |
5 |
3 |
3 |
2 |
|
8 |
1 |
6 |
32 |
3 |
3 |
|
4 |
0 |
2 |
29 |
1 |
1 |
|
4 |
1 |
1 |
103 |
0 |
1 |
|
4 |
1 |
3 |
8 |
2 |
1 |
|
4 |
0 |
5 |
12 |
4 |
1 |
|
5 |
0 |
7 |
1 |
5 |
2 |
|
5 |
1 |
8 |
12 |
5 |
3 |
|
3 |
0 |
5 |
0 |
4 |
1 |
|
3 |
1 |
3 |
21 |
2 |
1 |
|
2 |
1 |
3 |
26 |
1 |
2 |
|
2 |
0 |
5 |
11 |
3 |
2 |
|
8 |
1 |
5 |
39 |
2 |
3 |
|
8 |
0 |
4 |
4 |
2 |
2 |
|
6 |
1 |
6 |
7 |
1 |
4 |
|
6 |
0 |
7 |
5 |
4 |
3 |
|
6 |
0 |
4 |
3 |
3 |
1 |
|
6 |
1 |
6 |
11 |
4 |
2 |
|
9 |
0 |
3 |
3 |
2 |
1 |
|
9 |
1 |
3 |
27 |
1 |
2 |
|
7 |
0 |
2 |
23 |
1 |
1 |
|
7 |
1 |
1 |
82 |
0 |
1 |
|
2 |
0 |
3 |
3 |
1 |
2 |
|
2 |
1 |
3 |
32 |
1 |
2 |
|
3 |
0 |
7 |
3 |
5 |
2 |
|
3 |
1 |
4 |
23 |
3 |
1 |
The following explanation of species diversity comes from:
Botkin and Keller, 2000, Environmental Science: earth as a Living Planet, John Wiley & Sons Inc. publishers.
Analysis: There are several ways to measure the number of species in an area. Species diversity consists of two related components, species richness and the relative abundance of species or species evenness. We will use 2 commonly used measures of species diversity/evenness:
Formulate Dependent Variables:
1. Mean Vascular Plant Species Richness
- Total the number of species for each frame (Sj). (j is the frame or sample number.)
- Calculate the mean number of species per frame for frames placed within leafy spurge patches (Treatment = 1) and a separate mean for those frames placed outside of leafy spurge patches (Treatment = 0) in the frame.
where n is the total number of sample frames per treatment.
2. Mean Vascular Plant Species Diversity using the Simpson Index (D) of Evenness which takes relative abundance of each species into account. The closer D is to 1.0 the more evenly represented the species are in the community.
where Dj is the Simpson Index calculated for each sample frame and pi is the proportion of each sample frame covered by each species (i).
Statistical Analysis: In order to determine if S or D are different in the leafy spurge patches versus outside of the patches we must determine the variance in Sj and Dj and test the null hypothesis that there is no difference in the mean measures of diversity between the two treatments (inside and outside the leafy spurge patches).
Assignment: Calculate the following means and standard deviation for inside and outside leafy spurge patch treatments.
- Endemic species richness
- Exotic species richness
- Total species richness
- Total species evenness (Simpson Index = D)
Make bar graphs with standard deviation bars (see example below) for each of the above comparing the mean values for the inside and outside leafy spurge patch treatments. The calculation of statistics and graphs can all be accomplished in Excel or your favorite spreadsheet program. Print out a table of your means and standard deviation and attach a hard copy of your graphs with labels. In a 3-4 sentence paragraph describe your results and determine whether or not you think that your results provide enough evidence to reject the null hypothesis. If the standard deviation lines on either bar include the top (mean value) of the other bar, there is probably no difference between the two mean values.
Null hypothesis (Ho): There is no difference in plant species diversity between areas within leafy spurge patches and areas outside of patches.
Fill in the mean and standard deviation values in a table exactly like this one:
Treatment Endemic Species Richness
Exotic Species Richness
Total Species Richness (S)
Total Species Evenness (D)
Inside Leafy Spurge Patch Mean (Std Dev) Mean (Std Dev) Mean (Std Dev) Mean (Std Dev) Outside Leafy Spurge Patch Mean (Std Dev) Mean (Std Dev) Mean (Std Dev) Mean (Std Dev) Create 4 bar charts that look like this:
Calculating Standard Deviation
The standard deviation (std_dev) is calculated from the variance in the sample of diversity measures that we took.
so
or
or
or
.
where
is the value for each observation,
is the mean (average) for a set of values and
is the total number of observations for the set of values.
There will be a help session in 346 LJH on Monday, September 25 at 5:30 pm.
