Leaf Litter Lab
Collaborators:
The entire class collaborated together to complete this experiment.
Introduction and Problem:
Biodiversity is a key component of a healthy ecosystem; it refers to the variety of organisms in that ecosystem. According to the background information, there are two components to biodiversity: species richness, a measure of the number of species living in that ecosystem, and species evenness, a measure of the relative abundance of different species making up the richness of a particular area. Using this information, scientists are able to calculate the Simpson's Diversity Index, a quantitative measure of biodiversity, of an ecosystem. Through this lab, the problem, "What is the level of biodiversity of leaf litter collected from the outdoor trail at Heritage High School and Mr. Gunsher's woods?", will be addressed.
Pre-Lab:1. Why would we want to rate the amount of biodiversity in a location?
Scientists might want to rate the amount of biodiversity in an ecosystem because biodiversity is a key component of a healthy ecosystem: ecosystems with high levels of biodiversity provide a wide range of natural resources for use by humans and other organisms, prevent environmental stress caused by human-related activities and natural events, and allow natural selection and evolution to occur over successive generations. Scientists might study ecosystems in order to determine potential causes and solutions to low levels of biodiversity, which could negatively impact the health of the ecosystems.
2. Examine the charts below and calculate the diversity indices for the three samples.
Hypothesis:
If both soil and leaf litter are to be collected from the Heritage High School Trail and Mr. Gunsher's backyard, the leaf litter samples will yield the most biodiversity due to a better habitat for insects to live in.
Parts of the Experiment :
- The independent variable is the location from which the samples are collected.
- The dependent variable is the level of biodiversity of the samples.
- The controlled variables are the materials, the season in which the samples were collected, and the amount of time each sample was placed under the light source.
- The control group consists of the samples of soil.
- The experimental group consists of the samples of leaf litter collected from both the outdoor trail at Heritage High School and Mr. Gunsher's woods.
Materials:
- samples of leaf litter
- samples of soil
- compound microscopes
- alcohol
- beakers
- Berlese funnels
- lamps
- invertebrate identification pages
Method:
1. Using large plastic bags, collect multiple samples of leaf litter and soil from a wooded area.
2. Place the samples of leaf litter into four Berlese funnels and place the samples of soil into two Berlese funnels.
3. Place a light source above each funnel and a beaker of alcohol beneath the funnel.
4. After a week, collect the beakers of alcohol and using a microscope, examine the organisms contained inside.
5. Using the invertebrate identification pages, identify the organisms and record the number of each species.
6. Using the formulas provided in the background information, calculate the diversity indices of each population of organisms from each location.
Data:ObservationsRelevant Information of Samples of Leaf Litter and Soil from Heritage High School Trail:Location: Wake Forest, North Carolina
Type of Community: Wooded Community
Date: Tuesday, September 16, 2014
Weather Description: Sunny, clear skies
Air Temperature: N/A
Soil Temperature: N/A
Relative Humidity: N/A
Time: 9:20-9:45 AM
Relevant Information of Sample of Leaf Litter from Mr. Gunsher's Woods Location: N/A
Type of Community: Suburban Community
Date: September, 2014
Weather Description: N/A
Air Temperature: N/A
Soil Temperature: N/A
Relative Humidity: N/A
Time: N/A
Data Tables
Heritage High School Trail: Leaf Litter
Total Number of Organisms: 94
Simpson's Index = 0.17
Simpson's Index of Diversity = 0.83
Simpson's Reciprocal Index = 5.9
Simpson's Index = 0.17
Simpson's Index of Diversity = 0.83
Simpson's Reciprocal Index = 5.9
Mr. Gunsher's Woods: Leaf Litter
Total Number of Organisms: 147
Simpson's Index = 0.27
Simpson's Index of Diversity = 0.73
Simpson's Reciprocal Index = 3.7
Simpson's Index = 0.27
Simpson's Index of Diversity = 0.73
Simpson's Reciprocal Index = 3.7
Heritage High School Trail:
Soil (Control)
Total Number of Organisms: 4
Simpson's Index = 0.5
Simpson's Index of Diversity = 0.5
Simpson's Reciprocal Index = 2.0
Simpson's Index = 0.5
Simpson's Index of Diversity = 0.5
Simpson's Reciprocal Index = 2.0
|
Pictures
|
Data Analysis
Through the data tables, it was made apparent that both the samples of leaf litter had high levels of species richness but low levels of species evenness. Both samples contained many organisms of different species, however, the relative abundance of each species compared to one another differ greatly. For instance, the sample of leaf litter collected from the trail contained 52 mites and 1 roach, and the sample collected from Mr. Gunsher's woods contained 53 springtails and 1 pseudoscorpion. On the other hand, the sample of soil had a lower level of species richness, but a higher level of species evenness: the sample only contained two different species (springtail and mite), but the relative abundance of each species compared to one another only differed by 2.
After the diversity indixes of each sample were calculated, it was clear that the sample of leaf litter collected from the outdoor trail had the highest level of biodiversity. The Simpson's Index of the sample of leaf litter from the trail was 0.17, its Simpson's Index of Diversity was 0.83, and its Simpson's Reciprocal Index was 5.9. The Simpson's Index of the sample of leaf litter from Mr. Gunsher's woods was 0.27, its Simpson's Index of Diversity of the sample was 0.73, and its Simpson's Reciprocal Index was 3.7. The Simpson's Index of the sample of soil from the outdoor trail was 0.5, its Simpson's Index of Diversity of the sample was 0.5, and its Simpson's Reciprocal Index was 2.0. The Simpson's Index of the sample of leaf litter from the trail was 0.33 less than that of the control sample; its Simpson's Index of Diversity was 0.33 greater than that of the control sample; its Simpson's Reciprocal Index was approximately 3.9 higher than that of the control sample. The data indicates that the sample of leaf litter collected from the outdoor trail had the higher level of biodiversity when compared to the control sample.
Conclusion:
The hypothesis predicted that 10 organisms would be found but only 6 were found in the sample. It also stated that there would be species evenness but the evenness was low for the sample.
1. The organisms moved away from the light down the funnel because they liked it better when it's damp,so when the light started the dry the leaves they had to move to somewhere more wet. Also, they like the dark better and tried to stay away from the sunlight (the lamp). This means that in the real environment, these organisms are deep in the soil.
2.The biodiversity of this litter is high.Many different types of organisms were found throughout each sample, and even a rare specimen of the pseudoscorpian was found in one of the samples from Mr. Gunsher's backyard. Both of the index's of the leaf litter were lower than the Simpson's Index of the soil, which indicates high biodiversity; the HHS trail sample was lower than the soil by .33 and the sample from Mr. Gunsher's backyard was smaller by .23.
3. An environmental scientist would have to make more than one measurement if he was calculating the biodiversity, because he will need to account for as many organisms as he can. He would take samples of a large forest by taking it piece by piece. For example: start from deep into the soil and work his way up.
Conclusion
After using the Simpson's Index, the data shown provided proof that the biodiversity throughout the leaf litter samples were higher than that in the soil sample. The Simpson's Index of the soil sample was .5 which was .33 higher than that of the HHS trail sample and .23 higher than the sample provided from Mr. Gunsher's Backyard. The data suggest that the hypothesis was correct. In Anup Shah's article about the importance of biodiversity she says "Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play". Throughout her article she speaks on the importance of biodiversity in a healthy ecosystem and how these ecosystems have better survival rates. She also speaks on the number of natural resources that biodiverse ecosystems provide. These resources include protection of water resources, soil formation and protection and pollution breakdown. In order to maintain high biodiversity throughout our Earth's ecosystems, humans need to reduce harmful activities.
Citation
"Why Is Biodiversity Important? Who Cares?" - Global Issues. N.p., n.d. Web. 02 Oct. 2014.
After the diversity indixes of each sample were calculated, it was clear that the sample of leaf litter collected from the outdoor trail had the highest level of biodiversity. The Simpson's Index of the sample of leaf litter from the trail was 0.17, its Simpson's Index of Diversity was 0.83, and its Simpson's Reciprocal Index was 5.9. The Simpson's Index of the sample of leaf litter from Mr. Gunsher's woods was 0.27, its Simpson's Index of Diversity of the sample was 0.73, and its Simpson's Reciprocal Index was 3.7. The Simpson's Index of the sample of soil from the outdoor trail was 0.5, its Simpson's Index of Diversity of the sample was 0.5, and its Simpson's Reciprocal Index was 2.0. The Simpson's Index of the sample of leaf litter from the trail was 0.33 less than that of the control sample; its Simpson's Index of Diversity was 0.33 greater than that of the control sample; its Simpson's Reciprocal Index was approximately 3.9 higher than that of the control sample. The data indicates that the sample of leaf litter collected from the outdoor trail had the higher level of biodiversity when compared to the control sample.
Conclusion:
The hypothesis predicted that 10 organisms would be found but only 6 were found in the sample. It also stated that there would be species evenness but the evenness was low for the sample.
1. The organisms moved away from the light down the funnel because they liked it better when it's damp,so when the light started the dry the leaves they had to move to somewhere more wet. Also, they like the dark better and tried to stay away from the sunlight (the lamp). This means that in the real environment, these organisms are deep in the soil.
2.The biodiversity of this litter is high.Many different types of organisms were found throughout each sample, and even a rare specimen of the pseudoscorpian was found in one of the samples from Mr. Gunsher's backyard. Both of the index's of the leaf litter were lower than the Simpson's Index of the soil, which indicates high biodiversity; the HHS trail sample was lower than the soil by .33 and the sample from Mr. Gunsher's backyard was smaller by .23.
3. An environmental scientist would have to make more than one measurement if he was calculating the biodiversity, because he will need to account for as many organisms as he can. He would take samples of a large forest by taking it piece by piece. For example: start from deep into the soil and work his way up.
Conclusion
After using the Simpson's Index, the data shown provided proof that the biodiversity throughout the leaf litter samples were higher than that in the soil sample. The Simpson's Index of the soil sample was .5 which was .33 higher than that of the HHS trail sample and .23 higher than the sample provided from Mr. Gunsher's Backyard. The data suggest that the hypothesis was correct. In Anup Shah's article about the importance of biodiversity she says "Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play". Throughout her article she speaks on the importance of biodiversity in a healthy ecosystem and how these ecosystems have better survival rates. She also speaks on the number of natural resources that biodiverse ecosystems provide. These resources include protection of water resources, soil formation and protection and pollution breakdown. In order to maintain high biodiversity throughout our Earth's ecosystems, humans need to reduce harmful activities.
Citation
"Why Is Biodiversity Important? Who Cares?" - Global Issues. N.p., n.d. Web. 02 Oct. 2014.