Leaf Litter Lab
Prelab
1. Why would we want to rate the amount of biodiversity in a location?
Biodiversity increases sustainability of an ecosystem and makes it stronger. Having a variety of animals and plants ensures a sounder and more vibrant area. It's an important factor in evaluating an ecosystem.
2. Examine the charts below and calculate the diversity indices for the three samples.
Biodiversity increases sustainability of an ecosystem and makes it stronger. Having a variety of animals and plants ensures a sounder and more vibrant area. It's an important factor in evaluating an ecosystem.
2. Examine the charts below and calculate the diversity indices for the three samples.
Sample 1: Simpson's Index: 0.2
Simpson's Index of Diversity: 0.8
Simpson's Reciprocal Index: 5
Sample 2: Simpson's Index: 0.3
Simpson's Index of Diversity: 0.7
Simpson's Reciprocal Index: 3.3
Sample 3: Simpson's Index: 0.9
Simpson's Index of Diversity: 0.1
Simpson's Reciprocal Index: 1.1
3. Use the results from the previous question to describe the biodiversity of each sample.
While the first two samples are fairly diverse, with indices of diversity of 0.8 and 0.7, Sample 3 is hardly diverse at all, its index very low at 0.1. Species 1 has 100 organisms while all of the other species only have 1 each. In the other samples, the species richness is more spread out and there is more biodiversity. Sample 1 has the most biodiversity because it has an equal number of organisms in each species. Sample 2 has the next most biodiversity.
Simpson's Index of Diversity: 0.8
Simpson's Reciprocal Index: 5
Sample 2: Simpson's Index: 0.3
Simpson's Index of Diversity: 0.7
Simpson's Reciprocal Index: 3.3
Sample 3: Simpson's Index: 0.9
Simpson's Index of Diversity: 0.1
Simpson's Reciprocal Index: 1.1
3. Use the results from the previous question to describe the biodiversity of each sample.
While the first two samples are fairly diverse, with indices of diversity of 0.8 and 0.7, Sample 3 is hardly diverse at all, its index very low at 0.1. Species 1 has 100 organisms while all of the other species only have 1 each. In the other samples, the species richness is more spread out and there is more biodiversity. Sample 1 has the most biodiversity because it has an equal number of organisms in each species. Sample 2 has the next most biodiversity.
Lab
Question: How diverse is the ecosystem by Smith Creek Lake?
Hypothesis: I think the ecosystem will be fairly diverse, with a Simpson's Index of 0.4 or less, on Smith Creek Lake.
Variables:
Independent- location of leaves
Dependent- amount of organisms
Controlled- time, temperature
Objectives
- Calculate the indices of the Simpson’s Index.
- Quantify the Biodiversity of a Sample
- Understand the importance of Biodiversity of Leaf Litter
Materials
Compound Microscope
Berless Funnel
Leaf Litter
Alcohol
Source of Light
Procedure
1. Collect a sample of leaf litter. Be sure to collect the entire layer down to the soil.
2. Examine the sample and classify what you see the layer is composed of.
3. Place your sample into the Berlese Funnel under the light source. Place a small beaker of alcohol under the funnel. The hope is that small invertebrates will travel away from the light and fall into your alcohol.
4. The next day, collect your beaker and examine the organisms you have collected under the microscopes. You will need to calculate the number of each species you have, and identify them. Each person may work on a portion of the sample and put your numbers together. Use the Identification pages to name each species.
5. Use the information to calculate the diversity indices for your sample.
Observations
Location: along Smith Creek Bank
Type of Community: climax community, deciduous forest
Date: February 11, 2013
Time: 1:30 PM
Weather description: cloudy, overcast
Air temp: 17*C
Soil temp: 8.2*C
Relative Humidity: 82%
- Calculate the indices of the Simpson’s Index.
- Quantify the Biodiversity of a Sample
- Understand the importance of Biodiversity of Leaf Litter
Materials
Compound Microscope
Berless Funnel
Leaf Litter
Alcohol
Source of Light
Procedure
1. Collect a sample of leaf litter. Be sure to collect the entire layer down to the soil.
2. Examine the sample and classify what you see the layer is composed of.
3. Place your sample into the Berlese Funnel under the light source. Place a small beaker of alcohol under the funnel. The hope is that small invertebrates will travel away from the light and fall into your alcohol.
4. The next day, collect your beaker and examine the organisms you have collected under the microscopes. You will need to calculate the number of each species you have, and identify them. Each person may work on a portion of the sample and put your numbers together. Use the Identification pages to name each species.
5. Use the information to calculate the diversity indices for your sample.
Observations
Location: along Smith Creek Bank
Type of Community: climax community, deciduous forest
Date: February 11, 2013
Time: 1:30 PM
Weather description: cloudy, overcast
Air temp: 17*C
Soil temp: 8.2*C
Relative Humidity: 82%
Calculations
Simpson’s Index = 0.3
Simpson’s Index of Diversity = 0.7
Simpson’s Reciprocal Index = 3.3
Questions
1. What are two reasons the organisms move away from the light down the funnel? What does this indicate about the organisms?
The organisms want to burrow down where it's cool because they thrive in the coolness. They also prefer the dark, because if there's light it likely means predators are digging towards them. This says that the organisms are often prey to animals that dig for them.
2. Summarize whether you think the biodiversity of this litter is high or low density. If low, try to give some reasons why this might be.
I think the biodiversity of this litter is high density because the Simpson's Index of Diversity is a 0.7, equal to Sample 2 from the pre-lab. There are a varied number of organisms and a decent number of species in the litter. Species diversity is evident because the organisms have the right amount of moisture by the creek and nourishment from all the plant life.
3. Why would an environmental scientist need to make more than one measurement if he was calculating the biodiversity? How would you take samples of a large forest?
An environmental scientist would need to make more than one measurement if he were calculating the biodiversity because taking only one example doesn't present an accurate model. It would be like getting a glass of water from the ocean and saying that because there were no whales in the glass, there are no whales in the ocean. In order to take samples of a large forest, several samples from a wide area should be collected.
Simpson’s Index = 0.3
Simpson’s Index of Diversity = 0.7
Simpson’s Reciprocal Index = 3.3
Questions
1. What are two reasons the organisms move away from the light down the funnel? What does this indicate about the organisms?
The organisms want to burrow down where it's cool because they thrive in the coolness. They also prefer the dark, because if there's light it likely means predators are digging towards them. This says that the organisms are often prey to animals that dig for them.
2. Summarize whether you think the biodiversity of this litter is high or low density. If low, try to give some reasons why this might be.
I think the biodiversity of this litter is high density because the Simpson's Index of Diversity is a 0.7, equal to Sample 2 from the pre-lab. There are a varied number of organisms and a decent number of species in the litter. Species diversity is evident because the organisms have the right amount of moisture by the creek and nourishment from all the plant life.
3. Why would an environmental scientist need to make more than one measurement if he was calculating the biodiversity? How would you take samples of a large forest?
An environmental scientist would need to make more than one measurement if he were calculating the biodiversity because taking only one example doesn't present an accurate model. It would be like getting a glass of water from the ocean and saying that because there were no whales in the glass, there are no whales in the ocean. In order to take samples of a large forest, several samples from a wide area should be collected.
General Conclusions
Evaluation of Hypothesis: My hypothesis is valid because the biodiversity of the litter was high. The Simpson's Index was below 0.4, which I predicted. Other regions of the Smith Creek area may have had smaller or larger Index numbers but this sample fits with my hypothesis.
Accuracy: Because this data only reflects the findings of one bag of leaf litter, it's possible that all information gleaned from this is anomalous and an outlier. It could be that samples other groups collected had higher or lower biodiversity. This sample is too small to be an accurate representation of all organisms in the ecosystem around Smith Creek, especially when it comes to organisms larger than insects, like squirrels and birds. In order to be more accurate, larger samples of Smith Creek organisms should be taken and information recorded from these larger samples.
Real-Life Application: Even if the biodiversity of an area is rich, it can be trouble keeping it that way. Several tropical rain forests are experiencing a declining rate of biodiversity as factors such as human interruption and the overuse of forest resources disrupts the homeostasis of the ecosystem (Kinver). Protecting the areas is a top priority, but unfortunately this is not always enough to maintain the biodiversity of that area. Though people are trying to promote protection of the environment, biodiversity in places like the forests of Africa, Asia, and South America is declining rapidly.
Kinver, Mark. "Protected Tropical Forests' Biodiversity 'declining'" BBC News. BBC, 26 July 2012. Web. 01 Mar. 2013.
Accuracy: Because this data only reflects the findings of one bag of leaf litter, it's possible that all information gleaned from this is anomalous and an outlier. It could be that samples other groups collected had higher or lower biodiversity. This sample is too small to be an accurate representation of all organisms in the ecosystem around Smith Creek, especially when it comes to organisms larger than insects, like squirrels and birds. In order to be more accurate, larger samples of Smith Creek organisms should be taken and information recorded from these larger samples.
Real-Life Application: Even if the biodiversity of an area is rich, it can be trouble keeping it that way. Several tropical rain forests are experiencing a declining rate of biodiversity as factors such as human interruption and the overuse of forest resources disrupts the homeostasis of the ecosystem (Kinver). Protecting the areas is a top priority, but unfortunately this is not always enough to maintain the biodiversity of that area. Though people are trying to promote protection of the environment, biodiversity in places like the forests of Africa, Asia, and South America is declining rapidly.
Kinver, Mark. "Protected Tropical Forests' Biodiversity 'declining'" BBC News. BBC, 26 July 2012. Web. 01 Mar. 2013.