Collaborators:
Gabrielle Langlois, Haki Bradley, Wisam Salah, Melissa Daria
Introduction and Problem:
Although it may appear to be the most inert component of any habitat, leaf litter plays a crucial role in habitats. It maintains the diversity of an ecosystem, and it does this by inhabiting several invertebrates. The combination of leaf litter and organisms that inhabit it are good indicators of an ecosystems overall health. Thus, the problems that will be addressed through this lab is, 'What is the biodiversity and Simpson's Index of samples of leaf litter?' and 'How does the biodiversity of leaf litter affect the overall health of the habitat?' According to the background information, the biodiversity of a habitat can be quantified using the Simpson's Diversity Index. These indices take into account two important components of biodiversity: species richness and species evenness. These measurements are helpful in understanding how current environmental problems affect the biodiversity and sustainability of habitats. “Forest floor litter invertebrates provide an ideal system in which to investigate the effects of urbanization and disturbance because of their abundance and diversity" (Schneider, Anna). For example, if certain functions are not taking place in a habitat, it is possible that deforestation, the introduction of invasive species and pollution threaten the abundance and overall health of the ecosystem. Therefore, by determining the biodiversity of our leaf litter samples, we are gaining a better understanding of why the biodiversity of leaf litter is important to the resilience and wellbeing of an ecosystem.
Diversity Indicies of provided chart:
Sample 1: 0.1837
Sample 2: 0.2491
Sample 3: 0.9242
After calculating the Simpson's Indices for the three samples above, it is evident that sample 1 is much more diverse and healthy when compared to samples 2 or 3. "Water resources are an important consideration for sustainable agriculture and environments to thrive." Because of this known fact is a strong possibility that Sample 1 is located near a water source while Sample 3 is most likely not. Overall, these three indices can tell us a lot about the biodiversity of the habitat in which the samples originated from.
Hypothesis:
If the diversity of leaf litter samples from the woods at Heritage High School are computed, then the combined samples will produce a Simpson's Index below 0.2 due to the abundance of life that exists in the habitat, but will produce a Simpson's Index lower than that of the fall class data.
Parts of an Experiment:
Materials:
Methods and 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.
Data and Data Analysis:
Gabrielle Langlois, Haki Bradley, Wisam Salah, Melissa Daria
Introduction and Problem:
Although it may appear to be the most inert component of any habitat, leaf litter plays a crucial role in habitats. It maintains the diversity of an ecosystem, and it does this by inhabiting several invertebrates. The combination of leaf litter and organisms that inhabit it are good indicators of an ecosystems overall health. Thus, the problems that will be addressed through this lab is, 'What is the biodiversity and Simpson's Index of samples of leaf litter?' and 'How does the biodiversity of leaf litter affect the overall health of the habitat?' According to the background information, the biodiversity of a habitat can be quantified using the Simpson's Diversity Index. These indices take into account two important components of biodiversity: species richness and species evenness. These measurements are helpful in understanding how current environmental problems affect the biodiversity and sustainability of habitats. “Forest floor litter invertebrates provide an ideal system in which to investigate the effects of urbanization and disturbance because of their abundance and diversity" (Schneider, Anna). For example, if certain functions are not taking place in a habitat, it is possible that deforestation, the introduction of invasive species and pollution threaten the abundance and overall health of the ecosystem. Therefore, by determining the biodiversity of our leaf litter samples, we are gaining a better understanding of why the biodiversity of leaf litter is important to the resilience and wellbeing of an ecosystem.
Diversity Indicies of provided chart:
Sample 1: 0.1837
Sample 2: 0.2491
Sample 3: 0.9242
After calculating the Simpson's Indices for the three samples above, it is evident that sample 1 is much more diverse and healthy when compared to samples 2 or 3. "Water resources are an important consideration for sustainable agriculture and environments to thrive." Because of this known fact is a strong possibility that Sample 1 is located near a water source while Sample 3 is most likely not. Overall, these three indices can tell us a lot about the biodiversity of the habitat in which the samples originated from.
Hypothesis:
If the diversity of leaf litter samples from the woods at Heritage High School are computed, then the combined samples will produce a Simpson's Index below 0.2 due to the abundance of life that exists in the habitat, but will produce a Simpson's Index lower than that of the fall class data.
Parts of an Experiment:
- Independent Variable: Location where the leaf litter sample is collected.
- Dependent Variable: Level of biodiversity of the leaf litter sample.
- Controlled Variables: Alcohol, beaker petri dish, microscope, berlese funnel, filter screen, amount of light each sample was exposed to, and the amount of leaf litter collected.
- Control Group: Fall class data
- Experimental Group: Sample of leaf litter collected from the forest of HHS.
Materials:
- Leaf Litter
- Alcohol
- Beaker
- Petri Dish
- Microscope
- Berlese Funnel (milk jug)
- Source of Light
- Filter Screen
- Invertebrate Identification Pages
Methods and 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.
Data and Data Analysis:
Observations:
Photographs:
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Spring Class Data:
Fall Class Data:
Analysis:
There is much to analyze and conclude about the spring class data when compared to the fall class data. At first, looking into the bag containing the leaf litter sample, it gave no indication as to the biodiversity that composed it. However, a compound microscope enabled groups to notice that the samples contained several microscopic invertebrates. Among these, the two most abundant species found in the sample were Beetle mites (photo #7) and ticks. Nevertheless, the fact that these two species dominated the sample was not detrimental to the evenness that was noted in the sample. There were not outliers in the data, which means that the evenness was quite high. In addition, the fact that more species were found in leaf litter sample than expected indicates a rather decent species richness. The fact that a total of fifteen different species were found in a small sample of the habitat being examined indicates that there is an abundance of species among Heritage's forest floor. With this in mind, the Simpson's Diversity Indices that were acquired from the collected data were nothing short of predictable. With a Simpson's Index of 0.14, a Simpson's Index of Diversity of 0.86 and a Simpson's Reciprocal Index of 7.14, the consensus among the group was that the leaf litter sample collected from the forest floor of Heritage High School had a high biodiversity. When compared to the fall class data though, the spring data seems to be not up to par. The Simpson's Indices are much closer than expected, as the fall class had an index of 0.11. The species richness, however, is much greater and more significant in the fall class data. The fact that a total of twenty two different species were discovered in a small leaf litter sample signifies that there is a much greater abundance of species among the area where their samples were collected.
Spring Data Calculations:
Simpson's Index (D): 0.140137
Simpson's Index of Diversity (1-D): 0.859863
Simpson's Reciprocal Index (1/D): 7.13587418
Conclusion:
The final results of this experiment cannot be expressed as conclusive. First of all, the background information for this lab emphasizes the importance of taking multiple samples of leaf litter in order to poole the data and get a better estimate of overall diversity. In order to take samples of a large forest to gain a much clearer and outright consensus, the class could have spread out among the forest and gathered their group's sample in a place that was not around other group's. In spite of this not being the case, the results of this experiment ratify the hypothesis that if the biological diversity of a leaf litter sample from the trail at Heritage High School is quantified, then the sample will yield a Simpson's Index (D) below 0.2. The calculated Simpson's Index was 0.14 for the sample of leaf litter, which means that it is even more diverse than predicted. However, it should be noted that the time of day, season, weather, humidity, temperature, and location all impacted the calculated biodiversity for that specific leaf litter sample, and therefore it cannot be used to estimate the diversity of the forest as a whole. For example, the time of day could have skewed the results in that detritivores have the tendency to crawl under leaf litter whenever they are exposed to sunlight. This is done in order to maintain cool during the day, and to hide from predators. When exposed to the light from the lamps, these organisms adhered to this behavioral adaptation by moving away from the light and into the beaker of alcohol. Still, these indices can add to the understanding of how the biodiversity of leaf litter impacts such environmental factors as soil health (Schneider, Anna). Moreover, due to the fact that it was wintertime and close to 30 degrees Fahrenheit when the samples were collected, the spring class data was not particularly equal in its variables to that of fall class data. Also, the location at which the fall class gathered their leaf litter samples was near a water source where as the spring class gathered samples away from a water source and deeper in the woods. This could have most definitely skewed the data and comparisons overall.
After further research from the Seasonal Science and Grounds and Landscaping readings, I have concluded that with a Simpson's Index of 0.14, the class's samples of leaf litter from the forest floor had a high level of biodiversity. The forest's plant growth and surrounding areas plant growth is supported by nutrients that are provided by soil dwelling organisms. These organisms include the invertebrates that inhabit leaf litter. This is where leaf litter comes in, for "decomposing leaf litter releases nutrients into the soil and also keeps it moist" (Lin, Kevin). If the leaf litter were diverse, then it would have an abundance of invertebrates that would in turn decompose the leaf litter and release nutrients back into the soil. The habitat displayed much biodiversity of the leaf litter which in turn allows the vegetation to thrive. This relationship further supports the fact that organisms in an ecosystem are joined together, which forms a need to protect biodiversity if sustainability is the goal. "If we want to sustain our environment, we have to preserve the fine natural balance of interconnected webs of life"(Shneider, Anna). Part of this 'natural balance' relies on the biodiversity of leaf litter, and that is why it is such an important part of any habitat. Not only that, but we as humans must understand that we play an crucial role in maintaining this natural balance. Low biodiversity usually comes from a high level of human interaction. This could be anything from walking through the forest to spraying harmful pesticides on or around the habitat. The problem with low biodiversity is that the ecosystem affected takes longer to replenish itself and when it does, it is a much less diverse ecosystem. An ecosystem with a high level of biodiversity is more stable and therefore healthier. As one can see, humans have the ability to threaten the biodiversity of leaf litter and the overall health of habitats. Thus, as members of this joined system, we must all play a role, first by realizing that the biodiversity of leaf litter is important to the health and resilience of an ecosystem.
There is much to analyze and conclude about the spring class data when compared to the fall class data. At first, looking into the bag containing the leaf litter sample, it gave no indication as to the biodiversity that composed it. However, a compound microscope enabled groups to notice that the samples contained several microscopic invertebrates. Among these, the two most abundant species found in the sample were Beetle mites (photo #7) and ticks. Nevertheless, the fact that these two species dominated the sample was not detrimental to the evenness that was noted in the sample. There were not outliers in the data, which means that the evenness was quite high. In addition, the fact that more species were found in leaf litter sample than expected indicates a rather decent species richness. The fact that a total of fifteen different species were found in a small sample of the habitat being examined indicates that there is an abundance of species among Heritage's forest floor. With this in mind, the Simpson's Diversity Indices that were acquired from the collected data were nothing short of predictable. With a Simpson's Index of 0.14, a Simpson's Index of Diversity of 0.86 and a Simpson's Reciprocal Index of 7.14, the consensus among the group was that the leaf litter sample collected from the forest floor of Heritage High School had a high biodiversity. When compared to the fall class data though, the spring data seems to be not up to par. The Simpson's Indices are much closer than expected, as the fall class had an index of 0.11. The species richness, however, is much greater and more significant in the fall class data. The fact that a total of twenty two different species were discovered in a small leaf litter sample signifies that there is a much greater abundance of species among the area where their samples were collected.
Spring Data Calculations:
Simpson's Index (D): 0.140137
Simpson's Index of Diversity (1-D): 0.859863
Simpson's Reciprocal Index (1/D): 7.13587418
Conclusion:
The final results of this experiment cannot be expressed as conclusive. First of all, the background information for this lab emphasizes the importance of taking multiple samples of leaf litter in order to poole the data and get a better estimate of overall diversity. In order to take samples of a large forest to gain a much clearer and outright consensus, the class could have spread out among the forest and gathered their group's sample in a place that was not around other group's. In spite of this not being the case, the results of this experiment ratify the hypothesis that if the biological diversity of a leaf litter sample from the trail at Heritage High School is quantified, then the sample will yield a Simpson's Index (D) below 0.2. The calculated Simpson's Index was 0.14 for the sample of leaf litter, which means that it is even more diverse than predicted. However, it should be noted that the time of day, season, weather, humidity, temperature, and location all impacted the calculated biodiversity for that specific leaf litter sample, and therefore it cannot be used to estimate the diversity of the forest as a whole. For example, the time of day could have skewed the results in that detritivores have the tendency to crawl under leaf litter whenever they are exposed to sunlight. This is done in order to maintain cool during the day, and to hide from predators. When exposed to the light from the lamps, these organisms adhered to this behavioral adaptation by moving away from the light and into the beaker of alcohol. Still, these indices can add to the understanding of how the biodiversity of leaf litter impacts such environmental factors as soil health (Schneider, Anna). Moreover, due to the fact that it was wintertime and close to 30 degrees Fahrenheit when the samples were collected, the spring class data was not particularly equal in its variables to that of fall class data. Also, the location at which the fall class gathered their leaf litter samples was near a water source where as the spring class gathered samples away from a water source and deeper in the woods. This could have most definitely skewed the data and comparisons overall.
After further research from the Seasonal Science and Grounds and Landscaping readings, I have concluded that with a Simpson's Index of 0.14, the class's samples of leaf litter from the forest floor had a high level of biodiversity. The forest's plant growth and surrounding areas plant growth is supported by nutrients that are provided by soil dwelling organisms. These organisms include the invertebrates that inhabit leaf litter. This is where leaf litter comes in, for "decomposing leaf litter releases nutrients into the soil and also keeps it moist" (Lin, Kevin). If the leaf litter were diverse, then it would have an abundance of invertebrates that would in turn decompose the leaf litter and release nutrients back into the soil. The habitat displayed much biodiversity of the leaf litter which in turn allows the vegetation to thrive. This relationship further supports the fact that organisms in an ecosystem are joined together, which forms a need to protect biodiversity if sustainability is the goal. "If we want to sustain our environment, we have to preserve the fine natural balance of interconnected webs of life"(Shneider, Anna). Part of this 'natural balance' relies on the biodiversity of leaf litter, and that is why it is such an important part of any habitat. Not only that, but we as humans must understand that we play an crucial role in maintaining this natural balance. Low biodiversity usually comes from a high level of human interaction. This could be anything from walking through the forest to spraying harmful pesticides on or around the habitat. The problem with low biodiversity is that the ecosystem affected takes longer to replenish itself and when it does, it is a much less diverse ecosystem. An ecosystem with a high level of biodiversity is more stable and therefore healthier. As one can see, humans have the ability to threaten the biodiversity of leaf litter and the overall health of habitats. Thus, as members of this joined system, we must all play a role, first by realizing that the biodiversity of leaf litter is important to the health and resilience of an ecosystem.
Citation(s):
Lin, Kevin. "Seasonal Science: What Lurks in the Leaf Litter?" Scientific American Global RSS. N.p., 18 Oct. 2012. Web. 02 Oct. 2014. <http://www.scientificamerican.com/article/bring-science-home-leaf-litter-biodiversity/>.
Shneider, Anna. "Grounds and Landscaping." Seattle University, n.d. Web. 02 Oct. 2014. PDF. <http://www.seattleu.edu/WorkArea/DownloadAsset.aspx?id=120512>.
"Water Resources." , Improving Management of Water Resources and Biodiversity. N.p., n.d. Web. 27 Feb. 2015. <http://www.futurefarmonline.com.au/farm-research/water-resources>.
Lin, Kevin. "Seasonal Science: What Lurks in the Leaf Litter?" Scientific American Global RSS. N.p., 18 Oct. 2012. Web. 02 Oct. 2014. <http://www.scientificamerican.com/article/bring-science-home-leaf-litter-biodiversity/>.
Shneider, Anna. "Grounds and Landscaping." Seattle University, n.d. Web. 02 Oct. 2014. PDF. <http://www.seattleu.edu/WorkArea/DownloadAsset.aspx?id=120512>.
"Water Resources." , Improving Management of Water Resources and Biodiversity. N.p., n.d. Web. 27 Feb. 2015. <http://www.futurefarmonline.com.au/farm-research/water-resources>.