leaf litter lab
Collaborators-
Griffin Matthews and Mr. Gunsher's 1st period AP Environmental Science Class in its entirety.
Griffin Matthews and Mr. Gunsher's 1st period AP Environmental Science Class in its entirety.
Abstract-
An experiment was conducted to measure the biodiversity of leaf litter in the temperate forest. Samples were taken of leaf litter from the forest behind the school and put them into homemade berless funnels and were left for 5-7 days under a heat lamp, undisturbed. The insects in the leaves eventually crawled down through the funnel, through the gauze, and into a beaker of rubbing alcohol where they were trapped. The beakers full of insects were observed and calculations were made to find the biodiversity in the leaves on the forest floor. Our result was that the leaf litter is quite biologically diverse in the temperate forest we have access to. The organisms we found varied and is further elaborated on below.
An experiment was conducted to measure the biodiversity of leaf litter in the temperate forest. Samples were taken of leaf litter from the forest behind the school and put them into homemade berless funnels and were left for 5-7 days under a heat lamp, undisturbed. The insects in the leaves eventually crawled down through the funnel, through the gauze, and into a beaker of rubbing alcohol where they were trapped. The beakers full of insects were observed and calculations were made to find the biodiversity in the leaves on the forest floor. Our result was that the leaf litter is quite biologically diverse in the temperate forest we have access to. The organisms we found varied and is further elaborated on below.
Problem-
How biologically diverse is the leaf litter compared to the soil on the forest floor?
How biologically diverse is the leaf litter compared to the soil on the forest floor?
Hypothesis-
If we take leaves and soil from the forest floor and run them through the experiment, then the leaves will have a higher biodiversity than soil because there are more nutrients in leaves than in soil as well as leaves being more damp and cool.
If we take leaves and soil from the forest floor and run them through the experiment, then the leaves will have a higher biodiversity than soil because there are more nutrients in leaves than in soil as well as leaves being more damp and cool.
Parts of the Experiment-
Control Group- Control sample of soil from forest.
Experimental Group- Leaf samples from the forest.
Independent Variable- Location of which the samples originated.
Dependent Variable- Amount of biodiversity in samples.
Control- Control sample of soil from forest.
Control Group- Control sample of soil from forest.
Experimental Group- Leaf samples from the forest.
Independent Variable- Location of which the samples originated.
Dependent Variable- Amount of biodiversity in samples.
Control- Control sample of soil from forest.
Materials-
Compound Microscope
Berless Funnel
Leaf Litter
Rubbing Alcohol
Heat Lamp
Soil
Gauze - Goes on bottom of funnel for critters to crawl through into the alcohol.
Rubber Band - Holds gauze to bottom of funnel.
Heat Lamp Stand
Compound Microscope
Berless Funnel
Leaf Litter
Rubbing Alcohol
Heat Lamp
Soil
Gauze - Goes on bottom of funnel for critters to crawl through into the alcohol.
Rubber Band - Holds gauze to bottom of funnel.
Heat Lamp Stand
Methods-
1. Find a temperate Forest.
2. Fill up 8 berless funnels full of leaf litter and 1 of soil. Take note of leaves and soil, general observations.
3. Set up experiment (shown in diagram). From top of apparatus: heat lamp, berless funnel with leaf litter, gauze, beaker with alcohol.
4. Leave at rest for 5-7 days .
5. Observe critters in alcohol with microscope. The information should help calculate the diversity.
1. Find a temperate Forest.
2. Fill up 8 berless funnels full of leaf litter and 1 of soil. Take note of leaves and soil, general observations.
3. Set up experiment (shown in diagram). From top of apparatus: heat lamp, berless funnel with leaf litter, gauze, beaker with alcohol.
4. Leave at rest for 5-7 days .
5. Observe critters in alcohol with microscope. The information should help calculate the diversity.
Data-
Date of Collection- September 18th
Humidity- 28% relative humidity
Temperature- 19 degrees celsius
Weather- Sunny
Location- Wake Forest, NC
Type of Community- Temperate forest
Time- 7:25 am - 8:45 am (this might mean there was more dew at this time which leads to damper leaves which leads to more organisms)
Humidity- 28% relative humidity
Temperature- 19 degrees celsius
Weather- Sunny
Location- Wake Forest, NC
Type of Community- Temperate forest
Time- 7:25 am - 8:45 am (this might mean there was more dew at this time which leads to damper leaves which leads to more organisms)
Chart (above) - Credit to Michael Goss (lab parter). I was having issues with Excel for some reason.
Total Leaf Litter: 142 - Total Soil: 1
Data Analysis-
After Calculating the Simpson indexes, the numbers that came out were a 0.215 Simpson's index, a 0.785 Simpson's index of diversity, and a 4.55 for Simpson's reciprocal index. So, the leaf litter is quite diverse. There is no diversity for the soil. This means that the hypothesis stands and leaf litter is astonishingly more diverse compared to the soil. Though is hard to believe that there could be that few of organisms in soil.
After Calculating the Simpson indexes, the numbers that came out were a 0.215 Simpson's index, a 0.785 Simpson's index of diversity, and a 4.55 for Simpson's reciprocal index. So, the leaf litter is quite diverse. There is no diversity for the soil. This means that the hypothesis stands and leaf litter is astonishingly more diverse compared to the soil. Though is hard to believe that there could be that few of organisms in soil.
Conclusion- Keep in mind that lab questions are in the conclusion as well.
The results support the hypothesis quite well. A total of one organism for the soil was much lower than expected but further supported the hypothesis that more organisms would be living in the leaf litter as opposed to the soil. Granted, 8 funnels for leaves and 1 for soil were used. So, inevitably the number of organisms would be higher, but the biodiversity would remain constant regardless. There must be on average more than one mite per scoop of dirt. With another trial, the hypothesis could be supported with even greater accuracy. Also, since organisms such as insects can crawl upside down, one would imagine that some would find a way out and miss the beaker entirely. So, the funnel could have been placed directly over the beaker. Another possible flaw is the length of time of which the lamp would need to be on to make sure all organisms had escaped the leaves is not known. Not to mention that it would be unknown how many organisms died without escaping that were never counted.
The reason the organisms were forced downward was because of a combination of heat and dryness. Insects prefer cool, damp habitats and even in the height of summer, leaves are usually cool and mostly damp to a certain extent. The heat lamp heats the leaves and dries them out. Then the organisms crawl downward over the course of a few days. I think this is high density for temperate forest leaf litter because this article (Link to Scientific American Article) mentioned that performing their version of the biodiversity of leaf litter lab worked best in fall when the the ground was cooler and damper. Also, 142 identified organisms in our sample size seems high to me. If an environmental scientist was calculating the biodiversity of an entire forest, then they would take samples of similar sizes in strategically placed spots in the forest to get a broader view of the biodiversity. On another note, I think our experiment is much more accurate than the experiment described in the article.
The results support the hypothesis quite well. A total of one organism for the soil was much lower than expected but further supported the hypothesis that more organisms would be living in the leaf litter as opposed to the soil. Granted, 8 funnels for leaves and 1 for soil were used. So, inevitably the number of organisms would be higher, but the biodiversity would remain constant regardless. There must be on average more than one mite per scoop of dirt. With another trial, the hypothesis could be supported with even greater accuracy. Also, since organisms such as insects can crawl upside down, one would imagine that some would find a way out and miss the beaker entirely. So, the funnel could have been placed directly over the beaker. Another possible flaw is the length of time of which the lamp would need to be on to make sure all organisms had escaped the leaves is not known. Not to mention that it would be unknown how many organisms died without escaping that were never counted.
The reason the organisms were forced downward was because of a combination of heat and dryness. Insects prefer cool, damp habitats and even in the height of summer, leaves are usually cool and mostly damp to a certain extent. The heat lamp heats the leaves and dries them out. Then the organisms crawl downward over the course of a few days. I think this is high density for temperate forest leaf litter because this article (Link to Scientific American Article) mentioned that performing their version of the biodiversity of leaf litter lab worked best in fall when the the ground was cooler and damper. Also, 142 identified organisms in our sample size seems high to me. If an environmental scientist was calculating the biodiversity of an entire forest, then they would take samples of similar sizes in strategically placed spots in the forest to get a broader view of the biodiversity. On another note, I think our experiment is much more accurate than the experiment described in the article.
Citations-
Lin, Kevin, and CityScience. "Seasonal Science: What Lurks in the Leaf Litter?: Scientific American." Seasonal Science: What Lurks in the Leaf Litter?: Scientific American. Scientific American, 18 Oct. 2012. Web. 05 Oct. 2013.
Lin, Kevin, and CityScience. "Seasonal Science: What Lurks in the Leaf Litter?: Scientific American." Seasonal Science: What Lurks in the Leaf Litter?: Scientific American. Scientific American, 18 Oct. 2012. Web. 05 Oct. 2013.