This project is aimed at creating an algorithm that optimizes subway headway by running multiple simulations and using graphical analysis on the datapoints gather from the simulations to determine the most efficent headway. The simulation is able to find the most efficent headway by balancing total minutes waited and amount of trains used in the system, using this to calculate the headway that balances both.

Abstract

Graphical abstract

Mycorrhizal networks are symbiotic relationships between mycorrhizae and plants; the fungi can receive and send molecules from the plants it forms this relationship with. The fungi are able to create relationships with multiple plants, allowing molecules to be transferred between plants. The relationship has been hypothesized to be based on carbon: fungi vary molecules transferred based on the amount of carbon received. This hypothesis has been debated, with multiple differing sources of evidence. The amount of CO2 in the atmosphere has increased over twenty percent by 2022. This is largely due to human pollution. Plants use CO2 in a process called photosynthesis in which plants isolate carbon, which could be used in the network. Mycorrhizal networks are essential to plant survival; Therefore, understanding how the increase of CO2 affects it is vital to predicting the effects of pollution on ecosystems. An experiment was conducted on how the amount of carbon dioxide a plant is exposed to affects the rate at which the plants transfer molecules between themselves. The percentage of CO2 both plants were exposed to was varied, with one plant given Florestine, and the amount of transfer being measured by the light amount. The results showed that as carbon dioxide increases, the glow of the plants increases, showing a positive relationship between CO2 and the rate of transfer within mycorrhizal networks. This provides evidence that as global warming increases, the relationship between the plants and mycorrhizae increases, and the plants receive molecules that benefit its survival.

Research Question

Hypothesis

How does Carbon Dioxide affect the rate of transfer in Mycorrhizal Networks?

As CO2 exposure is increased, the root lengths of plants will increase, showing an increase in the rate of nutrient transfer.

Background

Mycorrhizal networks are symbiotic relationships between mycorrhizae fungi and plants. In this relationship, the fungus within the soil can receive and send molecules from the plants it forms the relationship with, which is extremely beneficial to plants, as they can receive the nutrients that they are lacking (Gorzelak et al., 2015). The relationship between mycorrhizal fungi and plants has been hypothesized to be based on carbon. Plants give the fungi carbon molecules, and the fungi send helpful molecules to the plants. Fungi survive off breaking dead matter into carbon, and plants rely on nitrogen, phosphorus, and other nutrients in the soil. The hypothesis of the carbon relationship between plants and fungi has been long debated, with multiple studies providing evidence for and against the relationship (Fellbaum et al., 2014). The biggest way plants receive carbon is from CO2 (Bassham & Lambers, 2024). However, the amount of carbon dioxide in the atmosphere has increased by over twenty percent within the years 1979 and 2022, largely due to the use of fossil fuels, as well as numerous other human activities that lead to the production of carbon dioxide, which hascontinued to be used and exploited since the industrial revolution (Atmospheric carbon dioxide, 2022). Plants use carbon dioxide to create sugars needed for growth, in a process called photosynthesis. Plants can take in carbon dioxide and isolate the carbon to form sugars it will consume for energy (Bassham & Lambers, 2024). As the amount of carbon dioxide increases within the atmosphere, plants will have greater opportunities to absorb carbon dioxide and therefore come into possession of a significantly greater amount of carbon. How is Mycorrhizal networks affected? If the symbiotic relationship between plants and Mycorrhizal networks was correctly hypothesized to be based around carbon, an increase of carbon dioxide would allocate plants more carbon, strengthening the mycorrhizal relationship. Since Global warming has been expanding rapidly, it is important to understand how such an environmentally impactful effect is impacting the plants around us, especially mycorrhizal networks. I am conducting an experiment on how carbon dioxide exposure will affect the rate of molecule transfer through a mycorrhizal network by varying the percentage of carbon dioxide both plants are exposed to and measuring the change in each plant’s root length. As the amount of carbon dioxide increases, the change in the root lengths will increase, showing a positive relationship between carbon dioxide and the rate of transfer within mycorrhizal networks, effectively showing the effects global warming has on mycorrhizal networks, furthering our understanding of how ecosystems have been affected by climate change.

Procedure

For this project, A chamber out of a 2-inch diameter PVC pipe was created (figure 2) inspired by the 2014 study conducted by Carl Fellbaum et al. A 50-micron mesh was placed directly in-between the pipe, creating two sides of the pipe. By doing this, the roots of the plants were prevented from interacting with each other. This ensures that the plant receiving the transferring molecules will not accidentally pick it up from the soil or the roots of the plant, meaning it has to be through the mycorrhizal fungi. I then sealed the bottom of the pipe with a 2-inch diameter PVC pipe cap. A plant was placed on one side of the mesh, and then nutrient capsules containing nitrogen and phosphorous on the other side. The testing chambers had soil containing 500 spores per gram of soil of a Rhizaphagus fungi mix. The control contained just the soil. Plants were then placed at 640 ppm of CO2 (ambient level), 900-1300 ppm, and 1500-1900 ppm, with testing plants and control plants in both. The average root length of the plants before the experiment and after two days of the experiment was taken, with greater increase in root length showing more nutrient transfer. A t - test was run on the results to identify the difference of mean leangths between the elevated CO2 and the normal CO2.

Results

Analysis

The graphs show the growth of roots before and after the experiment. The Normal Carbon and Elevated Carbon have a mix of Rhizophagus fungi. Each plant was placed in a growth chamber separated in half by a 50-micron mesh. On one side of the chamber the plant was placed; on the other side, nutrient capsules containing nitrogen and phosphorus were placed. The Normal Carbon was placed in 640 ppm of CO2, while the Elevated Carbon was placed in a range of 900 ppm to 1300 ppm. The roots were measured before being planted, and again after two days. After the two days, the Elevated Carbon on average showed significantly less root growth than the Normal Carbon, showing that CO2 has a negative relationship with molecule transfer in mycorrhizal networks, as the Elevated Carbon passed less nutrients than the normal Carbon, leading to less root growth, which could show that this network does not follow the excepted relationship with carbon, providing evidence that CO2 actually reduces the rate of transfer.

Discussion

After running the t-test, the Elevated Carbon on average showed significantly less root growth than the Normal Carbon, showing that CO2 has a negative relationship with molecule transfer in mycorrhizal networks, as the Elevated Carbon passed less nutrients than the normal Carbon, leading to less root growth, which could show that this network does not follow the excepted relationship with carbon, providing evidence that CO2 actually reduces the rate of transfer. The results provide evidence against the hypothesized relationship between carbon and the rate of transfer within mycorrhizal networks. In fact, the data suggests that carbon has a negative impact on the rate of transfer. Many past experiments have suggested both a positive, negative, and no relationship at all between carbon and mycorrhizal networks. The difference between the studies could be due to the type of fungi and plants used. Therefore, a future study is to repeat this experiment with different plants and fungi to see if there are any changes.

Atmospheric carbon dioxide | globalchange.gov. U.S. Global Change Research Program. (2022). https://www.globalchange.gov/indicators/atmospheric-carbon-dioxide#:~:text=the%20terrestrial%20biosphere.-,There%20is%20an%
20overall%20upward%20trend%20since%20data%20collection%20began,
than%2020%25%20in%2044%20years. Bassham, J., & Lambers, H. (2024, November 13). Photosynthesis. Encyclopædia Britannica. https://www.britannica.com/science/photosynthesis Fellbaum, C., Mensah, J., Cloos, A., Strahan, G., Pfeffer, P., Kier, T., & Beucking, H. (2014). Fungal nutrient allocation in common mycorrhizal networks is regulated by the carbon source strength of individual host plants. New Phytologist, 203, 646–656. doi: https://doi.org/10.1111/nph.12827 Gorzelak, M. A., Asay, A. K., Pickles, B. J., & Gorzelak, S. W. (2015). Inter-plant communication through mycorrhizal networks mediates complex adaptive behaviour in plant communities . AoB PLANTS, 7. https://doi.org/https://doi.org/10.1093/aobpla/plv050 Hasselquist, N. J., Metcalfe, D. B., Inselsbacher, E., Stangl, Z., Oren, R., Näsholm, T., & Högberg, P. (2016). Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. Ecology, 97(4), 1012–1022. https://doi.org/10.1890/15-1222.1 Ralls, E. (2024, October 4). A beginner’s Guide to Mycology. Earth.com. https://www.earth.com/earthpedia-articles/a-beginners-guide-to-mycology/ Ritchie, H., & Roser, M. (2024, March 18). Smallholders produce one-third of the world’s food, less than half of what many headlines claim. Our World in Data. https://ourworldindata.org/smallholder-food-production#:~:text=One%20of%20its%20reports%20states,80%25%20
of%20the%20world’s%20food. Schmitt, C., & Tatum, M. (2008). The Malheur National Forest. The Malheur National Forest Location of the World’s Largest Living Organism [The Humongous Fungus] . https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_033146.
pdf van der Heijden, M. G., Martin, F. M., Selosse, M., & Sanders, I. R. (2015). Mycorrhizal ecology and evolution: The past, the present, and the future. New Phytologist, 205(4), 1406–1423. https://doi.org/10.1111/nph.13288 郭涛, 习向银. (2013). Application method of arbuscular mycorrhizal fungus in large-scale tobacco cultivation (China Patent N0. CN103125251B). China Patent Agency. https://patents.google.com/patent/CN103125251B/en?q= (Mycorrhizal+fungi)&oq=Mycorrhizal+fungi

Stem Board