This project aims to evaluate the relationship between characteristics of an environment and the quantity and diversity of biomass within. Two sides nearby a river were sampled for biomass. Site 1 is a dry floodplain within ~75 meters of the Hoback River. Site 2 is a riparian area within 5 meters of the Hoback River. 25 m^2 plots were randomly selected and marked with flags samples for the areas. Unique species were identified and individuals from each species were counted. Counting individuals of grasses was calculated from a 1 m^2 plot within the sample site. Tree and shrub species were counted as individuals and both maximum and minimum diameter were measured to calculate area of each individual. These measurements were used to calculate species richness [# of species/m^2], biomass (M) [0.0112(A1.26)], and CO2 sequestration [1.835(M/m^2)].

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          Prior to sampling, it was hypothesized that, in general, the presence of biomass will be directly correlated with diversity and richness of species. Further, that biomass will be dependent on the availability of sunlight, shade, water, and fresh nutrient deposits. Included in the hypothesis was a definition of the environmental characteristics where ideal conditions were expected. Sunlight and shade refer to an ample amount of daytime sun access for photosynthesis while enough shade to prevent unnecessary loss of moisture in plant and soil. Water refers to access to a sustainable water table, either through a river or gently grading slopes that retain rainwater. Fresh nutrient deposits refers to deposition by a nearby river or through movement of animals (scat). This hypothesis was formed on the logic that these defined environmental conditions are essential for plant growth and richness. Past observations within the Greater Yellowstone Ecosystem align with this logic, specifically a noticeable increase in tree and shrub variety and density near surface water and the abundance of diverse wildflowers and other species within said zones. 

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          Site 1, hereafter called River Terrace, was observed as flat and riddled with 4-8” granite cobbles. The plant growth at the River Terrace was dry and brittle with exposed soil and no shade cover. Some ungulate scat, likely deer, was found near the sampling site. Soil from the River Terrace was tan colored, dry, fine sand, and rich with pebbles. Site 2, hereafter called River, was observed with tall, lush vegetation including varied trees, shrubs, and low-lying flora. It was partly shaded and a few degrees cooler than the River Terrace. Many more examples of ungulate scat were found, additionally trampled bedding areas. Soil from River was dark brown, damp and readily clumping, slightly sandy, with organic pieces from pine cones and roots.

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          Six unique species were identified at the River Terrace, as compared to eight unique species at the River. As described later, larger sample sites would have increased the number of unique species identified at the River, further drawing a distinction between the two sites. The ratio of species richness at River Terrace was calculated as 0.24 species/m^2 (971.04 per acre) while the River has a ratio of 0.32 species/m^2 (1294.72 per acre). The River sample contains 26.96 times more biomass (kg/m^2)  as compared to the River Terrace. Given an estimated 4000 kg as the Average American’s emission of CO2 annually, it was calculated how much area of each environment would be needed to sequester an individual’s emissions. The results of these calculations demonstrate that 0.53 acres of land similar to the River Terrace could sequester the Average American’s CO2 emissions. In stark contrast, 0.02 acres of land similar to the River could sequester the same volume of CO2. These results and other calculations are reported in Figure 1 and 2, see end of report (full data table available here).

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          The results of this sampling process support the initial hypothesis. In every sampled measure, the River surpassed the River Terrace in terms of biodiversity, biomass, and ability to sequester CO2. As considered in the hypothesis, biodiversity and biomass are dependent on the availability of water, sun, shade, and nutrients. While quantitative assessment of these environmental factors was not completed, the qualitative findings support this correlation. There also seems to be a direct correlation between biodiversity and biomass, which likely relates to the function of canopy systems (e.g. vertical growth allows for understory growth and diversity of conditions, thus diverse species). From these results, it is clear that the environmental conditions at the River support more dynamic biological systems. Further, riparian systems such as those observed at the River are crucial sites for carbon sequestration. 

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          These results are limited by several factors including the sample size, flora identification skills, and human error. Observations of areas, especially River (Site 2), included a multitude of species not accounted for in our randomized sample. By not including samples featuring these species, our calculations and comparisons of biodiversity are likely severely limited. Further, given more sample sites, it would be possible to chart more detail on the relationships of the environmental characteristics and biodiversity. Similarly, a lack of field identification resources made it difficult to correctly and completely identify unique species and could impact our results. Human error in totaling unique individuals could also significantly affect our calculations as they were based completely on visual observations. 

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          In the greater context of the Bridger-Teton National Forest, an ecosystem adapted and prone to wildland fires, this research holds key insights into biomass storage of CO2. On July 1, 2024, the Horse Creek Fire (Bondurant, WY) was ignited by lightning strike and has burned 30 acres to date (Teton Interagency Fire, 2024). If, for discussion’s sake, we assign each acre burned the same measures of biomass as the River (Site 2), 3,301,991.10 kg of biomass has burned equating to 6,059,153.68 kg of CO2 released into the atmosphere to date in the Horse Creek Fire. This is around 0.00045% of annual American emissions, or the yearly emissions of 1514 Americans. While these values are not accurate to the biomass being burned and may seem insignificant, it is thought provoking to consider. Today (July 13, 2024), there are 62 large active fires under management in the US, totaling 902,253 acres (30075.1 times more acres than Horse Creek) burned to date (National Interagency Fire Center, 2024). For consistency, consider that this is 13.72% of total yearly American personal CO2 emissions. 

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          Through this thought experiment, we learn two things. First, wildland fires release a significant amount of CO2 (and other greenhouse gasses) into the atmosphere from carbon sinks. Secondly, humans release far greater amounts of CO2 than natural causes like wildland fires. From these ideas, the value of preserving, and growing, natural carbon sinks like forests or riparian areas are clear. However, they are also vulnerable to natural disasters that are driven by climate change. As wildfires continue to become larger and frequent, they engage in a positive feedback loop with climate change. Overall, biomass as a natural carbon sink is an incredible topic of research for mitigation of climate change.

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References:​

          National Interagency Fire Center, C. (2024, July 10). National Fire News. National Fire News | National Interagency Fire Center. https://www.nifc.gov/fire-information/nfn 

          Teton Interagency Fire, C. (2024, July 11). Horse Creek. https://gacc.nifc.gov/gbcc/dispatch/wy-tdc/home/information/wildfires-incidents/2024/horse-creek