The purpose of our Sehome Hill survey experiment was to use the data collected to determine if current land mass, tree populations, densities, biomasses, and productivities would be sufficient enough to solve an increasing dilemma within the United States, and worldwide: is there an adequate amount of land area for reforestation to sequester the CO2 emissions of the United States? We collected data in teams of four individuals in staked 10m x 10m plots in scattered survey zones located throughout Sehome Hill. Within their respective zones, each group measured the plot’s aspect using a compass, the slope using a tape measure and protractor, and the canopy cover using a densitometer. From there, each group recorded the outside bark diameter of the number of live, standing trees with a trunk diameter of at least 10cm. The trees basal area was required to be at least 50% within the group’s staked plot area to be considered legitimate for the recording of their data. The collected data from each individual group was combined to ensure a rich experiment sample, and all averages shown in the data sets are based on six team’s plots. Our primary hypothesis was that there would be sufficient land area within the United States for reforestation to occur. We also hypothesized that coniferous trees would be the most abundant tree type on Sehome Hill. Therefore, we hypothesized that density, biomass, productivity, and any other recorded data would all reflect and be influenced by said statements by the larger amount of coniferous tree types. Our null hypothesis for each situation was that deciduous trees would be more common, and therefore would influence trends within our data.
Our first trend we observed is that of density. The density data collected in this experiment measured the average number of trees found per hectare on Sehome Hill (Figure 1). Specifically, deciduous trees vs. coniferous trees. We observe that coniferous trees are an astounding 2344% more dense per hectare than their deciduous counterparts (Figure 1). We furthermore observe this trend in the specific sub-species of coniferous trees. With an overabundance of coniferous trees, specifically Douglas Firs being nearly 720% more dense than the next most-dense coniferous tree, it is not surprising to see such large numbers (Figure 4). However, the lack of Red Alder data recordings (Figure 4) has likely impacted the overall average density of the deciduous species, which must be taken into account. The second densest tree species, the Western Hemlock, was 402% more dense than that of their Western Red Cedar counterpart, and only 150% more dense than the deciduous Big Leaf Maple.Next, we observe a trend within our data concerning biomass. The biomass in this experiment measured the megagrams of living and dead biomass per hectare on Sehome Hill. Once again, we observe that coniferous trees overall more abundant (Figure 4), and even more shockingly we observe a near 37,720% biomass for coniferous trees than for deciduous trees (Figure 4). We observe this to also come from the incredibly large sample size of Douglas Firs taken from the survey. With a biomass of nearly 36,580% higher than the next highest coniferous tree, it is no mystery that these numbers are as large as they are. We once again encounter the same conundrum as we did previously with density; our lack our Red Alder data (Figure 4) does not attribute to the overall biomass average for the deciduous population, and must be noted in the results. Western Hemlock’s were not rare to find in this survey, and their average Biomass was approximately 4,733% larger than that of their coniferous neighbors, the Western Red Cedar (Figure 2).
Finally, our last data trend to observe is that of productivity. Our data concerns both the productivity per hectare and productivity per tree. As with the past trends, coniferous trees had a much larger productivity on average, with approximately a 650% higher productivity per hectare, and approximately 519% higher productivity rate per tree than deciduous trees (Figure 3). We observe that both with productivity per hectare and per tree, Douglas Fir has nearly a 2,000% higher productivity rate per hectare than the next highest producing tree, and a 126% higher per tree than the next highest producing tree. We also observe that almost all trees produce very little per hectare with exception given to Douglas Fir. However, at the productivity per tree level, Red Cedar and Big Leaf Maple are about as productive as one another, Western Hemlock is approximately 200% more productive than the two species, and Douglas Fir is by far the highest producing species both per tree and per hectare (Figure 3).