Roels Corinne March 22, 2010 BIO 187 Monday 2:00 Lab Rebecca Clark Biology Report Higher Elevation on a Steep Landscape Provides Greater Plant Diversity Introduction When examining a landscape with a variety of elevations, it can be identified that the types of vegetation that grow at those different elevations can vary depending on their location. In several experiments, including those of Paul Rogers and colleagues, as well as Akira Itoh and his colleagues, the difference between the diversity of plant life has been documented in both Utah and Borean Forests respectively. The noted in both of their studies the amount of vegetation at each of the elevations, but also the diversity of the plant life as the landscape became higher and higher above sea level. On Tempe Butte (or "A Mountain"), we also identified that the top of the butte seemed to have more color and life than the bottom, so we identified that perhaps the plant life became more diverse at higher elevations. From this observation, we identified a question to answer with our to-be-gathered data; how does elevation affect plant diversity? We hypothesized that, at higher elevations, there would be more plant diversity because of the lessened amount of herbivores to consume the plants (they are more numerous at the bottom of the mountain), as well as the lessened amount of pollution, as the lower elevation plants are closer to the road where there is consistent traffic flow. We did predict that our hypothesis was going to be pretty accurate because, with knowledge of the appearance of Tempe Butte before we conducted the experiment, we knew that the landscape was more colorful towards the top of the mountain.
Methods We took a sample of an area of the mountain from low elevation to higher elevation, on two different sides of Tempe Butte so that we could compare the two different types of gradation in elevation; one had a gradual slope and the other was a steeper slope. We controlled certain variables such as the area of land that we were counting the vegetation in, as well as the distance between the areas in which we were collecting the data. By visual identification of the plants and physical counting of their frequency within a fixed amount of space, we were able to count how many of each plant there were. We collected data from four transects; two on the north slope at high and low elevation, and two on the south slope at high and low elevation. From this, we identified the differences in the richness and diversity in the plant life and were able to identify at which elevation the diversity was greatest.
Results When referencing tables 1-4 below, it is apparent that at a higher elevation, more types of vegetation were recorded. This would allow one to assume that at higher elevations, there is more plant diversity. However, in order to accurately calculate diversity, we must use the following equation:
Discussion diversity Because is measured both by the number of different species found at a certain location as well as how many of each individual species, we can determine that at higher elevation, there is a greater amount of diversity. Also, referring back to tables 1-4, we can see that in table 4, there are the most of each type of vegetation as well. These two
factors together help us to identify that at high elevation and high steepness are the most ideal situations to assure high variation in plant type. An explanation for our results is also that on a steeper landscape, acquisition of the plants there is a lot more difficult because the predators cannot balance well on the steep landscape. Some factors that could have affected our results could include the fact that "A" Mountain is a highly frequented hiking trail, and the prettier plants such as brittlebush and other plants with attractive flowers could be picked by trailwalkers. This could affect how many we inventoried, especially at the lower elevations where more people generally are. Also, another thing that could have affected our data collection could be the sections that we decided to collect data from. This would be an important factor because on a rocky mountain like Tempe Butte, there are sections where the ground does not allow plants to grow because it's rocky, and therefore there would be fewer plants in general. Towards the top of the mountain, there is less space to choose from, and therefore the plants are closer together.
Data: Table 1: Data Collection Low Elevation Low Steepness Quadrat # Grass % Ground Covered Creosote Bush Hedgehog 1 55 6 1 2 60 6 1 3 60 8 Only the vegetation found in the area is included in the chart; we are excluding the plants that were not found. These other plants may have been found at other elevations or steepnesses, and are therefore included in those charts. Table 2: Data Collection Low Elevation High Steepness Quadrat # Grass % Ground Brittlebus Creosote Pincushion Covered h Bush 1 70 2 9 2 7 1 3 10 Chainfruit Cholla 1
Table 3: Data Collection High Elevation Low Steepness Quadrat Grass % Creosote Fishhook Hedgehog # Ground Bush Barrel Covered 1 40 6 8 3 2 40 11 8 3 30 17 3 1 Table 4: Data Collection High Elevation High Steepness Quadrat Grass % Brittlebush Creosote Fishhook # Ground Bush Barrel Covered 1 50 1 10 9 2 50 10 6 3 30 12 5 References:
Pincushion Staghorn Cholla 25 19 4
Chainfruit Cholla 1
2
3 Chainfruit Cholla 1
Hedgehog Pincushio n 4 1 3 23 8 11
Rogers, Paul C., Leffler, Joshua A. 2010. Landscape assessment of a stable aspen community in southern Utah, USA. Forest Ecology and Management 249-3: 487-495.
Itoh, Akira. Ohkubo, Tatsuhiro. 2010. Comparison of statistical tests for habitat associations in tropical forests: A case study of sympatric dipterocarp trees in a Bornean forest. Forest Ecology and Managenent 249-3: 323-332.