During our time at the Santa Rita Experimental Range, students are pairing off to research a biological question on the range, with the intent of presenting their research to fellow students and faculty back at Luther. Each group is tasked with framing their own research question; projects range from studying the moisture in the rangeland soils to observing the composition between different species of trees on the Florida Saddle Trail.
To get some more insight into what each of the groups is working on, I interviewed members of each research team.
Katherine and Lena are studying the pollinators of the manzanita shrub, specifically buzz pollinators (pollinators that use vibration to pollinate such as bees and various flies). They are also looking at non-buzz pollinators (such as butterflies) around the manzanitas. The first step in their project is to capture the pollinators. In order to get the pollen off of the insects, they apply some preservative jelly on the areas where pollen should be present. By observing specimens under the microscope, they can detect the type of pollen on each insect. Different kinds of pollen are unique, so by comparing the pollen found on different insects they can see what flowering plants they have been visiting.
Claire and Kita are looking at the water potential of mesic (wet) and xeric (dry) slopes of the Mexican blue oak at different times of the day. In order to get this comparison, the two use a pressure bomb. The pressure bomb uses nitrogen gas to virtually wring the water out of the stem of the leaf. High water potential is seen if more pressure is needed for water to appear, while less water potential needs less pressure.
Piper and Laura’s project focuses on the biodiversity and biomass of the forbs and grasses between pastures that have been grazed by cattle and those that have not. What they are trying to find is how cattle affect the biodiversity and biomass of the vegetation on which they graze. In order to measure the density of the vegetation, they use a quadrat which is a square made of PVC pipe with strings draped across to create 25 quadrat points. The quadrat helps them get a sample of what vegetation grows in each rangeland pasture.
Evan and Allie’s project consists of observing the prickly pear cactus, specifically the engelmanii species. They are measuring the water density in the soil, cactus size, and how much it has been used as a tasty snack for animals. They use a soil core (virtually a corkscrew type device that can dig up dirt) to measure soil conditions. The next step is to weigh the sample before and after dehydration to get the water weight. Their current goal is to try to see if the water density in the soil, as well as the plant, can be correlated with the amount of predation on each specific plant.
Brennan and Sara are observing the competition between pine trees, specifically, the density of Douglas firs after a burn. Each day they hike 3 to 4 thousand feet to conduct their research. Once at their site they measure the density and species of trees around a Douglas fir after determining if it is alive or dead. They also take note of if the saplings are under the tree canopy or not. If there is an established Douglas fir, they measure the diameter of its trunk. To simplify things, they are trying to observe the growth between the pines after a forest fire as well as determine which trees are doing well.
Jorge and Annelise are looking at the predation rates on the edge of the trails. To test their hypothesis, they planted eggs at 12 different sites with three eggs at each site. One egg is placed at 10, 50, and 100 meters from the trail. Each day they check their sites to see if any of the eggs have been eaten. So far, about six have been taken. They think that the most likely predators of the eggs are skunks, birds, and mice.
Katherine K. and I are working on answering the question, “How do soil makeup and water content in the soil affect the vegetation present?” We are locating sites at altitudes between 3000-4500 feet. At each site, we measure the water content in soil from a shaded area and a sunny area after dehydrating it. In regards to measuring vegetation, we are using quadrats to ensure a representative sample of the vegetation population. When we get back to Luther, we will use a simple concoction of water and dish soap to separate the layers of sand, silt, and clay in samples and draw correlations between the vegetation and the soil.
Overall, this has been an invaluable learning experience for all. These study questions are just as unique as the ecosystem in the Southwest and could not be replicated in Iowa. Learning about the unfamiliar is important as we will inevitably encounter them in our futures. As we finish up our projects, we will need to take the time and reflect on our experiences to contemplate how they will affect us as biologists.
