July 9, 2012
Environmental problems are complex entities which take a broad set of skills and understanding to properly address and mitigate. On Catalina Island three interns and I from USC are getting experience working with various conservation organizations seeing firsthand what it takes to properly preserve valuable and productive ecosystems. Last week we worked with Peter Dixon who is in charge of the native plant nursery on Catalina Island. From the early morning until the late afternoon we spent our time touring various ecosystems around Catalina Island looking for California Locoweed (Astragalus trichopodus var. lonchus), Vernal Barley (Hordeum intercedens), Fragrant Pitcher Sage (Lepechinia fragrans) and Black Sage (Salvia melifera). When we found the flora species of interest our group harvested 10% of the seed from each plant and counted maternal lines in order to keep track of the genetic diversity. All this work goes toward maintaining a viable seed bank, which is necessary for restoration and the retention of native and endemic species on Catalina. One of the species, Hordeum intercedens is a relatively rare grass on the island and proved to be especially difficult to locate given the abundance of similar invasive grasses.
Above: USC students survey a watershed on the east side of Santa Catalina Island. Photo Credit: Stephen Holle
Seed collection is especially important because grasses like H. intercedens face an immense amount of competition from invasive grasses, which often times have more dense and broad distributions. Invasive grasses are one of many environmental problems on Catalina Island because their biomass contributes large amounts of nitrogen to the soil, which further promotes the spread of invasive plants such as fennel. A possible explanation for the persistence of invasive species on Catalina Island could be due to the increased influxes of nitrogen from invasive grasses and other plant species. As Peter Dixon explains, “native and endemic grasses on Catalina are typically found in dispersed distributions while invasive grasses have higher and broader population densities.” As a result long term “plant invasions increase soil nitrogen pools and total ecosystem nitrogen stocks” (Rout 2009) and contributes to invasive plant success and rapid colonization around the island. Given these ideas about nitrogen influxes and the spread of invasive plants my fellow interns and I are developing a short term project in order to understand the spread of invasive plants using applied conservation. Although our time is limited on Catalina Island, we look forward to establishing baseline studies for future continuation.
Rout, Marnie. “An Invasive Plant Paradox.” Science 324. (2009). 734. Online.
Editor’s note: The ENST Catalina Island Internship at USC Dornsife is offered as part of a summer internship program offered to undergraduate students in the USC Dana and David Dornsife College of Letters, Arts and Sciences. This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island. Students investigate important environmental issues such as ecological restoration, protected-area planning and assessment, and invasive species management. During the course of the internship, students will work closely with USC faculty and staff scientists from the Catalina Island Conservancy to support ongoing conservation and management programs being implemented on the island. Instructors for the course include David Ginsburg, Assistant Professor of Environmental Studies, Lisa Collins, Lecturer in Environmental Studies, and Tony Summers, Invasive Plant Program Supervisor from the Catalina Island Conservancy.
August 1, 2011
Before we discovered this, Lauren helped me in every way possible to locate a hydrometer. She guided me to Ellen Kelly, Assistant Director of Education, who let me look through some soil sampling equipment she had in the hope of locating a hydrometer. Meanwhile Lauren contacted main campus, and I called Naomi Martinez from the Environmental studies office and Tony Summers from the CHIRP office of the Catalina Conservancy. Lauren then had the idea to reach out to the Southern California Marine Institute, located on Terminal Island. I called Carrie Wolfe and after a quick check told me there would be a hydrometer on the Miss Christi the following morning. Everyone was so helpful that morning, we are so lucky to be working with these organizations and people.
After some computer work and an e-mail from Lisa letting me know if I looked through the lab I would find a hydrometer in a sea grant box. We started the soil texture analysis by creating a blank with 100 mL of our HMP solution and 900 mL of DI in a 1 L plastic graduated cylinder and mixing one of our samples with 800 mL of DI in a 1 L glass graduated cylinder. We covered the blank with parafilm and inverted the mixture 10 times in order to ensure it was consistent. Once we dropped in the hydrometer we realized that reading a hydrometer that only breaks the surface of the solution by a few inches would be difficult through the opaque plastic. However, we were able to get accurate readings and after taking readings at 30s, 60s and 10 minutes we inverted our soil sample 10 times and started the same process. The glass made reading the hydrometer much easier which was necessary because the soil, water and HMP mixture foamed slightly from being inverted.
By the end of the afternoon we had recorded the specific gravity and temperature at the previously mentioned intervals and 30, 60, 90 and 120 minutes for both mixtures. We covered both cylinders with parafilm to avoid evaporation or contamination and decided the next day to use the glass graduated cylinder only, due to the ease and accuracy of reading the hydrometer. Working on an island presents certain issues, access to commodities such as lab equipment or groceries are limited. Therefore, I will appreciate the things that USC and being more connected on the mainland provide than ever before. We left the lab organized and ready to return to the following day for our 24 hour readings.