USC Dana and David Dornsife College of Letters, Arts & Sciences

Today was our first day of collecting soil samples and transect data throughout Catalina. Lisa Collins came out on the morning boat with Lisa Chung and we took one of the Wrigley 13 passenger vans to Middle Ranch. We met up with Charlie who told us he had areas in mind that would be relevant to our study regarding soil in disturbed areas.

Our first stop was a riparian area not too far from Middle Ranch just along the road. We set up our transect by throwing the meter tape over the dense vegetation in the drainage.  This was not my first time using a transect tape, but it was my first time using a transect tape on land which was a different experience. While this was fun to set up, collecting our data proved challenging because a large percentage of the vegetation was poison oak and thorny blackberry plants. After weaving our way through the plants we had assembled our data about plant coverage, recording species name and abundance, at 3 meter intervals and we collected our soil sample from the 15 m mark. After a quick lunch we ran a second transect perpendicular to the first which was much easier to collect our data and soil sample as there was less plant cover, especially poisonous ones.

After we compiled our data from the Middle Ranch area, we drove to a ridge near Avalon where the Conservancy has established an exclosure, to keep deer and other animals from getting to the plants within.  These exclosures are particularly interesting because they are dominated by ceanothus arboreus or Catalina ceanothus. The difference in plant abundance and size was very obvious along our 2 transects. Although we haven’t seen the results of our soil analysis, it will be interesting to see if there is difference in the soils due to the presence of this plant. The exclosure had tall ceanothus covered in leaves whereas just a few feet away outside of the fence the same ceanothus were short with much smaller foliage.

To finish our collecting Charlie to us to an area of heavy Genista coverage and an area nearby where the conservancy had treated for these plants. Genista is a member pea family or Fabacea, a family which has root nodules that associate with symbiotic nitrogen fixing bacteria. This acts as a fertilizer for the plant. It will be interesting to see whether these Genista monocultures have an effect on total soil nitrogen as a result.   Charlie “scree surfed” down the steep slope along loose soil and rocks to collect our soil samples and then just hiked right back up. After a long day of data and soil collection we headed back to the Wrigley Institute and stuck around for a stress-free dinner with Lisa cooked by the wonderful staff.

For more pictures, check out today’s photo album: Day 30 Soil Sampling And Transecting At Avalon