By Jana Johnston and Jessi Laughlin
We were tasked with collecting base line data for the under story vegetation of Copeland Creek. To do this, we measured whole plot species richness as well as absolute and relative cover of herbaceous species by using a point intercept method and percent cover of shrub species using a line intercept method .
Our two objectives were 1) to increase ground cover of native species to 25% or greater by 2020 and 2) to ensure a 1 meter radius around native plants with 0% Himalayan blackberry (Rubus armeniacus) cover.
First, we located and mark all seven transect lines. The transect lines were established by previous classes so we were provided with GPS coordinates to locate these points. Once we found the point we marked each one by hammering a piece of PVC pipe into the ground and spray painting a bright pink arrow pointing to the location. Once we found all seven transects we moved on to data collection.
We used a point intercept method to measure herbaceous species. To do this we extended a measuring tape from the PVC pipe to the top of the creek bank facing north. Next we walked along the transect line with a flag dropping it at every half meter. At each point we recorded every species (or bare ground) the flag touched, as well as within a 5 cm radius of the flag. For any unknown species we encountered, we documented them on our “unknown species master list” and took a small sample to take back to the lab for identification.
We also collected whole plot species richness of herbaceous species. To do this we flipped a coin, student ID, car key or any other flippable item we had, to determine whether we would measure the east or west side of the transect. Once we decided this, we walked along the transect with a meter stick recording all species present within this area.
To measure percentage of shrub cover we used a line intercept method. Using the same seven transects, we took the measurement (meter) of any shrub foliage overlapping our transect. From these measurements we were able to calculate percent cover of each species for each transect. We also measured the shrub height at every 2m along the transect.
During this process we encountered several stabbing, stinging and poisonous plant species and acquired a few injuries along the way. We discovered, as we were expecting, that many sections of the creek have been over taken by invasive species particularly Himalayan blackberry. Himalayan blackberry is a huge problem because it can grow extremely fast and large, choking and shading out other plant species. For more information check out the problem species blog post. However we also found that many native plant species are thriving including snowberry, California grape and California rose.
Based off of our data it’s clear that in order to promote a healthier creek habitat the Sonoma State community and future Restoration Ecology classes need to focus on removing Himalayan blackberry especially around the native plants we are hoping to keep alive. Removing the Himalayan blackberry will allow for planting of more native species that will have a better chance of succeeding along the riparian corridor.
One of the most interesting parts of this process was seeing the dramatic shift in vegetation from the overgrown black patches to the bare redwood grove up stream.
Throughout this process we created a step by step lab guide for future students to use to collect the same data we did. As the creek restoration project continues, students will be able to document the progress of the understory vegetation and will hopefully see a shift from an invasive dominated habitat to a more healthy, fully-functioning native understory system.