Salt Creek Restoration- Species Identification and Seed CollectionNatalie Gonzalez, Assistant Conservation Scientist April 2, 2021
When planning for habitat restoration for a site that has been taken over by invasive plant species, revegetating with native species can both facilitate the reestablishment of the native plant community and suppress invasive species regrowth after removal. The presence of invasive species in an ecosystem suppresses native plant growth affecting the biodiversity and balance of that ecosystem. Selecting native species which historically occurred in that ecosystem or continue to persist in neighboring areas, is important because we know that those plants can grow there and we know that we are not assembling a new plant community at random. Our goal is for the ecosystem to eventually be restored to its pre-invasion, healthy state.
The desert is a harsh environment, yet we know that diverse plant communities span it. We had an idea of what the plant community would look like at our site and planned for a site visit in order to identify plant species as well as collect seed to begin propagation for the project. During mid-March of 2020 we visited the lower stretches of Salt Creek, just before it feeds into the Salton Sea, for this initial site visit. When we arrived, we did not know what native plant species would persist, if any, through the abundant stands of tamarisk.
Notably, the densest stands of tamarisk line the creek and thin out further inland where abundant water sources diminish. Where tamarisk is sparse or absent, desert life appeared to become more diverse. Along with our knowledgeable and long-time propagator, Bob Linstead, we set out to begin plant identification. One species seemed to abundantly persist in the understory of tamarisk, iodine bush (Allenrolfea occidentalis), so this became our first, observant based, species of interest. Hiking along the creek and some ways inland, we identified a total of 34 different species that day.
Of the species we identified during that site visit, I researched which species exhibit the greatest salinity tolerance as well as which species occur in riparian areas (when tamarisk is not taking over the entire riparian zone). As we know, tamarisk alters soil chemistry, increasing the salinity of the topsoil as it drops its salty leaves, so, if we were to hope for successful establishment of the native plants, we would have to pick species that have high salinity tolerance, as they will be planted in the soil where tamarisk once stood, as well as which species naturally occur in riparian ecosystems.
Once we identified and selected the appropriate species, we set out to collect seed at our project site which was relocated to the middle and upper stretches of Salt Creek. Seed collecting took a few trips. The timing of this project had us finding ourselves in search of seed in the fall which is not the most abundant time for seed. We continued to collect seed from iodine bush, four wing saltbush, cattle saltbush, Mojave sea-blite and goldenbush until February. We hope to collect seed from mesquite trees, which neighbor the creek, during the spring.