Heather Schneider, Santa Barbara Botanic Gardens
There are times when drying and storing seeds is not an option for the conservation of a plant species. This might be because the seeds cannot survive the freezing process, or maybe because the species no longer produces seeds in the wild. Researchers at the Santa Barbara Botanic Garden have been working with one such species, the Federally endangered Island Barberry, which no longer reproduces well naturally. While once found on several different channel islands, this species now occurs in a single location.
Santa Barbara BG has established an ex-situ population of this rare species, allowing them to both conserve the genetic diveristy in a controlled environment, and use these plants to perform experiments without adversely effecting the small wild population. In 2019 these researchers began a propagation study using this ex-situ collection of island barberry to determine the best propagation methods for the species. Their experimental design had 4 variables. They planted cuttings in both the winter and the spring, they took cuttings from source material of different ages, they tested the use of a heating pad in propagation, and they tested different rooting hormone concentrations. Their results clearly defined the best practices for propagating the species. Cuttings should be made from old growth source material, and should be planted in the winter rather than the spring without the use of a heating pad. Rooting hormone is effective at both a 1:10 and 1:15 dilution. With this information, researchers have been very successful in propagating cuttings from the wild population for reintroductions.
This project is a great example of the value of living collections and horticultural expertise in rare plant conservation. An ex situ population was used to curate best practice recommendations for use by everyone involved in saving this species. From the boots on the ground on Santa Cruz Island to the dedicated staff and volunteers at SBBG, these efforts have ensured the Island Barberry a fighting chance at survival.