By Tosha Comendant, Conservation Science Manager
The northern Bay Area is home to a diversity of rare fire-dependent plant communities. The recent fires burned tens of thousands of acres of habitat, providing opportunities to fill knowledge gaps in our understanding of how rare plant systems interact with fire. The Tubbs Fire that burned nearly all of Pepperwood Preserve presents both challenges and opportunities to track plant recovery, test land management practices, and develop strategies to better conserve rare plants pre- and post-fire.
Staff from Pepperwood’s Research and Preserve Management team have engaged a group of botanical experts to document “fire followers”—plants whose seeds stay buried in the ground until heat or smoke stimulates germination (learn more at our Fire Ecology for Non-Scientists: Fire Followers blog article). This spring, expert botanists Greg de Nevers and Peter Warner began filling a research gap at Pepperwood by surveying and documenting the occurrence of these remarkable plants. Greg de Nevers summarized the experience, saying:
Seeing the actual fire followers, rather than speaking in generalities about dormant seeds germinating, is incredibly inspiring. Literally seeing topography that was hidden beneath a blanket of vegetation is surprising and wonderful. Feeling the resurgence of life from the ashes inspires confidence in the resilience of the biosphere. – Greg de Nevers
The three weeks of surveys included random walks in chaparral transects and quadrats to estimate population abundance, and collection of geospatial information and voucher specimens (accessioned into Pepperwood’s Barnhart Herbarium and the California Academy of Sciences). As a result, the Pepperwood fire follower report contains a list and informational summary of approximately 65 species of fire followers and noteworthy plant associates. Seven species of native endemics (plants that germinate from the seed bank, appear for one to two years, and then only appear after next fire) were identified. The first three species listed below were not known at Pepperwood prior to the Tubbs Fire (Calandrinia breweri, Camissoniopsis hirtella, Caulanthus lasiophyllus, Cryptantha torreyana, Emmenanthe penduliflora, Silene antirrhina, and Triodanis biflora).
Another six species were categorized as native fire specialists, those most abundant in the first two years following fire and are expected to persist during early succession (Campanula angustiflora, C. griffinii, Crocanthemum scoparium, Githopsis specularioides, Heterocodon rariflorum, Nuttallanthus texanus).
Another 31 species were categorized as native opportunists that are abundant during early succession, but may persist at lower density in mature chaparral, or in other plant communities and includes perennial plants and shrubs that expanded their populations dramatically in the first year post-fire from soil-stored seed, or became larger or more visually prominent due to vigorous growth from perennating organs of various types. Four non-native postfire opportunists were identified.
In addition to expanding our baseline understanding of the location and abundance of rare fire following plants at Pepperwood, six species were found that are not obviously fire followers, but had not been previously recorded on the preserve. We’ve also identified species not previously recorded at Pepperwood and plants that have responded to the fire in striking ways.
To take the next step in documenting plant recovery and addressing research questions at Pepperwood, we partnered with Nomad Ecology to capture post-fire successional vegetation dynamics in the chaparral. There is high interest from land managers, ecologists, and botanists to better understand the cycle of annual or short-lived perennial species that benefit from or require fire as a part of their life cycle. Ten plots have been establishment in the approximately 140 acres of Pepperwood’s chaparral and shrub land that recently burned. The data and information on the composition, successional dynamics, and dominant post fire species behavior will be used by the Pepperwood team to inform our ecologically based adaptive management approach.