Seed Studies

Seed biology can play a large role in timing and methods of stewardship and natural resource management

Understanding the variables affecting seed germination, plant survival, production, and dispersal is crucial to timing plant surveys and designing effective native revegetation, noxious weed management, and habitat restoration projects.

Seed Germination of Rare Plants and Noxious Weeds

Nomad Ecology received a Local Assistance Grant from the California Department of Fish and Game, in partnership with East Contra Costa County Habitat Conservancy, to study effective management methods for invasive weeds. This project focused on seed germination experiments to determine the most effective timing for noxious weed treatments to avoid impacting rare plant populations managed by the Conservancy, while reducing weed abundance. These experiments allowed Nomad biologists to analyze and compare germination timing for three rare plant species (big tarplant [Blepharizonia plumosa], round-leaved filaree [California macrophylla], and shinning navarretia [Navarretia nigelliformis subsp. radians]) and two noxious weed species (barbed goatgrass [Aegilops triuncialis] and medusahead grass [Elymus caput-medusae]). Increased knowledge of species life cycles, especially in relation to other species of management concern, helps managers use seasonal variance to maximize weed control outcomes while reducing harm to sensitive species that may co-occur with invasive species. More information on this project can be found here:

Seed Banks Store Future Land Cover in the Ground

Nomad Senior Botanist Adam Chasey performed a pioneering investigation of seed banks on Southeast Farallon Island (SEFI), assessing species richness, density, distribution, and temporal variation, and through these the status of native and non-native seed banks on the island. These were compared with the above ground vegetation in order to reveal patterns within and between the above- and below ground communities. Results show that both the seed banks and above ground vegetation were heavily impacted by non-native species in richness, density, and cover, although native species remain present and widespread in both systems. Results suggest the existence of a largely homogeneous seed bank across the island, from which the annual expression in the aboveground vegetation is dependent upon numerous factors including disturbance, environmental factors, soil influence, germination cues, and seed input from previous seasons. By revealing a widespread and robust presence of native seeds in the seed banks, this study can help guide effective restoration of native vegetation on SEFI and provide a baseline dataset that future studies can use to assess impacts of ongoing and proposed management actions on Southeast Farallon Island and other temperate coastal ecosystems.