Although less commonly known, California’s nickname as the “Golden State” also refers to the golden hills and beautiful floral displays within the state’s grasslands. The California poppy (Eschscholzia californica) and goldfields (Lasthenia californica) once created a rich landscape that amazed the earliest of Spanish explorers. In the midst of these annual wildflowers, there were also resident perennial bunch grasses such as purple needlegrass (Stipa pulchra), wild rye (Elymus glaucus) and blue grass (Poa secunda), which caught the eyes of early botanists. Species composition can vary greatly with precipitation and soil type in California grasslands, but we have relied on early records to know how native forbs and grasses were distributed historically. Spanish colonists brought annual grass seeds that took well to California’s Mediterranean climate. Those seeds spread to become one of the largest plant invasions of modern times – almost 9 million ha of California grasslands are now dominated by non-native species.
Our research in this novel system addresses questions such as:
- What mechanisms have allowed annual grasses to invade and remain dominant?
- Do variable climate conditions provide “windows of opportunity” for these invasions?
- Why are some remnant native grasslands are able to resist conversion?
- How do we optimize restoration strategies to favor desired species?
California rangelands consist of the portion of these grasslands that are actively managed for agricultural industries within the state. The forage produced within these lands support livestock operations from the coast to the foothills of the Sierras. While many of the Mediterranean grasses that now dominate California provide excellent forage, others are noxious weeds that place the abundance and quality of this grazing resource at risk. Our lab is currently exploring several projects aimed at understanding how noxious invaders such as Medusahead (Taeniatherum caput-medusae) invade and spread across a landscape and whether grazing activities can influence these dynamics. To read more details about these projects visit the “Regime shifts and threshold dynamics in rangelands” project section.