Native plant response to fire in coastal prairies

Pyrodiversity, the variation in fire frequency, intensity, seasonality, and spatial extent across a landscape, is an important driver of biodiversity. It can create habitat heterogeneity that supports a wide range of plant and animal species (Gordijn and O’Connor, 2021). In grassland ecosystems like California coastal prairies, fire reduces aboveground biomass and thatch, increasing light availability and short-term nutrient availability. These changes promote native plant recruitment, particularly for forbs, by creating favorable conditions for seed germination and seedling establishment (Schellenberg et al., 2020; Reiner, 2007).

Fire also acts as an ecological cue. Many native California grassland species have evolved to respond to the heat, smoke, and fluctuating temperatures associated with fire. These signals can break seed dormancy and stimulate germination, allowing fire-dependent species to emerge from the seed bank (Keeley, 2001; Reiner, 2007). However, fire alone may not be sufficient to restore native plant communities—especially if native seed banks are already depleted due to long-term land use change or non-native dominance. Restoration efforts may require active interventions like seeding native species and managing post-fire invasions (Galloway, 2025; Reiner, 2007).

Native species in the seed bank

A recent study by Galloway (2025) examined the effects of prescribed fire on the native seed bank across four California coastal prairie sites. The study found that native seed banks were often small and patchily distributed, with high site-to-site variability. Prescribed fire did not consistently increase native forb or graminoid abundance or richness. At some sites, fire slightly enhanced the emergence of native forbs like Plantago erecta and Epilobium minutum, but overall, native species responded weakly. The study concluded that fire alone was insufficient to restore native seed banks, and that restoration likely requires additional actions such as reseeding and repeated burning tailored to site conditions (Galloway, 2025).

Notably, the timing of burns appears to be critical: sites burned before the rainy season retain more viable native seeds, while post-rain burns may damage imbibed seeds, reducing germination (Parker, 1990; Galloway, 2025). Additionally, some fire-sensitive species, like Sisyrinchium bellum and Danthonia californica, showed declines after fire, highlighting the species-specific nature of fire responses.

Cultural burning for geophytes

Geophytes, or “root plants,” such as Brodiaea, Calochortus, and Allium species, hold deep cultural and ecological significance for Indigenous communities in California. These species benefit from open, sunny habitats with periodic disturbance, conditions historically maintained through cultural burning practices (Anderson et al., 2016). Fire enhances geophyte reproduction by reducing thatch and competition, improving light and nutrient access, and stimulating seed dispersal. The suppression of Indigenous fire regimes has led to shrub encroachment and geophyte decline, particularly in coastal prairies. Reintroducing frequent, low-intensity fire can help restore the ecological conditions necessary for geophyte persistence (Anderson et al., 2016; Cuthrell et al., 2012).

Species-specific responses to burning in California coastal prairies

Research on the effects of fire on native vegetation show both increases and decreases in native species abundances post-burn in California coastal prairies, depending on the species. The table below summarizes the various studies available for the different guilds, species, types of fire, and seasonality of burns.

Functional Guild	Species	Type of fire	Season of fire	Effect of fire
Perennial Grass	California oatgrass (Danthonia californica)	Prescribed fire	Spring (late June)	↓ Decreases with fire (Bartolome et al., 2019)
Perennial Grass	California oatgrass (Danthonia californica)			↓ Decreases with fire (D’Antonio et al., 2002)
Perennial Grass	Purple needle grass (Stipa pulchra)	Prescribed fire	Spring (late June)	↑ Increases with fire (Keeley et al., 2023)
Perennial Grass	Purple needle grass (Stipa pulchra)	Wildfire		↓ Decreases with fire (Larios et al., 2013)
Perennial Grass	Purple needle grass (Stipa pulchra)	Prescribed fire after seeding 5 years prior	Fall	↓ Decreases with fire (Young et al., 2015)
Perennial Grass	Blue wildrye (Elymus glaucus)	Prescribed fire after seeding 5 years prior		↓ Decreases with fire (Young et al., 2015)
Perennial Grass	Big bluegrass (Poa secunda)	Prescribed fire	Fall	↓ Decreases with fire (Young et al., 2015)
Perennial Grass	Meadow barley (Hordeum brachyantherum)	Prescribed fire	Spring (late June)	↑ Increases with fire (Carlsen et al., 2017)
Perennial Grass	Saltgrass (Distichlis spicata)	Prescribed fire	Spring (late June)	↑ Increases with fire (Bartolome et al., 2019)
Perennial Forb	Western blue-eyed grass (Sisyrinchium bellum)	Prescribed fire	Spring (late June)	↓ Decreases with fire (Bartolome et al., 2019)
Annual Forb	Large flowered fiddleneck (Amsinckia grandiflora)	Prescribed fire	Spring (late June)	↑ Increases with fire at moderate frequencies (Carlsen et al., 2017)
Annual Forb	Combination of forbs: Fringed red-maids (Calandrinia ciliata), notchleaf clover (Trifolium bifidum), and Tomcat clover (Trifolium willdenovii)	Prescribed fire after seeding 5 years prior	Fall	↑ Increases with fire (Young et al., 2015)
Annual Forb	Combination: true babystarts (Linanthus bicolor), California sandwort (Minuartia californica), Chilean bird’s-foot trefoil (Lotus wrangelianus), Sky lupine (Lupinus nanus), and pinpoint clover (Trifolium gracilentum)			↑ Increases with fire (DiTomaso et al., 1999) – look for citation with Reiner et al. 2007