Long-term monitoring of a highly invaded annual grassland community through drought, before and after an unintentional fire.

Questions: 1) How did seedling numbers and species composition change in the first year after a wildfire during drought, relative to pre-fire variation? 2) Has the community returned to pre-fire composition after five years? 3) Has the degree of dominance by exotic annual grasses changed? 4) Is there any evidence that drought conditions affected community cover, before or after fire?

Location: Exotic-dominated annual grassland in southern California, U.S.A.

Methods:  We monitored community cover and native annual forb densities for four years before and four (cover) to five (densities) years after an unintentional fire (fall 2013) coinciding with the spring 2012-2019 California drought. We also measured seedling emergence both before and during the first year post-fire. We assessed post-fire changes in cover and density relative to pre-fire variation, and tested correlations between community cover and annual rainfall measures.

Results: Seedling emergence declined strongly afte...