Invasion of Fennel (Foeniculum vulgare) into Shrub Communities on Santa Cruz Island, California
Beatty SW and Licari DL. 1992. Invasion of Fennel (Foeniculum vulgare) into Shrub Communities on Santa Cruz Island, California. Madroño. 39(1):54-66
Fennel (Foeniculum vulgare Mill.) was introduced to Santa Cruz Island in the 1850's, and is now present in 7.8% of the island grassland community. This study's goal was to determine the success of fennel invasion into chaparral and coastal sage communities bounding grassland infested by fennel, and whether fennel occurrence varied with physiognomic or disturbance parameters. Vegetation was sampled using line transects placed perpendicular to grassland/shrubland boundaries, in sites stratified by shrub community type, topographic position, and aspect. Results indicated that coastal sage was more susceptible than chaparral to invasion by fennel. Fennel cover in chaparral correlated positively with fennel cover in adjacent grassland, although fennel did not occur in chaparral past an average of 2-3 m. Where vegetation boundaries were most distinct, fennel was negatively correlated with shrub cover. Disturbance related to fennel occurrence only in grassland areas, and did not correspond to fennel invasion in shrub communities. With recent removal of grazers from the island, fennel expansion and natural vegetation recovery from grazing may be integrally related.
- Type
- Journal Article
- Authors
- Beatty, Susan; Licari, D
- Units
- CHIS
- Keywords
- Invasion, Plant Studies, Santa Cruz Island Channel Islands National Park CA, sweet fennel (Foeniculum vulgare)