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Native plant recovery in study plots after fennel (Foeniculum vulgare) control on Santa Cruz Island

Paula Power·Thomas R. Stanley·Clark Cowan·James R. Robertson
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Abstract

Santa Cruz Island is the largest of the California Channel Islands and supports a diverse and unique flora which includes 9 federally listed species. Sheep, cattle, and pigs, introduced to the island in the mid-1800s, disturbed the soil, browsed native vegetation, and facilitated the spread of exotic invasive plants. Recent removal of introduced herbivores on the island led to the release of invasive fennel ( Foeniculum vulgare ), which expanded to become the dominant vegetation in some areas and has impeded the recovery of some native plant communities. In 2007, Channel Islands National Park initiated a program to control fennel using triclopyr on the eastern 10% of the island. We established replicate paired plots (seeded and nonseeded) at Scorpion Anchorage and Smugglers Cove, where notably dense fennel infestations (>10% cover) occurred, to evaluate the effectiveness of native seed augmentation following fennel removal. Five years after fennel removal, vegetative cover increased as litter and bare ground cover decreased significantly ( P < 0.0001) on both plot types. Vegetation cover of both native and other (nonfennel) exotic species increased at Scorpion Anchorage in both seeded and nonseeded plots. At Smugglers Cove, exotic cover decreased significantly ( P = 0.0001) as native cover comprised of Eriogonum arborescens and Leptosyne gigantea increased significantly ( P < 0.0001) in seeded plots only. Nonseeded plots at Smugglers Cove were dominated by exotic annual grasses, primarily Avena barbata. The data indicate that seeding with appropriate native seed is a critical step in restoration following fennel control in areas where the native seed bank is depauperate.

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Monographs of the Western North American NaturalistArticle
90° N90° S · 180° W ← longitude → 180° E
Source-reported bounding extent: 33.94222067051576° to 34.093610452768715° latitude; -119.94117736816406° to -119.50721740722655° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Paula Power, Thomas R. Stanley, Clark Cowan, James R. Robertson. 2014. Native plant recovery in study plots after fennel (Foeniculum vulgare) control on Santa Cruz Island. https://doi.org/10.3398/042.007.0136

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