Invasive Plant Control

Invasive plants are defined as “plants that are not native to an environment, and once introduced, they establish, quickly reproduce and spread, and cause harm to the environment, economy, or human health” according to Cal-IPC. Invasive species are considered the second greatest threat to biodiversity worldwide and are the leading cause of species extinctions in island ecosystems.

Invasive plants are introduced to the landscape in a multitude of ways. Catalina Island has a strong history of ranching; during that time most of Catalina’s non-native species were introduced and became permanent residents. On occasion, plants that have been brought over from the mainland for gardens or decoration have escaped and moved out into the interior of the Island. One example is Genista linifolia, also known as flax-leaved broom which broke free from Avalon in, and now can be seen trying to gain a foothold around the Island

To date, thousands of hours and hundreds of thousands of dollars have been spent treating landscaping plants that have invaded the wildlands of the Island. Over time invasive plants, such as Genista and fennel, have invaded the Island, affecting flora, fauna, and ecosystem processes. There are now approximately 80 invasive plant species that were identified by the Conservancy as potential weeds in need of control and/or eradication.

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The entire Island has been mapped, and roughly 35 invasive species have been treated by the Catalina Habitat Improvement and Restoration Program (CHIRP) to keep them from further invading our rare native vegetative communities. CHIRP staff, in conjunction with other supporting staff on the Conservation and Education team, brought their comprehensive and complex understanding of the Island ecology and geography to bear in the fight against invasive species. Currently, the Conservation Team is working on contracting out invasive plant work to help progress the control of invasive species.

While out in the field, plant teams travel to the most remote locations on the Island, through steep and rugged terrain, to survey and collect data. The data gathered is then entered into a geographic information system (GIS – ArcMap) to produce maps for analysis, treatment, and navigation. These maps help current and future team members to identify the locations of not only invasive plants but also some of the rare and endemic Catalina Island species. Past and future maps help with monitoring and stopping the spread of invasive plant populations.