Channel Islands National Park is made up of five out of the eight Channel Islands located off of the southwestern coast of California. These islands are home to a diverse variety of both native and non-native species of plants, with each island capable of supporting different species due to the diverse geography and history of the islands. Populations of native plant species that inhabit islands are vulnerable to the threat of non-nation plants because of the limited geographic area available on an island. In Channel Islands National Park around 25 percent of all plant species of the islands are invasive. Among these invasive plant species found on the islands is the Olea europaea. Originally native to Europe, O. europaea was introduced to California’s Channel Islands around the year 1900. Commonly known as the olive tree, O. europaea is an invasive species on the islands that competes with the native plant species for sources of light, as well as altering plant communities that are already native the Channel Islands. These invasive olive trees are able to be transported across the islands by the feral pigs that inhabit the islands, as well as the local bird populations, the latter being responsible for the discovery of an olive tree seedling on the island of Santa Rosa, which was soon removed after its discovery. Out of the five islands that make up Channel Islands National Park, O. europaea is most commonly found growing on the island of Santa Cruz, but it has historically been found growing on the island of Santa Barbara as well. Outside of the National Park, non-native olive trees can be found on the mainland of California. O. europaea has also been introduced to the Hawaiian Islands, which alongside California, make up the only two states in the country to host this invasive species.
Picture Citation U.S. National Park Service, Terrestrial Invasive Plants https://www.nps.gov/common/uploads/photogallery/pwr/park/chis/ED61D02E-155D-4519-3EDF5C54E302C2D5/ED61D02E-155D-4519-3EDF5C54E302C2D5-large.JPG References United States Department of Agriculture, Natural Resources Conservation Service Olea europaea L. Available: http://plants.usda.gov/core/profile?symbol=OLEU Accessed on 10-15-16 U.S. National Park Service, Channel Islands National Park Plants. Available: https://www.nps.gov/chis/learn/nature/plants.htm Accessed on 10-14-16 U.S. National Park Service, Channel Islands National Park Terrestrial Invasive Plants. Available: https://www.nps.gov/chis/learn/nature/terrestrial-invasive.htm Accessed on 10-15-16
Channel Islands National Park 
I never knew that we had olive trees in the United States. They must have been brought by the early Europeans for sources of olives and olive oil.
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I found this article particularly interesting because I did not know a lot about the history of the olive tree. I knew it originated in Europe because I went on a trip to Italy and France after I graduated high school in 2013 and olive trees where everywhere; hillsides where covered with them along the highway. I was surprised to find out that we had olive trees in the States and that they were a somewhat harmful invasive species. Very informative article.
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Never thought about pigs spreading the propagation of a olive tree. you see the symbol of peace with a dove carrying a olive branch but nothing of a pig.
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