450 acres of Manzanita Park are designated as a Nature Preserve. It is a fine example of maritime chaparral habitat. One threat to the biological diversity of Manzanita Park is the spread of invasive non-native plant species. Invasive plants spread rapidly, forming monocultures which choke out native plants and provide less habitat for native species. Manzanita Park is infested with 3 invasive species; Jubata Grass, French Broom, and Yellow Star Thistle.

The most obvious invasive plant in the park is Jubata Grass, also referred to as pampas grass. This tough grass with its pinkish plumes has covered some parts of the park where the ground has been disturbed by roads or development. Many years ago, part of the park was used to grow strawberries and the areas where that activity occurred is now infested with Jubata Grass. Another area that is heavily infested with Jubata Grass is near the water tower, an area that was cleared and graded to put in the water system.

French Broom is also present in the park. It can be found in areas where the ground has been disturbed, mainly along roadsides. One other area that has French Broom is across from the water tower where the ground has been left exposed.

Yellow Star Thistle is only present in certain parts of Manzanita Park, but it is a plant we don't want to spread. It was probably brought into the park in straw that was used to stabilize banks. Most of this invasive plant is found near the main parking lot and below the BMX track. A very successful invader, Yellow Star Thistle has covered 10% of California. It is toxic to horses.

Invasive Plant Removal Efforts

In September of 2003, we began a grass roots effort to remove the invasive plants threatening Manzanita Park. The park staff and live-in volunteers were making efforts to control the Jubata Grass, but it is such a big problem that they weren't making much progress. We recruited some hard working teenage boys to work on the Jubata Grass.

First we started harvesting the plumes on the Jubata Grass to keep the seeds from spreading. Each plume can produce hundreds of thousands of seeds asexually by a process called apomixis, making the plant a severe threat to wildlands. In September and October we collected 103 bags of seed bearing plumes. Once the plumes throw their seeds, there is no particular benefit to collecting the plumes; they are just empty skeletons. Removing the plumes of Jubata Grass doesn't remove the plant, it just keeps it from spreading.

In the winter, we began digging out some of the Jubata Grass plants. This is very hard work. We borrowed some tools from the Monterey County Agricultural Commissioner's office. The Agricultural Commissioner's office is in charge of the local War On Weeds efforts, and they were happy to support our work. From December through April, we worked on removing Jubata Grass and French Broom. There is a special tool called a weed wrench used for removing broom plants. Broom can be pulled up by hand or dug out, but weed wrenches are designed to pull plants such as broom that have a long taproot.

By May the ground had become too dry to work on French Broom, so we took some time off. In June we began to see early plumes on the Jubata Grass, and by July we were back to work on the plume collecting for the second season. This season we have collected 176 bags of seed bearing plumes, and we aren't quite finished.