Difference between revisions of "Arundo donax in California's Central Coast Region"

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(Satellite Images of Salinas River Land Cover)
(Satellite Images of Salinas River Land Cover ["Salinas River." N and E. Google Earth. 2015 and 2016. April 5, 2018.])
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===Satellite Images of Salinas River Land Cover <ref name="google"> ["Salinas River." N and E. Google Earth. 2015 and 2016. April 5, 2018.] </ref>===
===Satellite Images of Salinas River Land Cover <ref name="google"> ["Salinas River."  36°21'45.24"N and 121°13'53.24"W. Google Earth. 4/2015 and 10/2016. April 5, 2018.] </ref>===
As seen in these Landsat 8 satellite land cover images, the Arundo invasion is under control since the start of the control programs.
As seen in these Landsat 8 satellite land cover images, the Arundo invasion is under control since the start of the control programs.

Revision as of 11:57, 5 April 2018

Figure 1: Arundo donax (giant reed). [1].

An environmental summary created by the ENVS 560/L Watershed Systems class at CSUMB.

Arundo donax: Invasive Plant

Giant reed (Arundo donax) is a perrenial invasive grass native to Eastern Asia. It is a persistent rhizomatous grass with high biomass production that was introduced to other continents by humans, for building material since many years [2]. This grass can reach up to 20 feet tall in height when healthy, with long, flat, and green leaves. It is considered an ecological threat since it spreads when its rhizomes come in contact with soil within wetlands. This grass spreads along riparian zones and lake shores, and competes with native vegetation for sunlight, water, and nutrients [3].

Arundo donax in the Central Coast

Figure 2: Encroachment of Arundo donax along Salinas River. Map by DENDRA Inc. [4].

Arundo has been spreading through Central California watersheds, and exacerbating flood prone areas [5]. Monterey and San Luis Obispo counties, as well as the San Francisco Bay Area, and Sacramento and San Joaquin River valleys have been impacted with proliferating stands of Arundo [5]. Stands of Arundo change direction of water flow, change the force of the river, and increase flood risk. The thick stands of Arundo can deflect the natural flow of the river into farmland and private properties[6]. High areas of biomass also increases the risk and severity of fires in these riparian zones, endangering native plants, and other species that find habitat in this area [7]. Approximately 1,900 acres of the 4,160 sq miles of the Salinas Watershed were encroached with Arundo in 2008, before any control programs started treating the stands along the Salinas River as seen in Figure 2 [4]. After the instigation of control programs, approximately 1,400 acres of Arundo remain in 2017 (pers. comm., E. Zefferman, RCDMC).

Flooding in Central Coast

The Salinas River has a long history of floods dating back to 1911, with the most recent flooding forecasted in February of 2017, after heavy rains [8]. With high precipitation rates in the area in the winter, proliferating Arundo stalks are further exacerbating flood risks in this region.

Local Solutions to Arundo Invasion

The two groups that are addressing this encroachment of Arundo in the Central Coast region are the Resource Conservation District, Monterey County (RCDMC), and the Monterey County Water Resources Agency (MCWRA) [4]. The Monterey County Agricultural Commissioner sbegan treating the Rundo by implementing spraying of scattered patches in the upper watershed (pers. comm., E. Zefferman, RCDMC). In 2011 the California Invasive Plant Council (CalIPC) prepared an Arundo donax Distribution and Impact Report in agreement with the State Water Resources Control Board (SWRCB) as seen in Table 1 [9]. In 2014 the RCDMC took over this project, and the RCDMC and DENDRA, Inc. conducted an Initial Study per the California Environmental Quality Act (CEQA) in the Salinas Watershed. The Initial Study resulted in a Mitigated Negative Declaration submitted to the California Department of Fish and Wildlife (CDFW) for the Salinas River Watershed Invasive Weed Control and Restoration Program, which is currently being implemented by the RCDMC in collaboration with the CalIPC [10].

Summary Table

The following table is extracted from the CalIPC Arundo donax Distribution and Impact Report of 2011 [9]. This document was submitted to the State Water Resources Control Board (SWRCB), summarizing details of the encroachment spanning from Northern California to Tijuana. The highest levels of invasion in the Salinas have been identified to be vegetated floodplains, vegetated low terraces, and vegetated upper terraces, similar to San Luis Rey River, Santa Ana River, Santa Clara River, Santa Margarita River, and Ventura River. While comparing distributions of Arundo in different watersheds, Salinas watershed Arundo patches are less continuous and less connected than the others across the state [9].

Table 1. Arundo acreage in central California by hydrologic unit according to 2011 Distribution and Impact Report [9].
Hydrological Unit Total Area (Acres) Treated Arundo (Acres) Untreated Arundo Total Arundo Percent Treated
Salinas 2,272,492 106.4 1,225.3 1,331.7 8%

Arundo Control Methods

Within the Arundo Control Program, the RCDMC uses these methods of control [7]. :

  • Chemically treat with broad-spectrum and target-species specific herbicides including glyphosate, imazapyr, or triclopyr, and will be formulated for approved use nar water bodies using backpack sprayers or hand-held power sprayers [7].
  • Removal of dead stands by mowing with attachments, by hand and carried to chippers

Since Arundo tends to encroach in riparian zones with native plants, methods of removal will ensure avoiding natives. Species specific herbicides will be used when possible to avoid broad spectrum eradication. After removal of Arundo, native plants like willow and California sycamore are restored in regions that are prone to erosion [7]. The rest of treated riparian areas are naturally restored (pers. comm., E. Zefferman, RCDMC).

Future of Arundo

Since the Salinas River watershed has the second-largest infestation of California, RCDMC has implemented the Arundo Control Program in 2008, to control all Arundo by the year 2028 [4]. Many stakeholders have been collaborating with RCDMC and private landowners in Monterey County, in order to restore native riparian vegetation. The RCDMC Control Program has been successful and treated a significant amount of Arundo since 2008 and bettered the river system with the help of private landowners, as seen in Table 2.

Table 2. Acerage of Treated Arundo in Salinas River Watershed (pers. comm., E. Zefferman, RCDMC)
Year Acerage of Arundo Treated
2014 113
2016 103
2017 120

Satellite Images of Salinas River Land Cover [11]

As seen in these Landsat 8 satellite land cover images, the Arundo invasion is under control since the start of the control programs.


  1. / CALIPC (California Invasive Plant Council). Arundo donax. Cal-IPC.
  2. / Pilu R, Bucci F, Badone FC, Landoni M. 2012. Giant reed (Arundo donax L.): A weed plant or a promising energy crop? African Journal of Biotechnology 11(38) 9163-9174.
  3. / Swearingen J, Bargeron C. 2016. Invasive Plant Atlas of the United States. University of Georgia Center for Invasive Species and Ecosystem Health.
  4. 4.0 4.1 4.2 4.3 / RCDMC (Resource Conservation District of Monterey County). Salinas River Arundo and Tamarisk Control. Salinas River Watershed Arundo Control Program.
  5. 5.0 5.1 / Wessel, Lindzi. 2016. Arundo: The invasive 'hair clog' of the Salinas River. The Californian..
  6. / Spencer DF, Colby L, Norris GR. 2013. An evaluation of flooding risks associated with giant reed (Arundo donax). Journal of Freshwater Ecology 28(3) 397-409.
  7. 7.0 7.1 7.2 7.3 / CDFW (California Department of Fish and Wildlife. 2014. Notice of Determination. Salinas Watershed Invasive Non-Native Plant Control (Project). RCD Monterey. .
  8. / Wright, T. 2017. Forecast calls for flooding on Salinas River this weekend. Santa Cruz Sentinel Weather.
  9. 9.0 9.1 9.2 9.3 / CALIPC (California Invasive Plant Council). 2011. Arundo donax Distribution and Impact Report. State Water Resources Control Board.
  10. / RCDMC (Resource Conservation District, Monterey County). 2014. Attachment E-Regulatory Documentation. Salinas River Watershed Invasive Weed Control and Restoration Program. RCDMC.
  11. ["Salinas River." 36°21'45.24"N and 121°13'53.24"W. Google Earth. 4/2015 and 10/2016. April 5, 2018.]



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