Removal of giant reed has numerous beneficial effects, including improvement of fresh water flow, water quality, native species habitat, and reducing threats from wildfire. Decrease in summer water flow reduces the flushing that takes place in the Bay and contributes to the accumulation of pollutants, upsetting the natural balance of freshwater and saltwater in the estuary. Studies funded through the Santa Ana Watershed Project Authority suggest that giant reed also lacks the canopy structure necessary to provide significant shading of riparian habitats, resulting in warmer water then would be found with a native gallery forest of cottonwood or willows. As a result, riverine areas dominated by giant reed tend to have warmer water temperature, resulting in lower oxygen concentrations and a lower diversity of aquatic animals and fish. No known native species of animal in California uses the giant reed as protective cover or forage, and its presence represents a loss of habitat.
Giant reed is also highly flammable throughout most of the year.
It appears to be highly adapted to extreme fire events, and can increase the probability and intensity of a wildfire. Additionally, giant reed rhizomes respond quickly after fire, sending up new shoots and rapidly outgrowing any native species that might have otherwise become established in a burned site. The purpose of this project was to eradicate several giant reed patches in the upper Chorro watershed with minimal impact to the landscape and native vegetation, and to investigate the cost and time required to implement such an endeavor. Though labor intensive, cutting the stems and treating with herbicides is the preferred method to avoid impacting adjacent vegetation and aquatic habitat. Implementing the Project Many of the plants in the Chorro Creek drainage were probably only three to five years of age when the planning and surveying for this project began.