Non-native Grasses Can Fuel Wildfires
Q&A with Nikki Hanson, a native plant consultant and supporter of GreenTown Los Altos’ efforts to promote native drought tolerant gardens to replace thirsty lawns.
Can you tell us more about how native grass can help protect the environment from wildfires? News media like Reuters and The New York Times in August have mentioned that non-native grasses like the Guinea grass have contributed to the risk of wildfires in Lahaina.
“The spread of flammable non-native grasses such as Guinea grass in areas of former farmland and forest have created large amounts of small, easily ignited materials that increase the risk and severity of fire.”
The crux of the problem is the same as anywhere-an invasive weed that’s densely growing, wide-spread, fine and quickly ignitable.
Many of California’s wild land habitats also have increased fire frequency due in part to an invasion of easily burnable vegetation. Hawaii with its mild climate and prime growing conditions is unfortunately even more vulnerable to invasive species and so has been inundated with invasive plants which definitely change the dynamics of the ecosystem in many ways. While invasive plants are not the sole culprit they certainly contribute to the fire risk in a significant way.
The article mentions that the non-native grasses were brought to Hawaii in the 19th century because they were drought tolerant. So how are native grasses better? They could also be invasive.
Native grasses are better because they are not invasive. Invasive means something takes over disproportionately and shifts the balance.
Native grasses in California’s wild landscapes act very differently than our widely prominent abundance of exotic, invasive, and mostly annual grasses. Examples of locally, native grasses to our California San Francisco Bay Area include: purple needle grass, foothill needle grass, June grass, California fescue, California oat grass (completely different than the annual weedy oat grass), and a variety of melic grasses, all of which are perennial bunch grasses which typically stay somewhat green even in the dry season (i.e. contain moisture and are not as burnable). The other difference is the way native grasses grow. They grow slower, don’t produce nearly as much dead material, and grow in distinct clusters with space between bunches, creating a situation where fire does not spread as rapidly or easily or as widely. Assuming the area is not also chalk full of invasive annual, dead grass material.
This is one of the many reasons I encourage land managers to use techniques and time mowing to favor native bunch grasses and deter invasive exotic grasses.
Note that drought-tolerant doesn’t necessarily mean that the plants are native. The drought-tolerant demonstration garden at the Woodland Library in South Los Altos consists of plants that are both native and drought tolerant. That’s ideal.
* The Woodland Library drought-tolerant demonstration garden is maintained by GreenTown Los Altos with the support of Nikki Hanson from cal-sisters.com and many community volunteers. If you’re interested in lending a helping hand at the garden or have a question for Nikki, contact firstname.lastname@example.org