For those of us who regularly walk along the Greenway, this fence may be a bit of a surprise! Let me explain why we are so excited to have started this experiment in landscape transformation.
On Saturday, March 7, volunteers at the monthly Greenway Work Party completed the first experimental step in our effort to manage wildfire risk in Parcel 1 of the Glen Park Greenway (Burnside Ave to Chilton Ave).
At the moment, a very large part of the open space in Parcel 1 of the Greenway is home to a dense growth of large fennel plants. These tall plants dry out in the summer and provide a significant source of fuel for wildfires. To manage this wildfire risk, the City mows the part of the fennel that lies nearest to the garden fences of the homes that would be most threatened by any wildfire. They mow the fennel at least once each year to create a space about two hundred feet deep containing much less potential fire fuel. However, extensive stands of fennel always remain outside of the mowed area.
Since the fennel is so frequently mowed, the Friends of the Greenway would like to plant California native grasses in its place. These grasses not only provide better habitat than fennel for a wider range of wildlife, they are also easier to mow as part of wildfire risk management. These native plants also provide other ecosystem services, in particular the retention of rain water and the sequestration of carbon in their very deep and extensive root systems.
One of the biggest challenges to this proposal is that we need to remove the fennel from the area that we would plant with grasses. Fennel is famously hard to remove. The fenced area contains our experiment with a method to remove fennel from a limited area. If this method works, we will be able to plant grasses in the fennel-free space inside the fence, and consider using this process over more of the mowed areas of Parcel 1 in the future.
The technique that we use inside of the fence is to lay out a simple drip irrigation system on top of the mowed plants, cover that with the remains of large cardboard boxes, top it off with old straw and anchor it all with netting stapled to the ground. By irrigating the soil we hope that any seeds in the soil will germinate, that any plants (including fennel stubble) will regenerate and sprout and that all of this old vegetation will be prevented from thriving because the straw-covered cardboard prevents any sunlight from reaching the leaves that sprout beneath it. When the time to plant the grasses arrives, we hope that we will be able to punch small holes through the cardboard and plant the grasses through those holes. The native grasses will be able to grow and thrive without competition from any fennel.
We look forward to seeing how well this works. If you take a closer look at our experiment, please be careful not to lean on the fence. Above all, please do not step on the straw-covered cardboard surface! This cardboard “sheet-mulch” is quite fragile and even the tiny holes that we make as we walk across it can allow sunlight through and make the sheet-mulch useless!
If you would like to join one of our monthly Work Parties on the Greenway, please email Greenway@GlenParkAssociation.org .
Our next Work Party will be on Saturday, April 11 from 9am to 12pm. I hope to see you there!