Thursday, March 31, 2022

What happens when an invasive grass parks itself in your parking lot

I had to laugh when I saw this parking lot island invaded by Imperata cylindrica (cogon grass). 

It really wasn't funny, but it does illustrate the problem faced by people who suddenly find masses of cogon grass in their property.

Parking Island with Cogon Grass
Intact Parking Island Flora (with an understory of ornamental grasses and short shrubs)
The persistent rhizomes make it hard to permanently eliminate the species once it encroaches en masse in an area. In this case, I imagine a piece of rhizome (or less likely, a seed?) managed to get into the soil during some activity, and over the years the grass spread throughout the island. Whereas the invaded island was almost entirely covered with the invasive species, the rest of the parking islands with intact flora had healthy looking shrubs and ornamental grasses in them. 

Maintenance crews may have simply pulled individual blades out (which would have done nothing to solve the problem), or perhaps even shrugged in defeat and hoped that the invader would somehow blend in with the rest of the plants.

Shrubs (red arrows) being engulfed by Cogon Grass
Unfortunately, by delaying any aggressive actions against the invader, they simply allowed it to strengthen its grip on the area, and since cogon grass grows very fast and slowly engulfs other plants around it unless it can be shaded out (impossible in this case due to the open nature of the island) the island now sticks out like a sore thumb when compared to the other islands in the parking lot.

The lesson of this story is that when an aggressive invasive shows itself in an area, don't delay in confronting it or you'll end up paying a much larger price later.

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