It wasn't easy to convince Tim to trim back the willow trees at the Princeton High School ecolab this past week. That's the detention basin that was only growing turf grass until the school gave permission for Tim's students and we community volunteers turn it into a very healthy native wetland. Maintenance isn't the right word for what we've done in the years since then, because though we "maintain" it, we also try to make it better and more diverse each year, while working to keep any one species from taking over. It's a kind of wild gardening.
Tim sees the willows as shade for the ponds (to keep them cool and discourage algae) and cover for the birds. I agreed, but also made the case that the rapidly expanding willows were making life harder for the 30 other native plant species meant to coexist there.
So we worked for a couple hours, trimming back the willows and doing general cleanup so that this detention basin can continue to thrive. Tim's turning the cut stems into a "corduroy" footpath.
Like any garden, this wild-looking wetland needs periodic rebalancing. The willows and the cattails--the two species most people associate with wet areas--are also the most aggressive and would over time displace the many shrubs, sedges and wildflowers that add to the diversity and beauty of the wetland.
The setting, with its elevated walkway and upscale fencing all around, is perfect for appreciating the tall wildflowers from above, as flying pollinators might. Even when the basin is performing its stormwater function, and fills completely with runoff during heavy storms, the plants bounce back after the water has drained out the next day.
Because the school sump pump that has serendipitously kept the wetland wet year-round was out of commission for awhile over the winter, there may need to be some restocking of crayfish and other aquatic species that have otherwise thrived from the beginning.
But that's all part of the ongoing balancing act, the periodic, strategic human interventions that are minor compared to the weekly mowing a lawn would have required. Our role is to make sure all the basic pieces of the puzzle--the sump pump, the plant and aquatic diversity--are present and in balance. Nature does the rest.