by Don Flora (a real scientist)
If your place is close to water you probably have an issue with buffers. You hear, correctly in most cases, that buffers are no-touch, conscript large amounts of the most valuable parts of your property, fill those parts with vegetation that you’d rather not have and certainly don’t want to tend, block your view, host critters that worry you, attract hip-booted agency honchos, and preclude fun places like tree houses and water-side campsites, pirate-flagged poles, and arbor-covered overlooks.
Proposals for wider buffers may well envelop your house, at least on paper, making it ‘nonconforming’, a situation that no future home buyer will welcome and which affects your net worth, your borrowing power, and the design and alteration of your home. Except for these small matters buffers may be fine.
But for what? Do they work? Need they be so big?
Shoreline and wetland buffers are said to manage stormwater and its pollutants, and provide habitat for wild things. There are fancier phrases but they boil down to these. It is assumed but not shown that buffers do these things better than your yard.
Narrow buffers can have large effects relative to stormwater’s pollutants. All across the land small buffers have, next to studied farms and pastures, corralled nitrogen (N), phosphorus (P), and/or sediments. N and P are key nuisance nutrients in streams and tidewater, and sediments urge P along, so their reduction, at least in some places, its important. “Small” here means 2 to 16 feet wide. “Corralled” here means a drop of at least 75 percent between the uphill and downhill sides of the buffer.
I’m aware of a score of small-buffer studies that found this much or more protection for adjacent waters.
Lean, efficient buffers of this sort are typically equipped with grass, usually the native fescue sort found in pastures and lawns. And fences, if livestock are about. Certain shrubs as well where wildlife or fish can benefit. These are all common in farm country and consistent with landscaping in exurban areas.
Are narrow buffers good for wildlife?
Yes, when they provide shade and nesting places. There are at least 8 native species of amphibians here of which 5 need water for breeding and then emerge to range widely, from hundreds of meters to several kilometers. Bullfrogs are voracious rogue foreigners, a limiting factor for the other amphibs, small fish, and small birds.
Overhanging shade is good for amphibians, a relatively easy habitat feature given the abundance of shrubs in and around wetlands. I’ve inquired about the effects of early-drying wetlands and learned that at least some water-needing amphibians hatch, mature, and go away before the water dries.
I asked a university ornithologist whether wider, denser shrubbery would be good for the birds that nest low and close to water. Shrubs like salmonberry can be pretty sparse. He said a 6- to 10-foot shrub buffer should suffice: predators find the nests anyway. He said the key thing that can be done for these creatures is to kill cats. Another example of predators rather than habitats as critical factors. Still another is eagles’ robbery of eggs and juveniles from heron rookeries. Buffer widths are rather irrelevant to predation.
So, if little buffers can pull their weight and more, should big buffers leave the roundhouse? Next month.