Sunday, July 7, 2013

The Beaver Meadow

A new grassy meadow grows in the basin of a former beaver pond
Typically, when beavers abandon a pond, the habitat quickly regenerates into meadow. Grass seeds and the seeds of many other plant species begin to sprout in the rich silted-up soil, and within a few weeks a lush sea of grass grows where once beavers swam. The beaver meadow continues to evolve; that is as long as beavers refrain from re-flooding the area. The first year, not much diversity will be encountered and the meadow is dominated by grass and only a few other easily perceptible plant species, but only a year later, plant diversity increases tremendously and a wildflower meadow is born.
 
Blue Vervain plants grow plentifully in the beaver meadow 
The old beaver dam is covered with wildflowers
Undoubtedly, many of us recognize the good work that beavers do by creating water impoundments –and therefore wetland habitat for scores of other creatures, but few of us give them credit for their gardening work. Even without a beaver meadow, a beaver dam can act as a raised garden –hosting thousands of blooms along its span and providing food resources for hummingbirds and butterflies as well as a source of forage and bedding material for muskrats and for the beavers themselves.
Square-stemmed Monkey-flower grows in the new meadow
Swamp Candles (or Yellow Loosestrife) is in the Primrose family
When our old farm fields are left alone to evolve as they will, most in our region become dominated by goldenrods and asters as well as alien invasives like spotted knapweed. These plants generally attain a lock on the habitat and will not easily be displaced. They will certainly not be nudged aside by any less aggressive flowers. In other regions of the country, fire acts a disturbance factor in the environment as it clears an area of its dominant plants and allows a new plant community to develop. In our area, it's the beavers introduce the disturbance factor and are therefore the fathers (and mothers) of distinct meadow types in a given environment.
Yellow Moth Mullein is in the snapdragon family
Northern Willow-herb has very small blooms
The succession of plants that colonize the beaver meadow are surprisingly different than those which dominate our adjacent old fields. A lot of this difference is by chance, since it depends on what plant seeds are inherent in the given environment. But in my experience new beaver meadows even in the same area will not all develop in the same way. This may be explained by the varying prevalence and reproductive success of local plants on a year-to-year basis.
 
A Northern Pearly-eye Butterfly at the meadow's edge
The first Hickory Hairstreak Butterfly of the season
Plant make-up in the beaver meadow will continue to evolve as the years go by. The first 2 years or so, annuals and biennials might make up a greater proportion of the meadow's diversity, but in subsequent years, perennials will become established and eventually  dominate –at least up until the meadow is re-flooded and transformed into a pond once more.
Not a beaver meadow - but our main wildflower meadow, now dominated by spiderwort
A small proportion of the spiderwort flowers are pale blue
Oddly enough, this year the meadow that once was home to Sarah's Pond is now hosting an outstanding bloom of Moth Mullein. Just where all those Mullein seeds came from is a mystery. I've never seen more than a few of these plants in the surrounding fields for the past dozen years. It’s conceivable that these seeds, along with those from dozens of other diminutive species were there all along, lurking in the silt at the bottom of the pond –biding their time and waiting for their chance to sprout.
 
A buck lays down and remains partially hidden in a corner of the field

A Spring Azure Butterfly (very small) lands on my shoulder 
Blue Vervain, which dominated the beaver meadow last season is back again in a big way this year. The copious amount of rainfall that we've received in the last several weeks have suited them fine, and they are growing taller than usual, and mingling well with the tall mulleins.

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