T & L Adventures: 5-28-16: Parker river NWR, MA

Parker River NWR on Plum Island, MA: 5-28-16

"Management" of Barrier Islands:
Early concepts of barrier island management viewed total protection as the desired goal. This was achieved by such methods as planting trees, building seawalls, and erecting dune fences.

Black Pines

In the fall of 1953, refuge personnel planted Black pines in the dunes for stabilization.

In the "wisdom" of the time, it wasn't taken into account that this species of tree was native to mountainous regions of Europe and was not a typical dune species.

Dune fences were man's feeble attempt to "manage" the dunes.

Needless to say, they didn't work well.

Modern understanding of the natural ecological processes, however, recognizes that the strength of barrier islands lies in their dynamic character. It is the natural movement of the sand dunes that allows such important habitat as the vernal pools (see yesterday's post) and the maritime forest to develop.

Two plants critical to dune stabilization in the area of Plum Island are Beach Heather and Beach Grass.

Beach Heather

This plant is one of the dominant vegetation types of the dunes. It is also referred to as Poverty Grass due to its ability to grow in nutritionally poor sand, thus creating better growing conditions for other plants by enriching the soil with nitrogen.

To help conserve what water it collects, Beach Heather's scaly leaves are covered with fine, hair-like structures that insulate against wind-accelerated moisture loss and act like mirrors to reflect the drying, hot rays of the sun.

Above the surface it forms a thick carpet, sometimes of an acre or more, that impedes sand movement. Below the surface its network of tough rootlets binds the sand together.

Beach Grass

Beach Grass co-mingles with the Heather to stabilize the dunes. This plant is a "lover of sand" and is supremely adapted to the harsh and unstable conditions of the dunes. Stimulated by the shifting sand, root-like rhizomes extend horizontally under the surface while sending new shoots above.

This interlocking maze of subsurface runners, combined with a carpet of grass above, helps anchor the dun in place. The rhizomes collect moisture but are supplemented by a series of vertically-growing tap roots up to 40 feet long! Above ground, the grass's long and narrow stems and blades expose minimum surface area to the drying wind and sun. The blades sometimes even roll into tubes which further reduces water loss.

Adult male Yellow Warbler

We have seen more of this species than we've ever seen before and when we see them singing in the sunlight it's hard not to keep photographing these beauties.