Sandy’s Impacts on The Walking Dunes Cranberry Bog

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The American Littoral Society’s semi-annual visit to the Walking Dunes cranberry bog in early June recorded some unusual observations. First, evident from quite a distance, was the browned leaves (needles) of the scattered pitch pines that are found growing in and adjacent to the bog. Many—and, in a few cases, all—of the needles were killed. We speculated that this was another example of Hurricane Sandy’s impact on our local flora by way of wind-driven salt spray.A close inspection revealed that most of the trees were alive and sprouting new leaves by way of their leaf buds located near the outer tips of twigs and branches, as well as adventitious buds hidden under the bark along the trunk and on branches. The latter are the buds that will remain dormant for years until stimulated to sprout by injury from fire, pruning, insects or, in this case, storm damage.

The next observation made as we approached the bog was a clear line of dead beach heather leaves, with the dead zone lower down on the flank of the dune, and the unimpacted, lush zone of heather higher up. Another evergreen, but growing very low to the ground on the dry sandy soils adjacent to but outside the bog—this observation pointed to a somewhat different culprit. Wind-driven salt spray should have impacted the entire beach heather community.

It seemed that the only explanation for the observation before us was that saltwater, not salt spray, was the main culprit. According to Suffolk County topographic maps, the Walking Dunes cranberry bog is situated a mere 1.5 feet above mean sea level, with the northwest corner of the bog connected, very narrowly, with the mix of fresh and salt marsh vegetation that covers a wide expanse of flatland extending northwestward toward Goff Point. This wide marsh sits just inside the low coastal dune line along the east shore of Napeague Harbor, at between 0.5 and 2 feet above mean sea level. Two small tidal creeks link this area with the harbor and provide a conduit for storm surges to inundate the meadow and bog.

That idea was given more validity by the third observation, made as we entered the bog itself: Most of the cranberry vines, yet another woody evergreen plant, had brown and dead leaves.

One of the main purposes of our early-June visit to the bog was to observe the unique orchids (grass pink and rose pogonia) in bloom there, and the insectivorous sundews (thread-leafed, round-leafed and spatulate-leafed). The sundews were thriving, but the orchids could not be found in the main bog.

I returned this past weekend, two weeks later, for a closer look at the situation. All three evergreens in and near the bog—the cranberry, heather and pitch pine—seem to be recovering from the severe dousing of saltwater. However, very few of the cranberry vines have produced flowers, and the outlook for cranberry picking this fall does not look very good.

Since my last visit, we’ve had a few good soaking rainfalls, and the bog is now inundated with fresh water. Fowlers toad tadpoles are numerous there, and growing quickly. Another species in the bog that seemed unharmed by Sandy, and in fact appears to be more robust this year than ever, is the mighty phragmites.

I did a very cursory survey of the orchids flowering in the southern half of the approximately 1-acre bog. There, over an area of approximately 20,000 square feet, I located fewer than 20 orchids (all grass pinks). In striking contrast, a smaller, disjunct section of cranberry bog measuring 500 square feet and within 100 feet of the main bog had 80 orchids in flower. (I did not examine all these closely, but all those I did were grass pinks.)

Orchids are very complex plants that rely on a symbiotic relationship with soil fungi to thrive. Did last fall’s saltwater inundation impact the orchids directly, or did it kill the key soil fungi and impact the orchids indirectly? And how long will it take for the orchid colony to rebound?

It will be interesting to monitor these changes in the Walking Dunes cranberry bog.

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