Marsh-grass Dieback in Virginia


Background:
Robert "Bob" Christian (of East Carolina University) contacted Merryl Alber and Robert Twilley to alert us to some interesting observations concerning marsh dieback in coastal Virginia. The affected area is the Upper Phillips Creek marsh, which is the ocean side of the peninsula opposite Hog Island, VA. This is close to the Virginia Coast Reserve - LTER research site.

What follows are notes from our correspondance with him and some photos he sent.

Bob wrote (JF editted):

"I was able to take a better look at the dieback area of UPC and fly over the peninsula, thanks to Art. Here are a few photos from the trip."

Photos of marsh at the Virginia Coast Reserve - LTER site (Upper Phillips Creek marsh, about 50 hectares at 37o 27’ 38”N and 75o 50’ 04” W).

(Each photo opens in a new window.)

standing dead / creekbank / close-up / distance / fly-over

Photos courtesy of Amanda Floyd and Robert Christian.

"Some of what we learned:

1. There does not seem to be a comparable dieback elsewhere on the islands or to the south of Brownsville, at least as we were able to pick out by air. I really did not get as good a view north of Brownsville or around Upper Phillips Creek.

2. The extent of the brown area is greater than I originally thought.

3. Most dieback is in the short S. alterniflora area between the boardwalk and the creek (near the SET site 2)

4. Some Distichlis and S. patens did turn brown near the boardwalk.

5. The brown looks like last year’s growth rather than this year’s. There is little to no growth underneath.

6. There were no signs of snails or herbivory causing the browning.

Here’s what we did:

1. We set out 4 30-m transects that passed between brown and “normal” areas. The first 2 are between the boardwalk and creek. Transect 1 runs 95 o from SET 2A; transect 2 runs 338 o from between SET 2A and 2B. Transect 3 runs at 56 o from boardwalk toward woods just beyond path to SET 2A. Transect 4 goes of boardwalk at 30 o toward woods from near the met station remains. This last transect is not in S. alterniflora.

2. I walked each transect and identified areas of normal growth, some brown, mostly brown and all brown and identified any species growing amid the brown."

Pat Willis adds:

"I can tell you for sure that the die off is from last year's growth. Since I have been taking readings monthly since last June, I was waiting for the alterniflora to "green-up" or grow since last year and that hasn't happened. There was no period of growth at all in the dead area since last year. Also, at site 4, some of the short form alterniflora has not grown up, but in a few places it has."

 

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