Monday, 17 March 2014

The remarkable plant communities of a Florida saltmarsh

Our journey through the saltmarsh channels around Dutton Island was full of interest, but perhaps the most fascinating aspect was the remarkable plants which inhabit this ecosystem.

Seb resting with the stern of his kayak in the Spartina grass (Spartina alterniflora).  The dense stands of this grass appear, at first glance, unremarkable......

 Our guide Matt is highly knowledgeable and has a real passion for this environment.  He explained that the Spartina Grass is a "keystone" species, one which actively alters its environment.  The development of a saltmarsh is dependent upon seeds of the grass floating to a place where it can take root.  It spreads asexually by rhizome systems and, over thousands of years, builds up a dense matrix of vegetable matter which in turn allows sediments and mud to build up, eventually forming areas of drying ground.

Any species in a coastal marsh has to be incredibly tough, tolerant to salt, wind and extremes of both moisture and temperature.  This colonising species allows the growth of other less tolerant plants and, eventually, dry land which can support stands of trees.  The trees provide nesting sites for many of the birds in the marsh as well as opportunities for land animals.

Below the water, the shelter and diminished flow allows the deposition of mud, perfect for the rich invertebrate life of the marsh and for Oysters.  The oyster beds filter the rich water and also provide a barrier to damaging storm surges.

All this from an unremarkable looking grass!

Along the edges of one of the man-made channels adjacent to the marsh the raising of the spoil banks has provided a leg-up for a surprising variety of trees, including Junipers adjacent to small Palms.

The trunk of a long-dead pine made a striking shape, and was drilled with holes drilled by a woodpecker, the standing dead wood still a valuable part of the whole ecosystem

Back out along the Intracoastal Waterway, we stopped on a tiny beach for a short break.  A fallen tree here gave us a close-up view of another remarkable plant which festoons trees, particularly Live Oaks all across north Florida - Spanish Moss (Tillandsia usneoides).

It isn't Spanish in origin, nor is it a moss.  Resembling "old man's beard" lichen found in norther boreal forests, it isn't a lichen either.  This fascinating flowering plant is an epiphytic species - it takes all its nutrients and moisture from the air and from rainfall. Related to Bromeliads, the plant forms hanging pendants up to 6 metres long and does particularly well in the high humidity of Florida.  It doesn't harm the host tree, merely using it as a frame on which to grow, though sometimes the weight of Spanish Moss pendants can break off branches from trees.

The saltmarsh of Florida is a superb environment, and home to some truly remarkable plant species.  I'm very grateful to Matt for sharing his deep passion for and knowledge of this special place.


  1. Ian, that's a fascinating area and one I've visited many times as two good friends both teach at a nearby university. Had to laugh because I visit your site for the wonderful pictures of Scotland - and now I get an area I know well. Hope your visit was great.

  2. Hi Ian, when we lived in Ontario (many years ago), a winter break in Florida was an annual treat. I often thought about paddling there but couldn't help but wonder if there might be alligators in those grasses. Maybe that's more the Everglades...and my imagination? :) A very interesting read. Warm wishes, Duncan.

  3. Hi Ian love the sunshine, please bring some back with you!


  4. Hi Dan, normal Scottish service will be resumed quite soon :o) It was a super place to paddle, quite unlike anything in Scotland

    Kind regards

  5. Hi D & J, I

    I certainly don't think you fit the stereotypical "snowbird" profile! We were assured that there aren't gators in the St John's River area....lthough I checked all the boats for teeth marks :o)

    Kind Regards to you both

  6. Hi Douglas - I really will try - it seems to have been a commodity in short supply while I've been away! :o)

  7. Looks like a great trip and a great informative guide.

  8. Hi Lee, it was a really pleasant day, and for me was really enhand=ced by Matt's enthusiasm and knowledge

    Kind regards