Blythburgh Marshes

BLYTHBURGH

MARSHES

FOR the past 30 years the river scene at Blythburgh has been a familiar sight: now a change has taken place. The great expanse of water which has been seen at high tide has not been confined to the course of the banks. Thirty years ago, breaks occurred in the river walls, atfirstfloodingone area of marshes, then another until 486 acres of the Blythburgh, the Angel and the Bulcamp marshes were lost to farming.

In May, 1953, a Start was made on the rebuilding of the wall which protects the 80 acres of the Blythburgh marshes which are adjacent to the main road on the north side of the bridge over the river Blyth. The work continued slowly and whilst the tide had been shut out by the end of the year, the work was by no means completed. In the high spring tides of January 3rd, 1954, the sea found weak places in the wall and damage occurred. The tide came in and again the engineers followed up with new work.

This land is to be reclaimed for farming and during the next five or six years whilst the salt content of the soil is reducing and various works are carried out to assist soil conditions, it will provide an extremely interesting ecological study of salt tolerant flora.

In late August, 1953, parts of the area were dry enough to walk over and soil samples were taken. These showed that after 30 years offlooding,the soil, an organic silty clay loam, contained just under 15 tons of salt per acre. If one considers that a soil dressing of 5 cwts. per acre of agricultural salt is the maximum which is applied to sugar beet, a crop which is able to utilize salt as a plant food, it will be realised that very considerable leaching of salt has to take place before the land is capable of again growing grass or other crops.

In the meantime, whilst the various processes of reclamation continue, the plant life is to be recorded. Prior to the new enclosure, Spartina townsendii and Halimione portulacoide established at the foot of the wall adjacent to the road : as the land dried, Spergularia salina and marginata became establish with these plants. In June, 1954, two or three small colonies of Spartina had established themselves out in the centre of the marsh and noticeably in areas which lay constantly wet or alongside small Channels where water had found a level to run off. This water comes from a fresh source from springs in the higher sandy hill to the north. Atriplex hastata and patula were in small quantity with plants of Aster tripolium, Suaeda maritima and little of the grass Puccinellia maritima.

At the end of August, 1954, Spergularia marginata was found in a wide area over the marsh. Aster tripolium was more evident

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BLYTHBURGH MARSHES

and making better growth alongside water Channels. T h e dominant plant of the whole area was Suaeda maritima.

Atriplex hastata has established itself in the dry areas but the plants were not the normal size and it will be seen that as the salt decreases, both the size of the plants and their numbers relative to other salt tolerant flora will increase. There is no Atriplex littoralis established on the marsh, but it can be found on the wall.

Salicornia stricta is not yet abundant: most is found in damp low places with a few plants of S. ramosissima.

Halimione portulacoides is found, but so far it is a rare find. Equally there are only isolated plants of Glaux maritima.

In wet areas and alongside running water, there is a small colonization of Phragmites communis and Juncus gerardi, which will no doubt spread considerably next year. In similar conditions are two interesting finds. A single plant of Polygonum aviculare which I have previously noted has a salt tolerance up to 0.3% NaCl, appears to have relations with hardier constitutions.

T w o strong plants of Ranunculus sceleratus Standing erect 2\ ft. high were flourishing in the high salt content.

P. J.

O.

TRIST.

SEA CLUB RUSH. Scirpus maritimus L. : F O U N D by Mr. T . B . Ward of the Essex Field Club on the joint excursion to the Stour Valley, by a pond in the Gravel Pit at Thorrington Street. " This is," he said, " the furthest inland that I have observed it." He had previously found this plant near a pond at the highest point in Essex at Danbury 350 ft. above sea level.

T h e normal habitat of Scirpus maritimus is near the coastline in wet conditions, either fresh or salt, but it more freely colonizes in salt conditions. Of the salt tolerant flora, the majority have a ränge of salinity which is tolerated. This rush is an exception.

At Minsmere, in 1949, it was growing in salt conditions which ranged from 0.05% to 0.9%* : but it had colonized the bare mud of the marsh (where wartime seawater flooding had killed the sward) more freely where the salt exceeded 0.4%. On the other hand, it finds a safer habitat when establishing itself outside the defences of a tidal river and is generally found behind the mark of high spring tides, on a line with Juncus gerardi.

When found in marsh ditches near a river wall, it is frequently an indication of a seepage of sea water through the base of the wall into the ditch : and if in Company with Spergularia salina and Salicornia spp. there is no further doubt of the presence of salt.

P . J. O .

* g salt (NaCl) per 100 g dry matter.

TRIST.