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SANDPIT COVERT MARSHES, BLYTHBURGH, III By P . J . O . TRIST

IN 1953, these marshes were re-enclosed after having lain lost to the tidal waters of the River Blyth for thirty years. Previous accounts of the re-appearance of natural flora are recorded in Vol. IX, Pts. I and III. With the exception of 1957, annual observations have been made and the accompanying list shows the gradual reappearance of the various species. In the first two years after re-enclosure, the only plants recorded were a few halophytes which are very tolerant to high saline conditions. At the same time, the sah (NaCl) in the soil has over the past five years fallen considerably and it will be seen that all of the original immigrants continue to persist, with the exception of the Cord Grass (Spartina tozvnsendii) and two species of Salicornia*, of which a few plants were found in 1954 and 1955. The more common species, S. stricta, has continued to persist in isolated depressions. Date of Sampling. NaCl % in 6" soil Sept. 1953 1.57 „ 1954 1.29 „ 1955 1.80f „ 1956 0.57 Apr. 1957 0.40 „ 1958 0.12 In 1954 Spartina established itself in several small colonies, but by September, 1956, the normal conditions for its growth had been considerably altered and the plant disappeared. Both the Carex otrubae and Ranunculus sceleratus were isolated colonies, introductions on or near ditch banks. By 1955, in spite of a rise in the salt percentage in the soil, due to a breach in the wall causing new flooding in December, 1954, the salt marsh ränge of flora common to this area started to establish itself, but over large areas Salicornia stricta and Suaeda maritima remained the dominant flora. Juncus, Scirpus, Eleocharis and Typha were all confined to low places, old tide Channels or near the sides of ditches : in fact, in close proximity to places where fresh water stood or moved. The Atriplex spp. neither formed a dominant ground cover nor grew into such large plants as were seen on other marshes after the 1953 floods. This can be explained : first, the number of plants on the old river walls was not great and the possible release of viable seeds would be limited. Secondly, by comparison with conditions elsewhere after the 1953 flood, the Sandpit Covert *Sclicornia prostrata and ramosissima (identified by Kew). t F u r t h e r salt water flooding in December, 1954.


SANDPIT COVERT MARSHES

69

marsh had been tidal-washed daily for thirty years and the surface soil structure and the general Standard of soil fertility were of a very different order. From 1955 to 1956 the average sah content of the top 6" of soil feil from 1.80% to 0.57%. A considerable reduction, but still too high to allow the re-appearance of any new flora with the exception of a few isolated plants of CEnanthe lachenalii near fresh water, Juncus maritimus which will tolerate high salinity, and Agrostis gigantea growing on the ditch sides with root access to fresh water. No records were taken in 1957, as on casual Observation there appeared to be little change in the ground cover in mid-summer. In the spring of 1958, the average salt content was reduced to 0 . 1 2 = after attention had been given to surface drainage. From 1953 with salt at 1.57% to 0.12% in 1958 represents a reduction of 1 4 | tons of salt per acre. A soil still very high in potassium though extremely low in phosphate and nitrogen nevertheless allowed the establishment of twenty-six new species recorded in 1958 (some of which may have entered in 1957). Of the new flora, eleven are Gramineae : Medicago hispida (Hairy Medick) is a new immigrant and the only representative of the Papilionaceae. From the 1953 /54 lists, it will be seen that the most salt tolerant flora still persist in spite of a considerable change in conditions, but as soon as cultivations proceed, few of these plants will survive under a new sward and grazing conditions. T w o of the marshes at the Bulcamp end were reseeded in August, 1958, and the intention is to reseed the remainder in 1959. In conclusion, I would wish to acknowledge the ready cocoperation of the owners and occupiers concerned.

Aster tripolium Spergularia salina S. marginata Suaeda maritima Halimione portulacoides Glaux maritima Salicornia stricta S. ramosissima S. prostrata Spartina toivnsendii Puccinellia maritima Atriplex patula Phragmites communis Juncus gerardi

1953

1954

1955

1956

1958

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SANDPIT COVERT MARSHES

1953 1954 1955 1956 1958 Polygonum aviculare V Ranunculus sceleratus V Atriplex hastata A. littoralis Carex otrubae Triglochin palustris Agropyron pungens Sonchus arvensis Juncus acutiflorus * Schoenoplectus tabernaemontani Scirpus maritimus Eleocliaris palustris Typha latifolia Epilobium hirsutum Rumex crispus Plantago major P. maritima Agrostis gigantea Juncus maritimus (Enanthe lachenalii Achillea miltefolium Picris echioides Senecio erucifolius S. vulgaris Matricaria maritima Cirsium arvense C. repens Sonchus asper S. oleraceus Epilobium parviflorum Mentha aquatica Plantago coronopus Sisymbrium officinale Medicago hispida Heracleum sphondylium Chenopodium rubrum Glyceria fluitans G. maxima Poa annua P. trivialis Holcus lanatus Festuca rubra Lolium perenne Bromus mollis Dactylis glomerata Alopecurus geniculatus Hordeum marinum

V V V V V V V V V

V V V V V V V V V

V V

V V V V V V V V

V V V V V V V V V V V

V V V V V V V

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V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V

* Schoenoplectus tabernaemontani : previously recorded in error f

Sandpit Covert Marshes, Blythburgh, iii  
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