THE SOIL FUNGI OF THE DOVEY SALT MARSHES

S ummary . In this investigation of the fungi of the soil of the Dovey Salt Marshes (Ynyslas) 48 fungi were isolated. Twelve of the species found do not appear to have been recorded before for the British Isles. The area investigated is a badly aerated, stiff, tenacious clay, alkaline in reaction ( p H 8), with a high water content, due mainly to periodical inundations by tidal salt water. Method of investigation consisted in taking samples of soil from a depth of 11/2 and 31/2 inches and either planting portions of this directly on to specially prepared media, or first shaking up a portion in water and then inoculating the prepared media with some of the suspension. Three fungi– Torula allii, Penicillium hyphomycetis and Fusarium oxysporium var. resupinatum —were almost invariably present in every sample of soil: almost equally common were Trichoderma lignorum, T. Köningi, Hormodendron cladosporoides, Mucor circinelloides and Periconia felina . Most of the fungi found are species found above ground as saprophytes, and may have been introduced into the soil by drainage, etc. The writer considers fungi are active only in association with organic material. The vegetation covering this marsh shows marked zonation: soil samples were chiefly taken from the Glycerietum and Aimerietum. The same species of fungi were common to the two associations. Glyceria maritima is a most effective silt binder, because the stele of its rhizomes and roots consists almost entirely of lignified tissue which does not yield to the activities of the soil fungi; Armeria maritima is not so effective a silt binder because the stele of its rhizomes and roots contains very little lignified tissue—at a depth of a foot, the tap roots of Armeria are little more than hollow tubes, the interiors having been removed by fungi and bacteria.