Soil Algae and Symbiosis

Abstract

The study of soil algae, as such, began seriously at the commencement of the nineteenth century with the works of Vaucher, Diliwyn, Agardh and Lyngbye. In 1895 Graebner, in a study of the heaths of Northern Germany, gave the first account of soil algae as ecological constituents, and subsequently many ecologists have shown that soil algae are pioneers on bare primary or secondary soil where they prepare the ground for the higher plants that follow. An agricultural, manured soil also has a rich flora, while the same species are to be found in unmanured soils, though not in such numbers. This flora consists of about 20 species of diatoms, 24 of Cyanophyceae and about 20 species of Chlorophyceae. As might be expected, persistently damp soils have a more varied and extensive collection of algae than have generally dry soils. In the case of the diatom component of the soil flora it has been found that it is more abundant when the soil is rich in phosphates and nitrates, so that the soil salts may also be of importance.