Seed-bed substrates and revegetation of Calluna heathlands following burning

The role of partially decomposed organic matter, coarse and fine roots, leaves and twigs of ericaceous plants, mat mosses, such as Hypnum jutlandicum, Hylocomium splendens, Pleurozium schreberi, and lichens, such as Cladonia impexa and C. arbuscula, in retaining water was studied by thermal analysis. Presence of organic matter increases the water retention property of the soil which helps seedling regeneration. More seedlings survived in sites containing thicker organic matter on the surface. Charred organic matter, mat moss and lichen patches, however, inhibit seedling establishment. When relative energy required to remove unit mass of water from the seed-bed component was compared, lichen showed the maximum value (1.76), closely followed by mat moss, fine roots, leaves, stems, and large roots of ericaceous plants. Seedlings on the exposed sites with thin organic matter on top are liable to periodic desiccation in summer, causing seedling mortality. Vegetative regeneration, however, is not affected by summer drought provided the heather is burned in "building' or early "mature' phase. -from Authors