NATURAL REGENERATION OF PINE AND BIRCH ON THE HEATHER MOORS OF NORTH-EAST YORKSHIRE

Abstract

Both pine ( Pinus sylvestris L.).and birch ( Betula pubescens Ehrh.) usually invade after a fire, the invasion reaching greatest force after 3 to 5 years, then falling off rapidly probably with the return of the heather ( Calluna ). Pine seedlings only grow vigorously if their tap-roots reach the pan, when secondary roots are developed extensively. In birch the tap-root is not well developed, but secondary roots spread vigorously sending down sinkers to penetrate the pan. Regeneration of birch is helped by rotten stumps and roots which its mycorrhizal roots explore. The root forms are compared and contrasted and the findings compared with the work of Laitakari and Erteld.