MIDDLE-HOLOCENE TIMBERLINE FLUCTUATION - INFLUENCE ON THE GENESIS OF PODZOLS (SPODOSOLS), NORRA-STORFJALLET MASSIF, NORTHERN SWEDEN

Fluctuations of the altitudinal position and composition of the timber line in northern Sweden have occurred in response to climatic changes following deglaciation (c. 8800 yrs BP). In this study a soil sequence of predominantly Podzols (Spodosols) was analysed to determine if the soil profiles located above the present timberline were actively form ing in the low-alpine environment, or whether they represent relict fe atures of a once stronger pedogenic regime. The results of the soil an alysis indicate a relatively uniform parent material with increasing f ines near the surface reflecting aeolian influxed sediment. The soil p rofiles located above the timberline are generally characterized by da rker colours, although with a lower accumulation of organic carbon and either similar or higher iron and aluminium in the spodic horizon tha n are found in the profiles located below the timberline. The alpine P odzols, generally located in protected swales, are quite distinct from Brunisols (Inceptisols) and Regosols (Entisols) found in slopes and s wells on the predominantly undulating morainic and glaciofluvial lands cape. This appears to indicate that Spodosols located above the presen t timberline are not actively being modified under the present low-alp ine environmental conditions, but rather were initiated during the Atl antic Chronozone when a dwarf or stunted forest extended to approximat ely 900 m above sea level.