DOES SOIL CHANGE CAUSE VEGETATION CHANGE OR VICE-VERSA - A TEMPORAL PERSPECTIVE FROM HUNGARY

The long-term relationship between major climatic change, vegetation c hange, and soil development is complex and poorly understood. In north eastern Hungary, for example, geochemical and pollen studies from a la ke sedimentary sequence indicate that in the early postglacial, vegeta tion changed from a coniferous to deciduous forest, and soils from a p odzol to brown earth. But which changed first? Did climatic warming re sult in a transformation from one soil type to another, which in turn resulted in a change in forest composition, or did the vegetation chan ge first and subsequently alter the soil? How long did these soil tran sformation processes take? And what mechanisms were involved in the de velopment of a brown-earth soil from a podzol? This paper presents the results of a study addressing some of these questions using palaeoeco logical analyses of a sedimentary sequence from lake Kis-Mohos To in n ortheastern Hungary. A proposed model for the process by which a podzo l becomes transformed into a brown earth is presented, and possible tr iggering mechanisms are discussed. Results suggest that in northeaster n Hungary the postglacial increase in deciduous populations was not co nsequent on soil type; rather, deciduous trees increased on podzolic s oils, and this increase was one of the triggering mechanisms responsib le for the development of brown-earth soils.