Introduction

The natural forest, its tree-species composition and dynamics are functions primarily of climate and secondarily of soil parent materials. Soil, the living upper layer of soil, is created by climate, soil parent materials, flora and fauna. If a fire, storm or insect calamity destroys a tree stand at the climatic climax stage, pioneer plants occupy the site and start a serial succession towards the climatic climax plant community.

Natural forests proper are very rare in present day Europe. The majority of them are in the boreal coniferous zone of European Russia and in small areas of Finland, Sweden and Norway. Only isolated remnants can be found in remote and mostly inaccessible mountain areas in Europe. All other European forests are man-made tree communities maintained by silvicultural and logging measures. Some of them have been degraded by poor logging practices, pasturing and wild fires, often on lands degraded by erosion.

Whatever the current tree-species composition, age and density structure or management regime, there are natural forces inside a forest ecosystem affecting stand dynamics and awaiting the chance to commence succession towards a true climax. Knowledge of the natural forest ecosystems is therefore the basis for analysing the current and future condition of forests and formulating policies and management regimes for developing multi-functional forests which satisfy the needs of man and society (Fig. 4.1, part 1).

The effects of man's activities on forests are dependent on the nature of economy for which the forests have been used. The principal types of economies are presented in Fig. 4.1, part 2. They form the basis for studying and understanding the history of forests and the changing values which forests represent.