Forests of the temperate region: gaps in knowledge and research needs

Abstract

Gaps in knowledge of current and past forest ecosystem research in the temperate zone of Europe are discussed and research priorities are defined. Since the last Ice Age the forest ecosystems of this region have undergone fundamental changes mainly caused by climatic and anthropogenic influences. Hence, today’s temperate forests hardly represent the natural ecosystem development state. However, the implementation of the sustainability concept as the dominant principle of modern forestry in the early 19th century allowed to predict and maintain forest productivity in the longer run. Despite timber production forest management has to cover public demands such as recreation, groundwater protection, and biodiversity. But it is still unclear whether all these requirements can be fulfilled economically and in agreement with the concept of ecological sustainability. Even though the understanding of forest ecosystems has increased enormously in recent decades, this improved understanding has resulted, somewhat paradoxically, in a demand for further knowledge, both more precise in nature and broader in scope. The ongoing discussion on forest stability is based on the experience that predictions of an enhanced dieback of forests did not come true. On the contrary, the growth of many European forests has been accelerated since several decades, illustrating a fundamental lack in the understanding of the productivity of forest ecosystems. In conclusion, specific gaps of knowledge are identified with regard to (i) the impacts of elevated CO 2 and nitrogen on the stability and resilience of forest ecosystems, (ii) the functioning of old-growth (semi-)natural forests and the development of scientifically based concepts for forest transformation, (iii) the multiple interactions between forest and adjacent management systems, (iv) the afforestation of set-aside and abandoned areas, and (v) the intensification, methodological complementation and diversification of the monitoring of forest sites belonging to the EU ‘level-two-programme’.