Historical declines and diebacks of central European forests and present conditions

Abstract

Human activities had reduced the central European forested area to less than 20% by the end of the Middle Ages but increased it again to 30% of the original area during the industrial period. Detailed reports on declines and diebacks have been available since the 18th century. Beginning in the second half of the 19th century, in highly industrialized areas, smoke damage occurred until effective measures were taken to lower SO2 concentrations. Almost complete recolonization of devastated areas by conifers has been observed since the 1960s, with few exceptions, for example, the Ore Mountains in Czechoslovakia. The suggestion that a large‐scale decline of European forests (Waldsterben) has taken place since 1979/1980 is not corroborated by 10 years of intensive research. Annual surveys fail to show the expected increase in foliage deficit, a shift from lower to higher damage classes, an increase in mortality, or increasing growth depression in recent decades. No correlation between the spatial and temporal distribution of air pollutants and damage classes has been found. Comparison of old and new photographs and evaluation of old studies on leaf indexes show that similar patterns of crown conditions caused by fluctuating site conditions and diseases have always occurred to a similar extent. Thus, Waldsterben may be understood as a problem of new awareness of old and only partly explained phenomena.

Returning forests analyzed with the forest identity

“…Germany illustrates a transition in density or growing stock sharper than in area. Although the German forest area nearly doubled after the Middle Ages (7), it scarcely increased between 1988 and 2002. On the other hand, German growing stock increased rapidly to an average of 320 m 3 ͞hectare (ha) (4).…”

Carbon gains and recovery from degradation of forest biomass in European Union during 1990–2005

“…It is unclear, however, whether an improvement of the data quality may have affected the latest estimates for 1990-2005. The drivers of change act at a time-scale of decades or even centuries, and the change in forests occurs only gradually in the long term (Kandler, 1992;Mather, 1992;Houghton, 1994;Grainger, 1995;Kauppi et al, 2009, this volume).…”

“…Therefore, gains in forest area must be perceived as a recovery from deforestation, while an expansion of biomass per hectare can be interpreted as a recovery from forest degradation. Historically, the forests of present-day EU27 ceased to shrink and started to expand in the 19th or early 20th century depending on the region (Kandler, 1992;Mather, 1992, see also Kauppi et al, 2009, this volume). After deforestation was brought to a halt, rising average density, as a result of a recovery from long-endured forest degradation, has become the defining feature of forest change in the region.…”

Changing stock of biomass carbon in a boreal forest over 93 years

“…Old-growth forests have been rare in Europe for a long time. Rather a recovery has been under way in Europe from past deforestation and forest degradation (Kandler, 1992). Forests gain biomass in many areas of temperate and boreal zones (Myneni et al, 2001), but lose area and biomass in other parts of the world (DeFries et al, 2002).…”