What was done
Relying heavily on the work of Spiecker et al. (1996), the authors review what is known about the increasing trends in the growth rates of Pinus sylvestris, Picea abies, Fagus sylvatica and a number of other trees over the preceding 50 years, focusing on the likely causes of what they call the "recent, unexpected changes in height, diameter and volume growth patterns of existing and long-standing trees in European forests."

What was learned
In the words of the authors, "most forest stands and individual trees studied, belonging to a wide range of species, showed an unexpected positive shift in the pattern of growth rates, predominantly in the last 50 years."  Specifically, they report that "average volume growth rate has increased by around +50% and height growth rate by around +10%," with stands showing this type of response "distributed widely across central Europe and the southern boreal zone."

With respect to the phenomena behind these observations, Hunter and Schuck say "the consensus of workers in the scientific field is that any recent acceleration in growth rates is likely to be the result of fertilization by CO2, fertilization by anthropogenic N, and changes in temperature and/or rainfall," since "all of these factors have been shown to increase growth rates of trees in controlled environments."

What it means
The growth rates of European forests have increased so dramatically over the last half-century that their harvest in Europe today is estimated to be "70% or less of what is really sustainable."  In other words, far more trees could be felled for commercial purposes than the number that is currently being cut.  Because of the incessant spreading of doom and gloom by climate alarmists, however, the authors report that "the European public have been negatively affected by the 'forest decline' debate and believes that their forests are generally in a poor state," when, in reality, nothing could be further from the truth.

Reference
Spiecker, H., Mieikainen, K., Kohl, M. and Skovsgaard, J.  1996.  Growth Trends in European Forests; Studies from 12 Countries.  European Forest Research Institute Report 5, Springer-Verlag, Berlin, Germany.