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Scots Pine Stands of Estonia Are Growing Ever Better Nowadays
Parn, H. 2012. Changes in the radial growth of two consecutive generations of Scots pine (Pinys sylvestris L.) stands. Baltic Forestry 18: 12-24.

The author writes that "the potential productivity of a forest site has been regarded as natural and stable in a long-term perspective (Elfving et al., 1996)," but he notes that "environmental changes such as increase of CO2 in the atmosphere, deposition of pollutants and climate changes since the 1950s have had various effects on the forest ecosystems," and that "the increasing human impact on the environment makes the stability of the site conditions questionable."

What was done
Determined to learn if these environmental changes may have impacted the growth of Scots pine trees, Parn studied the growth history of trees of identical cambial age but two different calendar ages at two different sites: Koiguste on Saaremaa island, the largest of the Estonian islands in the Baltic Sea, and Pirita in North Estonia near the Estonian capital. The age of the old stand at the Koiguste site was 160 years and that of the young stand 55 years; while the ages of the old and young stands at the Pirita site were 155 and 55 years, respectively. At both of these locations, in the words of Parn, "the differences in the radial growth of successive stand generations were assessed using the average tree ring widths of the same cambial age of stands at age of 30, 40 and 50 years."

What was learned
The Estonian researcher reports that "the radial growth of young generations exceeded that of old stands at the same cambial age," and he states that "approximately similar results were obtained when latewood widths were used instead of the tree-ring widths in the analysis." In addition, he says that "a fairly strong positive effect of the mean temperatures of the spring months on the latewood width can be observed." And he notes that a similar "strong link between the latewood width and spring temperatures was described by Miina (2000) for Scots pines in eastern Finland, by Savva et al. (2003) for pines from different provenances in Russia, and by Drobyshev et al. (2004) for pines in the Komi Republic."

What it means
As for what was responsible for his findings, Parn suggests that "it may be assumed that long-term climate change may have caused, at least partly, the increasing growth of young generations of pine," and he also suggests that "the increased nitrogen deposition and elevated CO2 level during the second half of the 20th century may have had some positive influence." We further add, in this regard, that much the same thing has been found and suggested by Soule and Knapp (2006), with respect to the effect of the air's rising CO2 concentration on the growth of ponderosa pine trees in the United States, as well as by a host of other studies - see Forests (Modern Growth Trends) in our Subject Index. Thus, what climate alarmists claim to be bad for the biosphere - rising temperatures and atmospheric CO2 concentrations - appear to actually be having a positive effect on the planet's trees and, by inference, much of the rest of the biosphere as well.

Drobyshev, I., Niklasson, M. and Angelstam, P. 2004. Contrasting tree-ring data with fire record in a pine-dominated landscape in the Komi Republik (Eastern European Russia): recovering a common climate signal. Silva Fennica 38: 43-53.

Elfving, B., Tegnhammar, L. and Tveite, B. 1996. Studies on growth trends of forests in Sweden and Norway. In: Spiecker, H., Mielikainen, K., Kohl, M. and Skovsgaard, J.P. (Eds.) Growth Trends in European Forests. EFI Research Report No. 5. Springer-Verlag, Berlin, Germany, p. 61-70.

Miina, J. 2000. Dependence of tree-ring, earlywood and latewood indices of Scots pine and Norway spruce on climatic factors in eastern Finland. Ecological Modeling 132: 259-273.

Savva, Y.V., Schweingruber, F.H., Vaganov, E.A. and Milyutin, L.I. 2003. Influence of climate changes on tree-ring characteristics of Scots pine provenances in southern Siberia (forest-steppe). IAWA Journal 24: 371-383.

Soule, P.T. and Knapp, P.A. 2006. Radial growth rate increases in naturally occurring ponderosa pine trees: a late-20th century CO2 fertilization effect? New Phytologist doi: 10.1111/j.1469-8137.2006.01746.x.

Reviewed 1 May 2013