What was done
The authors used tree-ring data from the Catalan Ecological and Forest Inventory "to study the temporal variability of Scots pine stem radial growth (period 1901-1997) across a relatively large region (Catalonia, NE Spain) situated close to the southern limit of the distribution of the species." This inventory "included a total of 10,664 plots randomly distributed throughout the forested area of Catalonia." Scots pine was present in 30.2% of the plots, and it was the dominant tree species in 18.4% of them.

What was learned
Martinez-Vilalta et al. say their results "showed an overall increase of 84% in Scots pine BAI [basal area increment] during the 20th century, consistent with most previous studies for temperate forests" and in harmony with the greening of the earth phenomenon that has accompanied the historical increase in the air's CO2 content, on which we regularly report (see Greening of the Earth in our Subject Index). And in this regard, they make a point of stating that "this trend was associated with increased atmospheric CO2 concentration," which they interpreted to be "a fertilization effect."

Over the same time period, the five researchers additionally note that "there was also a marked increase in temperature across the study region (0.19°C per decade on average)," and they report that "this warming had a negative [our italics] impact on radial growth, particularly at the drier sites." However, they found that "its magnitude was not enough to counteract the fertilization effect."

What it means
As the title of one of the DVDs we offer for sale on our website declares: The Greening of Planet Earth Continues.