Increased tree growth in temperate and boreal forests has been proposed as a direct consequence of a warming climate. Acid deposition effects on nutrient availability may influence the climate dependency of tree growth, however. Collection of soil samples and tree cores in 2001-02, where soils were previously sampled and archived in 1926 and 1964, has now enabled soil chemistry to be tracked with growth of Norway spruce through the 20th century. The Norway spruce-Scots pine forest, 40 km southeast of St. Petersburg, Russia, has not been disturbed since 1900, other than by periodic removal of deadwood and saplings to prevent overcrowding, some selected harvesting (most prior to 1900 and none past 1940), and elevated levels of acid deposition. Differences in soil chemistry on the three dates reflected a two stage acidification process. From 1926 to 1964, inputs of acidity were neutralized by replacement of exchangeable Ca and Mg with exchangeable H. From 1964 to 2001, neutralization of acid inputs was largely accomplished by mobilization of Al, which indicated a shift from cation exchange to weathering of Al-bearing minerals as the primary source of acid neutralization. The decrease in the ratio of Ca to Al in the rooting zone between 1964 and 2001 corresponded with a decreasing trend in ring-width increment and a suppression of climate effects on tree growth. Measured ring-width increment was strongly correlated with selected climate variables for 1891-1960 (p < 0.01; R2 = 0.44) but unrelated (p > 0.1) to any combination of the climate variables over the last 40 years. These responses appear to be linked to degradation of rooting zone conditions caused by acid deposition.