1300-year tree-ring width and density series based on living, dead and subfossil black spruce at tree-line in Subarctic Quebéc, Canada.

Living, dead and subfossil trees of black spruce (Picea mariana [Mill.] BSP.) were used to build a 1300-year chronology based on ring width and wood density. All density variables (maximum, minimum, earlywood and latewood densities) among the three types of trees were similar, whereas ring width was significantly higher in living trees than in dead and subfossil trees. Correlation of the indexed series from living and dead trees and from dead and subfossil trees that grew during the same periods were higher for maximum density (r = 0.70, 0.63) and mean latewood density (r = 0.65, 0.66) than for minimum density (r = 0.16, 0.35) and ring width (r = 0.15, 0.49), respectively. Maximum density and mean latewood density were significantly correlated with all temperature variables: mean annual (January–December) and growing season (May– September) temperatures, sum of degree days and frost-free days. Accordingly, maximum and latewood density in tree-rings of spruce stems at tree-line can be considered as a function of summer-temperature distributions and different types of trees can be combined for the reconstruction of long-term climatic trends due to their synchronous variations. [ABSTRACT FROM AUTHOR]