1300-year tree-ring width and density series based on living, dead and subfossil black spruce at tree-line in Subarctic Quebec, 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 d ensity. All density variables (maximum, minimum, earlywood and latewood den sities) among the three types of trees were similar, whereas ring width was significantly higher in living trees than in dead and subfossil trees. Cor relation 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 fo r minimum density (r = 0.16, 0.35) and ring width (r = 0.15, 0.49), respect ively. Maximum density and mean latewood density were significantly correla ted with all temperature variables: mean annual (January-December) and grow ing season (May-September) temperatures, sum of degree days and frost-free days. Accordingly, maximum and latewood density in tree-rings of spruce ste ms at tree-line can be considered as a function of summer-temperature distr ibutions and different types of trees can be combined for the reconstructio n of long-term climatic trends due to their synchronous variations.