The Dendroclimatic Signal in White Spruce (Picea Glauca) Ring-Widths, Central Northwest Territories

White spruce samples were collected at 10 sites along a latitudinal gradient in the central Northwest Territories near treeline. Extending to 1643, the chronologies represent the oldest tree ring-width records in the region. Composite chronologies were developed: COMP1 is composed of five sites situated in the northern part of the sampling area; COMP2 is composed of the three southernmost sites. Growth patterns of COMP1 and COMP2 are highly synchronous until the 1930s. After the 1930s, COMP1 exhibits increasing growth, while COMP2 exhibits decreasing growth. COMP1 is positively correlated with summer temperatures and precipitation. COMP2 is inversely correlated with summer temperatures and May precipitation. Rising temperatures may have caused landscape scale patterns of moisture stress at COMP2 sites and improved growing conditions at COMP1 sites. The earlier onset of the growing season is hypothesized to have shifted the limiting factor for growth of COMP1 from July to June precipitation at ~1977.