SUMMARYThe response of chlorophyll and carotenoid concentration, specific leaf area and dry weight fraction in shoots of Sitka spruce (Picea sitchensis (Bong.) Carr.) to season and photon flux density has been measured. Shoots were sampled from different heights in the canopy at two forest sites, one thinned, the other unthinned. An increase in specific leaf area and a decrease in dry weight fraction was found in shaded shoots. At both sites, there was a seasonal variation in pigment content, with a summer maximum for chlorophyll and a winter maximum for carotenoid. Pigment content was constant throughout the canopy on the thinned site, but was higher in shaded shoots from the unthinned site.