Influence of dust deposition and climate on the radial growth of Tsuga canadensis near its northern range limit

We investigated the effects of dust deposition on the radial growth and sensitivity to climate of eastern hemlock [Tsuga canadensis (L.) Carriere] growing near its northern range limit in southern Quebec, Canada. We constructed a ring-width chronology from 1867 to 2007 for hemlock trees growing in an old-growth forest adjacent to a rock quarry. Significant decline in the radial growth of hemlock occurred after construction of the quarry in 1959, with a mean decrease of 42.7 % compared to previous growth rates and with major changes occurring 3-16 years after the quarry establishment. Moreover, the growth climate relationships changed from a predominant response to temperature and precipitation during the growing season before the quarry establishment, to weaker precipitation sensitivity and a stronger association with summer temperatures in year prior to growth. Our results indicate that the main response of the hemlock trees to dust deposition is reduced growth rates, but the change in growth climate relationships can also be related to this environmental stress.