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Harvard Forest Symposium Abstract 2017

  • Title: Ontogenetic patterns in tree phenology and bud dormancy
  • Primary Author: David Basler ()
  • Additional Authors: Andrew Richardson (Harvard University)
  • Abstract:

    Tree phenology sets the limit of seasonal activity and thus, potential productivity in all seasonal forests, including temperate hardwood forests. Leaf-out in spring and leaf fall in autumn mark the start- and end-points of the growing season. Thus, phenology has been recognized to play an important role for many ecosystem processes and is a key determinant of species distribution (Chuine and Beaubien 2001; Vitasse et al. 2014b). The environmental controls of phenology may vary based on a species’ life-history strategy (Caffarra and Donnelly 2010; Körner and Basler 2010), but the timing of phenological events is generally well-adjusted to local climate- and site-conditions, in order to ensure long term survival (Larcher 2003). Different studies suggest that such adjustments are likely genetically fixed and may influence the response of phenology to a warming climate (Bennie et al. 2010; Alberto et al. 2013). Yet, it seems that the timing of these phenological events often shifts with plant age, with very young trees performing a ‘riskier’ strategy than older trees. While this pattern is to some extent influenced by the presence of canopy coverage (Augspurger and Bartlett 2003; Richardson and O' Keefe 2009), it is most likely ontogenetic and not only driven by different microclimatic conditions in the forest understory (Vitasse 2013; Vitasse and Basler 2014). . To date, however, few studies have addressed the changes in phenology during a tree’s ontogeny (development from seedling to a mature tree).

    Through assessment of spring phenology, the much less studied autumn phenology and, the development of bud dormancy during winter across multiple age-classes of trees at Harvard Forest, we aim to reveal when and how the timing of phenological events changes during the maturation of trees. Simultaneously, this we want to assess whether the variation of phenological spring and autumn events of different tree species in a forest stand decreases with increasing tree-age.

    Knowledge of age-related phenological shifts is helpful in understanding intraspecific variation of phenology within a population, which also allows for improved accuracy of predictions of phenology in a warmer climate. Quantitative data on age-related phenological shifts allows further estimating and possibly accounting for the inaccuracy when extrapolating findings from young to mature trees, as many climate change experiments are, due to obvious practical reasons, conducted with seedlings or young trees.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions