Factors influencing size inequality in peatland black spruce and tamarack: Evidence from post-drainage release growth

• Author(s) / Creator(s)

  • Yin, F.
  • MacDonald, S. E.

• 1 We used tree ring analysis to determine stem radius and thus examine size variation over time in two even-aged (approximately 40-year-old) mixed populations of black spruce and tamarack established on peatlands in a boreal forest. We also followed the response of one of these populations to improved edaphic conditions over 8 years following drainage. 2 Populations of trees in undrained areas showed a decline in size variability over time until age 20–25 years, after which size heterogeneity was relatively stable. 3 For trees in undrained areas there was a relationship between age and size for the first 20–25 years, but this relationship then broke down due to a period where relative growth rate and size were inversely related. 4 For the population of trees in the drained area, smaller trees (i.e. those that had been growing more slowly prior to drainage) showed significantly greater drainage-induced release growth, while larger trees (those growing faster prior to drainage) showed an initial reduction in growth following drainage and, overall, less release growth. 5 The response of tamarack to drainage was more dramatic than for black spruce. 6 Despite extensive variation in tree size, drainage dramatically reduced variability in growth rate among trees of each species, such that size variability in the populations declined. 7 We postulate that the heterogeneity of microsites with respect to edaphic conditions, perhaps associated with the hummock to hollow microtopographic gradient, has a major influence on growth variation, and hence size inequality, in peatland populations of black spruce and tamarack.

• Date created

  1999

• Subjects / Keywords

  • Competition
  • Relative growth rate
  • Peatlands
  • Size variability
  • Microsite
  • Forest heterogeneity

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R3Q584

• License

  © 1999 Wiley. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.