Estimates and relationships between aboveground and belowground resource exchange surface areas in a Sitka spruce managed forest

A. J. Butler, N. Barbier, J. Cermak, J. Koller, C. Thornily, C. McEvoy, B. Nicoll, M. P. Perks, J. Grace, P. Meir

Research output: Contribution to journalArticlepeer-review

Abstract

Our knowledge of the nature of belowground competition for moisture and nutrients is limited. In this study, we used an earth impedance method to determine the root absorbing area of Sitka spruce (Picea sitchensis (Bong.) Carr.) trees, making measurements in stands of differing density (2-, 4- and 6-m inter-tree spacing). We compared absorbing root area index (RAI(absorbing); based on the impedance measure) with fine root area index (RAI(fine); based on estimates of total surface area of fine roots) and related these results to investment in conductive roots. Root absorbing area was a near-linear function of tree stern diameter at 1.3 m height. At the stand level, RAI(absorbing); which is analogous to and scaled with transpiring leaf area index (maximum stomatal pore area per unit ground area; LAI(transpiring)), increased proportionally with basal area across the three stands. In contrast, RAI(fine), was inversely propotional to basal area. The ratio of RAI(absorbing) to LAI(transpiring) ranged from 7.7 to 17.1, giving an estimate of the relative aboveground versus belowground resource exchange areas. RAI(absorbing) provides a way of characterizing ecosystem functioning as a physiologically meaningful index of belowground absorbing area.

Original languageEnglish
Pages (from-to)705-714
Number of pages10
JournalTree physiology
Volume30
Issue number6
DOIs
Publication statusPublished - 1 Jun 2010

Keywords

  • absorbing root surfaces
  • earth impedance
  • fine roots
  • plant allometry/scaling
  • RAI:LAI ratio
  • root area index
  • EARTH IMPEDANCE METHOD
  • FINE-ROOT BIOMASS
  • TREE HEIGHT
  • ELECTRICAL MEASUREMENT
  • NORWAY SPRUCE
  • SOIL DEPTH
  • WATER-USE
  • PLANT
  • GROWTH
  • FLOW

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