Tree carbon allocation dynamics determined using a carbon mass balance approach

New Phytol. 2015 Jan;205(1):147-59. doi: 10.1111/nph.12993. Epub 2014 Aug 26.

Abstract

Tree internal carbon (C) fluxes between compound and compartment pools are difficult to measure directly. Here we used a C mass balance approach to decipher these fluxes and provide a full description of tree C allocation dynamics. We collected independent measurements of tree C sinks, source and pools in Pinus halepensis in a semi-arid forest, and converted all fluxes to g C per tree d(-1) . Using this data set, a process flowchart was created to describe and quantify the tree C allocation on diurnal to annual time-scales. The annual C source of 24.5 kg C per tree yr(-1) was balanced by C sinks of 23.5 kg C per tree yr(-1) , which partitioned into 70%, 17% and 13% between respiration, growth, and litter (plus export to soil), respectively. Large imbalances (up to 57 g C per tree d(-1) ) were observed as C excess during the wet season, and as C deficit during the dry season. Concurrent changes in C reserves (starch) were sufficient to buffer these transient C imbalances. The C pool dynamics calculated using the flowchart were in general agreement with the observed pool sizes, providing confidence regarding our estimations of the timing, magnitude, and direction of the internal C fluxes.

Keywords: carbon allocation; carbon balance; flux partitioning; phloem transport; soluble sugars; starch; tree compartment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbohydrates / analysis
  • Carbon / metabolism*
  • Carbon Cycle*
  • Forests
  • Israel
  • Pinus / anatomy & histology
  • Pinus / metabolism*
  • Plant Roots / metabolism
  • Solubility
  • Trees / anatomy & histology
  • Trees / metabolism*

Substances

  • Carbohydrates
  • Carbon