title: Tree carbon allocation dynamics determined using a carbon mass balance approach.
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.
authors.affiliation: Institute of Botany, University of Basel, Basel, Switzerland.
authors.forename: Tamir
authors.initials: T
authors.lastname: Klein
authors.forename: Günter
authors.initials: G
authors.lastname: Hoch
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D065928:Forests; D007557:Israel; D028223:Pinus / Q000033:anatomy & histology / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D012995:Solubility; D014197:Trees / Q000033:anatomy & histology / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D002244:Carbon
keywords: carbon allocation; carbon balance; flux partitioning; phloem transport; soluble sugars; starch; tree compartment