TY - JOUR
T1 - Biogeochemical factors contributing to enhanced carbon storage following afforestation of a semi-arid shrubland
AU - Grünzweig, J. M.
AU - Gelfand, I.
AU - Fried, Y.
AU - Yakir, D.
PY - 2007
Y1 - 2007
N2 - Ecosystems in dry regions are generally low in productivity and carbon (C) storage. We report, however, large increases in C sequestration following afforestation of a semi-arid shrubland with Pinus halepensis trees. Using C and nitrogen (N) inventories, based in part on site-specific allometric equations, we measured an increase in the standing ecosystem C stock from 2380 g Cm -2 in the shrubland to 5840 g Cm-2 in the forest after 35 years, with no significant change in N stocks. Carbon sequestration following afforestation was associated with increased N use efficiency as reflected by an overall increase in C/N ratio from 7.6 in the shrubland to 16.6 in the forest. The C accumulation rate in the forest was particularly high for soil organic C (SOC; increase of 1760 g Cm-2 or 50 g Cm-2 yr -1), which was associated with the following factors: 1) Analysis of a small 13C signal within this pure C3 system combined with size fractionation of soil organic matter indicated a significant addition of new SOC derived from forest vegetation (68% of total forest SOC) and a considerable portion of the old original shrubland SOC (53%) still remaining in the forest. 2) A large part of both new and old SOC appeared to be protected from decomposition as about 60% of SOC under both land-use types were in mineral-associated fractions. 3) A short-term decomposition study indicated decreased decomposition of lower-quality litter and SOC in the forest, based on reduced decay rates of up to 90% for forest compared to shrubland litter. 4) Forest soil included a significant component of live and dead roots (12% of total SOC). Our results suggest a role for increased N use efficiency, enhanced SOC protection and reduced decomposition rates in the large C sequestration potential following afforestation in semi-arid regions. These results are particularly relevant in light of persistent predictions of drying trends in the Mediterranean and other regions.
AB - Ecosystems in dry regions are generally low in productivity and carbon (C) storage. We report, however, large increases in C sequestration following afforestation of a semi-arid shrubland with Pinus halepensis trees. Using C and nitrogen (N) inventories, based in part on site-specific allometric equations, we measured an increase in the standing ecosystem C stock from 2380 g Cm -2 in the shrubland to 5840 g Cm-2 in the forest after 35 years, with no significant change in N stocks. Carbon sequestration following afforestation was associated with increased N use efficiency as reflected by an overall increase in C/N ratio from 7.6 in the shrubland to 16.6 in the forest. The C accumulation rate in the forest was particularly high for soil organic C (SOC; increase of 1760 g Cm-2 or 50 g Cm-2 yr -1), which was associated with the following factors: 1) Analysis of a small 13C signal within this pure C3 system combined with size fractionation of soil organic matter indicated a significant addition of new SOC derived from forest vegetation (68% of total forest SOC) and a considerable portion of the old original shrubland SOC (53%) still remaining in the forest. 2) A large part of both new and old SOC appeared to be protected from decomposition as about 60% of SOC under both land-use types were in mineral-associated fractions. 3) A short-term decomposition study indicated decreased decomposition of lower-quality litter and SOC in the forest, based on reduced decay rates of up to 90% for forest compared to shrubland litter. 4) Forest soil included a significant component of live and dead roots (12% of total SOC). Our results suggest a role for increased N use efficiency, enhanced SOC protection and reduced decomposition rates in the large C sequestration potential following afforestation in semi-arid regions. These results are particularly relevant in light of persistent predictions of drying trends in the Mediterranean and other regions.
UR - http://www.scopus.com/inward/record.url?scp=35548929420&partnerID=8YFLogxK
U2 - 10.5194/bg-4-891-2007
DO - 10.5194/bg-4-891-2007
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AN - SCOPUS:35548929420
SN - 1726-4170
VL - 4
SP - 891
EP - 904
JO - Biogeosciences
JF - Biogeosciences
IS - 5
ER -
