Document: SHE-3-59-42

SOM dynamics and afforestation: Species affects and implications for global change.

MORRIS, S.J.* ¹, S.HAILE-MARIAM ¹, S.BOHM ¹, J.SIX ², K.PAUSTIAN ², E.T.ELLIOTT ², E.GREGORICH ³ and E.A.PAUL ¹

Michigan State Unviersity, East Lansing, MI 48824 ¹
Colorado State University, Fort Collins, CO ²
Agriculture Canada, Ottawa, Ontario, Canada ³

Abstract:
Afforestation of agricultural lands is important for sequestration of C in mitigating the effects of elevated CO₂ on global change. Tree biomass is the predominant sink for C, but 30% of the sequestered C may be in the slow and resistant soil C pools. Afforestation increases soil and plant N at rates that exceed deposition inputs. We measured soil C and N sinks and evaluated the role of specific tree species in controlling C and N sequestration in soils and above and belowground forest biomass. Sites with native forests, agriculture, afforested deciduous and afforested coniferous on the same soil type were sampled for profile C and N to a depth of 1m. An acidic loam deciduous soil in Michigan, sequestered 0.35 Mg C ha^-1yr^-1 and 0.03 Mg N ha^-1yr^-1. The N inputs were much higher than could be accounted for in precipitation. A sandy, deciduous Ohio site sequestered 0.50 Mg C ha^-1yr^-1 and 0.02 Mg N ha^-1yr^-1. Afforested, coniferous MI and OH stands did not show increases in C and N over the agricultural comparison. In contrast, afforested coniferous sites on calcareous till in Canada showed storage of C and N. Understanding the effect of this species-texture interaction on C and N sequestration is essential for evaluating the global C budget and the effects of N deposition on afforested soils.

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This abstract is being presented at: 3:30 PM in session:
Oral Session #52: Carbon Storage in Ecosystems.