Title Carbon fluxes to the soil in a mature temperate forest assessed by ¹³C isotope tracing
Author/s Steinmann K, Siegwolf R, Saurer M, Korner C
Year 2004
Journal Oecologia 141:489-501
Abstract Photosynthetic carbon uptake and respiratory C release from soil are major components of the global carbon balance. The use of ¹³C depleted CO₂ (δ¹³C = -30‰) in a free air CO₂ enrichment experiment in a mature deciduous forest permitted us to trace the carbon transfer from tree crowns to the rhizosphere of 100-120 years old trees. During the first season of CO₂ enrichment the CO₂ released from soil originated substantially from concurrent assimilation. The small contribution of recent carbon in fine roots suggests a much slower fine root turnover than is often assumed. ¹³C abundance in soil air correlated best with temperature data taken from 4 to 10 days before air sampling time and is thus rapidly available for root and rhizosphere respiration. The spatial variability of δ¹³C in soil air showed relationships to above ground tree types such as conifers versus broad-leaved trees. Considering the complexity and strong overlap of roots from different individuals in a forest, this finding opens an exciting new possibility of associating respiration with different species. What might be seen as signal noise does in fact contain valuable information on the spatial heterogeneity of tree-soil interaction.
Keywords Soil respiration · carbon turnover · functional groups · stable isotopes
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Research project The Swiss Canopy Crane Project (SCC)