Tree species’ influences on soil carbon dynamics revealed with natural abundance 13C techniques

• Published in: Plant and soil Vol. 400; no. 1-2; pp. 285 - 296
• Main Authors: Snell, Helen S. K, Robinson, David, Midwood, Andrew J
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-03-2016; Springer
• Subjects: Acer pseudoplatanus; Agricultural soils; biodegradation; biomass; Biomedical and Life Sciences; carbon; carbon dioxide; carbon sinks; Cell respiration; Clay soils; Ecology; Forest soils; fractionation; greenhouse gas emissions; hybrids; interspecific variation; land use; Larix; Life Sciences; Organic soils; Plant Physiology; Plant roots; Plant Sciences; Regular Article; roots; soil; Soil organic matter; Soil respiration; Soil science; Soil Science & Conservation; spectroscopy; stable isotopes; Trees; Soil carbon mean residence time; Stable isotope partitioning; Carbon dioxide emissions; Mycorrhizal strategy; Soil organic matter SOM turnover; Natural abundance 13C; Tree species differences; Microbial decomposition; Soil respiration; δ13CO2; Chamber; Root respiration
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-015-2731-y

BACKGROUND AND AIMS: The carbon (C) sequestration potential of land-use practices is increasingly important. Trees sequester atmospheric C into biomass and above and belowground litter but may also prime the decomposition of soil organic matter (SOM). We compared the influence of Acer pseudoplatanus (Sycamore) and Larix x. europlepsis (Hybrid Larch) on soil C decomposition. METHODS: We used natural abundance ¹³C to partition soil-surface CO₂ efflux into root and SOM sources. CO₂ was sampled from incubated root-free soil and from live tree roots using in-situ chambers. Combined surface efflux δ¹³CO₂ was measured using dynamic chambers and cavity-ringdown spectroscopy. RESULTS: Under Sycamore, CO₂ emissions were dominated (80–90 %) by root respiration. SOM contributed 10–20 % with a mean residence time of centuries. Under Larch, 24–33 % of total CO₂ efflux was root respiration, the remainder originating from an SOM pool with a turnover time of decades. Total soil C stocks were similar between the two plot types. Root-respired δ¹³CO₂ was consistently different by c. 2 ‰ between the species. CONCLUSIONS: The decomposition rate of soil C and its mean residence time are markedly different under the two tree species. Species differences in root-respired δ¹³CO₂ may reflect plant C allocation or respiratory fractionation.