Rising atmospheric CO 2 concentrations have increased interest in the potential for forest ecosystems and soils to act as carbon (C) sinks. While soil organic C contents often vary with tree species identity, little is known about if, and how, tree species influence the stability of C in soil. Using a 40 year old common garden experiment with replicated plots of eleven temperate tree species, we investigated relationships between soil organic matter (SOM) stability in mineral soils and 17 ecological factors (including tree tissue chemistry, magnitude of organic matter inputs to the soil and their turnover, microbial community descriptors, and soil physicochemical properties). We measured five SOM stability indices, including heterotrophic respiration, C in aggregate occluded particulate organic matter (POM) and mineral associated SOM, and bulk SOM δ 15 N and ∆ 14 C. The stability of SOM varied substantially among tree species, and this variability was independent of the amount of organic C in soils. Thus, when considering forest soils as C sinks, the stability of C stocks must be considered in addition to their size. Further, our results suggest tree species regulate soil C stability via the composition of their tissues, especially roots. Stability of SOM appeared to be greater (as indicated by higher δ 15 N and reduced respiration) beneath species with higher concentrations of nitrogen and lower amounts of acid insoluble compounds in their roots, while SOM stability appeared to be lower (as indicated by higher respiration and lower proportions of C in aggregate occluded POM) beneath species with higher tissue calcium contents. The proportion of C in mineral associated SOM and bulk soil ∆ 14 C, though, were negligibly dependent on tree species traits, likely reflecting an insensitivity of some SOM pools to decadal scale shifts in ecological factors. Strategies aiming to increase soil C stocks may thus focus on particulate C pools, which can more easily be manipulated and are most sensitive to climate change.
Bibliographical noteFunding Information:
This research was partly supported by the National Science Foundation (DEB 0128958, DEB 0128944, DEB‐0816935, and OISE IE080018), the SoWa Research Infrastructure, funded by MEYS CZ (LM2015075 and EF16_013/0001782 – SoWa Ecosystems Research), and the Czech Science Foundation (18‐24138S). All authors declare no conflict of interest. We thank Cindy Prescott and an anonymous reviewer for their valuable comments on the manuscript. We thank Ingrid Kogel‐Knabner, Gabriele Albert, and Maria Greiner for technical assistance.
National Science Foundation, Grant/Award Number: DEB 0128958, DEB 0128944, DEB-0816935, OISE IE080018; SoWa Research Infrastructure, funded by MEYS CZ, Grant/Award Number: LM2015075, EF16_013/0001782; Czech Science Foundation, Grant/Award Number: 18-24138S
© 2018 John Wiley & Sons Ltd
- common garden
- heterotrophic respiration
- mineral associated SOM
- physical fractionation