Characterisation of spatial variability and patterns in tree and soil δ¹³C at forested sites in eastern Canada

Abstract

Wholistic isotopic studies provide a necessary foundation on which to build conceptual understanding of ecosystem development processes and provide the basis for further isotopic studies at a site or within an ecophysiological region. This study seeks to broadly characterise δ¹³C spatial variability and spatial patterns within soils and canopy tissues at five forest research sites in eastern Canada. We observe consistent and predictable patterns of leaf δ¹³C variation within trees and a consistent offset between woody and leafy tree tissues. Patterns are similar for both hardwoods and softwoods, but overall hardwoods had canopies that were more depleted in ¹³C. Soil carbon δ¹³C enrichment occurred with depth and appeared to vary according to site soil texture. Upper soil δ¹³C was intermediate between leaves and woody tissues, whereas deeper soil values suggested important contributions from more enriched tree tissues, such as persistent woody debris and possibly roots. The relationship between aboveground and belowground signatures suggests functional or developmental differences between study sites.

Keywords:

• Canada
• carbon-13
• forest
• isotope ecology
• natural isotope variations

Acknowledgements

This research was funded by The Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS) and the Atlantic Canada Opportunities Agency (ACOA) through research grants to L. Kellman.