Vertical root distribution and biomass allocation along proglacial chronosequences in Central Switzerland

ABSTRACT

Investigating changes in belowground functional plant traits is an important step toward a better understanding of vegetation dynamics during primary succession. However, in alpine glacier forelands, we still lack an accurate assessment of plant rooting patterns. In this study, we established two proglacial chronosequences with contrasting bedrocks to investigate changes in rooting patterns and biomass allocation with terrain age. We extracted soil cores up to 1 m depth and measured root traits every 10 cm of each drilled core. Furthermore, we sampled aboveground biomass determining the contributions of functional groups to total aboveground biomass. We found that root traits associated with the root economics spectrum varied significantly along the chronosequences. Vertical root distribution coefficients revealed that early successional communities had more evenly distributed root systems compared to late successional communities. Biomass allocation showed diverging patterns. We found evidence for both the isometric allocation and optimal partitioning hypotheses. In addition, we observed a significant correlation between rooting parameters and plant community composition, suggesting that the dominance of distinct plant functional groups was one important factor explaining the observed rooting patterns. Our results shed light on the often neglected belowground compartments during plant succession and contribute to a better understanding of hillslope functioning.

KEYWORDS:

• Biomass allocation
• chronosequence
• glacier forelands
• root traits
• plant community composition

Acknowledgments

We thank Thomas Michel and his team of the Alpin Center Sustenpass as well as Cècile Zemp from Hotel Klausenpasshöhe for accommodation and logistical support during the fieldwork. We thank Kyle Kovach for language editing.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This research is part of the HILLSCAPE project (www.hillscape.ch), which is supported by the German Research Foundation (DFG project number 318089487; funding to MSL: SCHE 695/9-1) and the Swiss National Science Foundation (project grant number 200021E-167563/1). The article processing charge was funded by the Baden-Wuerttemberg Ministry of Science, Research and Art and the University of Freiburg in the funding programme Open Access Publishing.