Low assimilate partitioning to root biomass is associated with carbon losses at an intensively managed temperate grassland

Arne Poyda*, Thorsten Reinsch, Inger J. Struck, R.H. Skinner, Christof Kluß, Friedhelm Taube

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Aims: This study aimed to investigate how efficiently assimilated carbon (C) is incorporated in plant biomass at an intensively managed old permanent grassland, how C is partitioned between shoots and roots and what are the implications for C sequestration. Methods: Using the eddy covariance technique, the atmosphere-biosphere exchange of CO2 was measured for two years at a sandy grassland site in northern Germany. In addition to aboveground net primary production (ANPP), belowground NPP (BNPP) was observed using the ingrowth core method. Results: The grassland showed a high productivity in terms of biomass yield (14.8 Mg dry matter ha−1 yr−1) and net CO2 uptake (−2.82 Mg CO2-C ha−1 yr−1). Photosynthetically assimilated C was converted to biomass with a high carbon use efficiency (CUE) of 71% during the growing season. However, a comparably low fraction of 17% of NPP was allocated to roots (fBNPP). Consequently, the main fraction of NPP was removed during harvest, turning the site into a net source of 0.29 Mg C ha−1 yr−1. Conclusions: Our study showed the flexibility of grass root growth patterns in response to alterations in resource availability. We conclude that highly fertilized grasslands can lose their ability for C sequestration due to low belowground C allocation.

Original languageEnglish
JournalPlant and Soil
DOIs
Publication statusE-pub ahead of print - 26 Nov 2020

Keywords

  • Black sands
  • Carbon equilibrium
  • Carbon partitioning
  • Eddy covariance
  • Permanent grasslands
  • Plant carbon use efficiency
  • Root growth

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