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Science Paper out now - open access link available here:

Werner, C., Meredith, L. K., Ladd, S. N., Ingrisch, J., Kübert, A., van Haren, J., ... & Williams, J. (2021). Ecosystem fluxes during drought and recovery in an experimental forest. Science, 374(6574), 1514-1518. (Open-Access)

This campaign is centered on the ERC-funded project VOCO2 and coordinated together with the new director of the Biosphere tropical rainforest Laura Meredith (University of Arizona, Tucson).

We have now successfully demonstrated the application of cutting-edge technology (δ13CO2 laser spectroscopy, high sensitivity PTR-TOF-MS and quantitative isotopic NMR spectroscopy) to characterize real-time carbon allocation into VOCs and CO2 using plant position-specific 13C-pyruvate labeling (labelled at the C1 or C2-carbon position) at the branch scale (Fasbender et al. 2018) and, more recently using entire plants. In the final stage of the ERC grant we conducted the world-wide first canopy positional labelling in the unique facilities of the tropical rainforest in the Biosphere 2 (Werner et al. 2021), Arizona, the world’s largest controlled growth facility: the Biosphere 2 Tropical Rainforest. The B2 TRF is the ideal location for this project because whole-ecosystem fluxes can be measured within the enclosed system, the environment is controlled, and the canopy can be accessed, which enables real-time monitoring of ecosystem and branch-level fluxes. This whole ecosystem labelling experiment is a unique opportunity to assess ecosystem processes – from the atmosphere, biosphere, soil and hydrology. Our methodological approach enables novel insights into all these different ecosystem components. Moreover, the biosphere is the world-wide sole system, where full ecosystem manipulation experiments are possible.

Photo 1 The Biosphere 2 Tropical Rainforest provides a unique opportunity to holistically evaluate mechanisms and interactions driving ecosystem-scale responses to stressors such as drought (Photo Laura Meredith)

An unprecedented 4-month labelling experiment was conducted by 1) simulating an ecosystem drought and recovery and 2) bringing in experts and equipment to enable simultaneous measurements of pools and fluxes at the atmosphere, vegetation (phyllosphere, stems), rhizosphere, microbiome and deep water soil processes.


The B2-WALD campagne will be ground-breaking in:

  • Tracing pools and fluxes at all levels throughout the ecosystems, disentangling ecosystem processes, interactions and feedbacks to an important climate change driver (drought) from the atmosphere, biosphere (including phyllosphere, rizosphere) and hydrology
  • Closing carbon and water budget at an ecosystem scales (in a unique closed facility)
  • Partitioning carbon allocation from the molecular to the ecosystems scale
  • Integrating metabolomics, genomics, volatilomics into ecosystem fluxes approaches in a truly interdisciplinary manner
  • deconvolution of the role of deep water reserves, quantifying the role of hydraulic lift by deep rooted trees to ecosystem water budgets by groundwater labelling


The Rainforest campaign produced massive amounts of diverse, but integrated (Bonnie Hurwitz, NSF EarthCube proposal), data to paint an exceptional picture of the movement of carbon and water through an ecosystem before, during, and after drought, as a function of diverse biological and abiotic drivers. The stable isotope label applied to the ecosystem can be studied in the years to come, asking how long carbon will remain stabilized in the soil for example.

Organization and Management

The campaign is co-led by Christiane Werner (Full Professor, University of Freiburg) and Laura Meredith (B2 Rainforest Science Director and Assistant Professor, SNRE, UA), with leadership and organization also by Nemiah Ladd (ERC-Postdoc, University of Freiburg). 



This is a large-scale, international research campaign, lead by the ERC-team based at the UA Biosphere 2 that brought in external contributions including personnel, equipment, and research capabilities.


The number of partners currently committed to the campaign, in addition to Biosphere 2 team members (6-8), is approximately 50 participants (MS Students to Professors) from 20 research groups and 13 institutions located both US (3 US universities including UA/B2) and EU (10 EU from Germany, Switzerland, Austria, and Scotland).

Related Links

Unprecedented drought in an artificial ecosystem may reveal how rainforests will cope with climate change - Science News

Ecosystem effects of Environmental Extremes - Science Perspective by Nico Eisenhauer and Alexandra Weigelt

Meredith Lab - University of Arizona

Drought in Biosphere 2 - University of Freiburg News

#B2WALD on Twitter


Werner, C., Meredith, L. K., Ladd, S. N., Ingrisch, J., Kübert, A., van Haren, J., ... & Williams, J. (2021). Ecosystem fluxes during drought and recovery in an experimental forest. Science, 374(6574), 1514-1518. (Open-Access)

 Ladd, S. N., Nelson, D. B., Bamberger, I., Daber, L. E., Kreuzwieser, J., Kahmen, A., & Werner, C. (2021). Metabolic exchange between pathways for isoprenoid synthesis and implications for biosynthetic hydrogen isotope fractionation. New Phytologist, 231(5), 1708-1719.