COS 163-2 - Linking forest productivity and sequestered carbon within cell walls with their climatic drivers at two European beech sites

Wednesday, August 9, 2023

10:15 AM – 10:30 AM PDT

Location: B115

Presenting Author(s)

JW

Jingshu Wei

School of Natural Resources and the Environment, University of Arizona, 1064 E Lowell Street, Tucson, AZ 85721, USA
Tucson, Arizona, United States

Coauthor(s)

GA

Georg von Arx

Swiss Federal Research Institute WSL; Oeschger Centre for Climate Change Research
Birmensdorf, Switzerland
AI

Andreas Ibrom

Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Denmark, Denmark
ZF

Zexin Fan

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun Town, Mengla County, Yunnan Province 666303, China, China (People's Republic)
MM

Martina Mund

Forestry Research and Competence Centre Gotha, Gotha, D-99867, Germany, Germany
AK

Alexander Knohl

Bioclimatology, University of Göttingen, Büsgenweg 2, D-37077, Göttingen, Germany, Germany
ZL

Zongshan Li

State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China, China (People's Republic)
RP

Richard L. Peters

Physiological Plant Ecology, Department of Environmental Sciences, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland, Switzerland
FB

Flurin Babst

School of Natural Resources and the Environment and Laboratory of Tree-Ring Research, University of Arizona
Tucson, United States
AK

Anne Klosterhalfen

Bioclimatology, University of Göttingen
Göttingen, Germany

Abstract: The allocation of carbon to wood tissue is a key process underlying tree biomass increment during the growing season. The net outcome of this process can be assessed using quantitative wood anatomy (QWA), a technique that provides cell-level insights into growth and carbon sequestration. In parallel to this carbon sink activity, eddy covariance (EC) methods enable access to photosynthetic carbon uptake (source activity) at forest stand level. Together, these observations help quantify carbon allocation with unmatched temporal resolution. However, existing research has rarely achieved these much-needed comparisons of QWA and EC data, limiting our understanding of the sub-seasonal connections and dynamics between carbon sink and source under a warming climate. To address this knowledge gap, we collected wood cores from two European beech forests that host long-term eddy covariance tower sites in Denmark (Sorø, DK-Sor) and Germany (Hainich, DE-Hai). We selected a subset of 10 trees per site to measure wood anatomical traits, such as cell lumen area (CLA), number (CN), and wall thickness (CWT). We then investigated the relationships between intra and inter-annual woody biomass increment (i.e., cells to tree rings), climate variations, and carbon fluxes to test two hypotheses: 1) EC-derived gross primary productivity (GPP) shows a varied response to seasonal climate variations, whereas wood anatomical traits are sensitive to environmental factors during more narrow time windows within the previous and current growing seasons; 2) GPP is unrelated to CLA, but more closely related to CWT in late summer when most cells have passed the enlargement phase and biomass increments in cell walls is at its peak. Our results show that European beech woody biomass production is more sensitive to variations in water availability than GPP. In turn, positive relationships were found between GPP and daily temperature, especially in summer, at both sites. These findings suggest that the seasonality of GPP is more pronounced than that of the biomass accumulation process. Our study offers a very detailed perspective on the carbon cycling of an ecologically and economically important tree species, and advances the empirical basis needed for improving next-generation vegetation models and climate mitigation.