ProDoc

Forest ecosystem responses to climatic drivers

This project is part of the program external page Plant Sciences and Policy of the Zürich-Basel Plant Science Center PSC PhD Program (SNSF ProDoc Grant-Number: PDAMP3 127227).

Context

The project aims at understanding time lags between climatic drivers and the respective ecosystem responses in terms of net ecosystem productivity (NEP) at the two long-term Swiss Fluxnet sites Davos (since 1997) and Lägeren (since 2005). The project combines knowledge from plant physiology, forest ecology and meteorology to disentangle the effects on NEP of actual physical drivers, and biotic conditions determined by past and recent climatic conditions.

Objectives

1. Identify climatic drivers of NEP at two contrasting forest sites
2. Quantify the impact of the climatic drivers on observed time lags of ecosystem responses
3. Assess the underlying physiological mechanisms explaining such time lags and therefore flux partitioning.
   

Policy Related Objectives

Understanding the natural processes determining the carbon balance of forest ecosystems is of great global interest for estimating country-specific carbon budgets within the United Nations Framework Convention on Climate Change (UNFCCC). We expect to provide relevant information to national administrations and to satisfy their demand for more precise, country-wide forest ecosystem carbon budgets.

Approach

1. Measure microclimate profiles, eddy covariance net ecosystem CO₂ and H₂O vapour exchange, continuous stem radius changes, and [CO₂] in tree stems at the two sites
2. Analyse statistical patterns of historic time series which quantify the time-dependent weight of climatic drivers on ecosystem responses.
3. Test the applicability of physiological concepts to explain the observed time lags and thus flux partitioning of CO₂ and H₂O vapour fluxes at the ecosystem level.
   

Publications

2017

• Haeni M, Zweifel R, Eugster W, Gessler A, Zielis S, Carrara A, Knohl A, Havránková K, Herbst M, Ibrom A, Lagergren F, Marek M, Matteucci G, Moors E, Olejnik J, Pavelka M, Pilegaard K, Pita G, Rodrigues A, Sanz MJ, Schelhaas MJ, Urbaniak M, Valentini R, Vesala T, Wu J, Buchmann N (2017) Winter respiratory C losses provide explanatory power for net ecosystem productivity. Journal of Geophysical Research – Biogeosciences 122: 243-260 doi: external page 10.1002/2016JG003455

2016

• Zweifel R, Haeni M, Buchmann N, Eugster W (2016) Are trees able to grow in periods with shrunken stems? New Phytologist 211: 839–849 external page doi: 10.1111/nph.13995

2014

• Zielis S, Etzold S, Zweifel R, Eugster W, Haeni M, Buchmann N (2014) NEP of a Swiss subalpine forest is significantly driven not only by current but also by previous year’s weather. Biogeosciences 11: 1627–1635 doi:external page 10.5194/bg-11-1627-2014

2013

• Zielis S, Etzold S, Zweifel R, Eugster W, Haeni M and Buchmann N (2013) Forest NEP is significantly driven by previous year's weather. Biogeosciences Discussions 10: 15587-15611. doi: external page 10.5194/bgd-10-15587-2013