Ozone Research, Quo Vadis? Lessons from the free-air canopy fumigation experiment at kranzberg forest

Empirical evidence underlines enhanced ground-level O₃ regimes as components of global change, although interaction responses of forest trees and ecosystems have only recently been addressed by research. One case study is the tree-level Kranzberg Forest Experiment, having been resumed for envisioning "next-generation" ecosystem-level O₃ research. Quantifying enhanced O₃ impact is highlighted as part of a multi-factorial, abiotic-biotic interaction network of experiments and monitoring sites, which challenge the required quantitative predictability of the plasticity, and hence, extent and risk in system response, given the significance of forests as global determinants of carbon storage and sequestration. Here, we outline such integrated research concepts, cross-linking experimentation, monitoring and modelling to scale up O₃ responses from internal tree processes towards zonobiomic spatio-temporal scales. The availability of conceptual and methodological means as pre-requisites is emphasized. The relevance of respective research for providing spin-offs within socio-economic contexts related to biogenic energy production and CO₂ emission trading is examined.