New flux based dose–response relationships for ozone for European forest tree species. (November 2015) - Büker, P.
Abstract: To derive O3 dose–response relationships (DRR) for five European forest trees species and broadleaf deciduous and needleleaf tree plant functional types (PFTs), phytotoxic O3 doses (POD y ) were related to biomass reductions. POD y was calculated using a stomatal flux model with a range of cut-off thresholds ( y ) indicative of varying detoxification capacities. Linear regression analysis showed that DRR for PFT and individual tree species differed in their robustness. A simplified parameterisation of the flux model was tested and showed that for most non-Mediterranean tree species, this simplified model led to similarly robust DRR as compared to a species- and climate region-specific parameterisation. Experimentally induced soil water stress was not found to substantially reduce POD y, mainly due to the short duration of soil water stress periods. This study validates the stomatal O3 flux concept and represents a step forward in predicting O3 damage to forests in a spatially and temporally varying climate. Highlights: We present new ozone flux based dose–response relationships for European trees. The model-based study accounted for the soil water effect on stomatal flux. Different statistically derived ozone flux thresholds were applied. Climate region specific parameterisation often outperformed simplified parameterisation. Findings could help redefining critical levels for ozone effects on trees. Abstract : New stomatal flux based ozone dose–response relationships for tree species are derived for the regional risk assessment of ozone effects on European forest ecosystems.