Effects of drought and warming treatments on CO2 fluxes in shrubland ecosystems across European environmental gradients

Shrubland ecosystems are vulnerable and typical ecosystems across European countries, but now they are facing a range of threats and an uncertain future because of climate change. Within the INCREASE project, six shrubland ecosystems along a geographical and climatic gradient across Europe from Wales and Denmark in the North, over The Netherlands to Hungary and Italy in the South, were exposed to ecosystem-level warming and extended periods of drought using automated curtain technologies. Sites ranged naturally from xeric to hydric. During our measurement period, mean annual precipitation (MAP) was reduced by 8-25%, while mean annual air temperature (MAT) was increased year-round by 0.2 - 0.9 ℃.

Previously, Reinsch et al. (2017) * showed that aboveground net primary production (ANPP) was relatively resilient to the climate treatments while soil respiration (R_s) was reduced in xeric to mesic sites but increased in the hydric site. However, quantification of the gross primary production (GPP) or ecosystem respiration (R_eco) rates and their responsiveness to climate manipulations have not previously been published. We will here present data from the six shrubland sites along the European climate gradient of the responses of GPP and R_eco to drought and warming expressed as annual relative change (%) from the untreated control along a Gaussen index (GI). Results are in contrast to the previously reported decrease in R_s responsiveness with increased aridity. For both R_eco and GPP rates, our preliminary results indicate that the more arid sites have a stronger, negative effect of drought suggesting different response patterns of autotrophic and heterotrophic components of the ecosystems.

*Reinsch, S., Koller, E., Sowerby, A. et al. Shrubland primary production and soil respiration diverge along European climate gradient. Sci Rep 7, 43952 (2017). https://doi.org/10.1038/srep43952