CR 41:221-232 (2010)  -  DOI: https://doi.org/10.3354/cr00847

ABSTRACT: Mechanisms controlling transient responses to elevated CO₂ concentration and climate change in an unfertilized grassland on the Swiss Plateau were examined in light of simulations with PROGRASS, a process-based model of grass–clover interactions. Daily weather for a series of transient climate scenarios spanning the 21st century were developed for the study site with the help of the LARS-WG weather generator. Changes in the length of dry and wet spells, temperature, precipitation and solar radiation defining the scenarios were obtained from regional climate simulations carried out in the framework of the PRUDENCE project. Compared to 1961–1990, the latter indicated that for 2071–2100 there would be a noticeable increase in temperature (roughly 3°C in winter and 5°C in summer), a significant drop in summer precipitation (of the order of –30%) and a nearly 2-fold increase in the length of dry spells. Assuming that clover is less drought-tolerant than grass, we examined whether clover abundance would decrease as a consequence of increasing heat and water stress, or be promoted on account of CO₂ stimulation. Results indicated that: (1) at our site, climate change alone did not curtail biological N₂ fixation to the point as to alter the composition of the sward but nevertheless entailed a decrease in grassland productivity; (2) increasing CO₂ clearly promoted clover growth (via feedbacks on nitrogen acquisition) and grassland productivity; and (3) even with CO₂ stimulation, the additional N input from symbiotic N₂ fixation was not sufficient to substantially improve the mineral N status of the system and promote grass competitiveness.

KEY WORDS: Climate change  · Elevated CO₂ · Grassland productivity · Biological N₂ fixation · Grass–clover interactions · Transient responses

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Cite this article as: Lazzarotto P, Calanca P, Semenov M, Fuhrer J (2010) Transient responses to increasing CO2 and climate change in an unfertilized grass–clover sward. Clim Res 41:221-232. https://doi.org/10.3354/cr00847 Export citation Share:    Facebook - - linkedIn