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The ability to predict C cycle responses to temperature changes depends on the accurate representation of temperature sensitivity (Q 10 ) of soil organic matter (SOM) decomposition in C models for different C pools and soil depths. Theoretically, Q 10 of SOM decomposition is determined by SOM quality and availability (referred to here as SOM protection). Here, we focus on the role of SOM protection in attenuating the intrinsic, SOM quality dependent Q 10 . To assess the separate effects of SOM quality and protection, we incubated topsoil and subsoil samples characterized by differences in SOM protection under optimum moisture conditions at 25 1C and 35 1C. Although lower SOM quality in the subsoil should lead to a higher Q 10 according to kinetic theory, we observed a much lower overall temperature response in subsoil compared with the topsoil. Q 10 values determined for respired SOM fractions of decreasing lability within the topsoil increased from 1.9 for the most labile to 3.8 for the least labile respired SOM, whereas corresponding Q 10 values for the subsoil did not show this trend (Q 10 between 1.4 and 0.9). These results indicate the existence of a limiting factor that attenuates the intrinsic effect of SOM quality on Q 10 in the subsoil. A parallel incubation experiment of 13 C-labeled plant material added to top-and subsoil showed that decomposition of an unprotected C substrate of equal quality responds similarly to temperature changes in top-and subsoil. This further confirms that the attenuating effect on Q 10 in the subsoil originates from SOM protection rather than from microbial properties or other nutrient limitations. In conclusion, we found experimental evidence that SOM protection can attenuate the intrinsic Q 10 of SOM decomposition.

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Despite the increasing attention on circular economy at the policy level, the implementation of circular business models in companies is still limited. Many companies are put off by the apparent complexity to translate the general concepts of a circular economy into their business practice. This paper presents the development and testing of a simulation board game that aimed to address this gap between theory and business practice. The board game, Risk&RACE, was developed with the purpose of enabling students and business executives to experiment with circular economy business models. The gameplay was tested with 120 users, and cognitive learning outcomes as well as learning dynamics were assessed using a survey. The results of the game workshops demonstrated that the game advanced the participants’ awareness of the need for a circular economy, their understanding of basic circular economy principles, and their insight in opportunities and challenges of circular business models at the company level. When reflecting on the game as a learning tool, players highlighted its engaging and realistic nature and praised how it stimulated strategic thinking. Complementing the gameplay with a debriefing discussion afterwards encouraged players to reflect upon their newly gained insights, deepening their learning experience.