Soil carbon is a major component in the global carbon cycle. Understanding the relationship between environmental changes and rates of soil respiration is critical for projecting changes in soil carbon fluxes in a changing climate. Although significant attention has been focused on the temperature sensitivity of soil organic matter decomposition, the factors that affect this temperature sensitivity are still debated. In this study, we examined the effects of substrate availability on the temperature sensitivity of soil respiration in several different kinds of soils. We found that increased substrate availability had a significant positive effect on temperature sensitivity, as measured by soil Q 10 values, and that this effect was inversely proportional to original substrate availability. This observation can be explained if decomposition follows MichaelisMenten kinetics. The simple Q 10 model was most appropriate in soils with high substrate availability.

No abstract

No abstract

Analysis and synthesis of large and complex datasets are increasingly important components of scientific research. To expose undergraduate students to these datasets and to develop valuable data analysis skills, a team of environmental scientists and education researchers created Project EDDIE (Environmental Data-Driven Inquiry and Exploration). Project EDDIE is a pedagogical collaborative that develops and assesses flexible modules that use publicly-available, large datasets that allow students to explore a range of concepts in the biological, earth, and environmental sciences. Modules have been implemented in a range of courses, class sizes, and institutions. We assessed six modules over eight courses, which were taught to total of 1,380 students. EDDIE modules led to significant improvements in students' competence using spreadsheet software and as well as their conceptual understanding of how to use large complex datasets to address scientific problems. Furthermore, students reported positive and informative experiences using large datasets to explore open-ended questions.

S U M M A R YThe Mongolian Altai is an intracontinental oblique contractional orogen related to the farfield effects of the Indo-Asian collision. Global Positioning System (GPS) data suggest that ∼10-15 per cent of total Indo-Asia convergence is accommodated across this orogen. The Höh Serh-Tsagaan Salaa fault system is one of several NNW-SSE-trending oblique contractional faults acting to partition strain and accommodate shortening and dextral shear in the Mongolian Altai. This fault zone displaces late Pleistocene alluvium along the southwest piedmont of the Höh Serh range in western Mongolia. Along the central third of the fault zone, strain is partitioned onto two separate strands, one that accommodates nearly pure dextral shear and one that accommodates thrust motion. We determined late Pleistocene rates of deformation along each of the Höh Serh-Tsagaan Salaa fault strands based on differential GPS surveys and cosmogenic nuclide 10 Be geochronology. Combining the measured offsets and 10 Be dates yields a minimum right-lateral slip rate of 0.9 +0.2/−0.1 mm a −1 ; the minimum shortening rate is 0.3 ± 0.1 mm a −1 , with uplift of at least 0.1 ± 0.1 mm a −1 . Resolving the shortening and dextral components of deformation yields a slip vector of 0.8 +0.2/−0.1 mm a −1 toward 336 • . This long-term deformation vector is consistent with the short-term strain field determined by GPS in the region and indicates that ∼20 per cent of Indo-Asian deformation in the Mongolian Altai (∼2 per cent of the total Indo-Asia strain accumulation) occurs along the Höh Serh-Tsagaan Salaa fault zone. Although rate data for other active faults in the Mongolian Altai are sparse, our results suggest that strain may be accommodated almost exclusively on discrete structures in this intraplate tectonic setting.