Extreme drought events have the potential to cause dramatic changes in ecosystem structure and function, but the controls upon ecosystem stability to drought remain poorly understood. Here we used model systems of two commonly occurring, temperate grassland communities to investigate the shortterm interactive effects of a simulated 100-year summer drought event, soil nitrogen (N) availability and plant species diversity (low/high) on key ecosystem processes related to carbon (C) and N cycling. Whole ecosystem CO2 fluxes and leaching losses were recorded during drought and post-rewetting. Litter decomposition and C/N stocks in vegetation, soil and soil microbes were assessed 4 weeks after the end of drought. Experimental drought caused strong reductions in ecosystem respiration and net ecosystem CO2 exchange, but ecosystem fluxes recovered rapidly following rewetting irrespective of N and species diversity. As expected, root C stocks and litter decomposition were adversely affected by drought across all N and plant diversity treatments. In contrast, drought increased soil water retention, organic nutrient leaching losses and soil fertility. Drought responses of above-ground vegetation C stocks varied depending on plant diversity, with greater stability of above-ground vegetation C to drought in the high versus low diversity treatment. This positive effect of high plant diversity on above-ground vegetation C stability coincided with a decrease in the stability of microbial biomass C. Unlike species diversity, soil N availability had limited effects on the stability of ecosystem processes to extreme drought. Overall, our findings indicate that extreme drought events promote post-drought soil nutrient retention and soil fertility, with cascading effects on ecosystem C fixation rates. Data on above-ground ecosystem processes underline the importance of species diversity for grassland function in a changing environment. Furthermore, our results suggest that plant–soil interactions play a key role for the short-term stability of above-ground vegetation C storage to extreme drought events.
The Experience API (xAPI) allows us to collect data about any type of learning experience or activity, but does that mean we should? Should we generate massive amounts of xAPI data for every possible type of interaction and then expect to make sense of it all later? This approach can be costly in terms of data storage, but also in terms of your time.
Sunday Blake dives into the latest in learning analytics and engagement data, and asks how universities can act upon it to make our interactions with students more human.
Dashboard is a prominent artefact that users interact with when it comes to learning analytics. What is a learning analytics dashboard ? Who is it for? What is the key to effective adoption of learning analytics dashboard? Listen to Martin Hlosta and Fabio Campos sharing their experience in supporting the use of learning analytics dashboard on a large scale.
Jon Udell on 21 JUL 2021
Suppose you're a member of a team that runs a public web service. You need to help both internal and external users make sense of all the data that's recorded as it runs. That's been my role for the past few years, now it's time to summarize what I've learned.
In this lecture series Bart Rienties (Professor of Learning Analytics, head of Academic Professional Development) will discuss how from the safety of your home you could use existing trace data to explore interactions between people (e.g., Twitter data, engagement data in a virtual learning environment, public data sets), and what the affordances and limitations of these trace data might be.