We welcome Josh Haussler to the Sala Lab. Josh recently has been accepted as a graduate student at ASU in the Environmental Life Sciences program. He has been part of the lab for several years and for several campaigns in the Chihuahuan Desert. We are looking forward to sharing with him many more fun times in the coming years.
A new paper from the Sala Lab published today in Ecology (see Publications)! Lara Reichmann is the lead author of this important work “Precipitation legacies in desert-grassland primary production occur through previous-year tiller density” that clearly showed the existence of legacies from previous years and documented the mechanism behind them. Legacies in aboveground net primary production were similar in absolute value for dry-wet and wet-dry precipitation transitions, and their magnitude was a function of the difference between previous and current-year precipitation. Tiller density accounted for 40% of legacy variability, while nitrogen and carry-over water availability showed no effect. Legacies of previous year accounted for a large fraction (20%) of inter-annual variability in production.
Congratulations Laureano on your new paper just published in Ecosphere!! This paper reports on a new system that alters precipitation for experimental plots from 80% reduction to 80% increase relative to ambient, is low cost, and is fully solar powered. This two-part system consists of a rainout shelter that intercepts water and sends it to a temporary storage tank, from where a solar-powered pump sends water to sprinklers located in opposite corners of an irrigated plot. The system showed high reduction/irrigation accuracy and small effect on temperature and photosynthetically active radiation. System average cost was ONLY $228 per module of 2.5 m by 2.5 m.
A recent article “Water controls on nitrogen transformations and stocks in an arid ecosystem” led by Lara Reichmann (see Publications) and published in Ecosphere showed novel interactions between water availability and nitrogen cycling. Net nitrogen mineralization was insensitive to changes in water availability but plant uptake was not. Consequently, mineral nitrogen accumulated under dry conditions because the mineralization was not affected while immobilization was constrained. The opposite was true, under wet conditions when mineral nitrogen was significantly reduced. The differential controls of water on inputs and outputs of mineral nitrogen yielded counterintuitive effects of water on leaching. Nitrogen leaching decreased with increasing precipitation driven more by nitrogen than water availability.
The South American Institute for Resilience and Sustainability Studies (SARAS) will gather scientists and artists in Punta del Este, Maldonado, Uruguay from December 16th to 19th, to synthesize our understanding of the determinants and consequences of abrupt grass-woodland transitions in different ecological systems. This is an interdiciplinary worshop involving economists, natural resource managers, ecologists, artists, and hydrologists.
A recent paper published in the Philosophical Transactions of the Royal Society PDF developed theory of regional and temporal controls of aboveground net primary production and tested hypotheses using existing long-term data. Legacies revealed by the association of current- versus previous-year conditions through the temporal series occur across all ecosystem types from deserts to mesic grasslands. Therefore, previous-year precipitation and ANPP control a significant fraction of current-year production; and legacies explain the difference between spatial and temporal models. The relative importance of current-versus previous-year precipitation changes along a gradient of mean annual precipitation with the importance of current-year PPT decreasing, whereas the importance of previous-year PPT remains constant as mean annual precipitation increases.