Goals
Synthesise existing data to assess under which plant communities, climate types, and land-use histories the dryland pulse paradigm works in explaining ecosystem patterns and controls in arid and semiarid ecosystems.
Evaluate the utility of the paradigm for different processes (e.g. primary productivity, soil respiration) and scales (e.g. plot-scale, ecosystem-scale) across the dryland biome.
Employ emerging numerical tools, including modelling and remote sensing, to assess the dryland pulse paradigm.
Refine / revise / reform the dryland pulse paradigm.
Plan for a targeted set of experiments to directly test a revised paradigm.
Intimately involve early career scientists and underrepresented scientific groups, and encourage them to play leadership roles in this important research area.
Rationale and scope
Dryland ecosystems are charactised by infrequent and variable precipitation and, in his seminal 1973 paper, Noy-Meir proposed hypotheses that placed dryland ecosystem controls into a 'pulse dynamics' framework. This framework has become a central tenet for dryland ecology and, while it had been frequently cited and built upon, the paradigm has not been directly tested.
Now is an ideal time to undertake a rigorous quantitative assessment of the pulse-reserve paradigm. In the past 40 years, the scientific community has accrued numerous experiments and datasets with which to test the paradigm. Further, several numerical tools have evolved that allow us to address these concept across multiple spatial and temporal scales.
Here we propose to bring together world-renowned dryland experts, numerical modellers, and remote sensors to evaluate datasets that did not exist in 1973 in the context of the pulse-reserve paradigm. We would use this information to directly assess and refine a framework for understanding how precipitation and soil moisture drive plant community composition, productivity, soil respiration, and coupled biogeochemical cycles. We have taken an initial look at the datasets and feel that, not only do the right data exist for reaching these goals, but they suggest a lack of support for the universality of the pulse-reserve paradigm.
Emerging evidence suggests that dryland plant activitiy determines biogeochemical cycles at the global scale and, in this context, a framework for understanding how climate regulates dryland function would be of great benefit for considering both current and future global function. In sum, we seek to continue Noy-Meir's legacy of elucidating precipitation controls in dryland, to put this legacy into a climate change context, and to utilise the wealth of dryland data and numerical tools that have accumulated in the last 40 years to create an improved framework on which dryland ecology can continue to build.
Organising committee
Sasha Reed (U.S. Geological Survey)
Osvaldo Sala (Arizona State University)
Scott Collins (University of New Mexico)
Scott Ferrenberg (U.S. Geological Survey)