Pushing precipitation to the extremes in distributed experiments: recommendations for simulating wet and dry years

• Autores: Knapp, Alan K.; Avolio, Meghan L.; Beier, Claus; Carroll, Charles J. W.; Collins, Scott L.; Dukes, Jeffrey S.; Fraser, Lauchlan H.; Griffin Nolan, Robert J.; Hoover, David L.; Jentsch, Anke; Loik, Michael E.; Phillips, Richard P.; Post, Alison K.; Sala, Osvaldo Esteban; Slette, Ingrid J.; Yahdjian, María Laura; Smith, Melinda D.
• Año de publicación: 2017
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Climate Extremes; Drought; Field Experiments; Precipitation Regimes; Wet Years
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Intensification of the global hydrological cycle, ranging from larger individual precipitation events to more extreme multiyear droughts, has the potential to cause widespread alterations in ecosystem structure and function. With evidence that the incidence of extreme precipitation years (defined statistically from historical precipitation records) is increasing, there is a clear need to identify ecosystems that are most vulnerable to these changes and understand why some ecosystems are more sensitive to extremes than others. To date, opportunistic studies of naturally occurring extreme precipitation years, combined with results from a relatively small number of experiments, have provided limited mechanistic understanding of differences in ecosystem sensitivity, suggesting that new approaches are needed. Coordinated distributed experiments (CDEs) arrayed across multiple ecosystem types and focused on water can enhance our understanding of differential ecosystem sensitivity to precipitation extremes, but there are many design challenges to overcome (e.g., cost, comparability, standardization). Here, we evaluate contemporary experimental approaches for manipulating precipitation under field conditions to inform the design of ‘Drought-Net’, a relatively low-cost CDE that simulates extreme precipitation years. A common method for imposing both dry and wet years is to alter each ambient precipitation event. We endorse this approach for imposing extreme precipitation years because it simultaneously alters other precipitation characteristics (i.e., event size) consistent with natural precipitation patterns. However, we do not advocate applying identical treatment levels at all sites – a common approach to standardization in CDEs. This is because precipitation variability varies >fivefold globally resulting in a wide range of ecosystem-specific thresholds for defining extreme precipitation years. For CDEs focused on precipitation extremes, treatments should be based on each site's past climatic characteristics. This approach, though not often used by ecologists, allows ecological responses to be directly compared across disparate ecosystems and climates, facilitating process-level understanding of ecosystem sensitivity to precipitation extremes.
Fil: Knapp, Alan K.. State University of Colorado - Fort Collins; Estados Unidos
Fil: Avolio, Meghan L.. National Socio-Environmental Synthesis Center; Estados Unidos
Fil: Beier, Claus. Norwegian Institute for Water Research; Noruega
Fil: Carroll, Charles J. W.. State University of Colorado - Fort Collins; Estados Unidos
Fil: Collins, Scott L.. University of New Mexico; Estados Unidos
Fil: Dukes, Jeffrey S.. Purdue University; Estados Unidos
Fil: Fraser, Lauchlan H.. Thompson Rivers University; Canadá
Fil: Griffin Nolan, Robert J.. State University of Colorado - Fort Collins; Estados Unidos
Fil: Hoover, David L.. Southwest Biological Science Center; Estados Unidos
Fil: Jentsch, Anke. University of Bayreuth; Alemania
Fil: Loik, Michael E.. University of California; Estados Unidos
Fil: Phillips, Richard P.. Indiana University; Estados Unidos
Fil: Post, Alison K.. State University of Colorado - Fort Collins; Estados Unidos
Fil: Sala, Osvaldo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. ; Argentina. Arizona State University; Estados Unidos
Fil: Slette, Ingrid J.. State University of Colorado - Fort Collins; Estados Unidos
Fil: Yahdjian, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. ; Argentina
Fil: Smith, Melinda D.. State University of Colorado - Fort Collins; Estados Unidos