Ecological effects of El Niño in terrestrial ecosystems of western South America

Abstract

I make a summary review of how El Niño/Southern Oscillation (ENSO) determines peculiar atmospheric and oceanographic conditions in western South America, thus affecting precipitation patterns in adjacent land masses, with cascading effects on marine and terrestrial plants, on sea and land birds, and on marine and terrestrial mammals. With regard to terrestrial ecosystems, I discuss the following biotic responses to El Niño‐driven precipitation: 1) aboveground vegetation flushes immediately among herbs but not among shrubs. 2) The seed bank is quickly replenished of ephemeral seeds, but perennial seeds recover one year later. 3) Small rodents irrupt within months of El Niño arrival, but larger ones take a full year to increase. 4) Predator numbers lag one year behind their mammal prey, with smaller predators responding more quickly. Considering these responses, I offer a simplified model of El Niño‐driven bottom‐up control in terrestrial ecosystems of western South America. Apart from the direct links already described, there is a weak feedback loop between the plant compartments (vegetation and seeds) and their herbivores: primary productivy is the driving force, and is little affected by herbivory. Another weak feedback loop links herbivores and their predators: the latter seem to just “surf” over prey levels, skimming excess prey.

Notes on the floral biology and pollination syndrome of Echinopsis chiloensis (Colla) Friedrich & G.D.Rowley (Cactaceae) in a population of semiarid Chile

“…Most columnar cacti are hermaphrodite plants that strongly depend on animals for reproduction (Gibson & Nobel 1986). While columnar cacti often rely on bats as pollinators in the tropics (e.g., Nassar et al 1997, Fleming & Valiente-Banuet 2002, Ibarra-Cerdeña et al 2005, more generalized and mixed pollination syndromes have been suggested to be prevalent in temperate ecosystems (Fleming et al 1996, 2001, Valiente-Banuet et al 2002. The few studies performed on pollination syndromes in extra-tropical South America provide support to such generalization.…”

“…The climate is of a semiarid Mediterranean type with most rainfall concentrated in the winter season. Mean annual precipitation is 167 mm (data from 1974 to 1999), with ample inter-annual variation and long-lasting droughts alternated with unusual years of high precipitation that seemingly co-occur with ENSO events (Jaksic 2001 (Medel et al 2004). Additional cactus species are represented by the columnar Eulychnia acida Phil., and the spheric-shaped Cumulopuntia sphaerica (Foerster) E.F. Anderson and Eriosyce aurata (Pfeiff.)…”

Global weather and local butterflies: variable responses to a large‐scale climate pattern along an elevational gradient

“…Large-scale climatic phenomena, such as the El Nin˜o Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), influence weather patterns around the world and provide an opportunity to evaluate the effects of climatic variation on natural populations (Holmgren et al 2001, Jaksic 2001, Stenseth et al 2003, Hallett et al 2004, Halkka et al 2006, Roland and Matter 2013. Such large-scale climatic phenomena are of particular interest because they have the potential to homogenize or synchronize biotic patterns of phenology or population abundance across large areas (Post and Forchhammer 2002, Stenseth et al 2003, Hallett et al 2004, Halkka et al 2006.…”

Subtidal macrozoobenthos communities from northern Chile during and post El Niño 1997–1998

“…phenomenon affecting physicochemical processes and biota in both marine and terrestrial ecosystems of western South America (Cowles et al 1977;Barber and Chavez 1983;Dayton et al 1999;Jaksic 2001). The coastal upwelling zone of the Humboldt current system (HCS) in the south-eastern Pacific is subject to strong variability during El Niño (the oceanographic component of ENSO) events (e.g., 1982-1983, 1997-1998), where this phenomenon has an important role as disturber agent causing modifications in the coastal biota at different scales (e.g., Glynn 1988;Camus 1990;Arntz and Fahrbach 1996;Arntz et al 2006;Vásquez et al 2006).…”