Document: JUL-3-32-1

Ephemeral plant responses to El Nio Current in a semiarid ecosystem of northcentral Chile.

GUTIERREZ, J.R.* ¹ and P.L.MESERVE ²

Universidad de La Serena, La Serena, CHILE ¹
Northern Illinois University, DeKalb, IL, USA ²

Abstract:
In northcentral Chile, as in other arid regions worldwide, drought years (5-7) are followed by 1-2 years of above-average precipitation. These infrequent but periodic pulses of water are often attributed to El Nio/Southern Oscillation (ENSO) events, which originate off the northeastern coast of Australia, causing multiple effects on the biota of the western coastline of the Americas. Cover and soil seed density of ephemeral plants in Parque Nacional Fray Jorge, northcentral Chile, has been monitored for 11 years (1989-1999) spanning two ENSO events (1991-92, 1997). There was a positive and significant response of ephemeral plants to rainfall increases caused by ENSO events. Some species were present aboveground only in ENSO years. This study suggests that species responding to the large infrequent water pulses associated with El Nios leave large seed reserves in this favorable "window" which allow them to persist in the system. The high productivity of ephemeral plants during a wet year negatively affected the plant productivity of the next year, suggesting nutrient limiting effects. The strong response of ephemerals and of the seed bank to the ENSO events demonstrate the importance of this phenomenon in replenishment, recouperation, and likely, maintenance of ephemeral vegetation in the semiarid region of Chile.

Keywords: semiarid systems, El Nio, ephemerals, rainfall pulses

This abstract is being presented at: 3:30 PM in session:
CLIMATE CHANGE