Lessons from farming in the Argentine Pampas: Ecological feedbacks, thresholds and collapses during the last century
by
Ernesto F. Viglizzo
INTA/CONICET, Environmental Management Program. Av. Spinetto 785, POB 302, (6300) Santa Rosa, La Pampa, Argentina
Coauthors: Federico C. Frank

The persistent declining supply of various ecosystem services is cause of increasing concern in the Pampas of Argentina. While the provision of services which have a market value (mainly food and fibre) persistently tend to increase, other non-marketable natural services such as erosion control, fresh water supply, climate and water regulation, water and air decontamination, habitat provisioning for biodiversity, nutrient cycling, etc. have tended to decline. From a temporal perspective, the rural environment in the Pampas showed two opposite changes in response to human intervention since the beginning of colonization, around 1880. The first change began in 1880 and lasted until the 1950's decade. The second (and opposite) one occurred between the 1960's and the beginning of the 21st century. Those changes affected the provisioning of essential ecosystem services through the 20th century. But beyond these variations, two ecological collapses occurred in the Pampas during the last century that drastically cut the provisiong of both, agricultural and ecological services. Apparently, some critical ecological thresholds have been surpassed in both cases. They can be explained by a negative interaction of natural and human drivers, and certainly provide useful lessons for the future. An extremely dry period that have interacted with strong human interventions (through over-grazing and over-cropping) during the first half of the 20 th century, was described as the main cause of the first collapse: the so-called “dust-bowl” of the Western Pampas. As consequence of this, a drastic removal of cattle, crops and even rural population seems to be the ecosystem feedback response to recover from this ecological collapse. At the end of the century, on the other hand, a humid period showed a negative interaction with a second intense farming wave. This was in turn considered a prime cause of extensive flooding in the same area, which has not still recovered from this second ecological incident.

Ecological changes and collapses in the Pampas can be interpreted through agro-ecological indicators. Supported by a so-called Agro-Eco-Index model, indicators that are related to the supply of ecosystem services have supported our cross-scale studies. The environmental behaviour of individual farms at the farm-scale, and the identification of geographical patterns of environmental degradation at the ecosystem-scale are essential inputs to describe and understand the whole ecological process. Looking at the future, if intensification proceeds in coming years as trends indicate, not surprisingly the Pampas will increase their importance as food supplier and price builder within the global market. But at the same time, intensification will affect the supply of critical ecosystem services, and might eventually be cause of unexpected ecological collapses.

Date received: January 11, 2005

Copyright © 2005 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caod-68.