Argentinean grasslands
Enhancing palaeoenvironmental reconstructions in Argentina
a bilateral programme for co-operative research between Germany and Argentina (PROALAR), funded by DAAD and MINCyT, 2013-2014; lead by Sonia Fontana (Germany) and Silvina Stutz (Argentina)
The project aims to study the development of plant communities and the evolution of aquatic systems to elucidate long term changes in vegetation and climate of the last 10,000 years throughout the Pampa plain. Our approach is to build up a network of multi-proxy lake records with a focus on understanding vegetation and lake dynamics in time and space, determining the different forcing factors controlling vegetation composition and trophic states. Sites are selected following the climatic gradient of the region and covering the entire modern range of grasslands in order to obtain a regional view. The new records are then combined with records from existing sites to provide quantitative climate reconstructions.
Previous work
The project builds on earlier collaborative effort initiated by Stutz and colleagues. This work has contributed to the understanding of late-Holocene climate and environmental changes in the south east of the Pampa grasslands (Stutz et al. 2010: Journal of Paleolimnology). Results of this research gave also insights into Holocene changes in trophic states of shallow lakes (Stutz et al. 2012: The Holocene). To explore alternative stable states in the aquatic systems, we integrate and compare three paleolimnological records from the region:
The three fossil records document similar lake developments during the mid and late Holocene, with changes occurring broadly at the same time. Three main phases are recognized: (i) a clear lake dominated by macrophytes that prevailed until ~700 cal. yr BP at lakes Lonkoy and Nahuel Rucá, and until ~400 cal. yr BP at lake Hinojales; (ii) afterwards the lakes changed to a turbid state dominated by phytoplankton; (iii) recently, the lakes have turned inorganic-turbid because of the high amount of suspended inorganic material, resulted from intensive farming. The shift from clear to turbid state may be caused by a regional climatic shift towards wetter conditions after 1000 cal. yr BP, during the Medieval Climate Anomaly. Clear and phytoplankton-turbid lakes occur today within the region, suggesting that additional factors may have played a role to cause the shift.
In addition, the research conducted by Tonello on quantitative climatic reconstructions adds a new perspective on the region’s environmental changes (Tonello and Prieto 2010: Ameghiniana).
The current need for a better interpretation of changes in vegetation composition and in trophic state of lakes throughout the Argentinean grasslands has lead to this new research activity. The outcome of this project will contribute significantly to understanding of drivers of biodiversity behaviour on long timescales.
Group members
University of Goettingen, Germany
University of Mar del Plata, Argentina
- Marcela Tonello
- Diego Navarro
- Guillermina Sánchez Vuichard