The multidisciplinary study of sediment cores from Laguna Zoñar (37°29′00″ N, 4°41′22″ W, 300 m a.s.l., Andalucía, Spain) provides a detailed record of environmental, climatic and anthropogenic changes in a Mediterranean watershed since Medieval times, and an opportunity to evaluate the lake restoration policies during the last decades. The paleohydrological reconstructions show fluctuating lake levels since the end of the Medieval Warm Period (ca. AD 1300) till the late 19th century and a more acute dry period during the late 19th century - early 20th century, after the end of the Little Ice Age. Human activities have played a significant role in Laguna Zoñar hydrological changes since the late 19th century, when the outlet was drained, and particularly in the mid-20th century (till 1982) when the spring waters feeding the lake were diverted for human use. Two main periods of increased human activities in the watershed are recorded in the sediments. The first started with the Christian conquest and colonization of the Guadalquivir River Valley (13th century) particularly after the fall of the Granada Kingdom (15th century). The second one corresponds to the late 19th century when more land was dedicated to olive cultivation. Intensification of soil erosion occurred in the mid-20th century, after the introduction of farm machinery. The lake was declared a protected area in the early 1980s, when some agricultural practices were restricted, and conservation measures implemented. As a consequence, the lake level increased, and some littoral zones were submerged. Pollen indicators reflect this limnological change during the last few decades. Geochemical indicators show a relative decrease in soil erosion, but not changes in the amount of chemical fertilizers reaching the lake. This study provides an opportunity to evaluate the relative significance of human vs. climatic factors in lake hydrology and watershed changes during historical times. Paleolimnological reconstructions should be taken into account by natural resources agencies to better define lake management policies, and to assess the results of restoration policies.
Bibliographical noteFunding Information:
Financial support for research at Laguna Zoñar was provided by the Spanish Inter-Ministry Commission of Science and Technology (CICYT), REN 2000–1136 Project ‘‘Arid periods in the Mediterranean areas of the Iberian Peninsula since the last glacial maximum: chronology, characterization and paleoclimate implications’’. Funding by projects REN 2003–02499GLO and PI 17/739/ FS is also acknowledged. We thank the Director and the staff of the ‘‘Southern Cordoba Lakes Natural Reserve’’ for their help during fieldwork and also for access to unpublished data. Dirk Verschuren (Gent University, Belgium) helped to retrieve and sample the cores. We are grateful to Piero Guilizzoni and Bill Last for their comments and criticisms that improved the manuscript.
Copyright 2008 Elsevier B.V., All rights reserved.
- Ecological restoration
- Human impact
- Late Holocene
- Olive cultivation
- Western Mediterranean