title: Sediment delivery and lake dynamics in a Mediterranean mountain watershed: Human-climate interactions during the last millennium (El Tobar Lake record, Iberian Range, Spain).
abstract: Land degradation and soil erosion are key environmental problems in Mediterranean mountains characterized by a long history of human occupation and a strong variability of hydrological regimes. To assess recent trends and evaluate climatic and anthropogenic impacts in these highly human modified watersheds we apply an historical approach combining lake sediment core multi-proxy analyses and reconstructions of past land uses to El Tobar Lake watershed, located in the Iberian Range (Central Spain). Four main periods of increased sediment delivery have been identified in the 8m long sediment sequence by their depositional and geochemical signatures. They took place around 16th, late 18th, mid 19th and early 20th centuries as a result of large land uses changes such as forest clearing, farming and grazing during periods of increasing population. In this highly human-modified watershed, positive synergies between human impact and humid periods led to increased sediment delivery periods. During the last millennium, the lake depositional and geochemical cycles recovered quickly after each sediment delivery event, showing strong resilience of the lacustrine system to watershed disturbance. Recent changes are characterized by large hydrological affections since 1967 with the construction of a canal from a nearby reservoir and a decreased in anthropic pressure in the watershed as rural areas were abandoned. The increased fresh water influx to the lake has caused large biological changes, leading to stronger meromictic conditions and higher organic matter accumulation while terrigenous inputs have decreased. Degradation processes in Iberian Range watersheds are strongly controlled by anthropic activities (land use changes, soil erosion) but modulated by climate-related hydrological changes (water availability, flood and runoff frequency).
authors.affiliation: Dpt. of Geo-environmental Processes and Global Change, Pyrenean Institute of Ecology - CSIC, Spain. Electronic address: ferbalos@ipe.csic.es.
authors.forename: Fernando
authors.initials: F
authors.lastname: Barreiro-Lostres
authors.affiliation: Large Lakes Observatory and Department of Geological Sciences, University of Minnesota Duluth, Duluth, MN 55812, USA. Electronic address: etbrown@d.umn.edu.
authors.forename: Erik
authors.initials: E
authors.lastname: Brown
authors.affiliation: Dpt. of Geo-environmental Processes and Global Change, Pyrenean Institute of Ecology - CSIC, Spain. Electronic address: amoreno@ipe.csic.es.
authors.forename: Ana
authors.initials: A
authors.lastname: Moreno
authors.affiliation: Instituto de Geociencias (CSIC, UCM), Calle José Antonio Nováis, 2, 3ª planta, 3b, Facultad de Ciencias Geológicas, Univ. Complutense, 28040 Madrid, Spain. Electronic address: mario.morellon@igeo.ucm-csic.es.
authors.forename: Mario
authors.initials: M
authors.lastname: Morellón
authors.affiliation: University of Pittsburgh, Geology and Planetary Science. 4107 O'Hara Street, Room 200, SRCC Building Pittsburgh, PA 15260-3332. USA. Electronic address: mabbott1@pitt.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Abbott
authors.affiliation: University of Pittsburgh, Geology and Planetary Science. 4107 O'Hara Street, Room 200, SRCC Building Pittsburgh, PA 15260-3332. USA. Electronic address: alh118@pitt.edu.
authors.forename: Aubrey
authors.initials: A
authors.lastname: Hillman
authors.affiliation: Institute of Earth Sciences Jaume Almera (ICTJA-CSIC), C/ Lluis Solé Sabaris s/n, Barcelona, E-08028 Spain. Electronic address: sgiralt@ictja.csic.es.
authors.forename: Santiago
authors.initials: S
authors.lastname: Giralt
authors.affiliation: Dpt. of Geo-environmental Processes and Global Change, Pyrenean Institute of Ecology - CSIC, Spain. Electronic address: blas@ipe.csic.es.
authors.forename: Blas
authors.initials: B
authors.lastname: Valero-Garcés
mesh_terms: D057231:Climate Change; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis*; D060106:Lakes / Q000737:chemistry*; D013030:Spain; D014876:Water Pollution / Q000706:statistics & numerical data*
keywords: Geochemistry; Iberian Peninsula; Karstic lake; Land use changes; Late Quaternary; Palaeohydrology; Resilience; Sediment delivery