Biogeochemical responses to Holocene catchment-lake dynamics in the Tasmanian World Heritage Area, Australia

Mariani, Michela and Beck, Kristen and Fletcher, Michael-Shawn and Gell, Peter and Saunders, Krystyna M. and Gadd, Patricia and Chisari, Robert (2018) Biogeochemical responses to Holocene catchment-lake dynamics in the Tasmanian World Heritage Area, Australia. Journal of Geophysical Research: Biogeosciences, 123 (5). pp. 1610-1624. ISSN 1944-1517

Full content URL: http://doi.org/10.1029/2017JG004136

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Biogeochemical responses to Holocene catchment-lake dynamics in the Tasmanian World Heritage Area, Australia
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Abstract

Environmental changes such as climate, land use, and fire activity affect terrestrial and aquatic
ecosystems at multiple scales of space and time. Due to the nature of the interactions between terrestrial
and aquatic dynamics, an integrated study using multiple proxies is critical for a better understanding of
climate- and fire-driven impacts on environmental change. Here we present a synthesis of biological and
geochemical data (pollen, spores, diatoms, micro X-ray fluorescence scanning, CN content, and stable
isotopes) from Dove Lake, Tasmania, allowing us to disentangle long-term terrestrial-aquatic dynamics
through the last 12 kyear. We found that aquatic dynamics at Dove Lake are tightly linked to vegetation shifts
dictated by regional hydroclimatic variability in western Tasmania. A major shift in the diatom
composition was detected at ca. 6 ka, and it was likely mediated by changes in regional terrestrial vegetation,
charcoal, and iron accumulation. High rainforest abundance prior ca. 6 ka is linked to increased
terrestrially derived organic matter delivery into the lake, higher dystrophy, anoxic bottom conditions, and
lower light penetration depths. The shift to a landscape with a higher proportion of sclerophyll species
following the intensification of El Niño-Southern Oscillation since ca. 6 ka corresponds to a decline in
terrestrial organic matter input into Dove Lake, lower dystrophy levels, higher oxygen availability, and higher
light availability for algae and littoral macrophytes. This record provides new insights on terrestrial-aquatic
dynamics that could contribute to the conservation management plans in the Tasmanian World Heritage
Area and in temperate high-altitude dystrophic systems elsewhere.

Keywords:Holocene, climate, Tasmania, geochemistry, nutrients, vegetation
Subjects:F Physical Sciences > F840 Physical Geography
Divisions:College of Science > School of Geography
ID Code:32130
Deposited On:08 Oct 2018 10:34

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