Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

VAN BELLEN, SIMON; MAUQUOY, DMITRI; RICHARD J. PAYNE; THOMAS P. ROLAND; TIM J. DALEY; HUGHES, PAUL; LOADER N.,; RICE, E; PANCOTTO V. A,

JOURNAL OF QUATERNARY SCIENCE

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2014 vol. 29 p. 463 - 474

0267-8179

Testate amoebae are abundant and diverse in Sphagnum peat bogs and have been used extensively as indicators of water table depths over decadal to millennial timescales. Although these unicellular protists are widely dispersed with globally similar hydrological preferences, regional variations in communities and ecology demand region-specific transfer functions. Here we present the first transfer function for southern Patagonian bogs, based on 154 surface samples obtained from transects in five bogs sampled in 2012 and 2013. Significant variance was explained by pH, electrical conductivity and, particularly, water table depth. Transfer functions for water table were constructed using weighted averaging and evaluated by cross-validation and independent test sets. The optimal transfer function has predictive ability, but relatively high RMSEP given the long water table gradient. The use of independent test sets, as well as cross-validation, allows for a more rigorous assessment of model performance than most studies. Results highlight the deterioration in performance that may result when applying transfer functions beyond those sites used in their construction. For a subset of locations we compare surface and subsurface samples to demonstrate significant differences in community composition, possibly due to vertical zonation. Our results provide the first quantification of hydrological optima and tolerances for a number of rarer species, which may include Southern Hemisphere endemics and pave the way for palaeohydrological reconstructions in southern Patagonian bogs.