A chironomid-based salinity inference model from lakes on the Tibetan Plateau


Zhang, E., Jones, R., Bedford, A., Langdon, P.G. and Tang, H. (2007) A chironomid-based salinity inference model from lakes on the Tibetan Plateau. Journal of Paleolimnology, 38, (4), 477-491. (doi:10.1007/s10933-006-9080-z).

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Description/Abstract

Previous studies have shown chironomids
to be excellent indicators of environmental change
and training sets have been developed in order to
allow these changes to be reconstructed quantitatively
from subfossil sequences. Here we present the results
of an investigation into the relationships between
surface sediment subfossil chironomid distribution
and lake environmental variables from 42 lakes on the
Tibetan Plateau. Canonical correspondence analysis
(CCA) revealed that of the 11measured environmental
variables, salinity (measured as total dissolved
solids TDS) was most important, accounting for 10.5% of the variance in the chironomid data. This
variable was significant enough to allow the development
of quantitative inference models. A range of
TDS inference models were developed using
Weighted Averaging (WA), Partial Least Squares
(PLS), Weighted Averaging–Partial Least Squares
(WA–PLS), Maximum Likelihood (ML), Modern
Analogues Technique (MAT) and Modern Analogues
Techniques weighted by similarity (WMAT).
Evaluation of the site data indicated that four lakes
were major outliers, and after omitting these fromthe
training set the models produced jack-knifed coefficients
of determination (r2) between 0.60 and 0.80, and
root-mean-squared errors of prediction (RMSEP)
between 0.29 and 0.44 log10 TDS. The best performing
model was the two-component WA–PLS model with
r2
jack = 0.80 and RMSEPjack = 0.29 log10 TDS. The
model results were similar to other chironomidsalinity
models developed in different regions, and
they also showed similar ecological groupings along
the salinity gradientwith respect to freshwater/salinity
thresholds and community diversity. These results
therefore indicate that similar processes may be
controlling chironomid distribution across salinity
gradients irrespective of biogeographical constraints.
The performance of the transfer functions illustrates
that chironomid assemblages from the Tibetan Plateau
lakes are clearly sensitive indicators of salinity.
The models will therefore allow the quantification of
long-term records of past water salinity for lacustrine
sites across the Tibetan Plateau, which has important implications for future hydrological research in the
region.

Item Type: Article
ISSNs: 0921-2728 (print)
Related URLs:
Keywords: chironomids, hydrological balance, lakes, Tibetan Plateau, transfer functions, Total Dissolved Salts (TDS)
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
G Geography. Anthropology. Recreation > GB Physical geography
Divisions: University Structure - Pre August 2011 > School of Geography > Environmental Processes and Change
ePrint ID: 55020
Date Deposited: 01 Aug 2008
Last Modified: 27 Mar 2014 18:37
Contact Email Address: p.g.langdon@soton.ac.uk
URI: http://eprints.soton.ac.uk/id/eprint/55020

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