Data for the journal article: 'Ecology of testate amoebae along an environmental gradient from bogs to calcareous fens in East-Central Europe: development of transfer functions for palaeoenvironmental reconstructions'

DATA DESCRIPTION: This repository provides training sets and R scripts for the development of three transfer function models that allow reconstructions of Holocene hydrochemical or hydrological (hydroclimatic) conditions from testate amoeba assemblages preserved in mires of East-Central Europe. Specifically, the repository contains (i) the full dataset and an R script for the development of the final MLRC model for inferring past water-mineral richness (expressed as pH) in various types of mires; (ii) the minerotrophic subset and an R script for the development of the final WAPLS com1 model for the reconstructions of past water-mineral richness (expressed as pH) in calcareous and rich fens; and (iii) the ombrotrophic subset and an R script for the development of the final PLS com2 model for inferring past depth to water table (DWT) in bogs and poor fens. Additionally, the repository includes the original versions of the full, minerotrophic and ombrotrophic training sets (i.e., the versions before removing outlier samples and rare taxa due to transfer function optimisation), and the compiled dataset, from which the three above-mentioned training sets were generated. For details, see Šímová et al. (2022).

ARTICLE ABSTRACT: Testate amoebae play an important role in biomonitoring and the understanding of peatland (palaeo)ecology. However, their application has been mainly limited to Sphagnum-dominated peatlands, especially ombrotrophic bogs. To facilitate wider use of these microorganisms, we explored their ecology along a gradient from mineral-poor acidic bogs to mineral-rich calcareous fens with tufa formation using a new calibration dataset of over 250 samples from East-Central Europe. Specifically, we examined environmental controls on testate amoebae along the complete gradient and separately in the minerotrophic (pH >5.5) and ombrotrophic (pH <5) parts. Based on these findings, we developed and statistically evaluated transfer function models for the dominant factors controlling the community composition of these protists. Multivariate statistical analysis showed that groundwater pH was the main driver of species composition in the full and minerotrophic datasets. In contrast, testate amoeba communities in the ombrotrophic dataset were primarily structured by depth to water table (DWT). Under leave-one-out cross-validation (LOO), the best-performing model for DWT gave a prediction error (RMSEP) of 5.43 cm. The most robust models for groundwater mineral richness yielded RMSEP_LOO of 0.45 and 0.27 pH units, for the full and the minerotrophic dataset respectively. This is the first study to present a complete set of testate amoeba-based transfer functions that allow reconstructions of Holocene hydrochemical and hydrological (hydroclimatic) variability in different mire types within one region. The new models open up the possibility for testate amoebae to become a valuable tool in palaeoecological research, although further work is needed to fully assess their performance and usefulness in practice.