Mire microclimate: Groundwater buffers temperature in waterlogged versus dry soils

Abstract

Ecosystems adapt differently to global warming through microclimatic factors. Mires are sensitive wetland habitats that strongly rely on local soil properties, making them a good model to understand how local climatic parameters counteract the effects of climate change. We quantified the temperature buffering effect in waterlogged mire soils as compared with adjacent dry soils. We buried dataloggers at 5 cm depth in waterlogged and dry points in eight mires of the Cantabrian Mountains (Spain, southwestern Europe) and recorded soil temperatures for ca. 5 years. We also compared our local measures with air temperatures predicted by the CHELSA model. Waterlogged soils had less diurnal thermal amplitude (−2.3 C), less annual thermal amplitude (−5.1 C), cooler summer maxima (−4.3 C) and warmer winter minima (+0.8 C). CHELSA air temperatures only correlated significantly (p < .05) with winter minimum soil temperatures (Pearson's r > .83), and CHELSA predictions were less accurate (higher root-mean-square error [RMSE]) for waterlogged soils, except for the summer maxima. We conclude that mire soils show a thermal buffer effect that insulates them from the surrounding landscape. This effect is stronger at the warm end of the climatic spectrum, that is, during summer and at lower elevations. These results highlight the potential refugial character of mires under global warming, and the need to integrate microclimate measurements into climate change models.

Spring water table depth mediates within‐site variation of soil temperature in groundwater‐fed mires

“…Along with previous studies (e.g. Fernández‐Pascual & Correia‐Álvarez, 2021), our results also suggest that thermal buffering is profound particularly in the cold part of the season. In the warm part of the year, however, the buffering was detected as well.…”

“…Frederick, 1974; Raney et al, 2014, 2016) and Europe (e.g. Fernández‐Pascual et al, 2015; Fernández‐Pascual & Correia‐Álvarez, 2021; Horsák et al, 2018). However, our study differs from all previous studies as we primarily focussed on the within‐site variation of the thermal buffering related to spring hydrology.…”

“…Frederick, 1974;Raney et al, 2014Raney et al, , 2016 and Europe (e.g. Fernández-Pascual et al, 2015;Fernández-Pascual & Correia-Alvarez, 2021;.…”

“…Since then, the groundwater buffer effect on soil temperature, maintaining soils warmer than air during cold periods and vice versa, has been repeatedly detected mostly from mire ecosystems (Ellenberg, 1988;Fernández-Pascual et al, 2015;Geiger et al, 2009;Raney et al, 2014;Raney et al, 2016). It has been demonstrated by a comparison with air temperatures derived from climate models (Fernández-Pascual et al, 2015;, and also with temperature measurements in dry soils at 10 cm depth (Raney et al, 2014(Raney et al, , 2016 and 5 cm depth (Fernández-Pascual & Correia-Alvarez, 2021). The importance of buffer effect for tree growth in mires (Raney et al, 2016) and species composition variance in mire flora, and terrestrial and aquatic fauna Schenková et al, 2020) has been clearly identified.…”

Habitat‐based biodiversity responses to macroclimate and edaphic factors in European fen ecosystems

“…However, fens with cold-adapted species also occur in mountain refugia within regions characterized by warmer macroclimates, where they have become increasingly rare (Jimenez-Alfaro et al, 2012;Peterson-Smith et al, 2008). These regions host relict populations of fen specialists in peripheral macroclimatic zones where climate warming is anticipated to diminish their capacity to survive in local refugia provided by fen types with specific edaphic conditions (Fernández-Pascual & Correia-Álvarez, 2021;.…”