Comparative Chemical Characterisation of Soils at Cypripedium Calceolus Sites in Latvia

Soil properties and plant species can predict population size and potential introduction sites of the endangered orchid Cypripedium calceolus

“…In opposition with the results of the vegetation types, and based on the total number of existing soil references (110 in Baize and Girard (2009) and 32 soil groups in IUSS (IUSS Working Group 2015)), we thus found that C. calceolus grows on a very limited range of soil types, attesting that C. calceolus preferentially grows on calcareous or dolomitic substrate (with average pH of 7.81). Moreover, the physicochemical characteristics results corroborate what is generally found in the literature: C. calceolus grows in soil with neutral to alkaline pH (Rusconi et al 2022) with the presence of calcium carbonates (in the form of CaCO 3 or CaMg(CO 3 ) 2 ) (Käsermann and Moser 1999) and with on average a high concentration of soil organic matter (Kļaviņa and Osvalde 2017). The observations regarding the humus forms, Mull-to-Moder, also support the notion that the rooting of this plant is where biological activity is relatively intense and where the organic matter is well and rapidly integrated into the soil matrix (Zanella et al 2018).…”

“…Moreover, C. calceolus seems to prefer richer substrates when in the shade compared to when growing in sunnier conditions, which may be due to the competition effect with other plant species (Käsermann and Moser 1999). Indeed, Kļaviņa and Osvalde (2017) noticed a positive relationship between the population size of C. calceolus and soil organic matter concentration. Finally, Devillers-Terschuren (1999) showed that C. calceolus grow better on moderately moist soils.…”

“…In Switzerland, C. calceolus has been found growing in as many as up to 14 different vegetation alliances, with a preference for the Cephalanthero-Fagenion (xerothermophilous beech forest) and the Erico-Pinion (basophilic subcontinental pine forest) alliances (Delarze et al 2015;Käsermann and Moser 1999), suggesting that woodland type is not so constraining as previously thought. Concerning soil properties, it has been shown that C. calceolus can grow on a large variety of soil types (Kļaviņa and Osvalde 2017;Rusconi et al 2022) -with some caveats. First, C. calceolus appears to grow better in base-rich soils containing calcium carbonates (Kull 1999), which usually occur over limestone or dolomite bedrock (Käsermann and Moser 1999;Kull 1999).…”

“…4) Is the population size of C. calceolus dependent on local edaphic properties? We hypothesised that while this plant species has broad ecological preferences, some facets of the vegetation or soil physico-chemical properties can be used to explain why some populations perform better than others (Devillers-Terschuren 1999; Kļaviņa and Osvalde 2017;Kull 1999;Onuch and Skwaryło-Bednarz 2014), and therefore, plant species performance, estimated using specific plant functional traits, could be linked to unique combinations of vegetation and soil properties, which ultimately would be used to inform more efficient conservation efforts.…”

Detecting preservation and reintroduction sites for endangered plant species using a two‐step modeling and field approach

“…Despite these findings, other ecological parameters found in the literature correspond to those we observed. Notably, soils of native populations always contained calcium carbonates (Käsermann & Moser, 1999; Kļaviņa & Osvalde, 2017; Kull, 1999). In summary, we observe that C. calceolus needs soils with a neutral to basic pH containing calcium carbonates, and requires a delicate balance of light, moisture, and bases richness (Devillers‐Terschuren, 1999).…”