Gypseous soils are widespread across drylands worldwide. They present remarkable challenges to plants and host a unique flora. We aimed to assess if the specificity and distribution of species on gypsum might be driven by species-specific germination responses to soil gypsum availability. We analyzed the germination of six gypsum specialists (gypsophiles) and four closely related generalist plant species (gypsovags) from the Iberian Peninsula and the Chihuahuan Desert in different field soils with contrasting concentrations of gypsum, pH and soil texture. Plant restriction to gypsum was unrelated to the germinating ability of seeds on different substrates. Irrespective of their affinity for gypsum, most species germinated better on mixed gypsum-calcareous soil and worse in the acidic soil treatment. Our data suggest soil pH and Ca availability were the main soil features driving seed germination, while the effect of gypsum content was generally not significant. The main exception was the Iberian gypsophile Helianthemum squamatum (L.) Dum. Cours., which showed increased germination on gypseous soils and higher germination in response to increased soil gypsum content. Except for this species, our findings indicate alkaline soils with high Ca availability favor the germination of most of the species analyzed, irrespectively of their gypsum content.

石膏质土壤广泛分布于世界各地的旱地。它们对植物提出了显着的挑战，并拥有独特的植物群。我们旨在评估石膏上物种的特异性和分布是否可能由物种对土壤石膏可用性的特定萌发反应驱动。我们分析了来自伊比利亚半岛和奇瓦环沙漠的六种石膏专家（满天星）和四种密切相关的通才植物物种 (gypsovags) 在不同石膏浓度、pH 值和土壤质地的不同田间土壤中的萌发情况。植物对石膏的限制与种子在不同基质上的发芽能力无关。不管它们对石膏的亲和力如何，大多数物种在石膏-钙质混合土壤上发芽得更好，而在酸性土壤处理中则更差。我们的数据表明土壤 pH 值和 Ca 有效性是驱动种子萌发的主要土壤特征，而石膏含量的影响通常不显着。主要的例外是伊比利亚满天星Helianthemum squamatum (L.) Dum。Cours.，这表明在石膏质土壤上发芽增加，并且随着土壤石膏含量的增加而发芽率更高。除了这个物种，我们的研究结果表明，具有高钙可用性的碱性土壤有利于大多数被分析物种的发芽，而不管它们的石膏含量如何。