Palacio Sara, Escudero Adrián, Montserrat-Martí Gabriel, Maestro Melchor, Milla Rubén, Albert María J
Pyrenean Institute of Ecology (CSIC), Av. Montañana 1005, Apdo. 202, 50192 Zaragoza, Spain.
Ann Bot. 2007 Feb;99(2):333-43. doi: 10.1093/aob/mcl263. Epub 2007 Jan 4.
Plants from gypsum habitats are classified as gypsophiles and gypsovags. The former include both narrow endemics limited to small gypsum areas and regionally dominant gypsophiles growing in gypsum areas of large regions, whereas gypsovags are plants that can grow both in gypsum and non-gypsum soils. Factors controlling the distribution of gypsum plants are still not fully understood.
To assess how the different types of gypsum plants deal with the stressful conditions of gypsum substrates, comparisons were made of the leaf chemical composition of four gypsovags, five regionally dominant gypsophiles and four narrow gypsum endemics growing in two massive gypsum areas of the Iberian Peninsula.
The chemical composition of gypsovags was clearly different from regionally dominant gypsophiles, while the chemical composition of narrow-gypsophile endemics was more similar to the chemical composition of gypsovags than to that of regionally dominant gypsophiles. Regionally dominant gypsophiles showed higher concentrations of ash, Ca, S, N, Mg P and Na, whereas gypsovags and local gypsophile endemics displayed higher concentrations of C and greater C : N ratios.
Such differences suggest that the three groups of gypsum plants follow diverse ecological strategies. It is suggested that regionally dominant gypsophiles might fit the 'specialist' model, being species specifically adapted to gypsum, whereas both gypsovags and narrow-gypsophile endemics might fit the 'refuge' model, being stress-tolerant species that find refuge on gypsum soils from competition. The analysis of the leaf chemical composition could be a good predictor of the degree of plants specialization to gypsum soils.
生长于石膏生境的植物可分为适钙植物和兼性适钙植物。前者包括局限于小块石膏区域的狭域特有种以及在大片区域的石膏地生长的区域优势适钙植物，而兼性适钙植物是既能在石膏土壤也能在非石膏土壤中生长的植物。控制石膏植物分布的因素仍未完全明了。
为评估不同类型的石膏植物如何应对石膏基质的胁迫条件，对生长在伊比利亚半岛两个块状石膏区域的四种兼性适钙植物、五种区域优势适钙植物和四种狭域石膏特有种的叶片化学成分进行了比较。
兼性适钙植物的化学成分与区域优势适钙植物明显不同，而狭域适钙特有种的化学成分与兼性适钙植物的更相似而非与区域优势适钙植物的相似。区域优势适钙植物的灰分、钙、硫、氮、镁、磷和钠含量较高，而兼性适钙植物和当地适钙特有种的碳含量较高且碳氮比更大。
这些差异表明这三类石膏植物遵循不同的生态策略。有人提出，区域优势适钙植物可能符合“专家”模式，即专门适应石膏的物种，而兼性适钙植物和狭域适钙特有种可能符合“避难所”模式，即耐胁迫物种，在石膏土壤上免受竞争。叶片化学成分分析可能是植物对石膏土壤专一化程度的良好预测指标。
