Chemical diversity and ecology of the genus Bryoria section Implexae (Parmeliaceae) in Finland

Bryoria section Implexae is a chemically and morphologically diverse group characterized by pendent growth form and non-spinulose branches. In this study, we examine the chemical diversity, distribution pattern and habitat preferences of European members of section Implexae in Finland. A total of 1253 specimens were collected from four vegetation zones and analysed with thin layer chromatography for secondary chemistry. Secondary chemistry of the specimens and vegetation zones had a significant interaction term in a generalized linear model (GLM) of sample frequencies, indicating that chemotype frequencies differed among vegetation zones. Forest structure interacted with vegetation zones and chemotypes indicating that chemotypes differed among forest structure classes, but also showing that forest structure classes differed among vegetation zones. The overall abundance of Bryoria spp. was significantly different among vegetation zones, increasing substantially from south to north. The abundance was also significantly higher in managed than in old-growth stands in the southern and in the middle boreal zones. This result may reflect the sampling scheme used in the study and shows that members of Implexae can thrive under favorable environmental conditions also in mature managed stands. Barbatolic acid was the most common chemotype, but its proportion clearly declined towards north. The characteristic distribution pattern suggests that the chemotype tolerates shady habitats typical for southern and middle boreal Picea-dominated forests in Finland. The gyrophoric acid chemotype was frequent in the middle boreal zone, but was relatively rare in the hemiboreal and northern boreal zones. The fumarprotocetraric acid chemotype occurred throughout the study area but was especially frequent in the southern boreal zone. The acid-deficient chemotype was most abundant in the northern boreal zone and was preferably late successional in the southern and middle boreal zones. Norstictic acid and psoromic acid chemotypes were both rare and continental in their distribution pattern and confined to the middle and especially northern boreal zones where the overall Bryoria abundance is high. According to this study, chemotypes in section Implexae have distinct ecological and climatic preferences despite the lack of genetic variation and this should be taken into account when using them as bioindicators.