Quantitative variation of usnic acid in response to elevation and microsite conditions in Usnea amblyoclada: Chemometric modeling for predicting the effects of climate change

Abstract

Mountain ecosystems offer a unique opportunity to investigate organism responses to different climatic patterns. In this study, we aimed to test the hypothesis that the usnic acid (UA) content per mass unit and the total extract yield of Usnea amblyoclada (Müll. Arg.) Zahlbr. would increase in exposed microsites (i.e., northern and flat microsites) and at higher elevations (i.e., 1800 m.a.s.l. and 2100 m.a.s.l.). A total of 27 U. amblyoclada extract samples were analyzed to assess UA concentration and total extraction yield. Generalized linear models revealed a significant difference in UA concentration among elevations (p > 0.01). Tukey’s post hoc test indicated that UA concentration was significantly lower at higher elevations (i.e., between 900 and 2100 m.a.s.l.), with no significant differences observed between the 1800 and 900 m.a.s.l. elevations, nor between the 1800 and 2100 m.a.s.l. elevations. In conclusion, our study provides insights into the relationship between UA content, elevation, and temperature in U. amblyoclada. These findings highlight the importance of considering temperature as the primary driver of UA concentration variations in this species, shedding light on the responses of organisms to distinct climatic patterns in mountain ecosystems.