(Collaboration between Gerhard Zotz and Maaike Bader, Marburg)

Bryophytes (mosses and liverworts) and lichens in the warm tropics have been suggested to exist at the edge of their physiological abilities, because they lose a large proportion of their daily carbon gain to nightly respiration, principally due to the high temperatures. A rise in temperature may therefore force bryophytes uphill and cause their complete disappearance from the lowland tropics, where they already have low abundances compared to higher elevations. We aimed to explain the observed elevational gradient in bryophyte abundance in the tropics and to predict the effects of climatic warming. We use experimental and modelling approaches, with transplant and laboratory experiments and gas exchange and fluorescence measurements, to determine carbon balances, acclimatization potentials and desiccation tolerance of a range of tropical lowland and montane bryophyte species in Panama. A specific approach is the study of the effect of climate change on hydration patterns, activity times and resulting carbon balances, and 2) the acclimatization potential of lowland species to higher temperatures, using active experimental warming.

A typical mossy tree trunk in the montane cloud forest of Fortuna (western Panama, 1200 m, featuring also a young bromeliad), and a typical moss-free tree trunk (covered only with crustose lichens) in the lowland rain forest on Barro Colorado Island (Panama Canal, 25 m).

Publications:

Zotz G, Bader MY. 2023. The physiology of lichens and bryophytes in the tropical lowlands. In: The First 100 Years of Research on Barro Colorado Island – Plant and Ecosystem Biology, Eds.: Muller-Landau HC, Wright SJ; Washington, D.C.

Bader MY, Moureau E, Nikolić N, Madena T, Koehn N & Zotz G. 2022. Simulating climate change in situ in a tropical rainforest understorey using active air warming and CO₂ addition. Ecology and Evolution 12: e8406. https://doi.org/10.1002/ece3.8406

Gómez González DC, Rodríguez Quiel C, Zotz G & Bader MY. 2017. Species richness and biomass of epiphytic vegetation in a tropical montane forest, western Panama. Tropical Conservation Science 10: 1-17.

Gómez González DC, Zotz G & Bader MY. 2021. The role of epiphytes in rainfall interception of a tropical montane cloud forest in Panama. Pages 203-212 in Dalling JW & Turner BL, editors. Fortuna Forest Reserve, Panama: interacting effects of climate and soils on the biota of a wet premontane tropical forest. Smithsonian Books, Washington, D.C.

Wagner S, Zotz G & Bader MY. 2014. The temperature acclimation potential of tropical bryophytes. Plant Biology 16: 117-124.

Wagner S, Zotz G, Salazar Allen N & Bader MY. 2013. Altitudinal changes in temperature responses of net photosynthesis and dark respiration in tropical bryophytes. Annals of Botany 111: 455–465.

Noris Salazar Allen, Smithsonian Tropical Research Institute, Panama

Herbario, Universidad Autónoma de Chiriquí, Panama