Predicting local responses of epiphytic lichen vegetation to regional climate change scenarios
(English)Manuscript (Other academic)
In northern Europe, projected climate change indicates annual warming and increased precipitation, especially during winter. The aim of this study was to assess potential responses to this of poikilohydric and epiphytic lichens that are closely coupled to the local atmospheric conditions, and consequently to climate change. Two scenarios, one moderate and another more intense emission scenario (SRES B2 and A2, respectively) for northern Europe, was used to assess regional climate changes. Both scenarios used the combination of projected changes in temperature (T), humidity (RH) and irradiance (I) towards the end of the 21st century. To generate local climate changes we used microclimate time series from 1993-94 of two contrasting habitats, an interior and an open site, and transformed them by superimposing the regional scenarios. We developed a physiological net carbon gain (NCG) model for Platismatia glauca on the responses of photosynthesis and respiration in relation to I, T and water content (WC), which was simulated by a lichen hydration model using RH and T, and growth. Carbon gain and growth was simulated for reference and the two climate local scenarios during one year, and validated against growth for the reference conditions. The growth response was two times higher at the lighter, exposed site compared to the interior site, in agreement with measured growth. However, the responses to climate change were not uniform locally or seasonally, mainly due to the changed patterns of hydration and whether irradiances were limiting or not during the wet periods. At the darker, interior site of the forest, growth was reduced due to climate change but was in contrast equal or increased at the lighter, exposed site. This was caused by a general increased growth during the more humid spring and a reduced or equal growth response during the drier summer and during the wetter, dark winter. The increasingly favored growth conditions at exposed sites will possibly favor lichens that can manage the potentially adverse effects of increased wind exposure at these sites. At darker sites, the lichens will likely be outcompeted by bryophytes that are better adapted to dark and wet conditions. It is thus likely that the realized niche of lichens will be reduced, with a shift in optimum abundance towards more exposed habitats, or even more reduced for pendulous lichens that are hampered by increased wind at the most exposed sites.
epiphytic lichen, Platismatia glauca, climate change scenarios, net carbon gain model, simulation, respiration, photosynthesis, growth
Research subject Ecological Botany
IdentifiersURN: urn:nbn:se:umu:diva-22542OAI: oai:DiVA.org:umu-22542DiVA: diva2:216983