Growth and ecophysiological acclimation of the foliose lichen Lobaria pulmonaria in forests with contrasting light climates

Abstract

This study aims to assess biomass and area growth of 600 thalli of the old forest lichen, Lobaria pulmonaria, transplanted to three successional boreal forest stands with (1) natural rainfall regime, (2) additional moistening during dry days, and (3) additional moistening with added nutrients. Mean biomass growth during 100 days varied from 8.3% in the dark young spruce forest to 23.1% in the clear-cut area, with the old forest in between (16.0%). Additional moistening did not enhance lichen growth, probably because the transplantation period was wet. Nutrient additions slightly increased area growth compared to artificial water additions only. Growth was determined by a combination of external (forest stand, site factors) and internal factors (chlorophyll content, biomass per area). Transplants acclimated to high light by increasing thickness and chlorophyll a/b-ratio. Some visible bleaching and a strong positive correlation between chlorophyll content per area and lichen growth in clear-cuts suggest some high light-induced chlorophyll degradation. We believe that biomass growth and natural occurrence of L. pulmonaria is controlled by a delicate balance between light availability and desiccation risk, and that the species is confined to old forests due to a physiological trade-off between growth potential and fatal desiccation damage, both of which increase with increasing light. The discrepancy between potential and realized ecological niches is probably caused by a long-term risk to be killed in open habitats by high light during long periods with no rain.

Influence of sun irradiance and water availability on lichen photosynthetic pigments during a Mediterranean summer

“…Protection mechanisms vary according to the peculiarities of the species and the habitat and are mainly based on the arrangement of photosynthetic pigments and secondary metabolites (Kappen 1983;Gauslaa et al 2006) and physiological, anatomical and morphological plasticity of each species (Hyvärinen 1992;Pintado et al 1997).…”

Threatened forest lichen Lobaria pulmonaria - its past, present and future in Estonia

“…the selective cutting of forest or woodland, need not be harmful to individual specimens of L. pulmonaria if the host trees and the potential host trees remain intact. Moreover, the increased amount of light may favour the lichen in the habitat (Gauslaa et al, 2006;Coxson & Stevenson, 2007). Therefore we suggest that the restoration of overgrown wooded meadows in which L. pulmonaria is present should be done with special care, because abrupt changes in the light and moisture regime of the habitat likely affect the populations of L. pulmonaria.…”

Retention forestry and intensified biomass harvest: epiphytic lichen assemblages under opposing ecological effects in pine-dominated boreal forests

“…Indeed, lichen morphology is regarded as important in determining their ability to survive in open sites (Jairus et al, 2009). High light levels can be harmful for microlichens, especially those that lack a protective cortex (Hedenås and Hedström, 2007;Jairus et al, 2009), while certain foliose macrolichens may, on the contrary, benefit from the increased light (Sillett et al, 2000a;Gauslaa et al, 2006) or from higher precipitation at ground level after harvest (Boudreault et al, 2013).…”