Light use efficiency of dry matter gain in five macro‐lichens: relative impact of microclimate conditions and species‐specific traits

Abstract

Relations between irradiance (I) and lichen growth were investigated for five macro-lichens growing at two sites in Sweden. The lichens represented different mycobiontphotobiont associations, two morphologies (foliose, fruticose) and two life forms (epiphytic, terricolous). The lichens were transplanted at two geographically distant sites in Sweden (1000 km apart) from Sept 1995 to Sept 1996 in their typical microhabitats, where microclimate and growth were followed. Between April/May and Sept 96, the terricolous species had a dry matter gain of 0·2 to 0·4 g (g DW) -1 and the epiphytes 0·01 to 0·02 g (g DW) -1 . When related to area, growth amounted to 30 to 70 g m --2 for the terricolous species and to 1 to 4 g m --2 for the epiphytes. There was a strong correlation between growth and intercepted irradiance when the lichens were wet (I wet ), with 0·2 to 1·1 g lichen dry matter being produced per MJ solar energy. Across the 10 sets of transplants, light use efficiencies of dry matter yield (e) ranged between 0·5 and 2%, using an energy equivalent of 17·5 kJ g --1 of lichen dry matter. The higher productivity of the terricolous species was due to longer periods with thallus water contents sufficient for metabolic activity and because of the higher mean photon flux densities of their microhabitat. A fourfold difference in photosynthetic capacity among the species was also important. It is concluded that lichen dry matter gain was primarily related to net carbon gain during metabolically active periods, which was determined by light duration, photon flux density and photosynthetic capacity.

Tansley Review No. 117

“…It was found that P max across species was well correlated with both their Rubisco and Chl a concentrations. The correlation between P max and Chl a is also in agreement with other studies of lichens (Tretiach & Pecchiari, 1995 ;Valladares et al, 1996 ;Palmqvist & Sundberg, 2000) ; some additional examples are shown in Fig. 1.…”

“…Similarly high growth rates have also been recorded for terricolous Peltigera and Nephroma species (Sundberg et al, 1999c) and for the cushion-forming Cladonia portentosa (Hyva$ rinen & Crittenden, 1998). However, annual increases in biomass are not always as high ; some are 2-3% yr −" (Renhorn et al, 1997 ;Palmqvist & Sundberg, 2000). Growth rates also vary between years and sites and even between individual lobes of the same thallus (Armstrong, 1993).…”

“…Typically, lichens contain 1-3 g of water g −" d. wt at maximal hydration (Blum, 1973 ;Rundel, 1988), whereas gelatinous lichens can contain 20-30 g of water g −" d. wt when external water films are included (Lange et al, 1993). However, depending on environmental conditions, lichen WCs can alter from complete dryness to full hydration and vice versa within a few minutes (Lange et al, 1993 ;Sundberg et al, 1997b ;Palmqvist & Sundberg, 2000).…”

“…2c). After the lag period, both electron transport and CO # assimilation are gradually induced in a biphasic Palmqvist & Sundberg (2000). CO # gas exchange (blue) was measured with an infrared gas analyser (IRGA) as in Palmqvist (1993), with a cuvette allowing the attachment of the optic fibre for fluorescence.…”

Effects of Modern Forest Management on Winter Grazing Resources for Reindeer in Sweden

“…The growth of the lichens is strongly related to the amount of light they receive during their wet active periods. Palmqvist and Sundberg (2000) have reported the growth amounting to 30-70 g/m 2 /year for ground living lichen and 1-4 g/m 2 /year for arboreal lichen. The distribution and abundance of lichens in boreal forests is connected to the characteristics of forest stands and the soil.…”