Photosynthetic responses of three common mosses from continental Antarctica

Abstract

Predicting the effects of climate change on Antarctic terrestrial vegetation requires a better knowledge of the ecophysiology of common moss species. In this paper we provide a comprehensive matrix for photosynthesis and major environmental parameters for three dominant Antarctic moss species (Bryum subrotundifolium, B. pseudotriquetrum and Ceratodon purpureus). Using locations in southern Victoria Land, (Granite Harbour, 77°S) and northern Victoria Land (Cape Hallett, 72°S) we determined the responses of net photosynthesis and dark respiration to thallus water content, thallus temperature, photosynthetic photon flux densities and CO 2 concentration over several summer seasons. The studies also included microclimate recordings at all sites where the research was carried out in field laboratories. Plant temperature was influenced predominantly by the water regime at the site with dry mosses being warmer. Optimal temperatures for net photosynthesis were 13.7°C, 12.0°C and 6.6°C for B. subrotundifolium, B. pseudotriquetrum and C. purpureus, respectively and fall within the known range for Antarctic mosses. Maximal net photosynthesis at 10°C ranked as B. subrotundifolium > B. pseudotriquetrum > C. purpureus. Net photosynthesis was strongly depressed at subzero temperatures but was substantial at 0°C. Net photosynthesis of the mosses was not saturated by light at optimal water content and thallus temperature. Response of net photosynthesis to increase in water content was as expected for mosses although B. subrotundifolium showed a large depression (60%) at the highest hydrations. Net photosynthesis of both B. subrotundifolium and B. pseudotriquetrum showed a large response to increase in CO 2 concentration and this rose with increase in temperature; saturation was not reached for B. pseudotriquetrum at 20°C. There was a high level of variability for species at the same sites in different years and between different locations. This was substantial enough to make prediction of the effects of climate change very difficult at the moment.

Diurnal changes in photosynthetic activity of the biological soil crust and lichen: Effects of abiotic factors (Petuniabukta, Svalbard)

“…In polar regions, lichens dominate on rock surfaces or inside rocks and stones (endolithic communities) but are also found on the surface of moss turfs (Pannewitz et al 2005). The absence of roots for water uptake and of epidermis and cuticula as a water-preserving protection characterizes lichens as poikilohydrous plants.…”

A first approach to calculate BIOCLIM variables and climate zones for Antarctica

“…The coldest and driest areas in the world can be found in Continental Antarctica, comprising the main part of the continent and the eastern part of the Antarctic Peninsula. The Ross Sea region which includes extensive ice-free areas such as the McMurdo Dry Valleys (comprising about 15% of the ice-free surfaces in Antarctica; Cary et al 2010) is one of the most important study areas for terrestrial life in cold deserts (Colesie et al 2014b;Green 2009;Øvstedal and Smith 2001;Ruprecht et al 2012b). By contrast, Maritime Antarctica includes the warmest parts of the continent, comprising the west side of the Antarctic Peninsula north of about 72°S.…”

“…Various studies in the past dealt with biodiversity and/or ecogeographic distribution in bacterial (e.g., Bottos et al 2014), hypolithic (Khan et al 2011), and endolithic communities (Yung et al 2014); soil crusts (Colesie et al 2014a), mosses (Schroeter et al 2011), or lichens (e.g., Castello 2003Green et al 2011b;Hertel 2007;Øvstedal and Smith 2001;Ruprecht et al 2010;Ruprecht et al 2012b) as well as macroflora in general (Peat et al 2007); springtails, mites (McGaughran et al 2008;Stevens et al 2006), and nematodes (Adams et al 2014). Most of these terrestrial biodiversity studies were conducted along the latitudinal gradient at the Ross Sea coastline.…”

Photosynthetic activity in three vascular species of Spitsbergen vegetation during summer season in response to microclimate

“…Kappen et al (1998) used simultaneous gasometric and fluorometric measurements in foliose li− chen species Umbilicaria aprina. Since that time many studies focusing diurnals of Antarctic lichens and mosses (Schlensog and Schroeter 2001;Schroeter et al 2011;Pannewitz et al 2005) have been performed. Some of them (e.g.…”