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Photosynthesis in a widespread and important sub-Arctic moss and lichens species in pine ecosystems of the ZOTTO tower footprint area

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EGU2020-5066, updated on 10 Mar 2020
https://doi.org/10.5194/egusphere-egu2020-5066
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
Photosynthesis in a widespread and important sub-Arctic moss and
lichens species in pine ecosystems of the ZOTTO tower footprint
area
Daria Polosukhina1, Oxana Masyagina2, and Anatoly Prokushkin1,2
1Institute of ecology and geography, Siberian federal university, Krasnoyarsk, Russia
2Sukachev Institute of Forest SB RAS, Federal Research Center «Krasnoyarsk Science Center SB RAS», Krasnoyarsk, Russia
In boreal forests, bryophytes and lichens usually dominate the ground floor layer and contribute
up to 50% of ecosystem gross CO2exchange (Bisbee et al. 2001; Goulden & Crill 1997). Sphagnum
spp. are the most important contributors in wetland C uptake, and feathermosses and lichens play
a significant role in well-drained sites (Nilsson & Wardle 2005; O’Connell et al. 2003; Jarle W. Bjerke
et al. 2013). Given their important ecological roles in such a widespread biome, it is surprising that
still a few studies have attempted to understand the intrinsic factors that control moss-lichen
cover carbon dynamics specifically under ongoing climate change in high latitudes.
The aim of this work was to determine the stocks of moss-lichen stratum and photoassimilation
activity of its dominant species during the growing season. The study has been conducted in
Central Siberia near Zotino tall tower observatory (ZOTTO, 60 ° N, 89 ° E) in lichen- and
feathermoss-dominated pine forests. First, to assess the phyto (bio) mass stocks the grass-shrub
and moss-lichen layers were sampled in 100 replicates in each type of forest from 20x25 cm
subplots (S = 50 cm2). The intensity of CO2photoassimilation was determined in situ by Walz
GFS-3000 (Heinz Walz GmbH, Effeltrich, Germany) infrared gas analyzer. Photosynthetic activity of
lichens and feathermosses was measured during the growing season of 2018 in June, July, August
and September around the mid-day time. For every time point we also analyzed CO2exchange
dependence from temperature, photosynthetically active radiation (PAR) and CO2 concentration.
The dominants of ground vegetation for the moss-lichen layer were Cladonia stellaris, Cladonia
rangiferina,Cetraria islandica,Pleurozium schreberi,Hylocomium splendens,Aulacomnium
palustre. The moss-lichen layer accounted for 78-96% of the total phytomass of ground floor in
studied pine forests and comparable (486 g/m2) to the photosynthetic phytomass of the tree
canopy (pine needles). During the growing season, carbon assimilation by the moss-lichen layer
varied in a relatively narrow range: from 38 ± 4 to 42 ± 5 mgCO2/ m2/ hour for lichen C. stellaris
and from 93 ± 11 to 99 ± 13 mgCO2/ m2/ hour for moss P. schreberi. Thus, moss-lichen layer
dominants maintained high photoassimilation activity throughout the growing season.
Temperature increased the intensity of CO2assimilation and no inhibition was observed at
maximum T used in our study (+40 ° C). There were no differences in the temperature
dependence of CO2photoassimilation between feathermosses and lichens. However, they differed
in dependence from PAR. Mosses showed 2-fold larger response of CO2assimilation intensity to
increase of PAR comparatively to lichens. The rate of photosynthesis of both moss and lichen
showed log growth with increasing CO2levels up to 2000 ppm. Compensation poit was varying
from 170 to 284 ppm.
This study was supported by the Russian Foundation for Basic Research project № 18-05-60203
"Landscape and hydrobiological controls on the transport of terrigenic carbon to the Arctic
Ocean".
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