TITLE:
Early Snowmelt Enhances the Carbon Sequestration of Hummock-Forming Sphagnum Mosses on Boreal Wetlands
AUTHORS:
Niko Silvan, Kari Jokinen
KEYWORDS:
Sphagnum Mosses, Boreal Wetlands, Mire Microtopography, Carbon Dynamics, Global Warming
JOURNAL NAME:
Open Journal of Ecology,
Vol.6 No.3,
February
15,
2016
ABSTRACT: Sphagnum mosses are
globally important owing to their considerable peat-forming ability and their
potential impact on global climatic cycles acting as a long-term net carbon
sink. However, changes in climatic conditions due to global warming may affect
the relations between Sphagnum mosses
and vascular plants but also the competition among Sphagnum, and thus alter the accumulation of carbon on boreal
wetlands. Sphagnum mosses are a plant
genus with a favorable ability to grow in low solar irradiance and temperature
conditions compared to vascular plants. This may be increasingly beneficial in
increased wintertime temperatures and predated snowmelt conditions. To
understand particularly the importance of early spring photosynthetic activity
and thus the role of the length of growing season on carbon balance, we
analyzed the CO2 exchange of Sphagnum mosses with closed chamber technique in two categories of microtopographical
habitats, hummocks and lawns, during four seasons 2010-2013 on a raised bog in
Central Finland. During CO2 exchange measurements, instantaneous net
ecosystem exchange (NEE) and ecosystem respiration (RE) were measured. Our
results show that the mean measured seasonal NEE, i.e. the instantaneous net carbon sequestration, of hummocks was
generally only slightly higher than the NEE of lawns, but the mean measured
seasonal RE of hummocks was clearly and significantly higher than the RE of
lawns in every study year. A reason for the observed still higher seasonal
carbon sequestration of hummocks than that of lawns besides the slightly higher
rate of carbon accumulation was the longer duration of physiologically active
growing season. Therefore, hummock-forming Sphagnum mosses exposed firstly from snow cover showed to get the extra time for
photosynthesis and thus extra benefit compared to other mire plants. This may
be further enhanced by the expansion of hummock-forming Sphagnum moss dominated raised bogs towards northern aapa-mire region due to the global warming.