Effects of bryophyte and lichen cover on permafrost soil temperature at large scale
Bryophyte and lichen cover on the forest floor at high latitudes exerts an insulating effect on the ground. In this way, the cover decreases mean annual soil temperature and can protect permafrost soil. Climate change, however, may change bryophyte and lichen cover, with effects on the permafrost...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-09-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/10/2291/2016/tc-10-2291-2016.pdf |
| Summary: | Bryophyte and lichen cover on the forest floor at high latitudes exerts an
insulating effect on the ground. In this way, the cover decreases mean annual
soil temperature and can protect permafrost soil. Climate change, however,
may change bryophyte and lichen cover, with effects on the permafrost state
and related carbon balance. It is, therefore, crucial to predict how the
bryophyte and lichen cover will react to environmental change at the global
scale. To date, current global land surface models contain only empirical
representations of the bryophyte and lichen cover, which makes it impractical
to predict the future state and function of bryophytes and lichens. For this
reason, we integrate a process-based model of bryophyte and lichen growth
into the global land surface model JSBACH (Jena Scheme for Biosphere–Atmosphere Coupling in Hamburg). The model simulates bryophyte and lichen cover on upland sites. Wetlands are not included. We take into account the dynamic nature of the thermal properties of the bryophyte and lichen
cover and their relation to environmental factors. Subsequently, we compare
simulations with and without bryophyte and lichen cover to quantify the
insulating effect of the organisms on the soil.
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We find an average cooling effect of the bryophyte and lichen cover of 2.7 K
on temperature in the topsoil for the region north of 50° N under
the current climate. Locally, a cooling of up to 5.7 K may be reached. Moreover,
we show that using a simple, empirical representation of the bryophyte and
lichen cover without dynamic properties only results in an average cooling of
around 0.5 K. This suggests that (a) bryophytes and lichens have a
significant impact on soil temperature in high-latitude ecosystems and (b) a
process-based description of their thermal properties is necessary for a
realistic representation of the cooling effect. The advanced land surface
scheme, including a dynamic bryophyte and lichen model, will be the basis for
an improved future projection of land–atmosphere heat and carbon exchange. |
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| ISSN: | 1994-0416 1994-0424 |