I recently had the opportunity to visit Jiesnnalvárri again—this time in March, a stark contrast to my visit in August 2023. The subarctic tundra around the Kevo Subarctic Research Institute offers a unique glimpse into the extreme seasonal changes that shape plant life. In just a few months, the landscape transforms from green mountain birch forest and open shrub and lichen dominated tundra to a frozen, snow-covered expanse.
Winter: Snow and Ice
In March, the tundra was completely covered in snow and ice. While it may seem like an inhospitable environment, this snow plays a crucial role in protecting the plants beneath. Snow acts as an insulator, preventing the soil from reaching extreme subzero temperatures (Bokhorst et al., 2017; Christiansen et al., 2018).
For mosses and other tundra plants, this insulating effect can mean the difference between survival and death. Deeper snow cover improves plant survival rates by shielding them from harsh freezing conditions (Bokhorst et al., 2017, Semenchuk et al., 2015). The importance of snow depth goes even further, as it creates a more stable environment for microbial activity. This can lead to better nutrient retention in the soil, which benefits mosses and other plants when the snow melts in spring (Wipf, 2010).
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| Jiesnnalvárri in winter |
Summer: Green and Alive
By summer, Jiesnnalvárri is almost unrecognizable. The snow has melted, and the tundra bursts into life, with mosses and vascular plants taking full advantage of the brief but intense growing season.
Interestingly, the snow from the previous winter continues to influence plant survival even in summer. The moisture retained in the soil after snowmelt helps prevent drought stress, acting as a water reservoir for mosses during dry periods (Krab et al., 2018). At the same time, snow cover during winter may protect mosses from desiccation by reducing frost damage, ensuring they can quickly "reboot" once temperatures rise (Semenchuk et al., 2015).
Fun fact; While the snow and ice may pretend a moist and water rich environment, Kevo is acutally one of the driest region in Finland by preceptitaion (Kersalo & Pirinen 2009).
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| Jiesnnalvárri in summer |
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| Tetralophozia setiformis in Winter, exposed by the strong winds |
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| Tetralophozia setifromis in Summer |
References
Bokhorst, S., Jaakola, L., Karppinen, K., Edvinsen, G. K., Mæhre, H. K., & others. (2017). Contrasting survival and physiological responses of sub-Arctic plant types to extreme winter warming and nitrogen. Planta.
Christiansen, C., Lafrenière, M., Henry, G., & Grogan, P. (2018). Long‐term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO2 gain but reduces soil carbon and nutrient pools. Global Change Biology.
Krab, E., Roennefarth, J., Becher, M., Blume‐Werry, G., Keuper, F., & others. (2018). Winter warming effects on tundra shrub performance are species‐specific and dependent on spring conditions. Global Change Biology.
Semenchuk, P., Elberling, B., Amtorp, C., Winkler, J., Rumpf, S., & others. (2015). Deeper snow alters soil nutrient availability and leaf nutrient status in high Arctic tundra. Biogeochemistry.
Wipf, S. (2010). Phenology, growth, and fecundity of eight subarctic tundra species in response to snowmelt manipulations. Plant Ecology.
Kersalo, J., & Pirinen, P. (2009). Suomen maakuntien ilmasto [The climate of Finland’s regions]. Finnish Meteorological Institute.