Tanja Jylänki


Plant ecology, arctic light environment

Light-driven host-symbiont interactions under global warming induced host range shifts, project leader Docent Kari Taulavuori, funded by Academy of Finland

Light is probably the most important contested resource among plants. Light quantity (irradiance) determines photosynthetic potential until level of saturation, and thereby net primary production. Light quality (spectral composition) affects plant phenotype through many photomorphogenic processes, and acts as a signal for metabolic regulation. Light duration (daylength, photoperiod) is responsible for adjusting biological clock for phenological events. Changes in any of these characteristics of plant light environment can cue phenological transitions, such as flowering and seed germination, and determine biomass partitioning between foliage, roots and supporting tissues, as well as the allocation of photosynthates to symbiotic partners. Impacts of future climate change on vegetation have gained lot of interest during past years. Positive effects of global warming and CO2 on plant growth and belowground allocation have been found, while the light environment has been largely neglected in this context. It is therefore crucial to investigate how forest trees respond to changes in light climate when migrating towards north along with climate warming.
Light conditions at northern high latitudes are markedly different from the mid latitudes and likely to affect plant competitive performance during the growing season. Day length begins to extend from the vernal equinox onwards at an exponential rate, being 12 h on the 20th March, and reaching 24 h (i.e. polar day) by the summer solstice around 20th June everywhere northwards of the Arctic Circle (66.56°N) and lasting for two months at 70°N (Nilsen 1985; Taulavuori et al. 2010). In addition to short night, light environment in the north is characterized by lower light quantity (irradiance) compared to mid or low latitudes. For example, vegetation around the Arctic Circle in Scandinavia receives only about 55% of the irradiance of that in the Alps (47°N) (Körner 2003). Moreover, light quality is different since the polar summer nights are enriched with a relatively high proportion of diffuse blue because of the light scattering due to low angle of solar radiation (Taulavuori et al. 2010).


Valikoidut julkaisut

  • Taulavuori, Kari; Taulavuori, Erja; Saravesi, Karita; Jylänki, Tanja; Kainulainen, Aila; Pajala, Jonna; Markkola, Annamari; Suominen, Otso; Saikkonen, Kari (2017) Competitive success of southern populations of Betula pendula and Sorbus aucuparia under simulated southern climate experiment in the subarctic. - Ecology and Evolution 7 (12), 4507-4517 . [Original] [Self-archived]


  • Research visit to prof. Dr. Klaus Humbecks research group in Martin-Luther University of Halle-Wittenberg
    30.9.2017 - 8.12.2017