The range of climatic conditions along Norway from south to north and from coast to inland may cause local adaptations in our plant populations. We can uncover these adaptations through a common garden experiment.
Dwarf shrubs dominate the ground cover of heaths and forests covering 58 % of the land area in Norway. Therefore, they are very important players in the ecosystems. Still, we need more information about how they impact their environments and how they may be impacted by climate change.
Evergreen and deciduous dwarf shrubs have different ways of maximising their growth and carbon fixation during a year. Blueberry (Vaccinium myrtillus) is a deciduous species, producing all its leaves in spring and summer. The leaves are typically thin to keep the investment per leaf area low. Lingonberry (Vaccinium vitis-idaea) and crowberry (Empetrum nigrum) are evergreen species, which keep green leaves over winter and into the next growing season in addition to the new ones produced in spring and summer. Keeping the leaves for more than one season requires higher investments in thicker leaves with more structural tissues, making them tougher. Green leaves that overwinter may give the plants a head start for growth early in the season. On the other hand, it may also make them more vulnerable for frost damage in spring. The timing of changing from winter physiology to spring physiology in both overwintering leaves and buds needs to be adapted to the local climate for all plants. A period of increased temperature is the most common cue for starting bud break in spring in boreal areas. This is commonly studied by calculating the temperature sum above 5 °C needed for bud break. Along the latitudinal gradient from south to north in Norway, the mean temperature in spring varies and so will the temperature sum of a set number of days after the last frost. At the same time, we have a limited length of the growing season. Therefore, plants of the same species may be differently adapted to responding to elevated temperatures in spring, depending on their local climate. We want to study this to enable predictions of the effects of climate change.
Plants collected at four different places, ranging from 60 to 69 °N and from coast to inland, are cultivated in a common garden experiment. The environments of origin have differing climates. For instance, the coastal sites have less or no snow cover in winter, whereas the more continental sites normally have snow. A snow cover reduces the variability of temperatures experienced by the plants in winter and spring, filtering out the effects of very cold and very warm air. In addition, the southern sites have higher mean temperatures and longer growing season than the ones north of the polar circle, whereas the latter have more hours of light per day during the growing season. In the north, the first day of midnight sun is around 21st May in our sites. This may be while there is still a cover of snow, resulting in 24 h photoperiod being the first thing the plants experience after snowmelt. We assume that the local populations are adapted to their respective climate. We will simulate autumn, winter and spring in climate controlled growth rooms. As spring advances, equally for all plants, the timing of phenology events will be compared. The physiological activity (photosynthesis, respiration, transpiration) and morphology of old and new leaves will be measured. These are important traits for the effect of these plants on the carbon and water cycles in their ecosystem.
The master project is part of a larger project where you will meet scientists from UiO, the University of Bergen and University of British Columbia, Canada. The larger project is described here: https://betweenthefjords.w.uib.no/durin/