Mapping conservation priorities in alpine and subartctic Swedish lakes affected by rapid climate change

Swedish alpine and subarctic areas undergo rapid transitions due to climate change, especially in relatively humid areas where the forest vegetation is expanding. It has been suggested that lakes in these areas are in transition from clearwater into brownwater state, because of the humus layer building up in surrounding soils, with negative consequences, e.g., for the biomass production of zooplankton and fish. However, this idea remains a hypothesis to be tested at a large scale. We used the new high-resolution satellite Sentinel-2 to evaluate the relationship between lake color and forest succession in 250 widely distributed lakes across Sweden. Preliminary results show that lakes remain surprisingly clear in areas of recent forest expansion, suggesting that there is lag time before brownification occurs. Our study could be used to map regions that are sensitive to future water brownification