Responses of root phenology in ecotypes of Eriophorum vaginatum to transplantation and warming in the Arctic.

The effect of climate change on phenology and growth is less understood for belowground plant tissues than for aboveground plant tissues, particularly in high-latitude regions. Ecotypes within a species adapted to a locality may display different responses to climate change. We established two common garden plots in the Arctic tundra north of the Brooks Range in northern Alaska. Three ecotypes of Eriophorum vaginatum along a latitudinal gradient were transplanted into common gardens, and half of the transplants were warmed using open-top chambers (OTCs). Minirhizotrons were used to track the root phenology during the growing seasons of 2016 and 2017. Warming with OTCs (approximately +1 °C in air) did not affect the root biomass, root production or root phenology. The southern ecotype (from 67°16'N) of Eriophorum vaginatum transplanted northward experienced delayed startup and root production compared to two northern ecotypes (from 68°38'N and 69°25'N), although significant differences were not observed in the three ecotypes in terms of root production, root biomass and growth duration at the two sites. Our results suggest that as the climate warms, ecotypes of Eriophorum vaginatum may be able to adjust their duration of root growth and root productivity by phenotypic plasticity, although the degree of plasticity controlling the root startup time may vary between southern and northern ecotypes.