Spring is coming sooner to some plant species in the low Arctic of Greenland, while other species are delaying their emergence amid warming winters. The changes are associated with diminishing sea ice cover, according to a study published in the journalBiology Letters and led by the University of California, Davis.The timing of seasonal events, such as first spring growth, flower bud formation and blooming, make up a plant’s phenology — the window of time it has to grow, produce offspring and express its life history. Think of it as “nature’s clock.”