Phenological responses of herbaceous plants, shrubs, and tree seedlings to experimental climate change conditions in northern Minnesota

Abstract

Changing climate has been linked to changes in phenology, the timing of biological events such as leaf out and flowering. Phenological changes of herbaceous plants and shrubs remain less studied and thus less understood. This study takes place within the Boreal Forest Warming at an Ecotone in Danger (B4WarmED) project in Minnesota, examining phenological responses of herbaceous plants, shrubs, and tree seedlings to warming and reduced rainfall over. Warming extended the growing season, primarily through earlier leaf unfolding in the spring. Flowering advanced under warming, though more so for fall blooming species than for spring blooming species. Warming did not alter senescence for most species, though several species did delay senescence with warming. Community level phenological responses of the groundlayer and tree seedlings were not altered by rainfall treatments. Fall blooming species altered flowering phenology to rainfall manipulation. Two species diverged in flowering time in the warmest, driest treatment.