Under climate change, there's a growing interest in assessing whether trees and other species can keep pace with changing temperatures and rainfall, shifting where they are found, also known as their ranges, to track their suitable climates. To test this, a University of Maine-led research team studied the current ranges of hundreds of North American trees and shrubs, assessing the degree to which species are growing in all of the places that are climatically suitable. Researchers found evidence of widespread "underfilling" of these potential climatic habitats -- only 50% on average -- which could mean that trees already have disadvantage as the world continues to warm.