Aspen parkland refers to a very large area of transitional biome between prairie and boreal forest in two sections, namely the Peace River Country of northwestern Alberta crossing the border into British Columbia, and a much larger area stretching from central Alberta, all across central Saskatchewan to south central Manitoba near the United States border. Aspen parkland consists of groves of aspen poplars and spruce interspersed with areas of prairie grasslands, also intersected by large stream and river valleys lined with aspen-spruce forests and dense shrubbery. This is the largest boreal-grassland transition zone in the world and is a zone of constant competition and tension as prairie and woodlands struggle to overtake each other within the parkland.