At first glance, Harvard Forest seems like an ordinary woodland. Oak trees shade the terrain among small shrubs and other trees, mostly maple, birch and beech. Fallen leaves coat the ground below. What makes this 1,600-hectare patch of land in north central Massachusetts special is buried in the soil.
Some 10 centimeters below, scientists have installed a subterranean network of wires — some of which have been active for about 35 years — that warms the forest floor. By continuously heating the soil 5 degrees Celsius above ambient soil temperature, these wires imitate the warming effects of climate change for researchers who want to understand what a hotter world