Temperate deciduous forests cover the eastern third of North America and are also present in China, Japan, Korea and Western Europe. People often marvel at the many different types of trees comprising these forests, such as oaks, maples, hickories, walnuts, beech and sycamores. However, they tend to overlook the soils at the bases of these temperate deciduous trees, which provide the trees with the nutrients necessary for life and growth.
One of the most abundant types of soil in temperate deciduous forests is alfisol. Also known as brown forest soils, alfisols have two distinct layers: a top layer, consisting primarily of dead leaves, and a subsoil, which has a high content of clay. Alfisols derive their dark-brown colour from humus, which is decayed leaves and other organic matter. In comparison to the alfisols that are present in coniferous forests, alfisols in deciduous forests are less acidic and contain less iron and aluminium, according to Radford University.
While alfisols are common to the temperate deciduous forests of the northeastern United States, ultisols are common to the temperate deciduous forests of the southeastern United States. As Radford University notes, these clay-rich soils are much older than their alfisol counterparts and have undergone much higher levels of weathering and leaching. For this reason, ultisols provide poor aeration and lack nutrients. While primarily brown in colour, ultisols often contain streaks of red or yellow.
According to the forest resource Nearctica, rocky soils are common to the hillsides and rocky outcrops of temperate deciduous forests. The abundance of nonporous mineral particles in these soils makes them dry and infertile. In addition, the tendency of rocky soils to occur on slopes results in water draining away rapidly. For these reasons, only small deciduous trees, like hickories, are able to grow in rocky soils. The specific types of rocks comprising the soils can vary. However, when limestone is present, the soil's alkalinity is often elevated.
Sandy soils occur most frequently in temperate deciduous forests that stretch along coastlines, such as the forests of Cape Cod, Massachusetts and the Pine Barrens region of New Jersey. The soils consist of sand mixed with small amounts of dirt and are very low in nutrients. In addition, the soils are poor at retaining water. Despite these drawbacks, some trees, particularly pitch pines, are able to thrive in them. However, in most instances, the growth of these trees is stunted and they take on scrubby appearances.