Growing season length decreases northward 3. Most of eastern North America profoundly affected by glaciation during Ice Ages a. Region north of Ohio River covered by ice until 12-14,000 yr ago. Even south of this, climate much cooler during peak of glaciation. 2. recolonization of terrain north of glacial terminus. Some species have not yet fully reached climatic range limits.
Glaciated terrain has extensive glacial deposits, affects nature of substrates.
Rapid drainage, upland soils droughty. Sands are nutrient poor. Do not retain many nutrients. C. Fires are common, due to dry soils. Pines favored over broadleaf trees on dry, infertile soils.