648-653 Chapter 7. from readings pp. Earth's climate zones. Earth's major biomes. Rainfall not enough to support large stands of trees, disturbance prevents most trees from invading and becoming established, a few trees widely scattered. Grasses are adapted grazing -perennials, grow from basal meristem.
Some savanna receive as much rainfall as a tropical dry forest, others as little as deserts.
Scattered trees occur only where soils are well drained. Herbivores put selective pressure on vegetation -from grazing on short grasses and forbs to browsing of shrubs and trees. Theory of plate tectonics explains the movement of plants and geologic processes, developed from idea of continental drift. Produces the variety of landforms and sedimentary environments Figure 9-7. Rock Cycle Figure 9-10.