Grasslands, savanna - prairies, pampas, steppes. Rainfall too low for trees, lots herbivores. Now mostly farmland, overgrazed cattle ranches. Few parks are being overused. Desert spp adapted to have brief life during rainy season or deep tap roots.
Animals exhibit many water balance adaptations.
Hardwood climax, vertical stratification. Taiga Conifers Canada, Russia, Mongolia, Scandinavia 6. Arctic, hi altitude Permafrost, no trees, little precip. Moss and lichens, grass 7. Vertical stratification in temp, depth, light.