1) The document discusses soil regions and vegetation regions. Soil is a thin layer of weathered rock, humus, air and water that the world's food supply greatly depends on. (2) Humus refers to stable organic matter in soil that lends it a dark color and can remain for centuries. (3) There are typically four main biomes - forest, grassland, desert, and tundra - and the type of vegetation in each region depends on the climate and soil characteristics.

1. Chapter 3, Section 4 Soil and Vegetation

2. Soil Regions What is soil? A thin layer of weathered rock, humus, air, and water World’s food supply depends greatly on topsoil : top six inches of soil

3. Humus? -the organic material in soil lending it a dark brown or black coloration -In soil science, humus refers to any organic matter which has reached a point of stability, where it will break down no further and might, if conditions do not change, remain essentially as it is for centuries, if not millennia. -In agriculture, humus is sometimes also used to describe mature compost, or natural compost extracted from a forest or other spontaneous source for use to amend soil. It is also used to describe a topsoil horizon that contains organic matter.

4. Vegetation Regions Different climatic zones = different vegetation regions Ecosystem : an interdependent community of plants and animals Biome : the ecosystem of a particular region There are typically four biomes: forest, grassland, desert, tundra

5. Soil Differences Soil characteristic Wet Climate Dry Climate Warm Climate Cold Climate Depth Deep shallow deep shallow Texture Intermediate to fine Coarse Fine coarse Weathering Chemical Physical Rapid Slow Humus Content variable low low abundant Acidity acidic Not acidic Less acidity High acidity

7. Vegetation Region #1: Forestlands -either broadleaf or needleleaf Broadleaf: maple, oak, birch, cottonwood - also known as deciduous trees Typically deciduous trees lose or shed leaves at least once during year. Deciduous trees almost exclusively located in Northern Hemisphere Needleleaf: pine, fir, cedar - also known as coniferous trees (they are cone bearing)

8. Vegetation Region #2: Grasslands Flat regions, dotted with a few trees In Tropical Grassland region: called savannas In Northern Hemisphere: called steppe Look at the map on page 66. Using your prior knowledge of these areas how are grasslands different in Northern and Southern Hemisphere? Which continent has the greatest area of tropical rain forest? What vegetation regions are found in US? In Europe?

9. Vegetation Regions #3 and #4: Desert and Tundra Extreme climates Vegetation adapt to tolerate heat or cold In tundra: moss, lichen In desert: cacti, sagebrush

10. Human Impact on Environment What impact does man have on the environment?

11. Questions for thought What soil factors influence type of vegetation in a region? What is the difference between coniferous and deciduous trees? What is unique about vegetation in the desert and tundra regions?