Chapter 3 Rangeland Physical Characteristics Chapter 3 Rangeland

Chapter 3 Rangeland Physical Characteristics Chapter 3 - Rangeland Physical Characteristics 1

Chapter 3 Rangeland Physical Characteristics n Chapter Outline (cont. ) – Climate Types • • The Pacific Climate The Great Basin Climate The Southwestern Climate The Plains Climate The Eastern Climate The Florida Climate The Tropical Wet and Dry Climate Chapter 3 - Rangeland Physical Characteristics 2

Chapter 3 Rangeland Physical Characteristics n Chapter Outline (cont. ) – Topography • Aspect and Degree of Slope – Soils • • • Texture and Structure Depth p. H Organic Matter and Fertility Soil Classification – Influence of rangeland physical characteristics upon range animals. Chapter 3 - Rangeland Physical Characteristics 3

Precipitation n Precipitation See Fig 3 -1 – Most important single factor in determining the type and productivity of vegetation in an area • Forage production increases substantially with up to 500 mm or 19. 5 inches of rainfall per year. • When rainfall exceeds 19. 5 inches/year, soil characteristics assume greater importance in forage production. – Effectiveness of precipitation • Depends on total amount, distribution, relative humidity, type, and annual variability. Chapter 3 - Rangeland Physical Characteristics 4

Precipitation n Precipitation (cont. ) – Most rangelands receive less than 500 mm (19. 5”) of precipitation / year. – In the continental 11 western states 80% of the area receives less than 19. 5 inches / year. – In Africa, 50% of the area receives less than 19. 5 inches / year and 20% receives less than 9. 75 “/ year. – In Mexico, 75% of the area receives less than 19. 5 inches and 40% receives less than 9. 75” / year. Chapter 3 - Rangeland Physical Characteristics 5

Precipitation n Precipitation (cont. ) – Orographic Influences • Influence topography has on precipitation. – Air masses moving upward are cooler and tend to hold less moisture. – Air masses moving downward are warmer and can hold more moisture. – Drought • Dry weather when precipitation is less than 75% of the average annual amount. Chapter 3 - Rangeland Physical Characteristics 6

Precipitation Chapter 3 - Rangeland Physical Characteristics 7

Wind n Wind – Caused by uneven heating of land water areas. – Can substantially reduce precipitation effectiveness by increasing evaporation. – Hot winds during dry periods can greatly reduce forage production. Chapter 3 - Rangeland Physical Characteristics 8

Temperature n Temperature – Has a direct effect on forage production in relation to moisture available. (Hot and Dry , Cool and Wet) Chapter 3 - Rangeland Physical Characteristics 9

Frost Free Period n Frost Free Period – In areas where frost free days are limited, so is forage production. Chapter 3 - Rangeland Physical Characteristics 10

Humidity n Humidity – Amount of moisture in the air. – Areas with high humidity usually have higher forage production than areas with low humidity • Warm air holds more moisture than cold air. Chapter 3 - Rangeland Physical Characteristics 11

Climate Types n Climate Types – The Pacific Climate • Pacific Coastal areas of California, Oregon, Washington, and British Columbia west of the Sierra and Cascade Mountains. • Dry Summers and wet winters. • Relatively warm temperatures. • Mainly cool-season grasses (spring and fall) Chapter 3 - Rangeland Physical Characteristics 12

Climate Types – Precipitation Pattern Chapter 3 - Rangeland Physical Characteristics 13

Climate Types n Climate Types (cont. ) – The Great Basin Climate • Occurs in Washington, Oregon, Idaho, Nevada, Utah and eastern California east of Sierra and Cascade Mountains. • Spring is the main season for precipitation with dry summers. • Winters are cold compared to the Pacific Climate. • Cool-Season grasses are predominate because of the lack of summer moisture Chapter 3 - Rangeland Physical Characteristics 14

Climate Types Chapter 3 - Rangeland Physical Characteristics 15

Climate Types n Climate Types (cont. ) – The Southwestern Climate • Occurs in New Mexico, Arizona, southern Utah and Nevada and southwestern Texas. • Winter precipitation, spring drought, summer precipitation and fall drought. • Precipitation is infrequent and intense. • Shrubs and warm season grasses are favored due to the summer rains. Chapter 3 - Rangeland Physical Characteristics 16

Climate Types Chapter 3 - Rangeland Physical Characteristics 17

Climate Types n Climate Types (cont. ) – The Plains Climate • Occurs in the central United States. • Majority of precipitation falls in late spring and early summer. Light rains in fall and a dry winter. • Both cool and warm season grasses are present. Chapter 3 - Rangeland Physical Characteristics 18

Climate Types Chapter 3 - Rangeland Physical Characteristics 19

Climate Types n Climate Types (cont. ) – The Eastern Climate • Covers all of the eastern United States with the exception of Florida. • Precipitation occurs uniformly throughout the year. • Much of the natural vegetation is deciduous trees. Chapter 3 - Rangeland Physical Characteristics 20

Climate Types Chapter 3 - Rangeland Physical Characteristics 21

Climate Types n Climate Types (cont. ) – The Florida Climate • Covers the Florida peninsula • Precipitation occurs during summer (June to October) with a dry period from November to May. • Total precipitation per year averages 49. 5 to 58. 5 inches. • Most productive of all regions forages. Chapter 3 - Rangeland Physical Characteristics 22

Climate Types Chapter 3 - Rangeland Physical Characteristics 23

Climate Types Chapter 3 - Rangeland Physical Characteristics 24

Topography n Topography – Has a direct influence on climate and vegetation. – Aspect • Refers to the directional orientation of slopes. • Spring - South and West slopes offer more forage production due to the warming effect. • Summer - Animals prefer North and East facing slopes due to the cooler temperatures. – Degree of Slope • As slope increases, vegetation productivity decreases. – Precipitation is poorly used and difficult for animals. Chapter 3 - Rangeland Physical Characteristics 25

Soils n Soils – Primary factor in determining the potential forage production. – Comprised of minerals, organic materials, and living forms. – The most severe consequences of rangeland mismanagement of overgrazing is loss of soil – Texture: – Refers to size of the mineral particles in the soil. – Clay – Silt – Sand (fine, coarse, fine gravel, coarse gravel) Chapter 3 - Rangeland Physical Characteristics 26

Soils (Page 66 Fig 3. 7) Chapter 3 - Rangeland Physical Characteristics 27

Soils (Fig 3. 8) Chapter 3 - Rangeland Physical Characteristics 28

Soils n Soils – Texture (cont. ) – CLAY • Clay is the smallest particle size and has the most relative surface area. • Retains nutrients much better • It will retain it’s moisture because small particles have a much greater surface area for attracting and binding nutrients per unit volume than do large particles – SILT • Smaller than sand, but larger than clay Chapter 3 - Rangeland Physical Characteristics 29

Soils n SAND – Water enters coarse, sandy soils much more rapidly than fine clay because there is more space between particles – Western U. S. , sandy soils provide a more favorable habitat for plants, particularly grasses, than do clay soils. Chapter 3 - Rangeland Physical Characteristics 30

Soil n The water holding capacity of soil increases as particle size decreases because water clings to surfaces and small particles have relatively the most surface Chapter 3 - Rangeland Physical Characteristics 31

Soils n Soils – Structure • How soil particles are arranged. • Six basic types of soil structure – – – Platelike - Layered as leafy plates. Prismlike - Vertical Columns. Blocklike - Cubical aggregation *Spheroidal - round aggregates and easily shaken apart. Single-grained - Loose arrangement, doesn’t stick together. Massive - tightly compacted Chapter 3 - Rangeland Physical Characteristics 32

Soil Structure Chapter 3 - Rangeland Physical Characteristics 33

Soils n Soils (cont. ) – Depth • Determines how much moisture the soil can hold. • A deep soil with moderate precipitation will generally produce more forage than a thin soil receiving heavy precipitation. Chapter 3 - Rangeland Physical Characteristics 34

Soils n Soils (cont. ) – p. H • The status of a soil in regard to exchangeable mineral ions. • Expresses whether a soil is basic or acidic. • Basic soil - p. H of 10 or higher • Acidic soil - p. H of 4 or lower • Most soils in western United States are basic and most eastern soils are slightly acidic Chapter 3 - Rangeland Physical Characteristics 35

Soils n Soils (cont. ) – Organic Matter • Represents an accumulation of partially decayed and partially synthesized plant and animal residues. • Humus – Partially decomposed organic matter that has been incorporated into the soil. – Provides a small, yet constant supply of nutrients. – Binds soil particles. – Increases moisture holding capacity. – Provides food for microorganisms. • Grassland soils are higher in Organic Material than forests soils. Chapter 3 - Rangeland Physical Characteristics 36

Soils n Soils (cont. ) – Fertility • Next to water, fertility is the second most limiting factor to forage production in regions with less than 19. 5” / year. • Nitrogen is the most deficient element in rangeland soils. • Phosphorus, Potassium and sulfur are also deficient in most areas. • Selenium and molybdenum can cause both toxicity and deficiencies in livestock production. Chapter 3 - Rangeland Physical Characteristics 37

Soils n Soils (cont. ) – Soil Classification • Ten orders of the soil classification system. – Entisols » Found in the Rocky mountain area. » The youngest of soil orders. – Inceptisols » Found in the Pacific Northwest. » Formed from volcanic ash. – Aridisols » Found in the Southwest U. S. » Little profile development and dry more than 6 months of a year. Chapter 3 - Rangeland Physical Characteristics 38

Soils n Soils (cont. ) – Soil Classification (cont) • Ten orders of the soil classification system. – Vertisols » Found in Southcentral U. S. » High clay content that cracks when dry. – Mollisols » Natural grassland prairie soils. » High Organic Matter content. Chapter 3 - Rangeland Physical Characteristics 39

Soils n Soils (cont. ) – Soil Classification (cont. ) • Ten orders of the soil classification system. – Alfisols » Found in eastern deciduous forests. » Very similar to Mollisols. – Spodosols » Leached minerals soils found in Northeastern and Northcentral U. S. » Generally support coniferous forests. Chapter 3 - Rangeland Physical Characteristics 40

Soils n Soils (cont. ) – Soil Classification (cont. ) • Ten orders of the soil classification system. – Ultisols » Most leached soils in U. S. » Found primarily in Southwest U. S. » Soils are moist most of the time. » Support Savannah woodland forests. – Oxisols » Most developed of all soils. » Found in tropical areas. » Lowest fertile soils. » None in contiguous U. S. Chapter 3 - Rangeland Physical Characteristics 41

Soils n Soils (cont. ) – Soil Classification (cont. ) • Ten orders of the soil classification system. – Histosols » High Organic Matter (Peat). » Found in Minnesota and Louisiana in low land areas. Chapter 3 - Rangeland Physical Characteristics 42

Chapter 3 - Rangeland Physical Characteristics 43

Chapter 3 - Rangeland Physical Characteristics 44

Influence of Rangeland Physical Characteristics to Range Animals n Influences – Interaction between climate, soil, and topography determines the potential of a particular range to support livestock and wildlife. – Cold temperatures and heavy snow can have a definite adverse impact on range animals. – Climate and topography are important considerations in the selection of the type(s) of livestock for a range. Chapter 3 - Rangeland Physical Characteristics 45

Influence of Rangeland Physical Characteristics to Range Animals Chapter 3 - Rangeland Physical Characteristics 46