Biomes

1. Biomes and climate
• biome: group of similar ecosystems that cover a broad area
• major subdivisions of biosphere
• two types: terrestrial biomes and aquatic biomes
2. Climate
• average weather in an area over a long period of time
• weather is day to day explanation
• described in terms of temperature and precipitation
• climate of location depends on distance from the equator and distance above sea level
• factors also include location relative to ocean or mountain ranges
3. Temperature
• temperature falls from equator to poles
• climates can be classified as tropical, temperate, or arctic
• temperature falls from lower to higher altitudes 
• ex. from base of mountain to its peak
• ocean also plays an important role in temperature of an area
• coastal areas have milder climates because temperature of the ocean changes little from season to season
• affects temperature on nearby coasts
4. Moisture
• climates can be classified as arid, semi-arid, semi-humid, or humid
• moisture of biome determined by both precipitation and evaporation
• evaporation depends on heat from sun
• precipitation patterns result from movements of air masses and wind
• warm, humid air masses are moved north and south by global air currents
• air masses cool and cannot hold as much water
• drop moisture as precipitation
• air masses are much drier at about 30º north or south latitude
• dry climates are found at these latitudes
• warn and sunny, which increases evaporation and dryness
• dry climates are found near the poles as well
• extremely cold air can hold little moisture, so precipitation is low in arctic zones
• also have little evaporation because of the cold
• cold climates with low precipitation may not be as dry as warm climates with the same amount of precipitation
• distance from ocean and mountain ranges also changes precipitation
• one side of mountain range near the ocean may receive a lot of precipitation
• warm, moist air masses regularly move in from the water
• air masses begin to rise up over the mountain range
• cools and drops moisture as precipitation
• by the time it reaches the other side of the mountain range, they no longer contain moisture
• land on the other side of mountain receives little precipitation
• land is in the "rain shadow" of the mountain range
5. Climate and Plant Growth
• plants are the major producers in terrestrial biomes
• all other terrestrial organisms depend on them directly or indirectly for food
• plants need air, warmth, sunlight, water, and nutrients to grow
• climate is major factor in affecting number and diversity of plants that can grow
• climate determines average temperature and precipitation, length of growing season, and quality of soil
6. Growing season
• period of time each year when it is warm enough for plants to grow
• time and length of growing season determines which types of plants can grow in an area
• ex. near the poles, the growing season is very short because the temperature may rise above freezing for only a couple of months
• slow-growing plants are unable to survive
• near the equator, plants can grow year round if they have enough moisture
7. Soil
• plants need soil with nutrients and organic matter
• nutrients and organic matter are added to soil when plant litter and dead organisms decompose
• decomposition occurs very slowly in cold climates, so soil in cold climates are thin and poor in nutrients
• soil is thin and poor in hot, wet climates too because heat and humidity causes rapid decomposition, so little organic matter accumulates in the soil
• frequent rains leach nutrients from the soil
• thick, rich soil is found in temperate climates and is best for most plants
8. Biodiversity
• refers to number of different species of organisms in a biome
• biodiversity greater in wetter and warmer biomes, so generally decreases from equator to poles
• rainforest has highest biodiversity of any biome on Earth
9. Adaptations
• plants, animals, and other organisms evolve adaptations to survive through abiotic factors
• abiotic factors to which they adapt include 
• temperature, moisture, growing season, and soil
• biomes with dry climates have plants that adapt to aridity, such as special tissues for storing water
• biomes with severe cold or dry seasons have plants that maybe become dormant during that season of the year
• in dormant plants, cellular activities temporarily slow down so that the plants need less sunlight and water