Terrestrial Biomes

1. Terrestrial Biomes

2. Global Air Circulation & Regional Climates • Uneven heating of the Earth’s Surface • Air is more heated at the equator and less at the poles.

3. Global Air Circulation & Regional Climates • Seasonal changes in temperature and precipitation

4. Insolation B A C

5. Solar Energy

6. Rainy Season Seasonal shift in rainy/dry seasons

7. Cell 3 North Cold, dry air falls Moist air rises — rain Polar cap Cell 2 North Arctic tundra Evergreen coniferous forest Cool, dry air falls 60° Temperate deciduous forest and grassland Cell 1 North Desert 30° Moist air rises, cools, and releases moisture as rain Tropical deciduous forest Tropical rain forest 0° Equator Tropical deciduous forest 30° Desert Cell 1 South Temperate deciduous forest and grassland Cool, dry air falls 60° Cell 2 South Polar cap Cold, dry air falls Moist air rises — rain Cell 3 South Global Air Circulation & Regional Climates • Properties of air and water.

8. Tundra Boreal Forest Temperate Forest Prairies and Grasslands Chaparral Desert Tropical Forest Tropical Mountains Terrestrial Biomes of the World Biome – a large geographical region having a defining climate to which plants show a similar physiological adaptation.

9. Temperature and precipitation regulate plant growth, thus the regional distribution of biomes.

10. Global Distribution of Terrestrial Biomes Global Net Primary Productivity For Terrestrial Biomes

11. Net Primary Production of Terrestrial Biomes

12. Tundra • Windswept expanses where nothing stands taller than grasses and sedges. • Average temperature is -5°C. • Water is held as ice for most of the year; growing season is from May to August • Plant growth is inhibited • Decomposition and nutrient cycling is very slow; soils are rich in organic matter • Each year, only the top meter defrosts, below that the ground remains frozen year round - Permafrost

13. Tundra • The organic rich soil in the tundra called peat. • Due to the short growing season, all growth and reproduction must happen in a short period. • Young shoots are thus loaded with nutrients • Makes good grazing • Food is so abundant at this time that wading birds, ducks, geese and swans commonly migrate to the tundra; herds of caribou and reindeer arrive and support biting flies, midges, and mosquitoes. • Insects spend the winter as eggs, larvae or pupae. • Birds usually feast on the abundant newly-hatched insects

14. Tundra • Although there are a lot of individual birds, mammals, and insects, there are not many types of species. • Few plant species have evolved to withstand the harsh tundra climate. • Tundra has a low species diversity (# of species) • Naturally low diversity does not mean unimportant. • Tundra is essential to the well-being of animals such as ducks, geese, seals, polar bears, and caribou • Recovery from disturbance takes a long time • Tracks from vehicles are visible for several months

15. Tundra

16. Boreal Forest • Great fir forest of Canada and northern Eurasia. • Vegetation type is defined by seasonal expansion and contraction of the Arctic and continental polar air masses. • Polar air in the winter, continental air in the summer • Very cold winters, relatively warm summers so trees can survive

18. Boreal Forest • Many trees look like Christmas trees, not oak trees • Shape of tree is related to the ability to shed snow • Broken trees are not good competitors • Leaf morphology is important • Needles are more durable, can photosynthesize year round • conserve heat more efficiently • Boreal forests are low in species diversity, but not as low as tundra

19. Boreal Forest

20. Temperate Forest • Can be divide into evergreen and deciduous forest types. • Generally have a moist cool climate. • Sometimes referred to as temperate rain forests • Contain giant redwoods and Douglas fir • Redwoods can reach 120 m (~360 ft) in height. • High-quality wood makes these forests a valuable timber resource • Old Growth Forest

21. Temperate Forest (Deciduous) • Hot summers, cool winters (minimum temp rarely < -12C). • Rain is plentiful (75 – 200 cm / yr), long growing season, fertile soil, moderate diversity. • Species include oak, beech and maple. • Produce a new batch of leaves each year • Not as expensive as ‘freeze-proofing’ them • Early spring, a lot of light hits the forest floor and spring ephemerals take advantage of this. • Soils make good farmland and supports good lumber

23. Prairies and Grasslands • Climatically similar to temperate forests but are dryer. • Precipitation ranges from a low 40 mm (plants seldom grow taller than 0.5m) to a high of 80 cm (plants can grow more than 2 m – tall grass prairie). • Home to numerous herbivores • Grazing is an important ecological factor in these areas • Heat and aridity become important evolutionary factors • Panting, sweating, large ears, evapotranspiration

24. Prairies and Grasslands • Native grazers prevented any single plant from out competing the others. • Introduced domestic grazers (cattle or sheep for example) have different grazing patterns and the floristic composition has been resorted. • Soils are very rich – America’s bread basket. • Fire is an important component of grasslands. • Some areas may burn every three to five years (lightning) • Keeps trees from becoming established • Stopping these fires can alter the community, allowing trees to grow.

26. Chaparral • Wet and mild winter climate, dry and mild summer • Found in coastal California, Israel, parts of South America and Australia • Mediterranean climate • The summer drought is what drives this biomes ecology • Plants either limit the water they lose, or gain as much water as possible

27. Chaparral • Plants can limit water loss by producing small hard green leaves • Hardness due to a waxy outer covering used to prevent water loss • Most of these plants are evergreen, so they can photosynthesize during the wet part of the year • By retaining leaves year round – they are able to take advantage of all rainfall • Plants can gain as much water as possible • Deep tap roots • Extensive root system (bare ground between plants)

28. Chaparral • Eradication of top predators when these areas are settled leads to a proliferation of herbivores. • Sometimes, native herbivores have been replaced with goats • Goats are indiscriminate browsers and kill many of the plants they eat • Overgrazing has reduced many Mediterranean hillsides to bare rock with very few patches of vegetation • Urbanization in California

29. Chaparral

30. Desert • Dry air descends usually at Latitudes 20 – 30 North and 20 – 30 South. • Too dry to support most life forms • Cloudless skies permit wide temperature fluctuations • 50 C during the day, near 0 C at night. • Desert plants and animals must be obsessive about water retention

31. Desert Rainshadow

32. Desert • Desert animals usually hide from the full strength sun and come out when the temp is lower. • Top predators are usually snakes and lizards – need less water than mammals • Camels have a highly developed nasal structure that prevents water loss and its hair is efficient at reflecting the sun’s heat. • Desert plants can not escape the sun. • Evolution has shaped them to minimize exposure to the sun

33. Desert

34. Desert • Desert plants are also designed to retain as much water as possible. • Stem and leaves appear to be thick and fleshy, skin very leathery. • Needles create microclimate in still air. • Extensive root network; leaves are recycled

35. Desert

36. Tropical Forest • Key feature is constant temperature • Average temperature from one month to the other is usually within ± 2C • However, daytime temp may be 34 C during the day and 20 C at night. • Much rain: annual rainfall ranges from 2,000 mm to 15,000 mm (79 – 591 inches; 1.6 inches per day). • Wet and dry seasons • Length of dry season determines the areas ecology

37. Tropical Forest • Long Dry Season • Dry season = 6-8 months • Many trees drop their leaves during the dry season not to escape cold, but to prevent overheating • Short Dry Season • Dry season < 3 months • Tropical rain forest: 2,300 – 5,000 mm of rain per year (extreme years some places may get 15,000 mm = 50 feet).

38. Tropical Forest (Rain) • Huge diversity • Perhaps 50 - 75% of all organisms on Earth inhabit theses forests. • Temperate forest may have 20 - 30 tree species per hectare (2.47 acres); rain forests can support more than 350 – 450 tree species per hectare • To fit that many tress each species may only be represented once or twice • Most productive terrestrial biome • High temp, moisture, uninterrupted growing season • Decomposers / nutrient cycling

39. Tropical Rain Forest

40. Tropical Mountains • Go from tropical forest to shrubs to ice as you move up in altitude. • Similar phenomena seen as you move from the equator north

41. Tropical Mountain

42. High Alpine Tundra Elevation Tropical Forest Low Tropical Forest Temperate Deciduous Forest Northern Coniferous Forest Arctic Tundra High Moisture Availability Low

43. Tropical Mountains