Lecture Notes 7 Life On Land PDF

**Lecture 2 Life on Earth** 1. [Heating] of the earth a. Spherical surface -- uneven heating \> latitudinal variation b. [Tilt of the earth] on its axis - seasonality c. Air in the equator receives most heating because of direct sun light i. Warm air rises, carr...

**Lecture 2 Life on Earth** 1. [Heating] of the earth a. Spherical surface -- uneven heating \> latitudinal variation b. [Tilt of the earth] on its axis - seasonality c. Air in the equator receives most heating because of direct sun light i. Warm air rises, carrying lot of water ii. Air cools as it rises, and humidity condenses to cloud and eventually falls as rain, iii. Cold and dry air then descends to warm up and take up water, moving toward 1. equator, forming **Hadley cell** 2. mid latitudes, forming **Ferrel cell**. 3. Resulting in [tropical rain forest along equator] and [desert at 30 degree latitude] north and south 2. Climate diagram: how to plot, and how to read and predict biome likely to be present in a place? d. Monthly average temperature and rain fall iv. Freezing point and below -- no growing for plants, even if there is rain 4. Permafrost v. No rain or little rain -- no growing or little for plants, even if temperature is high 5. Desert 3. Soil, soil structure, and soil ecosystem e. "More organic carbon, living and dead, is stored below ground than above ground Soil horizons" vi. Can you list five living things as member of the soil biological community? f. Factors affecting soild structure: vii. *mineral material of the parent rock* viii. climate ix. topography x. organisms 4. [Terrestrial biomes: ] g. The geographic [distribution of terrestrial biomes] corresponds closely to variation in climate, especially prevailing temperature and precipitation. h. Major biomes: tropical rain forest, tropical dry forest, grasslands (savanna, prairie, steppe, pampas, veld) and woodland and shrubland, temperate deciduous forest, boreal/taiga forest, tundra. xi. Each biome has unique fauna and microflora as well as flora i. High mountains and diverse biomes: from low to high altitude similar to from low to high latitude. 1. [Human activities] (e.g., agriculture and city building) modify climate, biomes structure, soil, and hydrology, reshaping biological communities. 5. [Major Terrestrial Biomes] 1. ***[Tropical Rainforest]*** a. near equator (0-15° latitude), especially Amazon River basin (South America), Congo River basin (Africa), SE Asia b. warm year-round with \>250 cm rainfall/yr. (wet and dry seasons not as pronounced/dramatic as biomes \#2 and \#3 below) c. tall, multi-layered forest, may be \~300+ species of trees/hectare d. very high species richness overall, and for many taxa as well e. many species of animals are arboreal, some are restricted to the canopy f. poor soils often, fast decomposition and reabsorption of nutrients 2. ***[Tropical dry forest]*** a. 10-25° latitude, warm year-round but with pronounced wet and dry seasons b. Trees may drop leaves during dry season c. high species richness (not quite as high as trop. rainforest, however) d. better soils than tropical rainforest, therefore, greater human impacts (e.g., only \~2% remains in Central America and Mexico) e. animals may migrate during dry season 3. ***[Tropical savanna]*** a. tropical grassland with scattered trees (often legumes in genus, *Acacia* -- as in iconic savannas of Africa) b. also typically found at 10-20° latitude c. warm year-round w/ pronounced wet and dry seasons (but typically drier than trop. dry forest) d. fire plays a key role in maintaining this biome (reducing tree abund.) e. "birthplace" (i.e., evolutionary origins) of *Homo sapiens* f. "classic image" = Serengeti of Africa (see 'a' above) g. large herds of grazing mammals (e.g., wildebeest, zebra) common 4. ***[Temperate Grasslands]*** a. similar to tropical savanna but in more temperate/cooler latitudes (\~30-45° latitude) b. dominated by herbaceous (non-woody) plants, especially grasses c. often w/ deep, fertile soils; therefore, conversion to agricultural uses common (e.g. Midwestern United States) d. fire plays a key role in maintaining this biome e. large, grazing mammals are often common (e.g., bison) f. known by a variety of local names such as "[prairie]" in N.A., "[pampas]" in S.A., "[veldt]" in Africa, and "[steppe]" in Russia 5. ***[Chaparral]*** a. books calls this "[Mediterranean woodland & shrubland]" b. found in areas (typically 20-30° latitude) w/ hot, dry summers and cool, moist winters (known as a "Mediterranean climate") c. fires common in summer, critical to maintaining this biome. d. usually dominated by small trees and shrubs e. found around Mediterranean Sea, s. California, s. Australia, etc. 6. ***[Desert]*** a. low rainfall (\ a. 30-50° latitude -- definite seasons w/ warm summers and cool or cold winters b. most areas dominated by broad-leaf, deciduous trees (e.g., oaks, maples, ashes); some dominated by conifers (e.g., pines, redwoods) c. rainfall fairly consistent (on average) in all months (i.e., no wet and dry seasons); relatively fertile soils d. in east. North America, western Europe, Japan, Korea, east. China, etc. 8. ***[Northern Coniferous Forest]*** a. aka "[boreal forest]", "[taiga]" b. found north of temp. forest at 50-65° latitude c. dominated by needle-bearing conifers such as spruces, firs, larches d. world's largest terrestrial biome e. tree diversity very low f. seasonal but colder than temp. forest; acidic relatively infertile soils 9. ***[Tundra]*** a. poleward from north. coniferous forest (\60° latitude) b. little precip., but wet due to lack of evaporation due to cold temps. c. [Permafrost] (= permanently frozen subsoil layer) present (although this is melting as a result of global warming...) d. low-growing vegetation -- especially lichens, mosses, grasses, dwarf willows & birches 6. [Biome zones along mountain slope] j. As altitude increases, local temperature and humidity increase in short distance k. Biomes change from low to high altitude approximately in the same sequences as from low to high latitude a. In the Great Smoky Mountains, you find Temperate Broadleaved Deciduous Forest at lower arts, but you will find Boreal Coniferous Forest as you hike up the mountains. b. In Yellowstone National park, temperate deciduous forest dominate foothills below about 3,000 feet, Taiga / Boreal Coniferous forests dominate between approximately 3,000 and 10,000 feet, and the biome is more of tundra above 10,000 feet.  l. Large mountains also create local atmosphere circulation pattern, resulting in the so-called **rain-shadow** on the side of the mountain away from ocean current, sometimes forming deserts, such as the **Taklamakan Desert** in Central Asia because of the Himalayas and the **Mohave Desert in North America because of the Siera Nevada.**