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Life in Land.docx

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University of Waterloo
BIOL 150
Ken Oakes

soil - activity of soil organisms -influences the rates of carbon and nutrient cycling, soil respiration, transfer nutrients to vascular plants - provide food and habitat for larger organisms - key to the development of soil structure Soil: Foundation of Terrestrial Biomes - soil structure results from the long term interaction of climate, organisms, topography, and parent material - diagram illustrated - Plants secrete root exudates, along with the living roots and plant litter, serve as substrates for bacterial, fungal, and animal species. - Growth and activity of organisms provides stability to mineral components allowing development and maintenance of complex canals of air spaces and cavities within the soil - Climate affects rates of weathering of parent materials, leaching of organic and inorganic substances, erosion, and decomposition of organic matter through direct weathering effects - also alter decomposition by directly impacting the activity of soil organisms and indirectly altering soil activity by influencing the type and amount of plant species that can grow in a given area Natural History and Geography of Biomes - geography distribution of terrestrial biomes corresponds closely to variation in climate, especially prevailing temp. and precipitation Tundra: (starting at the most northerly areas of vegetation) - open landscape of mosses, lichens, dwarf willows, small ponds, clear streams , quite warm summer Geography: - covers most of the lands north of the Arctic circle - extends from northern-most Scandinavia, across Northern European Russia, through northern Siberia, across northern Alaska and Canada - reaches far south of Arctic circle into the Hudson Bay region of Canada - also found on the coast of Greenland and in northern Iceland Climate: - typically cold and dry - not as cold in winter or as warm in summer as boreal boreal forest to the south - defining characteristic of northern tundra: short summers - precipitation: less than 200mm to a little over 600mm - low avg annual temp. > precipitation exceeds evaporation Soils - soil building slow in old: rate of decomposition low > organic matter accumulates in deposits of peat and humus - surface soils thaw in summer but often underlain by layer of permafrost (many meters thick) : perm frozen later of soil that remains frozen even during summer freezing and thawing of surface soil combines with actions of water and gravity produce: - solifluction: slowly moves soils down slopes - brings stones to the surface of the soil, forming a netlike, or polygonal, pattern on the surface of tundra soils Biology : - herbaceous plants : especially grasses, sedges, mosses, lichens - lichens, associations of fungi and algae often eaten by reindeer and caribou - woody vegetation: dwarf willows and birches, variety of low-growing shrubs - short growth due to short summer: -slow growing plants, nearly all of the living biomass below ground - plants with very short and strong stems to withstand fierce winds of the north - one of the last biomes on earth that supports substantial no.s of large native mammals: caribou, reindeer, musk ox, bear, wolves - small mammals: fox, weasel, lemming, ground squirrel - birds: ptarmigan, snowy owl - insects: not as diverse as in biomes farther south but abundant (swarms of mosquitoes and insects in summer) Human Influences - intense exploration and extraction of oil, natural gas, and a variety of minerals - rapidly rising temperatures on the permafrost and rates of decomposition - patterns of global air and ocean circulation causing areas of arctic tundra rapidly warming - deep expanses of permafrost in the arctic: as permafrost melts, the rich organic material it contains becomes available to soil microbes and insects for decomposition = releasing amounts of CO2 into atmosphere > greenhouse effect and global warming Boreal Forest/Taiga: world of wood and water covering over 11% of earth's land area Geography: - confined to northern hemisphere - extends from Scandinavia, through European Russia, across Siberia, to central Alaska, and across all of central Canada in a band b/t 50 and 65 degree latitude - bounded in the south either by temperate forests or temperate grasslands and in north by tundra Climate: - winters usually longer than six months - summers too short to support temperate forest - fairly moderate climates (Sweden) moderated by the nearby Baltic Sea - some are variable: ranges from -70 in winter to over 30 in summer (annual temp. range of 100degree celsius) - precipitation moderate, ranging from 200-600mm - low temp and long winters > evaporation rates low > drought infrequent/brief (burn vast areas of boreal forest) Soils: - low fertility, thin, and acidic - low temp and low ph slow down decomposition of plant litter and the rate of soil building > nutrients largely tied up in a thick layer of plant litter that carpets forest floor - most trees in boreal forests have a dense network of shallow roots that, along with associated mycorrhizal fungi, tap directly into the nutrients bound up in this litter layer - topsoil (underlies litter layer) is thin Biology - dominated by evergreen conifers (spruce, fir, pines) - larch, a deciduous conifer, dominates in the most extreme siberian climates - deciduous aspen and birch trees : Canada (dominant during early stages of recovery following fire) - willows: along shores of rivers and lakes - mosses and other non-vascular plants along base of most trees and on forest floor - traps rainfall, home to insects and other organisms - steep vertical gradient in light from canopy to soil surface (leaves on outside of canopy absorbs much of the visible light, light levels attenuate as u move down in both intensity and color) - large expanses of bogs and fens dominated by moss species, these areas have waterlogged 'soils', with islands of vascular plants centered around a few trees and shrubs, home to plants that feed on insects - winter: migratory caribou and reindeer - year-round: mousse and woodland bison - wolf --- major predator - N. America: black bears, grizzly bears - Eurasia: brown bear - smaller mammals: lynx, wolverine, snowshoe hare, porcupines, red squirrels - nesting habitat for many birds that migrate from tropics each spring and year- round home of other birds (crossbills and spruce grouse) Human influences: - hunting and trapping impact populations of wildlife species - forest rapidly cut for lumber and pulp and oil and gas exploration (potential econ gain) Temperate Forest - largest living organisms on earth Geography: - found b/t 30 and 55 degree latitude - Asia: Japan, eastern China, Korea, eastern Siberia - Western Europe: southern Scandinavia to northwestern Iberia, from British Isles through Eastern Europe - northern Cali through southeastern Alaska - Southern Hemisphere: Chile, New Zealand, southern Aussie Climate: - temp forests may be either coniferous or deciduous at where temperatures not extreme and annual precipitation avg's anywhere from 650mm to over 3000mm - receive more winter precipitation than temp. grasslands - deciduous trees dominate (growing season moist and at least 4 months long - deciduous forests: winters 3 to 4 mths, usually mild (snowfall heavy) - coniferous forests: winters more severe or summers drier (conifers more abundant than deciduous - pacific coast of North America receive most precipitation during fall, winter, spring,and subject to summer drought Soils: - usually fertile - most fertile under deciduous forests (neutral or slightly acidic in pH, rich in organic matter and inorganic nutrients) - coniferous forests: less fertile due to acidity of the needles leading to reduced decomposition - nutrient movement between soil and vegetation: slower and more conservative in coniferous forests, more dynamic in deciduous forests (recycle about twice the amount of nitrogen than temperate coniferous forests of similar age) Biology: - Diversity of trees lower than tropical forests but biomass greater - Vertically stratified: o Ground level: herb layer > shrubs and saplings > shade-tolerant understory trees > canopy (top) o Sapling bank: saplings grow to fill open space rapidly when available o Tree canopy: small arboreal mammals such as deer mice, tree squirrels, flying squirrels o Forest floor: deer, bear, fox o Cavities of large trees: bats and other animals o Most important consumers : fungi and bacteria; consume the large quantities of wood stored on the floor; recycle nutrients Human Influences - tree plantations - many temperate deciduous forests able to recover following years of logging and agriculture Temperate Grassland - praires were home of the bison and pronghorn and nomadic cultures of Eurasia and N. Amer Geography: - largest biome in N america : Great Plains extend from southern Canada to Gulf of Mexico - Idaho and Washington and central valley and surrounding foothills of Cali. - Eurasia: eastern Europe to eastern China - S. Hemisphere: Argentina, Uruguay, S. Brazil, New Zealand, Aussie Climate - receive b/t 300 and 1000mm of precipitation annually - droughts may be several yrs - max precipitation in summer during height of growing season Soils - most productive are deep, basic or neutral, and fertile and has a lot of organic matter - black prairie soils of N. America and Eurasia - brown soils of more arid grasslands has less org. matter Biology - dominated by herbaceous vegetation - fire, drought, and grazing exclude woody vegetation - tress and shrubs limited to margins of streams and rivers - up to 80% of living biomass below groud in some grasslands - spring: up to 70 species flowers bloom - height of vegetation varies from 5cm (dry, short-grass prairies) to 300cm (wetter tall-grass) - animals: o big animals such as wolves, grizzly bears, bison, pronghorns pushed to mountains due to human pressures o smaller animals: grasshoppers and mice o intermediate size: burrowing (badger and prairie dog) and fleet (swift fox and prairie falcon) Human Influences - extent of agricultural developments in N America - most fertile farmlands > continuous agriculture caused loss of as much as 35% to 40% of org matter in soils in just 35 to 40 yrs of cultivation Mediterranean woodland and shrubland Geography - all continents except Antarctica - most extensive around Mediterranean Sea and in N. America (cali to northern Mexico) - central Chile, S. Australia, S. Africa - grow b/t 30 and 40 degrees latitude : majority in north of subtropical deserts in N. hem and south in S. hem Climate - cool and moist in fall, winter, spring - hot and dry summers - danger of frost varies, usually not severe - combo of dry summers and dense vegetation, rich in essential oils >>>
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