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Environmental variation Ecological variation is complex In spite of their variation, ecologists have classification schemes aggregate ecological variation into clusters with general similarity of structure and function Ojibway Prairie...

Environmental variation Ecological variation is complex In spite of their variation, ecologists have classification schemes aggregate ecological variation into clusters with general similarity of structure and function Ojibway Prairie Conservation Preserve 3  Biomes Biomes are clusters of ecosystems that have a general similarity of structure and function Biomes exist over an extensive geographic range, occurring anywhere in the world that environmental conditions are suitable 4  Biomes The biology of biomes is defined by climate We characterize biomes by late-successional Boreal forest vegetation and characteristic animals It is not the particular species that are present, Temperate grassland but the morphological and physiological traits of dominant organisms (plants and animals) Tropical rainforest 5  The global distribution of terrestrial biomes FIGURE 11.2 6 Terrestrial biomes in North America dominant organisms FIGURE 11.3 7  Biomes are defined by climate FIGURE 11.4 8 Biomes are defined by climate 9  bit y or da 5 36 tilled gives rise to seasonality - gives rise to variation Earth’s axis of rotation is tilted - in temperature at 23° relative to the plane of precipitation our orbit around the sun 10  N Autumnal equinox: Sun directly overhead (90°) at equator at Winter solstice: midday Sun directly overhead (90°) at Tropic of S Capricorn at midday N N 43º 90º 66.5º 66.5º 90º Sun hits the earth on its 43º full rotation S N at the Tropic S of capricorn Summer solstice : Sun directly overhead (90°) at Tropic of Cancer at midday Vernal Equinox: Sun directly overhead (90°) at equator at midday S 11  Windsor Costa Rica Ecuador 12 light: 12 dark in the tropics Annual variation in day length corresponds with distance from the equator 12 13  convective current dry cool air - Temperate Equator Temperate Warm air at equator rises è cools è water condenses è rains Cool dry air eventually returns to planet surface at about 30°N and 30 °S  desserts concentrated where there is cooler is drier air returning Global distribution of deserts results from the return of dry air near 30ºN and 30ºS  > - US > - desserts Creates general climatic and precipitation patterns at different latitudes  The global distribution of terrestrial biomes FIGURE 11.2 17  Tundra High latitude biome Growing season too short to support trees solar radiation in abundance only for a small of part the Low precipitation, low year evapotranspiration ↳ low movement of water into the atmosphere Permafrost prevents drainage temp cold icy soil/peat Dominant large herbivore in arctic tundra is Small shrubs, grasses, migratory caribou and sedges Dominant Organisms & large herbivores grasslands graze - on 18  Tundra The short growing season still allows many migratory birds to breed in the arctic biodiversity generally low Arctic Terns breeding in Arctic, move to Antarctic 19  Temperate zones Temperate zones lie between the Arctic / Antarctic and the Tropics of Cancer / Capricorn Variable vegetation, depending on latitude and the pattern of precipitation Marked seasonal variation is commonplace 20  Boreal forest (taiga) Dominated by coniferous trees Spread across the northern hemisphere Short but warm summers Support - Sustained growth Deciduous trees such as aspen and birch after disturbance such as fire FIGURE 11.5 21  Temperate deciduous forest Windsor z Cold short winters Summer warm and long enough to support many deciduous trees In Canada, highest tree diversity is in southern Carolinean forests High species richness is common in southern temperate deciduous forest 22  Fall leaf colouration Yellow and orange colours in fall leaves are carotenoids, unmasked by the breakdown of - chlorophyll The red colours are anthocyanins, newly by > - produced tree produced in the fall as - protection These colours are not a incidental product of leaf senescence 23  Fall leaf colouration Adaptive hypotheses for fall leaf colour Photoprotection hypothesis: red pigments protect against the harmful effects of light at low temperatures Coevolution hypothesis: red is a warning signal toward insects migrating to the trees in autumn 24  Fall leaf colouration Assigned reading: Why does fall foliage turn so red and fiery? It depends. New York Times Advanced reading: Unravelling the evolution of autumn colours. Trends in Ecology and Evolution 25  Temperate rainforest Vancouver ↳ area that receives 2m of rainfall over the = year Found only in western North America Bountiful precipitation all year Mild winters Highest conifer Trees in temperate rainforests can attain enormous girth diversity of all and height. biomes Abundant moss 28  Temperate grassland Also called prairie and steppe grasslands drier air provinces in praire ends up Low annual precipitation Insufficient moisture to support forests Cold winters, hot summers Fire and herbivores (bison) keep trees out in the more humid regions (tallgrass prairie) 29  never gets California 2 cold or rains Chaparral Mild, moist winters; hot dry summers; a “Mediterranean climate” South cost of France Poor soils and fires limit tree growth Dominant plants are shrubs Fires are a key part of chaparral system, but fire prevention has meant accumulation of fuel, threatening this biome 30  Deserts Too dry for closed vegetation bare exposed soil - sand Deserts occur in tropical, temperate, and even arctic climates Plants show strategies to tolerate arid climate: that plants Storing water very deep Survive have roots (succulents) Avoiding dry periods (annuals) Having deep roots CAM photosynthesis grab during CO2 the night - close Stoma during the day 31  Tropical savanna and dry forest Tropical climate with a dry season Long drought: savanna (grassland) with scattered trees Fire and large herbivores limit tree growth in savannas Short drought: dry forests with deciduous trees FIGURE 11.11 dropleavesprot againstadry perio rainfall to support the easy 32  Evergreen tropical rainforest > - close to equator No dry season period of 3 growth no No frost the where year ceases Diurnal temperature fluctuations are larger than seasonal fluctuations Often daily precipitation High productivity and biomass Complex vertical structure trees to send out large roots Support themselves FIGURE 11.12 > - soil is in nutrients 33  Lentic ecosystems Lakes and ponds with standing (non-flowing) water Ex. Northern Lake Great Lakes Characteristics are shape and volume, nutrient concentration, water transparency type define what of organisms found Distinct habitats are Littoral (shore) Pelagic (open water) Benthic (bottom) 34 Eutrophic vs oligotrophic ecosystems Nutrient concentration in lakes determines productivity Eutrophic: nutrient rich Ex Erie Lake Oligotrophic: nutrient. Eutrophic lake poor (Mesotrophic: intermediate nutrient levels) Oligotrophic lake 35  Lotic ecosystems Flowing water: rivers, streams Key characteristics: amount, speed, seasonal variation, and turbidity of water Primary productivity often not self-sustaining: consumers supported by upstream lakes or > - nutrients carry terrestrial ecosystems of nutrients may have seasonal pulses 36  Freshwater wetlands Characteristics determined by water nutrient content and variation in water level Bog Bogs: low productivity with no inflowing groundwater; acidic no open water stream , no Fens: mineral rich with inflowing groundwater; non-acidic Swamp Swamps: fertile wetlands dominated by trees or shrubs high productivity Marshes: fertile wetlands dominated by grasses Marsh 37  Marine biomes: open ocean upwellings driven radiation T by solar - Currents and upwellings and rotation of the earth , determine ecological variation in open ocean Low productivity per unit area But a lot of life sustained Frilled shark Pelagic: currents and upwellings cause variation environments deep water to life dying falling and down the bottom of the ocean Benthic: mostly heterotrophic environments Fed nutrients from other by Goblin shark 38  Marine biomes: open ocean Hydrothermal vents at ocean bottom show diverse life at high temperatures and pressures, based on primary production by chemosynthetic bacteria - use not ocean vents in order to drive growth of new biological tissue FIGURE 11.17 39  Marine biomes: continental shelf > - closer to the shore More productive than open ocean Help Ex. forests Nutrients from rivers or upwellings Seashores: ecology determined by bottom characteristics Estuaries: productive regions at Ex the. where Amazon marine/freshwater and r each Nile interface the Ocean Coral reefs: ecosystems built by animals ONLY FOUND TO THE CLOSE EQUATOR 40 have because photosynthesis can FIGURE 11.18 there is still access to sunlight  Anthropogenic ecosystems Ecological characteristics convergent in different climate zones Can be centuries old Often with adapted organisms Three clusters: Most ecosystems in inhabited – Urban areas are more or less – Rural influenced by humans. – Agroecosystems 41  Urban ecosystems Can have relatively high biodiversity due to heterogeneity, warm microclimate, and species introductions through humans Many species are alien, do not survive without human influence 42  Rural ecosystems Extensive networks of highways, railroads, electrical lines, industrial facilities, and towns associated with the harvest and processing of natural resources 43  Agroecosystems Modern agricultural practices can lead to unstable ecosystems with low diversity Centuries-old low- intensity agricultural practices may have resulted in high species diversity (e.g. European hay meadows) 44