Major World Biomes 2023-2024 Lecture Notes

World Biomes (cont’d) 2022-2023 Lecture 15 Freshwater biomes } Freshwater ecosystems are very sensitive ecosystems } Can be affected by adverse biotic factors } } } dammed / drained, an invasion of invasive species May succumb to abiotic factors such as climate change, natural weather events, etc. C...

World Biomes (cont’d) 2022-2023 Lecture 15 Freshwater biomes } Freshwater ecosystems are very sensitive ecosystems } Can be affected by adverse biotic factors } } } dammed / drained, an invasion of invasive species May succumb to abiotic factors such as climate change, natural weather events, etc. Classification: 1. 2. Lotic / Riverine Lentic / Lacustrine Freshwater biomes – Lotic 1. Lotic / Riverine } Any kind of terrestrial waters with a unidirectional flow ¨ } } creek, brook, river, spring, channel or stream, rivers Limited stratification Two main types: rapids and pools 1. 2. Rapids: areas where the water is fast enough to keep the bottom clear of materials Pools: deeper areas of water where the currents are slower, and silt & organisms build up Freshwater biomes – Lentic 2. Lentic / lacustrine } } } } } } aka wetlands Any kind of relatively still terrestrial waters Bodies of standing water on land (terrestrial) Range in size and may be seasonal (vernal) Natural or artificial Water may be fresh, salty or brackish ditches, seeps, potholes, pools, ponds and lakes ¨ salt marshes, mangroves, riparian regions, swamps, river deltas, low-lying areas that frequently flood ¨ Freshwater biomes – Lentic / lacustrine } Source of water: ¨ precipitation, run-off, rivers } and springs Larger bodies show vertical stratification of light & temperature ¨ Lakes may have layers of ecosystems influenced by light ¨ Ponds (shallower) are able to support a diverse range of water plants due to more light penetration. Freshwater biomes – Lentic / lacustrine } Transitional areas between land & water 1. 2. v Riparian: wetlands adjacent to rivers and streams Estuarine: wetlands associated with river sea boundary Have the highest diversity of species of all freshwater biomes q Birds, fur-bearing mammals, amphibians and reptiles Wetlands Freshwater biomes – Estuarine A transitional zone between river and ocean environments that is subject to: } 1. 2. marine influences (e.g., tides & waves) riverine influences (e.g., flows of fresh water and sediment) Most productive natural habitats in the world. } } feature a large number of organisms esp. fish and migratory birds Estuaries Major Terrestrial World Biomes 1. 2. 3. 4. } Tropical Rain Forest (TRF) Temperate Deciduous Forest (TDF) Desert Tundra (Arctic & Alpine) Others include: 5. 6. 7. Tropical Grassland or Savanna Temperate Grassland Taiga/Coniferous Boreal Forest/Pine Forest 1. Tropical Rain Forest Tropical Rain Forest } Location = 0 – 30 °N/S of the equator, } } between tropic of cancer & tropic of capricorn Significant TRF areas: 1. Central America 2. Northern South America 3. Western and Central Africa 4. 5. Asia and the East Indies Northeast-Eastern Australia Tropical Rain Forest } Non-seasonal climate } } } Consistently high temperatures all year } } } } } mean annual temperature ~ 25 –28 °C High humidity } } consistently hot & wet with no defined seasons year-long growing season Precipitation 200 –500 cm.year-1 Rains every afternoon Extensive inundation during rainy season Nutrient poor, shallow soils Highest species diversity } ~ ½ the world’s plant species Tropical Rain Forest - types } Tropical rainforests are further subdivided into 4 depending on the amount of precipitation experienced. For example: a. Lowland tropical rainforests: They receive the most rain per year b. Highland tropical rainforests: These kinds of rainforests are situated on the high peaks and tablelands c. Monsoon rainforests: This kind of tropical rainforest occurs in areas that experience strong seasonal wet and dry climate. Ø Climbers are usually the biggest feature of Monsoon tropical rainforests. a. Subtropical rainforest: similar to tropical rainforests only that it harbors a lesser number of species. Climbers and epiphytes are common here & most of the trees are buttressed Tropical Rain Forest - types Tropical rainforests are further subdivided into 4 depending on the amount of precipitation experienced. For example: Lowland tropical rainforests Highland tropical rainforests Monsoon rainforests Subtropical rainforests Tropical Rain Forest Flora } Dominated by tall broad-leaved evergreen trees } Vegetation arranged in at least 3 canopies } Dense closed canopy due to branching at the tree crowns } Dark, damp, sparsely-vegetated forest floor } } Trees support epiphytes } } receives ~ 2% of incident light plants that grow on host plants or objects for physical support only esp. to gain access to light in forests Trees also support lianas } long-stemmed woody vines rooted in the soil. Tropical Rain Forest Flora Tropical Rain Forest Flora Tropical Rain Forest Fauna } High diversity - about ½ the world’s animal species } } Some of the most beautiful, lethal, adorable, and strange animals on the planet Range: } Insects, birds, reptiles, amphibians and mammals } 90% of animals are arboreal (tree-dwelling) } Few ground-dwelling species } Animals adapted to high temperature & moisture } Abundant decay organisms & detritus feeders } appreciable rate of mineralization Tropical Rain Forest Fauna 2. Temperate Deciduous Forest } Seasonal climate –warm to hot summers and cold winters } } Located in the mid-latitude areas } } } } Eastern United States, Canada, Europe, China and Japan Droughts are rare } } annual average ~ 10°C with hot summers, & cold winters Precipitation ~ 75 - 150 cm/year Locations: } } found between the polar regions and the tropics Mean annual temperature range: -30°C to +30°C, } } seasonal changes happen every few months water unavailable in winter as snow/frozen conditions persist Fairly long growing season (6 months) Rich, well developed soils – fallen leaves → humus } Saprotrophic activity not as intensive as in TRF’s Temperate Deciduous Forest Temperate deciduous forest Temperate Deciduous Forest } Relatively high species diversity, second to TRF } Broad-leaved deciduous hardwood trees predominant } } e.g. oak, beech & maple… ≥ 40 m tall } most are perennials Adaptations: } } Leaves loss in autumn → cold season → dormancy thick bark for protection during the cold season } More light reaches forest floor compared to TRF } Light reaching forest floor varies seasonally: } more of the incident light gets to the forest floor during winter and spring when trees are leafless } } incident light intensity is least in winter, greatest in summer Understory of smaller plants & tree seedlings (< 10 m) } ground flora of ferns, lichens, bryophytes & herbaceous plants Temperate Deciduous Forest structure TDF Flora – spring /summer TDF Flora - autumn TDF Flora – late autumn/winter TDF Fauna } A variety of reptiles, mammals, birds, and insects } } raccoons, skunks, bears, squirrels, and wood mice, deer, elk, moose, coyotes, bobcats, mountain lions, reptiles, amphibians and insects Adaptations: 1. 2. 3. 4. Camouflage: resembling dead, decomposing leaves that cover the ground Hibernation: a state of inactivity Migration: movement of animals from freezing climatic conditions to more favorable climatic conditions Food storage: seeds and nuts collected in the summer and stored in tree hollows for consumption in winter TDF Fauna 3. Terrestrial Biomes - Deserts } A collection of habitats in arid environments as a result of little rainfall & very hot conditions } Location: 15 – 35 °N/S latitude } North America, Australia, Middle East, Asia, Northern Mexico, Northern & SW Africa } Deserts cover about ⅓ of the earth’s surface in ~ 60 nations } Average annual precipitation ≤ 25 cm (Sahara desert ~ 2 cm/year) } } Temperatures fluctuate daily/seasonally by 25 –30°C } Hot days ≥ 45°C Cold nights ≤ 0°C } Average yearly temperature range 7° – 38°C } } Skies are cloudless } } Received all at one time in a short rainy season a lot of direct sunlight shining on the plants Thin, nutrient poor soils with poor structure Desert Biomes - Types } 1. 4 types: Hot deserts: } 2. Coastal deserts: } 3. Peru and Chile Cold deserts: } 4. Sahara, Kalahari, Arabian, Australian, Australia, Peninsula, Mexico/ S.W. USA China, Mongolia, Iran, Afghanistan, S.W Africa, W. China, Argentina, South America, Middle East, Antarctica and USA Semi-arid deserts / Steppes: } USA, Canada, Ukraine and China Desert Biomes Flora } The soil is often sandy / rocky } } } } Winds are often strong, and dry out plants Sparse vegetation Perennial vegetation of widely spaced thorny shrubs & flowering annuals } } } unable to hold much water Vegetation adapted to drought conditions Diverse and very attractive } encourage pollination Growth restricted to short bursts Desert Flora } } } } } } } 90% of plant body underground as shallow, extensive root systems Succulent roots, stems & leaves Waxy coverings on leaves Shedding leaves Leaves modified to spines with thorns Reduced leaf area with sunken stomata Some have developed long tap roots } } } to be able to reach water tables Very short life cycles (within a few weeks) Wait until rain falls to germinate (some wait for years) Desert Biomes – Flora Desert Biomes – Flora Desert Biomes – Flora Desert Fauna } All highly adapted } } } } } } Desert-adapted insects Specialized desert reptiles (lizards & snakes) Specialized amphibians (frogs & toads) Specialized mammals (domesticated camels, kangaroo rats, kangaroos, rabbits) Some birds (owls) Physiologically adapted to withstand drought 1. 2. 3. 4. 5. 6. 7. Many survive by burrowing Some remain dormant Nocturnally active Crepuscular (dusk- or dawn-active) Special heat exchange mechanisms Some store water Some migrate Desert Fauna Terrestrial Biomes - Tundra } Biome that appears as a freezing wasteland } } from the Finnish word tunturia (means tree-less land) Biome that is furthest north (55 - 75° N) } south of the ice caps of the Arctic and extending across North America, Europe and Siberia Large biome (20% global land mass) } Seasonal climate with cold desert-like conditions. } } Temperature < 0°C for most of year Tundra Tundra Terrestrial Biomes - Tundra } } } } } Extensively dark winters Thick snow Icy, dry, strong winds Average temperature ~ -34 °C. Brief summers (2 -3 months) with average temperature ~ 3 –12 °C. } } } 8-10 week growing season Average annual rainfall < 25 cm Thin nutrient-poor soils with constant permafrost } water trapped in sediment / soil, and the cracks, crevices, and pores of rocks remains frozen for a minimum of two years Tundra flora } Low species diversity, scarce vegetation, no trees } } Buds are held near the ground – sheltered from wind and cold. } } } lichens, mosses, grasses, sedges, shrubs predominant Woody perennials present as dwarf trees (0.3 m tall) –due to winds. Extensive root systems Plants have short life cycles, special adaptations & show dormancy Tundra flora Summer in the Tundra Lichens - snow lichen and reindeer moss Tundra fauna } } Low species diversity Few permanent animals } } Survive by } } } } } } } some mammals, birds & seasonal insects Thick coat & undercoat Light-coloured coat Burrowing / hibernating Migrating Adapting to the persistent cold & irregular food supply Many migratory mammals (squirrels, wolves, reindeer) Reptiles & amphibians few / absent