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BIOL 4120: Principles of Ecology Lecture 5: Biome Concept in Ecology Dafeng Hui Room: Harned Hall 320 Phone: 963-5777

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Presentation on theme: "BIOL 4120: Principles of Ecology Lecture 5: Biome Concept in Ecology Dafeng Hui Room: Harned Hall 320 Phone: 963-5777"— Presentation transcript:

1 BIOL 4120: Principles of Ecology Lecture 5: Biome Concept in Ecology Dafeng Hui Room: Harned Hall 320 Phone:

2 Topics 5.1 Climate is the major determinant of plant growth form and distribution 5.2 Climate determine the boundaries of terrestrial biomes 5.3 Walter climate diagrams distinguish the major climate biomes 5.4 Temperate climate zones have average annual temperature between 5 and 20oC 5. 5 Boreal and polar climate zones have average temperatures below 5oC 5. 6 Climate zones with tropical latitudes have average temperatures exceeding 20oC 5.7 Biome concept must be modified for freshwater aquatic systems 5.8 Marine aquatic systems are classified principally by water depth

3 Biomes are classified according to the predominat plant types and climate

4 Concept of Biomes: F.E. Clements and V.E. Shelford, 1939 Combining broad-scale distribution of both plants and associated animals into a single classification Biomes: classified according to the predominant plant types Campbell 1996: the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment.

5 Biomes reflect adaptations of dominant plant life forms Why are there consistent patterns in the distribution and abundance of three dominant plant life forms that relate to climate and physical environment? Three general plant forms: trees, shrubs, and grasses.

6 Biomes reflect adaptations of dominant plant life forms These three forms represent different patterns of carbon allocation and morphology Grasses: less C to production of supporting tissue (stem) than do wood plants (shrubs and trees), more to photosynthetic tissues (leaves) Woody plants: shrubs allocate lower percentage to stem than trees. Trees: more to stem, advantage of height and access to light, cost more for maintenance and respiration. As environmental conditions become adverse for photosynthesis (dry, low nutrient, cold T), trees will decline in both stature and density until they are no longer able to persist as a component of the plant community.

7 Forests Within broad classes of forest and woodland ecosystem (trees are dominant or co-dominant), leaf form is another plant characteristic. Based on longevity of leaf Deciduous (live for only one year or growing season) Winter-deciduous (temperate regions, low winter T) Drought-deciduous (subtropical and tropical, leaf shed on dry periods) Evergreen (live beyond a year) Broadleaf-evergreen (tropic rainforest, no distinct growing season, year-round photosynthesis) Needle-leaf evergreen (growing season is short or nutrient availability constrains photosynthesis and plant growth) Economic model to explain adaptation of leaf form: cost to produce leaf and gain from photosynthesis.

8 Concept of Biomes: Major terrestrial biome types (eight, nine, and varies): Tropical forest, temperate forest, conifer forest (taiga and boreal forest), tropical savanna, temperate grasslands, chaparral (shrublands), tundra, and desert.

9 5.1 Climate is the major determinant of plant growth form and distribution Since organisms are adapted to the physical environments of their biomes, ranges of species are limited by these physical conditions In terrestrial environments, temperature and moisture are the most important variables, particularly for plants.

10 Related species may differ in their ecological tolerances, and distribute Differently

11 5.2 Climate defines the boundaries of terrestrial biomes (Walter)

12 Robert Whittaker, Cornell Uni. Biomes and climate Boundaries between biomes are broad and often indistinct Other factors: topography, soils, and exposure to disturbances such as fire

13 Nashville, TN Mean temperature: 14.9 oC, annual precipitation: cm Source: US Climate Data Temperate seasonal forest

14 Robert Whittaker, Cornell Uni. Biomes and climate Boundaries between biomes are broad and often indistinct Other factors: topography, soils, and exposure to disturbances such as fire

15 BIOL 4120: Principles of Ecology Lecture 5: Biome Concept in Ecology Dafeng Hui Room: Harned Hall 320 Phone:

16 Recap Climate and soil Soil profile, soil weathering process, soil order Biomes Climate is the major determinant of plant growth form and distribution Climate determine the boundaries of terrestrial biomes

17 5.3 Walter climate diagrams distinguish the major terrestrial biomes Precipitation and temperature interactively determine biomes To permit ecologically meaningful comparisons of climates between localities, Walter developed a climate diagram to illustrate seasonal periods of water deficit and abundance.

18 Each climate zone has a typical seasonal patterns of T and P.

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20 5.4 Temperate climate zones have average annual temperature between 5 and 20 o C Temperate seasonal forest biome (Climate zone VI) Temperate rain forest biome (Climate zone V) Temperate grassland/desert biome (Climate zone VII) Woodland/shrubland biome (climate zone IV) Subtropical desert biome (climate zone III)

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22 Temperate seasonal forest Forest ecosystems dominate the wetter regions of the temperate zone Deciduous forest covered large area of Europe and China, but mostly converted to croplands, only exist in eastern China North America, deciduous forests consist of a number of associations (next slide) Southern Hemisphere, temperate evergreen forest become predominant Asiatic broadleaf forest found in eastern China, Japan, Korea is similar to the North American deciduous forest

23 Large scale distribution of temperate forest in eastern US

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26 Grassland ecosystems Rainfall is very important: 250 to 800 mm Other factors: fire, and human activity (convert grassland to desert by overgrazing) Area: dropped from 42% to <12% of original size Location: mid-latitudes in mid-continental regions Typical: prairies of North America, steppes of central Eurasia

27 Grassland in North America a.Tallgrass prairie in Iowa, b.mixed- grass prairie; c.shortgrass steppe Tallgrass prairie Big bluestem, >1m Mixed-grass prairie Needlegrass- garma grass Shortgrass prairie Blue garma and buffalo grass

28 Aboveground primary productivity is related to MAP (52 grassland) Grasslands are most productive when MAP>800 mm and MAT > 15oC

29 5.4 Temperate climate zones have average annual temperature between 5 and 20 o C Temperate seasonal forest biome (Climate zone VI) Temperate rain forest biome (Climate zone V) Temperate grassland/desert biome (Climate zone VII) Woodland/shrubland biome (climate zone IV) Subtropical desert biome (climate zone III)

30 sclerophyllous: hard-leaved vegetation

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32 Desert Area: 25 to 35% Location: latitudes between 15 and 30o Cause: Global air mass circulation T: High in summer, could be cold in winter PPT: low, <150 mm Typical examples: majority in Northern Hemisphere, Sahara in Africa, Gobi in Asia, western North America

33 Deserts are not the same everywhere Cold desert: Great Basin of North America, the Gobi, Takla Makan, and Turkestan deserts of Asia Species: sagebrush, shadscale, chenopods, etc Hot desert: Mojave, the Sonoran, and Chihuahuan Vegetation: none to some combination of chenopods, dwarf-shrubs, and succulents

34 Hot desert: a. Chihuahuan Desert, b. Great Victorian Desert in Australia, c. Dunes in Saudi Arabian desert.

35 Plants and animals in Desert Survive of desert plants: Adapted to scarcity of water, low primary productivity Flowering only when moisture is present Fast grow, flower, produce seeds and die Deep-rooted (mesquite, taproots reach water table) CAM pathway, special leaf structure Survive of animals Support a diversity of animal life (bettles, ants, locusts, lizards, snakes, birds and mammals) Grazing herbivores: generalists, consume a wide range of species. Desert carnivores, such as fox and coyotes, have mixed diet include leaves and fruits.

36 5. 5 Boreal and polar climate zones have average temperatures below 5 o C Boreal forest biome (Climate zone VIII) Tundra biome (Climate zone IX)

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38 Black spruce in North America taiga (boreal forest) Some coniferous forest. A. Norway spruce, b. Rocky Mountaine subalpine forest, c. montane coniferous forest in Rocky Mountains

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40 Arctic Tundra Tundra is treeless plain Arctic tundra is a frozen plain, clothed in sedges, heaths, and willows, dotted with lakes, and crossed by streams Cold Temperature and low precipitation Two types: Polar desert: dry soil, less than 5% plant cover Wet tundra: up to 100% plant coverage, wet to moist soil Unique conditions: permafrost: isolate and protect soil OM vegetation: simple form, slow growth, allocate more to roots.

41 Arctic tundra Canada

42 Rocky Mountains alpine tundra

43 5. 6 Climate zones with tropical latitudes have average temperatures exceeding 20 o C Tropical rain forest biomes (Climate zone I) Tropical seasonal forest/savanna biome (Climate zone II)

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45 Tropic rain forest Location: Equatorial zone between latitudes 10 oN and 10 oS T: warm all year, monthly mean T>20 oC PPT: Rainfall occurs daily, min. monthly>60mm Typical example: Amazon basin of South America

46 Recap Climate zone with temperate climate zones have average temperatures between 5 and 20 oC Boreal and polar climate zones have average temperatures below 5oC Climate zones with tropical latitudes have average temperatures exceeding 20oC

47 Tropic rain forests in Amazon (a), Malaysia (b), and Northeast Australia (c) High net primary productivity (NPP) High diversity of plant and animal life 7% land surface, >50% plant and animal species 10-km2 contain 1500 species of flowing plants and 750 tree species. Richest area in Malaysia, 7900 species

48 90% of all primate species live in the tropical rain forest orangutan (an arboreal ape) Gibbons, langurs, macaques (Malaysian) Gorillas, and chimpanzees (Africa) Lemurs Beetles, butterflies

49 Vertical stratification of a tropic rain forest

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51 Tropical Savannas Location: Equatorial zone between latitudes 30oN and 30oS, Dry tropic and subtropical. T: warm all year, annual mean T>18oC PPT: distinct seasonality in rainfall, large interannual variation Typical example: South America

52 Tropical Savannas Savanna: means the treeless areas of South America Grassland with scattered trees. Characteristics: Occur on land surfaces of little relief, often on old plateaus, dissected by rivers, soil poor in nutrients, especially P Dominant species are fire-adapted, subjected to recurrent fires. Grass cover with or without wood vegetation is always present Woody component is short-lived (less than a few decades). Two-layer vertical structure (ground level grass + shrubs or trees) Support a large and varies assemblage of herbivores, invertebrate and vertebrate, grazing and browsing.

53 Interaction between annual PPT and soil texture in defining biomes Access by plants to soil moisture is more limited on the heavy textured soils (clay) than sandy oil.

54 5.7 Biome concept must be modified for aquatic systems Terrestrial biomes: classified by growth form of dominant vegetation reflects climate conditions. Aquatic biomes: in many aquatic systems, there is no “vegetation” form, only algae Classified primarily by physical characteristics such as salinity, water movement, and depth Freshwater aquatic: Flowing water: Streams and rivers Flowing water: Streams and rivers Standing water: lakes and ponds Standing water: lakes and ponds Wetlands Wetlands Estuaries Estuaries

55 Flowing water: streams and rivers Lotic systems: flowing fresh waters, such as streams and rivers Streams form wherever P exceeds ET, and excess water drains from the land. Riffles: water runs rapidly over a rocky substratum Pools: deeper stretches of more slowly moving water Riparian zone: terrestrial veg influenced by seasonal flooding Allochthonous: organic material that enters the aquatic system from the outside Autochthonous: home grow its organic material. Lack richness and diversity

56 Fluvial systems, as rivers are sometimes called

57 Standing water: lakes and ponds Lentic system: nonflowing water systems, such as lakes and ponds Layers of lake: Littoral zone Liminetic or pelagic zone Benthic zone

58 Wetlands: terrestrial and aquatic communities come together Lands consisting soil saturated with water and supports vegetation that specifically adapted. Include swamps, marshes, bogs (fresh water), salt marshes and mangrove (associated with marine environments) Plants can tolerate low O2 Important habits for a wide variety of animals, waterfowl, fish, invertebrates Protect coastal areas from ravages of hurricanes Wetland sediments immobilize potentially toxic or polluting substances dissolved in water and are thus natural water purifying plants. Wetlands

59 Estuaries are found at the mouths of river Mix of fresh and salt water Extremely productivity systems Estuaries

60 Human inputs into freshwater biomes Acid rain and eutrophication 1. Acid rain: combustion of fossil fuels, sulfur dioxide, nitrogen oxides pH<4 in steams and rivers 2. Eutrophication: addition of limiting nutrients, such as N, P to aquatic ecosystems. runoff: sewage, industrial wastes, fertilizers, animal wastes from agricultural lands. Oxygen depletion

61 5.8 Marine aquatic systems are classified principally by water depth Variation in marine environments: temperature, salinity, depth (which influence light and pressure), currents, substrata and at the edges of ocean and tides. Depth: Littoral zone (intertide zone): extends between highest and lowest tidal water levels. Neritic zone: extends to depth of 200m, high productivity. Oceanic zone: below neritic, sparse nutrient, low production.

62 Benthic zone Seafloor below oceanic zone. Photic zone: With sufficient light for photosynthesis Aphotic zone: no light for photosynthesis

63 Open ocean === desert But in: Coral reefs: shallow water of warm ocean, T>20oC year around very productive and high diverse Like tropical rain forest in terrestrial biome Problem: global warming, coral bleaching

64 Thank you!

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66 Winter-deciduous Drought-deciduous

67 Broadleaf evergreen in tropic rain forest in Australia Needle-leaf evergreen in Sierra Nevada, US

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71 BIOL 4120: Principles of Ecology Lecture 5: Biome Concept in Ecology Dafeng Hui Room: Harned Hall 320 Phone:

72 Recap Biomes, concept Climate is the major determinant of plant growth form and distribution Climate determine the boundaries of terrestrial biomes Walter climate diagrams distinguish the major climate biomes Temperate climate zones have average annual temperature between 5 and 20oC


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