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2006 -ENS-L3 The Earths ecosystems L3 English in Natural Science Slide 2 2006 -ENS-L3 Ecosystems Definition: any system where there is interaction between organisms and their environment. Two components Biocenosis: all organisms Biotope: physical medium (land, water, soil, air, etc) Species linked by a food web Exchange matter and energy Size Microecosystems: soil, bark of a tree Mesoecosystems: forest, lake Macroecosystems: valley, region, ocean Slide 3 2006 -ENS-L3 Niche Species occupy a limited niche multidimensional hypervolume in which the species can maintain a viable population (Grinnell, 1914; Hutchinson, 1957) Adaptation to environment Climate (latitude, altitude) Chemical factors (air, soil, water) Biotic factors: other species Factors determining the niche Resources: food, light, nutrients Other: space, time, body size Generalist = wide, tolerant Specialist = restricted, sensitive Slide 4 2006 -ENS-L3 Species co-existence Competition Two species cannot share the same niche either winner or loser exclude each other time food space A B A B B Symbiosis Sharing the same niche agreement Mutualism, commensalism (Rhizobium nodules and legume plants) Slide 5 2006 -ENS-L3 Decomposers Food web Producers Consumers Inorganic matter Losses Respiration Work Heat Input Solar energy Matter Slide 6 2006 -ENS-L3 Vegetation Consumers Producers Decomposers Phytofagous Herbivorous Predators Scavengers Energy loss Increased entropy Reduced biomass Terrestrial pyramid Slide 7 2006 -ENS-L3 Energy loss Increased entropy Reduced biomass Aquatic inverted pyramid Phytoplankton Zooplankton Predators Superpredators Scavengers Detritivorous Slide 8 2006 -ENS-L3 Communities Assemblages of species Same taxon Avoid competition Different niches Composition Dominant species Rare species Keystone species essential functional role Immigrants adapt, coexist or leave Dependent species Symbiotic Parasites Species% cover Sorghastrum natans24 Panicum virginatum12 Andropogon gerardi9 Ailphium laciniatum9 Desmanthus illioensis6 Bouteloua curtipendula6 Andropogon scoparius6 Helianthus maximiliana6 Schrankia nuttallii6 20 additional species (average 0.8% each) 16 Source: Rice, E.L. 1952. Ecology 33: 112-116 Tall-grass prairie (Oklahoma,USA) Slide 9 2006 -ENS-L3 Kinds of vegetation Forbs, herbs Grasses Ferns Epiphytes Emergent Floating Submerged Algae SHAPE Trees Shrubs Herbaceous Mosses Lichens Aquatic plants Slide 10 2006 -ENS-L3 Ecosystem types of the World Terrestrial - Aquatic Slide 11 2006 -ENS-L3 Terrestrial ecosystems Biomes: large terrestrial community units dominated by plants Six major biomes in the World Desert Tundra Grasslands Shrubland Savanna - woodland Forests Defined in relation to climatic patterns Slide 12 2006 -ENS-L3 Iceage Greenhouse Slide 13 2006 -ENS-L3 Deserts Rainfall: 30 o C Vegetation type: grasses, forbs, shrubs Types: cold (mountain); hot Area: 30 m Km 2 (20.5%) Slide 14 2006 -ENS-L3 Tundra Rainfall:< 1000 mm Temperature: -15 to -5 o C Vegetation type: mosses, lichens, grasses, shrubs Types: arctic (N pole); alpine (mountains) Area: 25 m Km 2 (17%) Slide 15 2006 -ENS-L3 Grassland Rainfall:250-600 mm Temperature: 2.5 to 15 o C Vegetation type: grasses + forbs = pasture Types: steppe (short); prairie; tropical (tall) Area: 12 m Km 2 (8.2%) Slide 16 2006 -ENS-L3 Shrubland Rainfall:250-600 mm Temperature: 2.5 to 30 o C Vegetation type: shrubs, grasses, forbs Types: Mediterranean; temperate; montane; tropical; scrubland (short) Area: 4.3 m Km 2 (3%) Slide 17 2006 -ENS-L3 Savanna Rainfall:600-1500 mm Temperature: 5 to 30 o C Vegetation type: trees, shrubs, grasses, forbs Types: woodland (temperate); tropical Area: 25 m Km 2 (17%) Slide 18 2006 -ENS-L3 Forest Rainfall:600-4500 mm Temperature: > -5 o C Vegetation: all types Types: taiga; temperate; subtropical; tropical evergreen (perennial); deciduous; mangroves Area: 31 m Km 2 (21%) Slide 19 2006 -ENS-L3 Agro-ecosystems Ecosystems that produce for human consumption Area: 16 m km 2 (11% of total land area) Two types: cropland (40%); grazing land (rangeland, 60%) Slide 20 2006 -ENS-L3 Biome transition Polar icecap Tundra Boreal forest (conifers, mixed) Temperate forest (deciduous) Mediterranean forest (evergreen) Shrubland Desert Savanna/grassland Tropical forest cold warm Slide 21 2006 -ENS-L3 Mountains (European Alps) Continental (Australian bush) Slide 22 2006 -ENS-L3 Aquatic ecosystems Dominated by animals of all kinds Freshwater (3 m Km 2 ; 2%) Lentic: lakes, ponds Lotic: streams, rivers Wetlands: marshes Saltwater Estuaries Coastal Coral reefs Oceans Shallow: continental shelf (benthic) Deep: pelagic, abyssal Slide 23 2006 -ENS-L3 Oceanic ecosystems light darkness Slide 24 2006 -ENS-L3 Succession Ecosystems are dynamic entities, not static Change in time: from simple to complex grassland shrubland forest Factors climate, nutrients, growth, competition, dispersal Slide 25 2006 -ENS-L3 Succession patterns Primary: start from scratch, bare soil Secondary: recovery after damage (I.e. natural disasters, human impact) Trends Increase total biomass/area Increase biodiversity more niches available complex structure T I M E Slide 26 2006 -ENS-L3 Secondary succession Natural disasters Fire Drought Flood Volcanic eruption Diseases Human impacts Deforestation Desertification Grazing Farming Resilience of organisms Adaptations Fire: Banksia sp. cones Drought: short life cycles (annual grasses, freshwater plankton) dormancy (fungi, seeds) Flooding: mangroves Renewal of ecosystems Recovery Re-colonization Re-building biome Slide 27 2006 -ENS-L3 Recovery Natural disasters give advantage to best adapted species Land management: fire favours grass livestock Slide 28 2006 -ENS-L3 Successional changes (15,000 yr) glaciers ICE SHEET Slide 29 2006 -ENS-L3 Tropical forests Last Ice Age sea level 100 m down boreal forests >> tropical forest Currently Less land area sea level UP boreal forests = tropical forest Slide 30 2006 -ENS-L3 References Mitchell B. Rambler, Lynn Margulis, Rene Fester. 1989. Global ecology : towards a science of the biosphere / - call 460 Odum, E.P. 1993. Ecology and our endangered life-support systems / - B-226 Tokeshi, M. 1999. Species coexistence: ecological and evolutionary perspectives / B-207