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  • 1. Ecosystem Processes and Biomes
  • 2. Overview Describing Life on Earth Taxonomic Hierarchy Classifying species Biogeographical Realms Trophic Hierarchy Energy and nutrient flow Food chains and Food webs Nutrient Cycles Ecological Hierarchy Communities and Assemblages Stability, succession and disturbance Terrestrial Ecosystems Biomes Biomes Formation classes
  • 3. Biogeography: the study of the distributions of plants and animals and related ecosystems; the geographical relationships with their environments over time
  • 4. The Biosphere The biosphere encompasses all of the living species on earth (Biodiversity) What the species are How they interact with each other How they are distributed over the globe Scientific perspectives derive from Evolutionary theory Genetic relationship between species Natural selection Interaction with each other through competition for resources Ecology Co-occurrence of species in given areas Competition (especially in food chains) regulates the flow of energy through Global classification based on Evolutionary linkages (Realms and Regions) Ecological relationships (Biomes)
  • 5. Hierarchies of Life Biodiversity is shaped by the interactions of species that result in the formation of stable groups (or unstable groups) of species through the regulation of the flow of energy and nutrients. Taxonomic hierarchies organization of related species Trophic hierarchies organization of energy and nutrient flow Ecological hierarchies organization of species into groups
  • 6. Taxonomic Hierarchy Taxonomy: the systematic classification of plants, animals and other life forms according to presumed natural relationships Taxon: a group or entity within a classification system (pl. taxa) Species specific Genus Family Order Class Phylum Kingdom general Groupings based on identified evolutionary relationships
  • 7. Species are classified according to: Morphology – similarity of physical and behavioral traits Reproductive criteria genetic relationships Species named with Latin binomials, according to taxonomic criteria Genus + Specific epithet Example: Genus Syzygium Syzygium inophylloides S. samarangense S. dealatum S. savaiiense Groupings into similar genera and families implies evolutionary linkage
  • 8. Kingdoms Kingdom Monera (prokaryotic bacteria and cyanobacteria) Kingdom Protista (eukaryotic single-cell organisms; protozoa, amoebas, multicellular algae) Kingdom Myceteae: fungi Kingdom Animalia: animals Kingdom Plantae: plants Links (1)
  • 9. Kingdom Plantae: Phyla Bryophyta: mosses Pteridophyta: ferns Coniferophyta: conifers (gymnosperms) Anthophyta: flowering plants (angiosperms) monocotyledons dicotyledons Others
  • 10. Kingdom Animalia Invertebrates Arthropods (Insects, spiders, mites, crustaceans) Mollusks Flatworms Roundworms Earthworms Jellyfish, corals Starfish, sponges Vertebrates Fish Amphibians Reptiles Birds Mammals
  • 11. There are roughly 1.8 million known species on Earth Estimates on total species vary between 4 million and 20 million Taxonomic distribution 56% Insects Beetles (Coleoptra) comprise 24% of the total 17% Other arthropods and invertebrates 14% Plants 9% Algae, protozoans, fungi 2.7% Vertebrates 1% Bacteria and viruses
  • 12. Numbers of described species by major taxa Insecta: 751,000 Plantae (Multicellular plants): 248,428 Non-insect arthropoda (mites, spiders, crustaceans): 123,151 Mollusca: 50,000 Fungi: 46,983 Protozoa: 30,800 Algae: 26,900 Pisces (fish): 19,056 Platyhelminthes (flatworms): 12,200 Nematoda (roundworms): 12,000 Annelida (Earthworms): 12,000 Aves (Birds): 9,040 Coelenterata (Jellyfish, corals): 9,000 Reptilia: 6,300 Echinodermata (starfish, etc.): 6,100 Porifera (sponges): 5,000 Monera (Bacteria, blue-green algae): 4,760 Amphibia: 4,184 Mammalia: 4,000
  • 13. Biogeographic Realms Realms As continental masses separated off from each other, their isolation from each other allowed their species to evolve separately, giving rise to unique assemblages Oceans form main barrier to spread, but also mountains, climatic conditions
  • 14. Trophic Hierarchy Organizing life according to the flow of energy Solar energy Critical role of plants: photosynthesis trophic levels, foodchains, efficiency, food pyramids Producers: plants (autotrophs) Consumers (heterotrophs) Primary consumers: herbivores Secondary consumers: carnivores Tertiary consumers: higher order carnivores, omnivores Food Chains & Food webs Chains indicate linear pathways of energy flow (single path) Food webs illustrate complex multiple pathways Efficiency: Loss of energy at each level
  • 15. Abiotic Components Light: photoperiod Climate: temperature and water Altitudinal zones (life zones) Increases in altitude mimic increases in latitude Normal lapse rate: temperatures cool with increasing altitude: changing climatic patterns Elemental cycles (biogeochemical cycles) Nitrogen cycle Carbon and oxygen cycle Limiting factors: an abiotic or chemical factor that is in short supply and inhibits ecosystems from operating at full potential.
  • 16. Trophism Producers, consumers, detrivores, decomposers Food chains and food webs Trophic levels Producers plants Primary consumers herbivores Secondary consumers carnivores Tertiary consumers higher level carnivores
  • 17. Critical Role of Plants A vital link between the abiotic and biotic components with help from soil biota Photosynthesis Stores Carbon dioxide, water, and energy Creates Carbohydrates and oxygen 6CO2 + 6H2O C6H12O6 + 6O2 Respiration Releases stored energy, carbon dioxide and water vapor C6H12O6 + 6O2 6CO2 + 6H2O Plants also intercept Nitrogen, a building block of proteins Net Primary Productivity: photosynthesis usually exceeds respiration.
  • 18. Net primary productivity results in increased biomass Biomass: net dry weight of organic material
  • 19. Consider also grass-fed beef; although similar inefficiencies exist, people cannot directly digest grass. In areas where agriculture is not viable, this makes ecological sense.
  • 20. Nitrogen Cycle, Revisited
  • 21. Carbon cycle, revisited
  • 22. Ecological Hierarchy Organization of life according to number of species and spatial scale Individual Species Individual Population Metapopulation Community Assemblages Guilds Ecosystem: communities plus trophic interactions Biomes: ecosystems on a global scale, differentiated by levels of abiotic inputs and primary productivity Biosphere
  • 23. Ecosystems Ecosystem: a self-regulating association of plants, animals and physical environment Ecology: the study of the various interactions between components of the environment
  • 24. Ecosystem Components Ecosystems have biotic and abiotic components Abiotic: solar energy input nutrient cycles nitrogen carbon
  • 25. Biotic Communities an assemblage of interacting plants and animals Competition Mutualisms Habitat the type of environment that a particular species lives in and is adapted to. Some species are adapted to one type of habitat “habitat specialists” Some species are adapted to several habitats “habitat generalists” Niche: the functional role a species plays in its community Habitat niche Trophic niche: producer, consumer, decomposer Reproductive niche Competitive exclusion principle An ecosystem is most stable when all of its niches are filled
  • 26. Range and Distribution The distribution of the abiotic resources that a species needs affects where that species can occur Climatic factors are important determinants of range Species that are limited to one or a few areas are referred to as endemics These species are often highly specialized to a particular niche Often the most efficient competitor for that niche, but are susceptible to change Generalist species often have a much greater spatial range than specialized species, and are more tolerant of change
  • 27. Stability, Succession, Disturbance Basic Concepts Stability: ability of a community to retain its species composition: most stable when all niches are filled Climax community Resilience: ability of a community to recover its original species composition after a disturbance Biodiversity: the number and abundance of species in an area Disturbance: an event that alters community composition, re-allocates stored nutrients, and alters nutrient pathways Succession: changes in species composition in a community over time as the community moves toward stability following a disturbance Biodiversity and stability High native biodiversity conveys ecosystem stability Prevent loss of energy and nutrients
  • 28. Disturbance When a disturbance is small in comparison to the community in question, the community quickly reincorporates the disturbance and reestablishes stability Example: tree fall, creating gaps in forest canopy When a disturbance is larger than a community and occurs relatively frequently, the type of disturbance structures the community composition “Disturbance Regime” Examples: Hurricanes, fire ecology When a disturbance is of similar spatial scale and occurs with a frequency comparable to succession rates, transformation of ecosystems can occur
  • 29. Ecological Succession Patch Dynamics Succession Seed banks (seeds already present at a location) Dispersal (seeds transported into a location) Areas of infrequent disturbance are more likely to return to original community composition Areas of frequent disturbance will change composition toward dispersible species from outside the patch Terrestrial Succession Primary Succession Occurs in areas with no vegetation example: lava flows example: surface mining Species adapted to growing on little or no soil (lichens, mosses) are often the pioneer species Secondary Succession Occurs where disturbance leaves some vegetation Rapidly dispersing, opportunistic species are frequent pioneer species
  • 30. Fire Ecology A disturbance regime Fire is a “natural” part of many ecosystems Especially in the western US Lightning strikes Native American land management created a “park-like landscape” that provided habitat for game Many tree species are adapted to fire, and require it to complete their reproductive cycles Fire suppression allowed accumulation of fuel, contributing to catastrophic fires Fire is now used as a management tool
  • 31. Ecosystems and Biomes Terrestrial Ecosystems self-regulating assemblages of plant and animal species interacting with each other and their abiotic environment The assemblage of plant species gives each ecosystem its defining character provides link between abiotic and biotic components (distinguishes ecosystems from communities) provides habitat and niche
  • 32. Biome: large, stable, terrestrial ecosystem Classification based on dominant vegetation forest savanna shrubland grassland desert tundra Ecotone: transition zone between biomes Formation classes: dominant vegetation within the general biome classes
  • 33. Formation Classes Equatorial and Tropical Rainforest (ETR) Tropical Seasonal Forest and Scrub (TrSF) Tropical Savanna (TRS) Midlatitude Broadleaf and Mixed Forest (MBME) Needleleaf Forest and Montane Forest (NF/MF) Temperate Rain Forest (TeR) Mediterranean Shrubland (MSh) Midlatitude Grasslands (MGr) Warm Desert and Semi-desert (DBW) Cold Desert and Semi-desert (DBC) Arctic and Alpine Tundra (AAT) (Ice)
  • 34. Equatorial and Tropical Rainforest Occur in tropical areas that receive high amounts of rainfall regularly throughout the year High net primary productivity and biomass Vertical arrangement of ecological niches Emergent Layer: Intense sunlight, high temperatures, strong winds, low humidity Canopy Layer: 90% of species live here; epiphytes, lianas, primates Understory: 2 – 15% of sunlight; dark, sparse, shade tolerant species Forest Floor: Less than 2% light. Decomposing organic matter Oxisols, Ultisols Represent approximately half of the world’s remaining forests
  • 35. Tropical Seasonal Forest and Scrub Also called Moist Deciduous forest On the margins of tropical rainforests Seasonal variation in rainfall Tropical Savanna climate Tropical Monsoon climate Semi-deciduous trees lose their leaves during the dry-season Oxisols, Ultisols, Vertisols, Alfisols Caatinga (Brazil), Chaco (Paraguay and Argentina), brigalow (Australia), dornveld (South Africa)
  • 36. Tropical Savanna Transitional between tropical forests and semi- arid tropical steppes and deserts Mixture of grasslands and small trees and shrubs Herbivores that move in herds are characteristic of landscapes that are wide open Fire-ecology disturbance regime Rainfall only occurs with ITCZ (less than 6 months) Dry conditions otherwise xerophytic vegetation Alfisols, Ultisols, Oxisols
  • 37. Midlatitude Broadleaf and Mixed Forest Moist continental climates humid sub-tropical hot-summer climate marine west coast climates cool summer, winter drought climate Mixture of deciduous and evergreen species Community structure greatly altered by human activity Ultisols, Alfisols, some Spodosols
  • 38. Needleleaf Forest and Montane Forest Also called boreal forests Taiga in in areas transitional to arctic or subarctic climates Humid microthermal climates Needleaf forests not common in S. Hemisphere Montane forests found world wide (altitudinal zonation) Evergreens Pine, spruce and fir Characteristic fauna Beaver, moose, snowshoe rabbit, lynx, wolverine Spodosols, Histosols, some Alfisols
  • 39. Temperate Rainforest Mostly in the Pacific NW of N America Relatively low diversity of tree species Tallest trees in the world: Giant Redwoods (Sequoia sempervirens) Evergreens, some deciduous Extremely wet climate Tongass National Forest, Alaska The world’s last pristine temperate rainforest Spodosols, Inceptisols
  • 40. Mediterranean Shrubland Mediterranean dry-summer climate Poleward of subtropical high pressure cells Stable high-pressure creates dry conditions Fire ecology disturbance regime Sclerophyllous vegetation hardy, drought resistant shrubs with deep roots and hard waxy leaves Chaparral Alfisols, Mollisols
  • 41. Midlatitude Grasslands The most heavily human modified biome mining of Mollisols for agriculture Very little of this biome left Fauna also characterized by herding herbivores Prairies of the Great Plains, Pampas of Argentina Mollisols, Aridisols
  • 42. Warm Desert and Semi-desert Subtropical high pressure cells create the dry conditions in these areas Atacama Desert, Chile Xerophytic shrubs, succulents, thorn trees Aridisols, Entisols
  • 43. Cold desert and Semidesert Higher latitudes than warm deserts Rainshadows and cold ocean currents influence the dryness Sage brush and scrub Many were former short-grass regions, transformed by intensive grazing Aridisols, Entisols
  • 44. Arctic and Alpine Tundra Northern hemisphere, bordering the Arctic ocean North of 10o latitude Tundra vegetation Mosses, lichens, short grass, some small trees Alpine tundra: high altitude zonation Fauna Lemmings, caribou, musk ox, arctic fox, polar bear Gellisols, Inceptisols, Entisols permafrost