# G2: Ecosystems & Biomes (4 hours).

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G2: Ecosystems & Biomes (4 hours)

G.2.1 Define gross production Total amount of energy trapped in organic matter produced by plants per area per time (kJ) net production Gross production – energy lost through respiration Biomass Dry weight of an organism (g m-2 yr -1)

gross production – respiration = net production GP – R = NP
G.2.2 Calculate values for gross production and net production using the equation: gross production – respiration = net production GP – R = NP Sample question!! Calculate % of energy moving up to herbivores

Food webs give more realistic image of ecosystem
G.2.3 Discuss the difficulties of classifying organisms into trophic levels. Food webs give more realistic image of ecosystem Omnivores especially difficult-- Depending on what eating, can be 1/2/3 consumer at different times

Higher trophic levels: low total biomass per unit area of ecosystem
G.2.4 Explain the small biomass and low numbers of organisms in higher trophic levels. Top predators must be large enough to overwhelm their prey, so can only be relatively few of them Higher trophic levels: low total biomass per unit area of ecosystem Biomass lost during each TLevel Cell respiration: biomass of glucose is lost, CO2, Water excreted Each successive level loses more and more biomass

Trophic Level Energy Flow (kJ m–2 yr–1) producers 20,810
G.2.5 Construct a pyramid of energy, given appropriate information. (Xref- pyramid of energy ) Trophic Level Energy Flow (kJ m–2 yr–1) producers 20,810 primary consumers 3,368 secondary cons tertiary consumers

G.2.6 Distinguish between primary & secondary succession, using an example of each.
CHANGE in abiotic and biotic factors in ecosystem over time...some species gradually replace others in a particular area Primary: Previously barren, lifeless area Newly created volcanic island Pioneer species usually lichens—tolerant to extreme temp changes and little/no soil; they decompose rock...soil forms moss can survive  seeds germinate  coconuts wash ashore, germinate; animals may swim/fly/carried on floats from other islands

Secondary: follows natural or artificial “upheaval” of the primary succession
MUCH faster b/c soil already present, may be existing seeds & roots Ex. Forest fire Primary Secondary Begins with no life Follows a disturbance of primary succession No soil Soil present New area (volcanic island) Old area (following forest fire) Lichen & mosses pioneers Seeds & roots already present Biomass low Biomass higher Production low (few plants) Production higher

Pioneer species to those that compete with others for nutrients
G.2.7 Outline the changes in species diversity and production during primary succession. OVERALL TRENDS: Few species to many Pioneer species to those that compete with others for nutrients Little to high diversity (mature forest is home to 100s species) Simple relationships to more complex (mutualism, competition, predation) More & more biomass at each stage of succ.

G.2.7 Outline the changes in species diversity and production during primary succession.
Foredune: no soil, only sand, p.succ. Starts here—lyme grass very salt tolerant, fast growing, roots stabilize dune; marram grass too, wide roots. LITTLE PLANT DIVERSITY Yellow dune: developing thin layer of soil b/c yrs of m.grass; more plants invade (sedge, etc); rabbits here, nutrients from poop ; summer dandelions/thistle. Humus builds as pioneers decay. MORE COMPLICATED, MORE SPECIES, SOIL BEING FORMED

Mature dune: final stage of succession. Can support a forest
G.2.7 Outline the changes in species diversity and production during primary succession. Grey dune: yrs of plants dying/decomposing, so layer of humus; it holds water; dune farther inland, less salt; thick shrubs eventually grow here Mature dune: final stage of succession. Can support a forest Wild flowers, trees, mosses/ferns in shade Thick humus b/c 200 yrs of plants; high moisture content Many insects, birds, mammals Cooler temp than foredune; less wind/blowing sand

Death/decay of plants/animals  humus
G.2.8 Explain the effects of living organisms on the abiotic environment with reference to the changes occurring during primary succession. soil development Death/decay of plants/animals  humus Quickly absorbs and releases water, good for plants Leaf litter creates more org matter, mixes with sand, creates deep, well-draining soil; can support tall trees accumulation of minerals Sand doesn’t hold moisture but humus & soil do, takes time to get structure to hold moisture and minerals to allow aeration of roots (structure IMPROVES) Bacteria, fungus (decomposers) active in recycling nutrients in soil w/humus (recycling INCREASES) reduced erosion Roots stabilize dune/soil, reduces erosion

G.2.9 Distinguish between biome & biosphere.
Biosphere: living part of earth (where organisms live) Crust, atmosphere Biomes: divisions of biosphere Each is part of biosphere Defined by community structure and vegetation

PLOTS temp and rainfall in a region
G Explain how rainfall and temperature affect the distribution of biomes. A climograph showing the biomes in G.2.11 can be used to illustrate the interaction between these two factors. PLOTS temp and rainfall in a region Tundra: organisms adapted to cold, dry Conif forest: plants conserve water when ground frozen, animals heavy coats in winter (summer-shed) Temp forest: wide range of conditions (many deciduous to reduce water loss in winter) Desert: specific adaptations for extreme heat and dryness (kangaroo rat’s specialized kidney; cacti’s spines) Trop forest: high temp, high rainfall

G.2.11 Outline the characteristics of six major biomes.
Temp Moisture Vegetation Desert Mostly very hot. Soil temps >60C (140F) daytime Low precip, <30cm/yr Cacti, shrubs w/water storage tissues, thick cuticles & other water-loss adaptations Grassland Cold winter temps; hot summers Seasonal drought; occasional fires; medium moisture Prairie grasses hold soil w/long roots; occasional fires prevent trees/shrubs from invading...and don’t forget the dead zebras.  Shrubland Mild winter temps; Long, hot summers Rainy winters, dry summers Dry woody shrubs killed by periodic fires; shrubs store food in fire-resistant roots; regrow quickly, produce seed that germinates only after fire!

G.2.11 Outline the characteristics of six major biomes.
Temp Moisture Vegetation Temp Decid Forest Very hot summer, very cold winter High rainfall evenly throughout yr. Winter: water may freeze for short time Deciduous trees (oak, hickory, maple) dominate. Warmer seasons—wide range of herbaceous plants on forest floor Tropical rainforest Very warm Very high precip (>250cm/yr) Plant diversity very high. Canopy of top layer, next layer is shrubs; ground layer is herb.plants and ferns. Vines, orchids, bromeliads on trees. Tundra Very cold; Summer-upper layer of soil thaws, but lower frozen (permafrost) Little precipitation Low-growing plants (lichen, mosses) and few grasses, shrubs. Permafrost prevents roots from growing deeply. Continuous daylight in summer allows plant growth & reproduction.

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