Element Cycling PDF

Element Cycling Element cycling involves the movement and transformation of abiotic and biotic forms of elements Includes inputs, outputs and internal cycling in an ecosystem Obeys the 1st law of thermodynamics: matter cannot be created nor destroyed Carbon cycle intricately linked network of b...

Element Cycling Element cycling involves the movement and transformation of abiotic and biotic forms of elements Includes inputs, outputs and internal cycling in an ecosystem Obeys the 1st law of thermodynamics: matter cannot be created nor destroyed Carbon cycle intricately linked network of biological and physical processes How organisms move carbon between neighbours and their surroundings shows the functioning of ecosystems and their persistence over time Primary producers Base of the food web Provide organic carbon to other organisms Cyanobacteria & eukaryotic algae, plants Primary consumers Consume primary producers Herbivores & grazers (many...) Consumed by secondary consumers, or carnivores & scavengers Decomposers / Detritivores Breakdown remains of other organisms to more basic compounds  Examples are fungus & earthworms Animal respiration and fungus/bacteria decomposition of dead plants/animals returns CO2 to the atmosphere The amount of CO2 removed from the atmosphere by photosynthesis and the amount returned by respiration are about equal. Energy does not cycle through an ecosystem new energy must continually be harvested A Trophic Pyramid forms because... building organic molecules is not 100% energy efficient one trophic level rarely consumes all the resources in the level below energy is lost to heat and work biomass decrease from one trophic level to the next Plants have independently evolved adaptation by convergent evolution to climate (i.e. leaf shape, red pigments in fall) Plants provide a physical structure for each terrestrial biome Herbivorous animals feed on the products of plants (leaves, stems, fruits, seeds), include small mammals and insects Carnivores are usually well recognized (birds, lions, tigers & bears...) Carbon in terrestrial habitats begin with atmospheric CO2 Photosynthesis converts this to organic Carbon as glucose All types of plants and lichen/algae do this on land Terrestrial Biomes Our 2 terrestrial biomes of focus are 1) Temperate Broadleaf/Deciduous forests & 2) Urban landscapes In both... Major primary producers are vascular plants, with additional production from mosses, lichens Major primary consumers are mammals, birds and insects Temp. Deciduous Forest A moderate climate and dominance of hardwood deciduous trees Four distinct seasons Springtime sun passes through seasonally leafless trees to reach a diverse understory flora Soils are rich in nutrients from annual leaf fall. The moderate temperatures and precipitation promote decomposition Higher biodiversity than Boreal forests, typically Birds and small mammals are numerous Larger mammals (grazers and carnivores/scavengers) also prominent Plentiful fallen plant material is decomposed by fungus and invertebrates like insects, worms, gastropods, crustaceans(!), nematodes, etc. 2. Urban Landscape Urban areas are full of life, but typified by disturbance Human propagated plant monocultures are disrupted by adventitious or resilient pioneer species Both native and non-native species are prominent Pollution, human-contact, physical barriers (i.e. pavement) all make up unique challenges of urban living Aquatic Biomes Our 2 aquatic biomes of focus are 3) Tropical Reef & 2) Freshwater Stream Aquatic biomes reflect climate, the availability of nutrients and oxygen, and the depth to which sunlight penetrates through water. In both of our biomes, depth often penetrates to the benthos. But one is marine and the other freshwater Biogeochemical Cycles in the Oceans Coral Reefs receive nutrients (N, P, especially) from various sources Freshwater and rain run-off enter from rivers and coastal run-off Cool water from open ocean can bring additional nutrients up from the depths Coral Reef The best-known reefs occur in shallow, tropical to subtropical environments deep sea reefs are also numerous in the ocean and super cool! but we won’t discuss them (take BIOL 450 Marine Biol) Nutrient levels are commonly low, but primary production is high and mostly tied to dinoflagellate algae that live within the tissues of corals Free-living algae occur in reefs, but are kept at low abundance by grazing fish Coral Reefs are hotspot of life in the ocean – both in terms of diversity and density Primary Producers Algae (endosymbiotic, plankton and macro algae) Consumers Corals & anemones (Cnidaria), fish, crustaceans, bivalves, gastropods, cephalopods, worms, echinoderms, and visiting verts (turtles, dolphins, whales, manatees, etc.) Aquatic Biomes - Freshwater Freshwater biomes include lakes and ponds, and rivers and streams Water chemistries varies with the types of terrain in which they are found, and nutrient levels can be low to extremely high Rivers/Streams are characterized by moving water. They, like lakes, vary tremendously in size and chemistry Because of currents, rivers are generally well oxygenated, although oxygen levels may be lower in slowly moving rivers on floodplains 4. Freshwater Stream In streams, producers include... plants and eukaryotic algae (both large and small) grow along river margins phytoplankton (small photosynthetic microbes) photosynthesize throughout the water column Insects are important consumers, but other invertebrates (crustaceans, gastropods & bivalves), fish, turtles, and birds can all be abundant and diverse Many consumers are filter feeders Also, in rivers / streams, the carbon cycle overlaps with terrestrial surroundings Leaves will enter the stream  Some organisms have life stages in both Terrestrial animals will take prey from the stream (and vice-versa) Animal waste / remains may enter water