Ecosystems Studying organisms in their environment organism population

Ecosystems

Studying organisms in their environment organism population community ecosystem biosphere

Essential Questions: • What limits the production in ecosystems? • How do nutrients move in the ecosystem? • How does energy move through the ecosystem?

Ecosystem • All the organisms in a community plus abiotic factors – ecosystems are transformers of energy & processors of matter • Ecosystems are self-sustaining – what is needed? § capture energy § transfer energy § cycle nutrients

Ecosystem inputs energy flows constant input of energy through nutrients cycle Matter cannot Don’t forget the laws of or be created Physics! destroyed biosphere nutrients can only cycle inputs § energy § nutrients

Generalized Nutrient cycling consumers producers consumers decomposers nutrients ENTERnutrients FOOD CHAIN made available = made available to producers Decomposition connects all trophic levels abiotic reservoir geologic processes return to abiotic reservoir

Carbon cycle CO 2 in atmosphere Diffusion Combustion of fuels Industry and home Respiration Photosynthesis Plants Animals Dissolved CO 2 Bicarbonates Photosynthesis Animals Plants and algae Carbonates in sediment abiotic reservoir: § CO 2 in atmosphere enter food chain: § photosynthesis = carbon fixation in Calvin cycle recycle: § return to abiotic: § respiration § combustion Deposition of dead material Fossil fuels (oil, gas, coal)

Nitrogen cycle abiotic reservoir: § N in atmosphere enter food chain: § nitrogen fixation by soil & aquatic bacteria recycle: § decomposing & nitrifying bacteria return to abiotic: § denitrifying bacteria Atmospheric nitrogen Carnivores Herbivores Plankton with nitrogen-fixing bacteria Birds Fish excretion loss to deep sediments Plants Death, excretion, feces Decomposing bacteria amino acids Ammonifying bacteria Nitrifying bacteria soil nitrates Nitrogen-fixing bacteria (plant roots) Nitrogen-fixing bacteria (soil) Denitrifying bacteria

abiotic reservoir: § rocks, minerals, soil enter food chain: § erosion releases soluble phosphate § uptake by plants recycle: § decomposing bacteria & fungi return to abiotic: § loss to ocean sediment Phosphorus cycle Plants Land animals Soluble soil phosphate Loss in drainage Decomposers (bacteria & fungi) Phosphates in solution Animal tissue and feces Loss to deep sediment Animal tissue Urine and feces Decomposers (bacteria and fungi) Rocks and minerals Aquatic animals Plants and algae Precipitates

abiotic reservoir: § surface & atmospheric water enter food chain: § precipitation & plant uptake recycle: § transpiration return to abiotic: § evaporation & runoff Water cycle Solar energy Transpiration Water vapor Evaporation Precipitation Oceans Runoff Lakes Percolation in soil Groundwater Aquifer

Transpiration Why does water flow into, up and out of a plant? We will discuss process in detail soon!

Breaking the water cycle • Deforestation breaks the water cycle – groundwater is not transpired to the atmosphere, so precipitation is not created forest desertification

Effects of deforestation 40% increase in runoff loss of water loss into surface water 80 nitrate levels in runoff Concentration of nitrate (mg/l ) u § 60 x loss in nitrogen § 10 x loss in calcium 40 loss out of ecosystem! 4 2 Why is 0 nitrogen 1965 so important? Deforestation 1966 Year 1967 1968

Energy flows through ecosystems sun Energy is incorporated into a community by what group? secondary consumers (carnivores) primary consumers (herbivores) producers (plants) loss of energy

Productivity • Primary productivity: Term for the rate which producers photosynthesize organic compounds in an ecosystem. – Gross primary productivity: total amount of photosynthetic biomass production in an ecosystem – Net Primary Productivity = GPP – respiration cost

§ Ecosystems with greater productivity are more stable and diverse than ecosystems with less productivity. u. Which ecosystems are most productive?

Inefficiency of energy transfer • Loss of energy between levels of food chain sun – To where is the energy lost? The cost of living!� 17% growth only this energy moves on to the next level in the food chain energy lost to daily living 33% cellular respiration 50% waste (feces)

Level 4 Tertiary consumer Food chains • Trophic levels – feeding relationships – start with energy from the sun – captured by plants • 1 st top carnivore Level 3 Secondary consumer carnivore Level 2 Primary consumer heterotrophs herbivore level of all food chains – food chains usually go up only 4 or 5 levels Level 1 Producer • inefficiency of energy transfer – all levels connect to decomposers sun autotrophs Decomposers Bacteria Fungi

Producers & Decomposers § Producers move matter from abiotic sources (air/soil) to biotic sources (food web) § Decomposers move matter from biotic sources to abiotic sources

Ecological pyramid sun • Loss of energy between levels of food chain – can feed fewer animals in each level 10% energy available for next level Notice only 1% of sunlight energy converted by plants

Humans in food chains • Dynamics of energy through ecosystems have important implications for human populations – how much energy does it take to feed a human? • if we are meat eaters? • if we are vegetarian?

What you need to be able to do: • Using the laws of conservation of matter and energy to do some basic accounting and determine different aspects of energy and matter usage in a community. • Remember: Inputs have to equal outputs

Sample problem • A caterpillar consumes 100 kcal of energy. It uses 35 kcal for cell respiration, and loses 50 kcal as waste. Determine the trophic efficiency for its creation of new biomass. – Total energy = 100 kcal – Lost and Respired: 35 + 50 = 85 kcal – Total energy for growth: 15 kcal • Efficiency = part/total = 15/100 =. 15 (or 15% or 3/20 as fraction)