I. Ecosystem A. Definition A unit of nature in which nutrients are cycled and energy flows. B. Abiotic factors: non-living components of the ecosystem. 1. Soil ph, salinity, temperature, texture. 2. Water ph, salinity, temperature, D.O. 3. Climate ph, temperature, precipitation, humidity. I. Ecosystem C. The cycling of inorganic materials: occurs from the non-living environment through the bodies of living organisms back into the non-living environment. Biotic (living) Abiotic (non-living) 1
D. 3 examples of ecosystems: 1. Pond 2.Grassland 3.Old growth forest II. A. The ultimate source of energy in most ecosystems is the: SUN 1. What percent of total light energy that reaches the earth is used in photosynthesis? 1% - 2% 2. An ecosystem is self-sufficient when supplied with light energy. B. The flow of energy occurs from AUTOTROPHS HETEROTROPHS. Energy flows in a unidirectional fashion (one-way). 2
II. 1. Producers (1 st trophic level) a. Autotrophs; make their own food from photosynthesis (sometimes chemiosynthesis) II. 2. Consumers a. Primary consumers or herbivores consume plant material 1) What happens to the plant material that is eaten by the primary consumers? a. Pass through as waste b. Used as energy c. Incorporated as biomass 2) How much plant material is converted to animal biomass? 100 lbs. grain 10 lbs. cow 1 lb. human 10% conversion! 3
II. 2. Consumers b. Secondary consumers or carnivores Carnivores: consume primary consumers (herbivores) II. 2. Consumers c. Third and fourth level consumers Carnivores: consume other carnivores 4
II. 3. Omnivores Eat both plant and animal tissues on a regular basis. Can feed on all levels. II. 4. Detritivores & Scavangers Eat detritus (nature s leftovers). Decomposers. 5
II. 4. Detritivores & Scavangers Eat detritus (nature s leftovers). Decomposers. Scavengers. II. 6
II. Pyramid of numbers D. Food Chains 1. Producer consumer relationships Harris hawk (3 rd order carnivore) Gopher snake (2 nd order carnivore) Spiny lizard (1 st order carnivore) Grasshopper (primary consumer herbivore) Grass (producer autotroph) 7
D. Food Chains 2. What is a food web? - Interconnected food chains. Producers: Green Plants Herbivores: Roadrunner, Pocket mouse, Skunk, Packrat, Insects, Quail, Coyote. 1 st Order Carnivores: Gopher snake, King snake, Skunk, Roadrunner, Quail, Coyote. 2 nd Order Carnivores: Roadrunner, Coyote, King snake. 3 rd Order Carnivores: Coyote III. Biogeochemical Cycles A. Define: The cycling of nutrients within an ecosystem. The movement of inorganic nutrients/elements. B. What substances are cycled in an ecosystem? Water & basic elements such as: C, H, O, N, P, K, S, etc. 8
III. Biogeochemical Cycles Nitrogen Cycle 1) Ammonification (Conversion of protein) Ammonifying Protein ammonia (NH 3 or NH 4 ) bacteria III. Biogeochemical Cycles Nitrogen Cycle 2) Nitrification (conversion of ammonia) Nitrite Nitrate Ammonia (NH 3 or NH 4 ) nitrite (NO 2 ) nitrate (NO 3 ) bacteria bacteria Nitrifying bacteria 9
III. Biogeochemical Cycles Nitrogen Cycle 3) Assimilation Uptake and incorporation of nutrients by plants or microbes. Nitrates (NO 3 ) assimilation Protein III. Biogeochemical Cycles Nitrogen Cycle b. What is denitrification? Conversion of nitrate (NO 3 ) Denitrifying bacteria N 2 (atmospheric nitrogen) 10
III. Biogeochemical Cycles Nitrogen Cycle c. What is nitrogen fixation? Nitrogen fixing Conversion of N 2 nitrate (NO 3 ) bacteria Nitrogen Cycle 11