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Transcript
Cycles of Life Life and Death, Nutrient Cycles, Sustainable Development Nutrient Cycles Why do the nutrients on the Earth need to be cycled? The Earth is considered a closed system. This means that there is little or no input of new materials from outside the system. Organics = H and C, often O and N (proteins, fats, sugars) Inorganics – not containing C and H Nutrients can be in the biotic environment or abiotic environment. The Carbon Cycle Plants make carbohydrates through a process known as photosynthesis. 6CO2 + 6H2O + E C6H12O6 + 6O2 Capture of carbon from atmosphere Carbon is returned to the atmosphere via cellular respiration. C6H12O6 + 6O2 6CO2 + 6H2O + E The Nitrogen Cycle Nitrogen is also very important and it will also circulate between the biotic and abiotic parts of the environment. Proteins and DNA Fertilizers contain N, P and K to facilitate growth If there is no fertilizer then how does the plant acquire N? Phosphorus Cycle Long and Short Cycles Long Rocks of the earth’s crust Phosphate ions (PO43-) dissolve out of rocks (due to solubility) and are absorbed by photosynthetic organisms Short Living organism’s waste is cycled. Agriculture and Nutrient Cycles Phosphate Accumulation 1. Algae growth = algal bloom 2. Bacteria break down algae and use oxygen to do so 3. Fish and animals die 4. Problems become worse Changes in Populations Changes to populations Growth = natality (birth rate); immigration Decline = mortality (death rate); emigration Limits on Populations Biotic Potential Maximum number of offspring that a species could produce if resources were unlimited. Carrying Capacity Maximum number of individuals of a species supported indefinitely by an ecosystem. Affected by 4 factors: Carrying Capacity Factors 1. 2. Materials and E amount of usable E from sun, as well as water, carbon and other essential nutrients Food Chains populations are affected by populations below (food source) and above (food source for others) Carrying Capacity Factors 3. Competition all individuals in a population are vying for the same resources Intraspecific Competition – same species Interspecific Competition – different species 4. Density only so many organisms can live in an area at one time Density dependent factors – aggression, neglect of offspring will decrease birth rate and increase death rate. Density independent factors – fire, flood, extreme weather Closing the Loop Sustainable Development Ecosystems are sustainable in that they perpetuate themselves indefinitely and require little or no additional materials each year. Sustainable development is taking this idea and applying it to humans Development that meets the needs of the present without compromising the ability of future generations to meet their own needs