Transcript chapter 2
Chapter Two Glossary Organic, inorganic, pesticide, pest, bioamplification, photosynthesis, cellular respiration, nitrogen fixation, denitrification, nutrients, fertilizer, natality, mortality, open population, closed population, biotic potential, carrying capacity, Chapter Three Litter, topsoil, humus, subsoil, bedrock, surface water, ground water, percolation, water table, acid deposition, The Carbon Cycle Carbon is an essential element to organic compounds and therefore life itself. Carbon is found in sugars, fats, DNA, RNA, vitamins etc. Carbon passes through a few different forms on Earth, together these forms make up the Carbon Cycle. see p. 62 figure1. Carbon does not move very quickly through its different forms and is said to be held in different reservoirs. Inorganic Reservoirs -CO2 in the atmosphere -CO2, CO3-2, HCO3-, CaCO3 in the oceans -by far the largest reservoir -CO2, CO3-2, HCO3-, CaCO3 in the soil see figure 2 p. 63 Organic Reservoirs -living things -peat (due to low oxygen conditions in bogs decomposition is very slow and the organic material becomes trapped) -fossil fuels (similar to peat but over much longer times and great pressure fossil fuels are formed) CHANGES IN POPULATIONS Population is affected by four factors, natality (births), mortality (deaths), immigration and emigration. Population growth is the sum of births and immigration minus deaths and emigration. Growth rate is the population growth expressed as a percentage of the old population. b i ( d e) growth rate 100% pop. Open populations are influenced by all four factors while a closed population is only affected by natality and mortality. LIMITS ON POPULATIONS p. 77-79 Biotic potential is the maximum number of offspring that a species could produce , if resources were unlimited. Factors Affecting Biotic Potential 1. Birth potential is the maximum number of offspring per birth. 2. Capacity for survival is the number of offspring that reach reproductive age. 3. Procreation is the number of times that a species reproduces each year. 4. Length of reproductive life depends on the age of sexual maturity and the number of years the individual can reproduce. LIMITING FACTORS The environment prevents populations from attaining their biotic potential. Food, water, territory, pollutants, competition, disease, sunlight, wind, temperature and many more can all be considered limiting factors. Without limiting factors populations would experience uncontrolled growth. Populations fluctuate due to the influence of these biotic and abiotic limiting factors (which change as well). Stability is achieved when an ecosystem is in equilibrium. The largest population an ecosystem can support indefinitely is called the carrying capacity. A population can exceed the carrying capacity of the ecosystem but not for long. LIMITS OF TOLERANCE Law of the minimum states that the nutrient in least supply is the one that limits growth. (Liebig) Law of tolerance states that an organism can survive within a certain range of an abiotic factor. DENSITY DEPENDENT FACTORS The density of a species depends on the population and the area it habitates. Density dependent factors affect a population because of the density of the population. Food supply, water quality and disease are some examples. Density independent factors affect a population regardless of population density. Fire and flood are two examples of this type of factor. homework: p. 80 2, 3a-c, 4, 5 (only ponder) Readings: 52-57, 70-73, 97-99, 106-110 Notes: 52-55, 97-98, 108-110 The Caterpillar Debate is Coming!!