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Chapter 19 Ecosystem Essentials. Vocalic Eruption in Iceland. Flight Cancellation. Earth’s Major Plates. Arrows represent 20 million years of movement. Figure 11.17. Biosphere.
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Vocalic Eruption in Iceland Flight Cancellation
Earth’s Major Plates Arrows represent 20 million years of movement. Figure 11.17
Biosphere The space on Earth where life exist forms a sphere which extends from ocean floor to ~8km altitude into the atmosphere. Ecosystem: A self-sustaining association of living plants, animals and microbes and their nonliving physical environment. 1) Natural ecosystems are open systems with respect to energy and matter. 2) Ecosystem boundaries often function as transition zone, not sharp demarcations. 3) Natural ecosystems can varying significantly in size
Ecology Ecology is the study of the relationship between organisms (human beings, plants, animals, microbes) and their environment. a) the living organisms have impacts on the environment. lichens/mosses grow on rocks soils growth of trees add litter to soils more fertile soil wolfs eat deer reduce deer population less grazing b) through altering the environment, their impacts also have feedbacks to themselves. lichens/mosses grow on rocks soils higher plants to grow lichens/mosses compete out Wolfs eat deer reduce deer population less food for wolf
Humans as Most the Active Agent Deforestation: timber economic gains better life more people more space for agriculture more food more people loss of other lives loss of resources soil erosion land degradation less food Agriculture more food more people expansion loss of other land (grass, forest, wetland …) fertilization/pesticide more food pollution disease Urban expansion better living more people expansion loss of other lands Fossil fuel use better living more people global warming/pollution
Ecosystem Components Like any system in general, it is made up of several components, each function independently yet in concert. • biotic individuals population Communities producers (plants), consumers (animals), decomposers • Abiotic Ecosystem Components soils, light, heat (temperature), water, air As ecosystems are open systems, there are constant flow of energy and matter through the system to keep the system alive.
Biotic and Abiotic Components Figure 19.2
Underside CO2 H2O stoma Losing water is the price to pay for gaining CO2 Plants also keep cool with transpiration (1) cools leaves (2) brings nutrients to where they are needed Small Leaves do the Big Job: Photosynthesis
Stomatal Regulation • Stoma opens when light shine on the leaf, thus opens during the day to absorb CO2 and closes during night to prevent unnecessary water loss. • Stoma closes when there is limited water in the soil. • Stoma closes when the air is too dry, i.e. high vapor pressure deficit. • Stoma closes to save water when CO2 concentration is high in the air.
GPP: Gross Primary Production, the amount of carbohydrate (C6H12O6) produced through photosynthesis is called GPP. Plant Respiration: All living organism needs energy to stay alive. Plants do too. Plants use about 50% of GPP they produce to stay alive. The respiration is the opposite process of photosynthesis. We call this respiration as autotrophic respiration (Ra). Gross Primary Production and Respiration Autotrophic respiration is use for two purpose: (1) to keep living tissues alive, called maintenance respiration. (2) To realize growth, call growth respiration. Note: Energy is not heat energy as said in the textbook, but energy in the form plant can use, ATP (Adenosine Triphosphate)
Net Primary Production NPP: Net Primary Production is the balance of GPP after plant respiration (autotrophic respiration) is taken away. NPP = GPP – Ra NPP is the part of photosynthesis product that can be used for growth, including Leaves Branches Stems Roots Part of NPP become food resources available for the consumers ( herbivores, carnivores, humans)
Biomass The dry weight of the living organisms. e.g. the total dry weight of leaves, branches, stems, and roots would be the biomass of a tree, not including the dead leaves or stems on the floor. For plants, Biomass is the accumulated NPP that stays as part of the living organism. Due to litter fall and mortality, Biomass is less than the annual NPP added up. Biomass is a cumulative figure, NPP is an annual figure. For forests, the biomass eventually levels off as the addition of growth from NPP breaks even with loss of biomass due to litter fall and mortality. Biomass vs. Net Primary Production
Net Primary Productivity Satellite measure of chlorophyll concentration Figure 19.7
Carbon Cycle and Balance Input: 6.3 (fossil) + 1.6 (landuse)=7.9 Output: 1.4 +1.7 =3.1 Balance: 7.9-3.1 = 5.8 Actual increase seen: 3.2 Missing 2.2 C in the atmosphere: missing sink Figure 19.10
Energy/Matter Flow in Ecosystems Producers, Consumers, and Decomposers Producers: Plants on land Phytoplankton in oceans Consumers: Primary (herbivores), secondary (carnivores), tertiary (carnivores), omnivores Decomposers: bacteria and fungi
Energy, Nutrient, and Food Pathways Figure 19.13