Biogeochemical Cycles: Part I Pathways of Elements in the Ecosystem FIELD BIOLOGY & METHODOLOGY Fall 2015 Althoff Lecture 06 Nutrients in the Ecosystem Compared to energy, __________ usually stay in the ecosystem (cycle between organisms & physical environment) Most originate in _____ or ____________ Most all have been _____ beforehence the cycling process Nutrients in the Ecosystemcont Each element follows unique route through the ecosystem Transformations result of ____logical, _____logical, and ____________ influences. Major Biogeochemical Cycles Carbon Nitrogen Phosphorus Sulfur Concentrations of CO 2 in the atmosphere have _________ since the beginning of the Paleozoic era (~450 MYA) Carbon 18% of the human body, 2nd behind oxygen In human body, essential forcarbohydrate formation & storage, major source of energy Carboncont As CO 2, 1 of 3 key items (solar radiation & H 2 0 are the others) in photosynthesis during which it is incorporated into sugar molecules (i.e., capture C) Carbon dioxide released during _________ (i.e., release C) Basic Carbon Cycle CO 2 in air, comes into plants, photosynthesis take place and sugars manufactured. Animals eat plants, burn sugars, in the process respiration releases carbon back into atmosphere as CO 2. Details in Ricklefs: p488, Fig. 23.5handout/next slide Carbon cycle (geometric tons) Other sources of Carbon... Weathering Combustion--______ influences GREAT here a) burning of forest, fuelwood b) fossil fuels for vehicles, electricity, and heat Human influence.cont Coal, wood, and petroleum products-- when burned--release CO 2 at rates that ________ normal pace of CO 2 removal Carbon SINKS & SOURCES SINKS: plants, through photosynthesis, & oceans through aquatic food chains (i.e., capture C) SOURCES: cellular respiration & combustion (i.e., release C) Carbon Cycle. Where is the greatest annual flux (i.e. change)? _________________ (assimilate ~ 35 Gigatons [GT] annually) ____________ Carbon Humans: years Redwoods: 1,000 years Coal & oil: millions of years CaCO 3 : millions of years ago Limestone: millions of years ago Nitrogen 3% of human body is N, ranks 4th behind O, C, & H In human body, N essential component of _________________________ In plants, essential component in chlorophylls of green plants Nitrogencont ___% of atmosphere is Nbut most living organisms cant use it in that form Nitrogen _______ (i.e., capture) controlled by microorganisms: a) bacteria (legumes) b) denitrification: bacteria & fungi release N back into atmosphere Nitrogen-fixing bacteria in root nodules Nitrogen into plants... Plants take up nitrogen through their root systems as NH 3 (ammonia) ends up in Leaves, plant tissues, & grain/seeds Basic Nitrogen Cycle N 2 in air, is fixed by bacteria in soil, taken up by plants, which are consumed by animals. Plants & animals die, decompose, and ______________ takes place by certain bacteria and fungi Details Ricklefs: p494, Fig handout/next slide Nitrogen cycle (geometric tons) Other sources. Lightning Volcanoes Urine & feces -- much bigger influence than often realized particularly where ______________ present in significant numbers (naturally, think large bison herds) (domestically, think feedlots) Human Influences... Livestock in confined areas Use of fertilizers which get into water systems through runoff or infiltration& soil sediments Burning fossil fuels Nitrogen SINKS & SOURCES SINKS: plants, particularly in the forests & soils SOURCES: air and denitrifying bacteria & fungi Global Change... No other global change (includes increased CO 2, human population, and increased deforestation) has occurred as abruptly as INCREASED ____________ ___________ in our natural ecosystems. Major concerns related to N-cycle Nitrates in drinking water Overproduction of algae in marine ecosystems Role of nitrous oxides in acid rain Reduced biodiversity in terrestrial ecosystems with high fertilizer input Key reference Vitousek, P.M., J. Aber, R. W. Howarth, G.E. Likens, P.A. Matson, D.W. Schindler, W.H. Schlesinger, and G.D. Tilman. Human alteration of the global nitrogen cycle: causes consequences. Issues in Ecology Series, Ecological Society of America. pdf version available under CLASSNOTES In summary. Unlike energy, nutrients are retained within ecosystemswhere they are _______ between physical and biotic componentshence the _________________ cycles All organisms require _________ carbon as the primary substance of life.organic carbon is the major source of energy in most animals and microorganisms Carbon _________ between organic forms (i.e., living organisms) and inorganic compartments of ecosystems via photosynthesis and respiration