BIO 373 1st Edition Lecture 23 Outline of Last Lecture I. Species Diversity contda. Hutchinson’s modeli. Paradox of the planktonb. Processes that promote coexistencei. Paineii. Intermediate disturbance hypothesisiii. Hacker and Gainesc. Lottery modeld. Consequences of Diversityi. Diversity-stability theorye. Species richness and community functionII. Energy in ecosystemsOutline of Current Lecture I. Energy in Ecosystemsa. Primary productioni. Gross primary productionii. Net primary production1. Variations in NPPThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Secondary productionc. Energy flowi. Trophic levels1. detritusCurrent LectureEnergy in Ecosystems- Primary Productiono = chemical energy generated by autotroph during photosynthesis and chemosynthesis Source of energy for all organisms from bacteria to humans Chemosynthesis is not as common so main focus is on photosynthesis Everything goes back to primary producer- Ex: secondary producers, carnivores, fossil fuels—energy came from primary producero Gross primary production (GPP)= amount of carbon fixed by autotrophs in an ecosystem Organic carbon being produced Depends on rate of photosynthesis Leaf area index= leaf area proportional to ground area covered by plant- Amount of potential photosynthesis depending on leaves (and thus chlorophyll—site of photosynthesis) available- Tundra—leaf area index is low- Temperate—leaf area index is higho Net primary production (NPP)= GPP- respiration Or GPP= NPP + respiration How is energy going to flow across ecosystem Measure plants when there is growth- Ex: grasslands are annual (they grow for the year then die)o Collect and measure dry weight- PROBLEM: roots also grow and they are missing from this informationo However, there are programs that can predict this- PROBLEM: secondary metabolites not accounted for On global scale- Satellites measure chlorophyll as a proxy for NPP (can do for terrestrial or aquatic)- In aquatic, NPP increases near continents because fertilizer runoff serves as nutrients Variation in NPP- Terrestrial ecosystemso Nutrient availability affects NPP o In terrestrial ecosystems, variation is largely defined by climate Water and sunlight affect photosynthesis If precipitation is too high, roots may not be gettingenough O2 or N2 concentration may decrease in the soil- High precipitation indicates lots of clouds, decreased sunlight, so decrease photosynthesis If temperature is moderately high, NPP is greater because metabolic rates (like photosynthesis) increase- Respiration also increases so at a point, too high of a temperature will decrease NPP- Aquatic ecosystemso In lake ecosystems, phosphorous availability drives NPP variationo Nutrients can also limit NPP in rivers and streams Due to effects on numbers of phytoplankton If a lot of turns along river, lots of sediment movement also affects nutrient levels and NPPo In marine ecosystems, limiting nutrients vary Iron can limit NPP because it is important to a particular phytoplankton common to these ecosystems (picoplankton) Iron deposited via sand and carried by wind- Latitudinal variation in NPPo Highest rates of terrestrial NPP near tropicso Declines in arid regions 25 degrees N and So Oceanic NPP peaks at mid latitudes Due to upwellingo High NPP in northern hemisphere due to large land mass- Secondary productiono = energy generated from consumption of organic compounds produced by other organismso Net secondary production (NSP)= ingestion- respiration- egestion – excretion Energy available for next trophic level to be consumed- Heat to environment, waste to detrivores, etc.- energy flowo trophic levels energy flow across ecosystems primary producers primary consumers (herbivores) secondary consumers (primary carnivores) secondary carnivores (eat primary carnivores) detritors (on same level as primary producers)<-> detrivores (on same level as herbivores) primary carnivores detritus= organisms not consumed by other organisms- all other organisms either end up consumed or as detritus- detritus greater in terrestrial ecosystems because a lot of energy isnot consumedo because in terrestrial ecosystems, plants do not move and in aquatic ecosystems they floato terrestrial plants have strong tissues (with lots of nutrients and fibers) to root themselves terrestrial herbivores only eat part of the plant—the nutritious parts more predation of herbivoreso terrestrial plants produce secondary metabolites to deter