Ch 8: Nutrient Regeneration in Terrestrial and Aquatic EcosystemsObjectivesIntrasystem (within 1) vs. intersystem (between 1 + 2) cycling in ecosystemsGeneralized model: nutrient cycle, including regeneration, in terrestrial ecosystem.Slide 5Nutrient regeneration occurs in the soil.Life in the soil and litter…inverts, bacteria, fungiNutrient regeneration from litter by:Depolymerization of large organic molecules in soil regulates nutrient cycling. Microbes + plants compete for small monomers (e.g. amino and nucleic acids)Leaf quality (e.g. toughness/chemicals) affects regeneration. Climate affects nutrient regeneration:Soil propertiesHow does vegetation aid nutrient retention? (lower movement from intrasystem to intersystem cycling)Annual dynamics/budget of intrasystem cycle*** What 3 components of the annual requirement account for the total requirement (=114.3)? What 2 processes provide resources to meet the total requirement (=114.3)? What 3 components of annual uptake account for total uptake (=92.1)? Is the forest in equilibrium? ExplainIntersystem cycling: Nutrients gained (input) and lost (output) by an ecosystemContrast intra- vs. inter-system cycling in a terrestrial ecosystem.Slide 17Nutrient inputs on land from:***What are two generalizations about nutrient input from the atmosphere?Nutrient losses (output) on land to:Nutrient BudgetsQuestion: Does the presence of vegetation affect the rate of nutrient output (loss) from an ecosystem? Hypothesis: IF vegetation increases soil stability and intrasystem recycling of nutrients, Experimental design:Slide 23Hubbard Brook watershed and experimental sitesHubbard Brook Ecosystem Study: How does deforestation affect streamflow and nutrient loss (output)?Weir (dam): method of gaining output dataMethod of gathering input dataResults:***What are two patterns? (1 general and 1 qualifying) What stats to do?Watershed studies of precipitation and stream chemistry*** What contributes to input? output? What are two main conclusions?***Summarize the pattern. What causes variation in amount of input?***Nutrients and Aquatic Productivity…What accounts for the highest and lowest levels?NPP of aquatic systems maintained by:Temperate lakes have annual cycles of nutrient availability and productivity:Productivity varies in temperate lakes:What element controls the trophic structure and productivity of lakes?Estuaries and salt marshes:Intra- vs. inter-system energy flow in a salt marsh. 10% of GPP exported.Ch 8: Nutrient Regeneration in Terrestrial and Aquatic EcosystemsObjectives•Terrestrial regeneration• Intrasystem cycling• nutrient regeneration in soil• annual dynamics/balance the books• Intersystem cycling• inputs vs. outputs•Aquatic regeneration• nutrients + productivity• timing of regeneration• sources of regenerationIntrasystem (within 1) vs. intersystem (between 1 + 2) cycling in ecosystems Ecosystem 12Input  output Ecosystem 2Input Output Ecosystem 1Generalized model: nutrient cycle, including regeneration, in terrestrial ecosystem.Intra…Inter…Figure 1Intrasystem cyclingFigure 1Nutrient regeneration occurs in the soil.•Rate depends on rate of ecosystem processes (e.g. decomposition + mineralization).•Productivity depends on regeneration of nutrients from litter: • decomposition • mineralization (organic --> inorganic)• uptake•Nutrients added by weathering of rock = slow•Nutrient uptake from soil by plants = fastLife in the soil and litter…inverts, bacteria, fungiNutrient regeneration from litter by:• leaching of soluble substances• maceration by large detritus feeders• fungi breakdown cellulose/lignin--> C,H,O• mineralization (organic--->inorganic) of P, N, and S by bacteriaDepolymerization of large organic molecules in soil regulates nutrient cycling. Microbes + plants compete for small monomers (e.g. amino and nucleic acids)Figure 2Leaf quality (e.g. toughness/chemicals) affects regeneration.Climate affects nutrient regeneration:• Decomposition rate and what seasons• Weathering rate and what seasons• Soil propertiesSoil properties•Eutrophic (rich) soils• in geologically active areas + young soils • rapid weathering of bedrock - adds• fresh nutrients•Oligotrophic (poor) soils• in old, geologically stable areas + old soils• intense weathering if high temperatures • and abundant water ---> • 1) high respiration --->acid pH• 2) removes clay and cations (e.g. Ca++)• 3) reduces storage capacity for nutrients• 4) high leaching of cations• 5) nutrient-pool soilsHow does vegetation aid nutrient retention?(lower movement from intrasystem to intersystem cycling)1 retain leaves for long time2 withdraw nutrients from leaves before drop (reabsorption)3 develop dense root mats near soil surface4 grab nutrients quickly before leached away5 store more nutrients in biomass, not soilAnnual dynamics/budget of intrasystem cycle•Storage•Annual requirement• make foliage• woody growth• leaching (throughfall and stemflow)•Annual uptake by roots• woody growth• returns from• leaching• litterfall•Reabsorption (before leaf fall)•Balanced if: annual requirement = uptake + reabsorption***What 3 components of the annual requirement account for the total requirement (=114.3)? What 2 processes provide resources to meet the total requirement (=114.3)?What 3 components of annual uptake account for total uptake (=92.1)?Is the forest in equilibrium?ExplainIntersystem cycling: Nutrients gained (input) and lost (output) by an ecosystem Ecosystem 12Input  output Ecosystem 2Input Output Ecosystem 1Contrast intra- vs. inter-system cycling in a terrestrial ecosystem.AtmosphereIntersystem cycling-->Input from waterflowNutrient inputs on land from:•Lithosphere (weathering of bedrock and soil)•Atmosphere–Wetfall (in precipitation)–Dryfall (particles)•Hydrosphere•Human Activities***What are two generalizations about nutrient input from the atmosphere?Figure 5Nutrient losses (output) on land to:•Atmosphere•Streams and groundwater•***Which cycle links terrestrial and aquatic ecosystems?Nutrient Budgets•Balanced (equilibrium): inputs = outputs•Unbalanced (non-equilibrium): •***inputs > outputs = ???• ***outputs > inputs = ???•Question: Does the