Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Slide 67Slide 68Slide 69Slide 70Slide 71Slide 72Slide 73Voting records by county 2008Voting records 2004Cotton production in 1860Slaves 1860: % of populationBlack Belt SoilsBlack Belt SoilsCretaceous coastline, 85 myaSlide 81Slide 82Slide 83Slide 84Responsee.g. Nitrate leachingTime Resistant: little responseResilient: rapid recovery???RESISTANCE versus RESILIENCESystems are rarely both resistant and resilient: Why? Once a resistant system is perturbed, recovery often slow. Resilient systems are often easy to perturbHigh ResistanceLow ResistanceLow Resilience High ResilienceStartingPointStartingPointRESISTANCE versus RESILIENCEGrasslands: burn often, limited impact, recover quicklyForests: burn rarely, huge impact, recover slowlyRESISTANCE versus RESILIENCETea Fire: November 13 2008Photo: November 22RESISTANCE versus RESILIENCEOne year later—December 30 2009HardwoodsPin CherrySpeciesNO leaching3 -0550 200How can resistance &resilience be different in a single system?secondary succession in northern hardwoodsBy considering different ecosystem processesRESISTANCE versus RESILIENCELowLowHighHighGlobalStabilityLocalStabilityRESISTANCE versus RESILIENCEHow can resistance &resilience be different in a single system?SW GrasslandsStratified LakesTropical Forest• What controls stability? Role of community composition?Ecosystem controls on RESISTANCE & RESILIENCEHow does the diversity of the community affect stability?• Stability vs. Diversity => Instability of species may stabilize processesPlant diversity can regulate soil nutrient availability & system productivityEcosystem controls on RESISTANCE & RESILIENCEYear1968 1969 1970 VariabilityAverage TempPrecipitation15.1 9014.7 8812.9 14751%25%Total Production 65.3 77.4 74.6 8.8%Sedges 14.3 10.7 27.6 50%Deciduous shrubs 8.3 13.9 11.2 25%Evergreen shrubs 35.7 47.3 22.0 36%Productivity of tundra plant communities across years with different weather patternsFrom: Chapin and Shaver. 1985. Ecology. 66: 564-576Ecosystem controls on RESISTANCE & RESILIENCEApproaches to studying ecosystem dynamics:Two basic approaches: (1) Input-output budgets (2) Mechanistic analysisEssentially these are top-down and bottom up perspectives in the hierarchy of scales.Budget: measurements at the ecosystem level => descriptiveecosystem measurement approacheswhole system measurements: “containerize” the systemsoil respiration by point measurementsstrengths and limitations of technique?Small vertical eddies in the air carry heat, water, and gases to and from the ground surface.Measure vertical windspeed, carbon dioxide (CO2) etc.ecosystem respiration by eddy flux towerssource: http://upload.wikimedia.org/wikipedia/en/1/11/EddyCovariance_diagram_1.jpgmeasuring water & nutrientsweirs: measure water flowextrapolationMeasure multiple sites and then multiply out to the total area of the siteVariabilityTension in ecosystem science:Questions are about “big picture” so require integration, but also require mechanism, which is reductionist.Strengths & limitations of approaches to studying ecosystems:Budgeting/Field measurements: Strengths: “Real” data on field processes Limitations:Non-mechanistic, scalestrengths & limitations of approaches to studying ecosystems with mechanistic analysisStrengths: • Mechanistic understanding & extrapolation• Generates experimentally testable hypothesesWeaknesses:• Non-field “real”: Need to scale back to field• May miss emergent properties that dominate the behavior of the system• It is easy to get caught up in the “reductionist fallacy”A mathematical description of the behavior of the system. CO2As material decomposes carbon is lost. How fast does material decompose?mechanistic analysis: modelsModelsA mathematical description of the behavior of the system.dC/dt = k * C * fM * fT dC/dt = Rate of mass loss k = Rate constant C = Amount of substrate fM = Moisture factor fT = Temperature factorWhat are the constants in the model?Dry Moist Flooded Soil MoistureDecomposition Rate 0 ºC 10ºC TemperatureDecomposition RateSource: http://www.nrel.colostate.edu/projects/century/Climate models allow us to develop these estimates at the global scale – when measurement is impossible!Ecosystem Structure: controls & componentsAims of ecosystem ecology:1. Simple, general models that apply broadly across ecosystems2. Describe differences between systems and identify unique characteristics• combining measurement & modeling to describe ecosystem feedbacks is essential to modern ecosystem studies.• determining what to include/reduce in experiments is a major & ongoing challenge in this science.What is an ecosystem?“An ecosystem consists of all the organisms and the abiotic pools with which they interact.”Chapin et al. pg. 4Components:• Organisms• Physical environment• Flows of energy and matter• Species interactions (matter and information)Questions• Why are there so many diverse ecosystems?• What components do we need to consider in terms of ecosystem function?• What are the driving factors producing the differences?Terrestrial Ecosystems: critical componentsvegetation = primary producerSoil physical/chemicaltexture, mineralogywater storage & movementnutrients (particularly metals: Ca, K, Fe) Biotic: decomposers – key in recycling organic nutrients?Grazing exclosure in MongoliaGoose exclosure in Hudson’s BayIn some ecosystems, herbivores can consume a lot of biomassSerengeti?source: http://upload.wikimedia.org/wikipedia/commons/e/e3/Dendroctonus_ponderosae.jpgstructure of ecosystems: controlsThe “Jenny State Factor Model”: Soil/Ecosystem = f(Cl, O, R, P, T,…) Cl = Climate O = Organisms R = Relief P = Parent material T = Time … = Other things These are the fundamental independent variables driving ecosystem developmentPublished in: Factors of Soil Formation, 1941Updated in: The