2Biotic Factors Abiotic Factors Ecology - Study of interactions between organisms and their environments.Ecosystems are communities of organisms and their abiotic environment.Biotic FactorsBiosphere – life-supporting layer of EarthBiotic factors – all living organisms in a biosphereAbiotic FactorsNonliving factors in an environmentExamples:Air currentsTemperatureMoistureLightSoil
4NATURAL CAPITAL Natural Capital = Natural Resources + Natural Services SolarcapitalAirAir purificationRenewableenergy(sun, wind,water flows)Climate controlUV protection(ozone layer)Life(biodiversity)WaterPopulationcontrolWater purificationWaste treatmentPestcontrolFigure 1.3Key natural resources (blue) and natural services (orange) that support and sustain the earth’s life and economies (Concept 1-1A).Nonrenewablemineralsiron, sand)LandSoilFood productionSoil renewalNatural gasNutrientrecyclingOilNonrenewableenergy(fossil fuels)Coal seamNatural resourcesNatural services
5Organization of LifeBiosphereEcosystemsCommunitiesPopulationsOrganisms
6Levels of Ecological Organization Organisms are living things that can carry out life processes independently.Species are groups of organisms that are closely related and can mate to produce fertile offspring.Populations are groups of organisms of the same species that live in a specific geographical area and interbreed.An important characteristic of a population is that its members usually breed with one another rather than with members of other populations.Communities are groups of various species that live in the same habitat and interact with each other.Habitats are places where an organism usually lives.Every habitat has specific characteristics that the organisms that live there need to survive. If any of these factors change, the habitat changes.
9Autotrophs vs. Heterotrophs Autotrophs fix their own energy from inorganic sourcesAutotrophs are the producers in an ecosystemHeterotrophs depend upon energy and carbon fixed by some other organismThey are consumers, detritivores, or decomposersA mixotroph gets its energy from inorganic sources, but relies on inorganic sources of carbon
12Atmospheric carbon is rarely limiting to plant growth Ecosystems produce and process energy primarily through the production and exchange of carbohydrates which depends on the carbon cycle.Once energy is used, it is lost to the ecosystem through generation of heatCarbon is passed through the food chain through herbivory, predation, and decomposition, it is eventually lost to the atmosphere through decomposition in the form of CO2 and CH4 . It is then re-introduced into the ecosystem via photosynthesis.However, the amount of carbon present in a system is not only related to the amount of primary production, as well herbivory and predation (e.g., secondary production), it is also driven by the rates of decomposition by micro-organismsAtmospheric carbon is rarely limiting to plant growthUp to now, we have discussed how ecosystems produce and process energy, primarily through the production and exchange of carbohydratesThis focus has also provided some insights with respect to the carbon cycle as wellThe energy cycle itself is a one way street, e.g., once energy is used, it is lost to the ecosystem through generation of heatCarbon is somewhat unique in terms of its cycle, because while carbon is exchanged through herbivory, predation, and decomposition, it is eventually lost to the atmosphere through decomposition in the form of CO2 and CH4It is then re-introduced into the ecosystem via photosynthesisHowever, the amount of carbon present in a system is not only related to the amount of primary production, as well herbivory and predation (e.g., secondary production), it is ultimately driven by the rates of decomposition by micro-organismsAtmospheric carbon is rarely limiting to plant growth
13Algae remove dissolved phosphorous from the water When we look at other nutrients, a somewhat different picture emerges than with the energy cycle – e.g., phosphorous in a food chain within a small pond.Algae remove dissolved phosphorous from the waterThe phosphorous is then passed through different trophic levels through herbivory and predation.At each level there is some mortality, and then the phosphorous is passed to decomposersThese organisms release phosphorous into the water where it is again taken up by primary producers and the whole cycle starts up againWhen we look at other nutrients, a somewhat different picture emerges than with the energy cycleHere we have an example of the pathways for exchange of phosphorous in a food chain within a small pondAlgae remove dissolved phosphorous from the waterThe phosphorous is then passed through different trophic levels through herbivory and predationAt each level there is some mortality, and then the phosphorous is passed to decomposersThese organisms release phosphorous into the waterWhere it is again taken up by primary producersAnd the whole cycle starts up againPoint – with most essential nutrients, there is a continuous recycling of nutrients
14Key Elements of Biogeochemical Cycles There are many different processes involved exchanges of the nutrients that are eventually used by the biotic component of our earthDiscuss key elementsFrom an ecosystem/community standpoint, we study nutrient cycling via understanding the exchange of materials and energy via food chains and food webs – e.g., the terrestrial or aquatic food websHowever, there are many different factors involved in nutrient cycling outside of the community itselfFrom an ecosystem/food web perspective, it is important to understandWhere do the nutrients that ecosystems use come fromWhat happens to the nutrients within the ecosystem itselfWhat happens to the nutrients once they leave the ecosystem?Once nutrients are cycled through an ecosystem, how do they get back?What are the rates of exchange of nutrients between the different pools where they are found
15Biogeochemical cycles Pathways tracing storage & exchange of chemical elements between living & nonliving systems via atmosphere, hydrosphere, lithosphere, & biosphere called biogeochemical cycles.Chemical reactions form basis of biogeochemical cycles and take place in the lithosphere, atmosphere, hydrosphere & biosphere.Chemical elements unavailable at right time or proper concentration can become limiting factors which restrict or prevent growth of individuals, population, or species.Have been greatly altered over time by earth's biota.Essential to long-term maintenance of life on earth.Can be altered by human activities; alterations have both + & - consequences. We must recognize & balance.
18Carbon Cycle· Carbon is foundation of all organic compounds, i.e. compounds containing C (& 1 C-H bond) & formed by living things.· Carbon cycle linked to biochemical cycles of C, O, & H· In gas phase, C stored in atmosphere primarily as CO2 & other organic & inorganic molecules.· CO2 exchanged between atmosphere & large bodies of water by diffusion.Plants remove C from atmosphere thru photosynthesis (Ps), light-dependent conversion of CO2 & water to organic sugars & free O2.Vegetation, primarily trees, major storehouse for C in living tissue.C returned to atmosphere through respiration, process of oxidizing sugars to release E, CO2, & water, or by burningC enters rock cycle as organic material carried to wetlands & oceans & slowly incorporated into newly-forming rock.
20Nitrogen Cycle· N2made biological available to organisms thru N fixation, conversion of N to NH3, NO3, or amino acids (AA).· Lightning accounts for some N fixation, but living things account for bulk of conversion.· Higher plants & animals may live in symbiotic association w/N-fixing microbes or cyanobacteria, ↑ soil & tissue concentrations of fixed N.· Free-living soil bacteria help cycle NH3 & carry out denitrification, release of fixed N from soils & waters to atmosphere, thus completing N cycle.· Fixed N is important limiting nutrient in oceans & terrestrial ecosystems.· Thru heavy use of agricultural fertilizers (containing industrially-fixed N) & thru combustion of fossil fuels & other materials, humans have accelerated flux of N in various phases of cycle & ↑ pollution of water & air.
22Human Impact on the Phosphorous Cycle Sewage treatment facilities and fertilizer also add large amounts of phosphates to aquatic systems, causing eutrophication (overfertilization) of lakes.Leads to increased algae!
23Rule of 10Only 10% of energy is transferred from one trophic level to the next.Example:It takes 100 kgs of plant materials (producers) to support 10 kgs of herbivoresIt takes 10 kgs of herbivores to support 1 kg of 1st level predator
24Organic matter in animals Dead organic matter Organic matter in plants Figure 1.4Nutrient cycling: an important natural service that recycles chemicals needed by organisms from the environment (mostly from soil and water) through organisms and back to the environment.DecompositionInorganicmatter in soil
25SymbiosisA long-term interaction between two organisms where "long-term" is defined in generations for at least one of the organisms and the interaction is physically intimate.Often the symbiosis will consist of one organism, the symbiont, living either on or inside of the other organism (the host).Symbioses can be classified in terms of the location of symbiont as well as in terms of the impact of the symbiont on the host. There are parasitic, mutualistic, or commensal symbioses in which the host is either harmed, helped, or neither harmed nor helped by the symbiosis, respectively (the symbiont, on the other hand, usually is helped by the interaction).
26Symbiosis – “living together” Relationship TypeSpecies ASpecies BCommensalism+MutualismParasitism-+ means the organism benefits0 means the organism neither benefits or is harmed- means the organism is harmed
30Causes of Environmental Problems Population growthWasteful and unsustainable resource usePovertyFailure to include the harmful environmental costs of goods and services in their market pricesInsufficient knowledge of how nature works30
31Some Resources Are Not Renewable Nonrenewable resourcesExist in fixed quantity in earth’s crust.Economically depleted when costs too much to obtain what is left.Energy resourcesMetallic mineral resourcesNonmetallic mineral resourcesSolutions:ReuseRecycle31
33Degradation of Normally Renewable Natural Resources and Services 33
34Our Ecological Footprints Are Growing - Biologically productive land and water needed to supply renewable resources and absorb waste for each individual.- Humanity’s eco footprint: exceeds by about 39% the earth’s ecological capacity.34
37Cultural Changes Have Increased Our Ecological Footprints 12,000 years ago: hunters and gatherersThree major cultural eventsAgricultural revolutionIndustrial-medical revolutionInformation-globalization revolution37
39NATURAL CAPITAL DEGRADATION Major Human Impacts on Terrestrial EcosystemsDesertsGrasslandsForestsMountainsLarge desert citiesConversion to croplandClearing for agriculture,livestock grazing, timber, and urban developmentAgricultureFigure 7.20Major human impacts on the world’s deserts, grasslands, forests, and mountains. Question: Which two of the impacts on each of these biomes do you think are the most harmful?Timber extractionSoil destruction byoff-road vehiclesRelease of CO2 to atmosphere from burning grasslandMineral extractionHydroelectric dams and reservoirsSoil salinizationfrom irrigationConversion of diverse forests to tree plantationsIncreasing tourismOvergrazing by livestockUrban air pollutionDepletion of groundwaterIncreased ultraviolet radiation from ozone depletionDamage from off-road vehiclesOil production and off-road vehicles inarctic tundraLand disturbanceand pollution from mineral extractionPollution of forest streamsSoil damage from off-road vehicles
40Studying Nature Reveals Four Scientific Principles of Sustainability Reliance on solar energyBiodiversityPopulation controlNutrient cycling40
41Solutions For Environmental or Sustainability Revolution 41