Abiotic Factors Nonliving factors in an environment Examples: –Air currents –Temperature –Moisture –Light –Soil Biotic Factors Biosphere – life-supporting layer of Earth Biotic factors – all living organisms in a biosphere Ecology - Study of interactions between organisms and their environments. Ecosystems are communities of organisms and their abiotic environment.
Air Air purification Climate control Water Water purification Waste treatment Nonrenewable minerals iron, sand) Natural gas Oil Soil Soil renewal Nonrenewable energy (fossil fuels) Solar capital Land Food production Nutrient recycling Coal seam Life (biodiversity) Population control Pest control Renewable energy (sun, wind, water flows) UV protection (ozone layer) Natural resources Natural services NATURAL CAPITAL Natural Capital = Natural Resources + Natural Services
Organization of Life Organisms Populations Communities Ecosystems Biosphere
Levels 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.
Autotrophs vs. Heterotrophs Autotrophs fix their own energy from inorganic sources – Autotrophs are the producers in an ecosystem Heterotrophs depend upon energy and carbon fixed by some other organism – They are consumers, detritivores, or decomposers A mixotroph gets its energy from inorganic sources, but relies on inorganic sources of carbon
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 heat Carbon is passed through the food chain through herbivory, predation, and decomposition, it is eventually lost to the atmosphere through decomposition in the form of CO 2 and CH 4. 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- organisms Atmospheric carbon is rarely limiting to plant growth
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 water The 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 decomposers These organisms release phosphorous into the water where it is again taken up by primary producers and the whole cycle starts up again
Biogeochemical 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.
Water cycle Evaporation Transpiration Precipitation Runoff Groundwater
Carbon 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 CO 2 & other organic & inorganic molecules. CO 2 exchanged between atmosphere & large bodies of water by diffusion. Plants remove C from atmosphere thru photosynthesis (Ps), light-dependent conversion of CO 2 & water to organic sugars & free O 2. Vegetation, primarily trees, major storehouse for C in living tissue. C returned to atmosphere through respiration, process of oxidizing sugars to release E, CO 2, & water, or by burning C enters rock cycle as organic material carried to wetlands & oceans & slowly incorporated into newly-forming rock.
Nitrogen Cycle N 2 made biological available to organisms thru N fixation, conversion of N to NH 3, NO 3, 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 NH 3 & 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.
Human 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!
Rule of 10 Only 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 herbivores –It takes 10 kgs of herbivores to support 1 kg of 1 st level predator
Decomposition Organic matter in animals Organic matter in plants Inorganic matter in soil Dead organic matter
Symbiosis A 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).
Symbiosis – “living together” Relationship Type Species ASpecies B Commensalism +0 Mutualism ++ Parasitism +- + means the organism benefits 0 means the organism neither benefits or is harmed - means the organism is harmed
Causes of Environmental Problems Population growth Wasteful and unsustainable resource use Poverty Failure to include the harmful environmental costs of goods and services in their market prices Insufficient knowledge of how nature works
Some Resources Are Not Renewable Nonrenewable resources Exist in fixed quantity in earth’s crust. Economically depleted when costs too much to obtain what is left. –Energy resources –Metallic mineral resources –Nonmetallic mineral resources Solutions: Reuse Recycle
Degradation of Normally Renewable Natural Resources and Services
Our Ecological Footprints Are Growing Ecological footprint: - 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.
Cultural Changes Have Increased Our Ecological Footprints 12,000 years ago: hunters and gatherers Three major cultural events –Agricultural revolution –Industrial-medical revolution –Information-globalization revolution
NATURAL CAPITAL DEGRADATION Major Human Impacts on Terrestrial Ecosystems Deserts Grasslands Forests Mountains Large desert cities Conversion to cropland Clearing for agriculture, livestock grazing, timber, and urban development Agriculture Soil destruction by off-road vehicles Timber extraction Release of CO 2 to atmosphere from burning grassland Conversion of diverse forests to tree plantations Hydroelectric dams and reservoirs Mineral extraction Soil salinization from irrigation Increasing tourism Overgrazing by livestock Depletion of groundwater Damage from off- road vehicles Urban air pollution Increased ultraviolet radiation from ozone depletion Land disturbance and pollution from mineral extraction Oil production and off-road vehicles in arctic tundra Pollution of forest streams Soil damage from off-road vehicles
Studying Nature Reveals Four Scientific Principles of Sustainability Reliance on solar energy Biodiversity Population control Nutrient cycling
Solutions For Environmental or Sustainability Revolution