GEO 110 Ecosystems PDF

Chapter 19 - Ecosystem Essentials Species Distributions Shift with Climate Change - Temperature and moisture are limiting factors - Changing climate or these factors - Species will: adapt, evolve, seek new habitat: move north, move up. go extinct Alien or Invasive Species in Ontario (from...

Chapter 19 - Ecosystem Essentials Species Distributions Shift with Climate Change - Temperature and moisture are limiting factors - Changing climate or these factors - Species will: adapt, evolve, seek new habitat: move north, move up. go extinct Alien or Invasive Species in Ontario (from: Invasive Species Centre) - Animals: Land animals and invertebrates (5) e.g. nutria - Insects (17) - Fish and aquatic invertebrates (20) - Aquatic plants (15) - Other plants (17) e.g. kudzu - Pathogens (8) e.g: Dutch elm disease - Biosphere: the sphere of life and organic activity, from ocean floor to 8 km altitude into the atmosphere. - Ecosystem: a self-sustaining association of living plants and animals and their nonliving physical environment. - Ecology is the study of relationships between organisms and their environment and among the various ecosystems in the biosphere. - Biogeography is the study of the distribution of plants and animals. Biotic components include: 1. Producers (plants) (self-feeders/ autotrophs) 2. Consumers (animals) 3. Detritus feeders (worms, mites) 4. Decomposers (bacteria, fungi) Converting Energy to Biomass - Plants turn sunlight into food. - About 270,000 species of plants exist, and most are vascular (with conducting cells). - Only about 20 species of plants provide 90% of the world’s food. Among these 20 species, wheat, maize (corn), and rice comprise half of the food supply. Photosynthesis and Respiration - Photosynthesis equation: Carbon Dioxide + Water + Solar Energy → Carbohydrate (sugar) + Oxygen - Respiration equation: Carbohydrate (sugar) + Oxygen → Carbon Dioxide + Water + Heat Energy - Net Photosynthesis = Photosynthetic Rate − Respiration Rate Elemental Cycles - The most abundant natural elements in living matter are hydrogen, oxygen, and carbon. - H, O, and C make up more than 99% of Earth’s biomass. - Biomass is the net dry weight of all organic matter and its stored chemical energy. In addition to hydrogen, oxygen, and carbon, nitrogen, calcium, potassium, magnesium, sulfur, and phosphorus are important nutrient elements for the growth of a living organism.  Earth’s biogeochemical cycles include recycling of gasses (O, C, and N) and sedimentary (nutrient) materials. The Nitrogen Cycle - Nitrogen cannot be directly used by plants. - Nitrogen-fixing bacteria in soil or on plant roots combine the nitrogen from the air in the form of nitrates and ammonia that can be used by plants to produce their own organic matter. - Anything feeding on the plants ingests the nitrogen. - The nitrogen in the organic wastes of these consuming organisms is freed by denitrifying bacteria. - The freed nitrogen goes back to the air. The Gulf of Mexico Dead Zone - Inorganic fertilizers produce excess nitrogen load in rivers and eventually to the ocean. - Increase growth of algae and phytoplankton. - Increase biochemical oxygen demand and diminish dissolved oxygen reserves. Disrupt the aquatic ecosystems. Food Chain and Food Web - Producers manufacture their own food. - Energy flows from producers to consumers and eventually detritivores. Such energy flow through the system is called food chain - Food web is a complex network of interconnected food chains. - Organisms that share the same basic foods are said to be at the same trophic level A Simplified Terrestrial Food Chain - Primary consumers (2nd trophic level) feed on producers (1st trophic level). - Since producers are always plants, the primary consumers are herbivores - A carnivore is a secondary consumer and primarily eats meat. - A consumer feeds on both producers and consumers is an omnivore - A tertiary consumer eats primary and secondary consumers and is referred as the top carnivore Detritivores and Decomposers - Detritivores are the final link in the endless food chain. They renew the entire system by releasing simple inorganic compounds and nutrients with the breaking down of organic materials. - Detritivores include detritus feeders and decomposers. - Detritus refers to all the dead organic debris. - Detritus feeders (e.g., worms, mites, termites, snails) consume detritus. - Decomposers are primarily bacteria and fungi that digest organic debris outside their bodies and absorb and release nutrients in the process. Ecosystem Components - An ecosystem includes biotic (living) and abiotic (nonliving) components. - Nearly all ecosystems depend on a direct input of solar energy, except a few ones in dark caves and on the ocean floor that depend on chemical reactions.  - A community is formed by interactions among populations of living animals and plants at a particular time. Habitat and Niche - Within a community, two concepts are important: habitat and niche - Habitat is the type of environment in which an organism resides or is biologically adapted to live. - Niche refers to the function or occupation of a life form within a given community. Stable Community - In a stable community, every niche is filled. - According to the competitive exclusion principle (Gause, 1934), two species cannot occupy the same niche (food or space) successfully in a stable community. The closely related species are spatially separated. - Each species operates to reduce competition and to maximize its own reproduction. This strategy in turn leads to greater diversity. Symbiotic Species - Symbiotic: Two or more species exist together in an overlapping relationship. - Two types of symbiosis: mutualism and parasitic. - Mutualism: Each organism benefits and is sustained over an extended period by relation. - Parasitic: Kill the host, destroy the parasite’s own niche and habitat. Abiotic Ecosystem Components - Flow of energy and the cycling of nutrients and water in ecosystems are important for ecosystem operations. - Light, temperature, water, and climate - Ecosystem types are directly related to conditions of light, temperature, water, and climate. Limiting Factors - The term limiting factor refers to physical, chemical, or biological characteristics of the environment that determine species distributions and population size. - Low temperatures limit plant growth at high elevations. - Lack of water limits growth in a desert; excess water limits growth in a bog. - Changes in salinity levels affect aquatic ecosystems. - Low phosphorus content of soils limits plant growth. - The general lack of active chlorophyll above 6100m (20,000 ft) limits primary productivity. Disturbance and Succession - Over time, communities undergo natural disturbance events such as windstorms, severe flooding, a volcanic eruption, or an insect infestation. - Human activities, such as the logging of a forest or the overgrazing of a rangeland, also create disturbance. Such events damage or remove existing organisms, making way for new communities. - When a community is disturbed enough that most, or all, of its species are eliminated, a process known as ecological succession occurs, in which the cleared area undergoes a series of changes in species composition as newer communities of plants and animals replace older ones.  - Each successive community modifies the physical environment in a manner that favours a different community. - More commonly encountered in nature is secondary succession, which occurs when some aspect of a previously functioning community is still present. - Traditionally, communities of plants and animals were thought to pass through several successional stages, eventually reaching a mature state with a predictable climax community—a stable, self-sustaining assemblage of species that would remain until the next major disturbance. Ecosystem Biodiversity - A critical aspect of ecosystem stability and vitality is biodiversity (a combination of biological and diversity). - Biodiversity includes the number of different species and quantity of each species, the genetic diversity in species, and ecosystem and habitat diversity. - Greater biodiversity in an ecosystem results in greater stability and greater productivity. Biodiversity and Agricultural Ecosystems - An artificially produced monoculture community such as a field of wheat is vulnerable to failure due to weather or attack from insects or plant diseases. - For sustainable agriculture, simply planting multiple crops could bring more stability to the ecosystem. Terrestrial Biomes (Chapter 20) What is a Biome? Large, stable terrestrial ecosystem defined by specific plant/animal communities and climate. Six main types: forest, savanna, grassland, shrubland, desert, tundra. Types of Vegetation ○ Winter-deciduous trees - lose leaves in cold seasons. ○ Drought-deciduous shrubs - lose leaves in dry seasons. ○ Annual herbs - live for one growing season. ○ Bryophytes - mosses and other spore-producing plants. ○ Lianas - woody vines. ○ Epiphytes - plants that grow on other plants for support. Forests - Rainforests: High rainfall; tropical (evergreen) and temperate (mix of broadleaf/needle-leaf trees). - Seasonal forests: Distinct wet/dry seasons; mostly deciduous trees. - Broadleaf mixed forests: Temperate zones, mix of broadleaf and needle-leaf trees. - Coniferous forests: High latitudes/elevations; needle-leaf, cone-bearing trees. - Grasslands: Fertile midlatitude regions; "breadbaskets" for agriculture (grains, soybeans, livestock). - Deserts  - Warm deserts: Low precipitation due to subtropical high pressure. - Cold deserts: Higher latitude, drier, cooler. - Polar deserts: Very cold, minimal vegetation (Antarctica, Greenland). - Tundra Arctic Tundra: Extreme north, near Arctic Ocean. Alpine Tundra: High elevations, above tree line. A boundary zone between different but adjoining ecosystems at any scale is an ecotone Ecosystems separated by different climatic conditions usually have gradual ecotones, whereas those separated by differences in soils or topography may have abrupt boundaries. Tropical Savanna (TRS): Large grassland areas with scattered trees and shrubs. Location: Transitional biome between tropical forests and deserts. Climate: ○ Rainy Season: Receives rain for less than 6 months when the Intertropical Convergence Zone (ITCZ) is overhead. ○ Dry Season: Remainder of the year is dry due to subtropical high-pressure cells. Fire Cycles: ○ Early Dry Season Fires: Can encourage tree growth by clearing ground cover. ○ Late Dry Season Fires: Can harm vegetation by killing trees and seeds. Boreal and Montane Forest Boreal Forest (Northern Needle-leaf Forest): ○ Characteristics: Dominated by needle-leaf trees; less dense in northern areas, where it transitions into arctic tundra (known as the taiga). Montane Forest: ○ Location: Found at high elevations on mountains worldwide. ○ Characteristics: Composed of needleleaf forests adapted to mountain climates. Temperate Rainforest: Lush, dense forests located in wet, humid regions. Vegetation: Broadleaf and needleleaf trees, epiphytes, large ferns, and thick undergrowth. Climate: Corresponds to Marine West Coast climates (middle to high-latitude west coasts). Precipitation: High rainfall, up to 400 cm annually. Mediterranean Shrubland: Also known as temperate shrubland, found in regions with dry summers. Climate: Mediterranean, characterized by hot, dry summers. Vegetation: ○ Dominated by low-growing, drought-resistant shrubs.  ○ Shrubs typically 1-2 meters tall, with deep roots, leathery leaves, and irregular, low branches. Solar Energy to Earth and the Seasons (Chapter 2) Solar Energy: Energy from the Sun’s nuclear fusion, providing light and heat to Earth. Sunspots: Magnetic storms on the Sun with an 11-year cycle; cooler than surrounding areas. Solar wind: Charged particles emitted by the Sun, causing auroras near Earth’s poles (Aurora Borealis in the north, Aurora Australis in the south). Reasons for Seasons Earth’s Tilt (23.5° angle): Tilted axis causes seasonal changes in temperature and sunlight. Earth’s Revolution (365.25 days): Orbit around the Sun creates annual seasons. Earth’s Rotation (24 hours): Daily cycle of day and night. Axial Parallelism: Earth’s axis remains aligned with the North Star (Polaris). Sphericity: Earth’s shape affects sunlight distribution across latitudes. 1. Key Seasonal Dates ○ Winter Solstice (Dec 21/22): Sun is at Southern Tropic (23.5°S). ○ Spring Equinox (Mar 20/21): Sun is over the Equator. ○ Summer Solstice (Jun 20/21): Sun is at Northern Tropic (23.5°N). ○ Fall Equinox (Sep 22/23): Sun is over the Equator. Chapter 3: Earth’s Modern Atmosphere Atmosphere Overview Mixture of gasses essential for life, developed over 4.6 billion years. Extends up to 480 km; beyond that lies the exosphere ("outer sphere"). 1. Composition ○ Permanent Gases: Nitrogen (78%), Oxygen (21%), others (1%). ○ Variable Gasses: Water vapor (0-4%), CO₂ (0.0035%). 2. Pressure and Density ○ Air pressure decreases with altitude. ○ Higher density near Earth’s surface due to gravity. 3. Atmospheric Layers ○ Heterosphere (80-480 km): Distinct layers; lighter gases (H₂, He) at top, heavier (N₂, O₂) lower.  ○ Homosphere (0-80 km): Mixed gases, with the ozone layer (19-50 km). 4. Temperature Profile of Atmosphere ○ Troposphere: Surface to 18 km; weather, biosphere, water vapor, pollution. ○ Stratosphere: 18-50 km; contains the ozone layer, temperature increases with altitude. ○ Mesosphere: 50-80 km; coldest layer. ○ Thermosphere: 80-480 km; hottest layer, same as heterosphere. 5. Ozone Layer and UV Radiation ○ Ozone Depletion: Caused by CFCs, creating ozone holes. ○ UV Index: Measures solar radiation intensity. 6. Air Pollution ○ Natural Sources: Winds, landscape, temperature inversions. ○ Anthropogenic Sources: Carbon monoxide, smog, sulfur oxides, particulates, acid rain. Chapter 4: Atmosphere and Surface Energy Balances 1. Solar Energy and Insolation ○ Insolation: Incoming solar radiation, primary energy for Earth’s system. ○ Energy Balance: Varies by latitude and longitude. 2. Energy Processes ○ Reflection: Radiation bounces back to space; Albedo is the reflectivity (e.g., snow has high albedo). ○ Absorption: Radiation absorbed and converted; influenced by CO₂ and water vapor. 3. Scattering and Refraction ○ Scattering: Alters light direction without changing wavelength (e.g., blue sky due to shorter wavelength scattering). ○ Refraction: Bends light as it passes between media, creating phenomena like rainbows. 4. Greenhouse Effect and Atmospheric Warming ○ Atmosphere traps heat, moderating Earth’s temperatures through greenhouse gases. 5. Urban Heat Island Effect ○ Cities are warmer than surrounding areas due to less vegetation and more heat-absorbing surfaces (pavement, buildings).