Chapter 4 - Characteristics of Ecosystems PDF

Chapter 4- Characteristics of Ecosystems Lesson 4.1- Interactions Within Ecosystems ==Ecology: study of interactions between organisms and their living and non-living environment; word was made by Ernst Haeckel in 1866; in Greek means the study of the place where one lives. ==Abioti...

Chapter 4- Characteristics of Ecosystems Lesson 4.1- Interactions Within Ecosystems ==Ecology: study of interactions between organisms and their living and non-living environment; word was made by Ernst Haeckel in 1866; in Greek means the study of the place where one lives. ==Abiotic factors: non living factors that influence an organism; ex sunlight, temperature ==Biotic factor: living factors that influences and organism; ex another organism Ecological Studies: Can start at the individual organism level. Focuses on how organisms interact with their environment, affecting growth, feeding, and reproduction. Organisms in Ecosystems: Organisms rarely live in isolation, they live in groups or populations (members of the same species). Populations of different species together form a community within an ecosystem. Examples of a community include various species like pike, perch, tadpoles, and algae in a lake. Ecosystem Studies: Ecologists: ==Study the community of organisms and how they interact with abiotic and biotic factors. They also investigate entire ecosystems, which are made up of living things and the physical environment. Example: In a forest ecosystem, they might study how sunlight affects plants and animals. Ecotone: a transition area between ecosystems; contain species from both bordering ecosystems. Biodiversity Benefits: ==Ecosystems with higher biodiversity are more stable and resilient. Predators in diverse ecosystems are less reliant on a single prey species. If one prey population declines, predators can switch to alternative prey. Ecotones and Stability: Provide alternative food sources.  ==Help protect species from extinction by offering a variety of resources. Figure 1: This is an example of an Artificial Ecosystem ==Artificial Ecosystems: Are ecosystems that are planned or maintained by humans. Examples: schoolyards, local parks, farms, and managed forests. Human influence controls changes within the ecosystem (e.g., trees grow but the overall appearance stays the same over the years). Humans select plants that are given an advantage over others. Natural Ecosystems: ==Not planned or maintained by humans. Examples: lakes, rivers, forests, deserts, and meadows. The living community freely interacts with the physical and chemical environment. Subtle, natural changes occur as different species relace one another. Only plants suited to the natural environment thrive. ==Humans are a natural part of many ecosystems, even in natural ecosystems, but do no plan or control changes in natural ecosystems. Ecological niche: An organisms role in a ecosystem; includes an organisms place in food web, habitat, breeding area, time of activity; each species has a niche, reducing competition for resources. Owl vs. Hawk Example: Owls: Hunt at night ==(nocturnal). Short, broad wings help them navigate dense forests. Hawks: Hunt during the day ==(diurnal). Long wings make them better suited for open fields and grasslands. Although both birds may prey on similar species, they are not in competition because of their different niches. Adaptations for Niche: Eyesight: Hawks excel at detecting changes in color and motion. Owls see poorly in daylight but excel in detecting motion in the dark and have excellent hearing. Hunting Strategies: Owls are adapted for hearing rustling noises of small animals like rodents at night. Hawks target prey in more open environments, often high in trees. Competition and Niche Partitioning: Different species occupy different niches to reduce competition. Example: Warblers in forests occupy different parts of trees (some prefer tops, others lower branches) to avoid direct competition (shown in Figure 6). Biodiversity in Forests: ==Natural forests, with trees of different ages and heights, offer more niches, leading to higher biodiversity. ==Planted forests with trees of the same age and height have fewer niches, resulting in lower biodiversity. Disturbance in Ecosystem: ==Exotic Species: A New species entering an ecosystem they are not native to. A new species entering an ecosystem leads to competition for niches with native species. Natural Introduction of Exotic Species: Animals can move between ecosystems; plant seeds can be carried by wind or animals. New routes or environmental changes can introduce species to new areas.  Example: North and South America connecting 5 million years ago led to a mix of animal species, where Northern species often outcompeted Southern species. Human Introduction of Exotic Species: Main Causes of Species Decrease: Human introduction of species is the second-largest cause of species extinction, after habitat loss. Introduced species often lack natural predators or diseases, allowing their populations to grow unchecked. Native species may struggle to compete for resources like space, food, and reproduction sites. Prey species may not have developed defenses against introduced predators. Case Study – Starlings: In the 1890s, a Shakespeare fan released birds from the UK into Central Park, including starlings. Starlings multiplied rapidly, becoming one of the most widespread bird species in North America. In Alberta, starlings outcompete mountain bluebirds and swallows for nesting sites, leading to a decline in bluebird populations. Impact in Canada: Over 3000 introduced species have established themselves in Canada, causing disruptions in natural ecosystems. Exotic species, such as Canada thistle, require billions of dollars annually to control. Lesson 4.2- Terrestrial and Aquatic Ecosystems ==Biome: A large geographical region with a specific range of temperatures and precipitation; each biome supports a unique community of plants and animals adapted to the local environment; Ex. Tundra, Taiga, Grassland, Deciduous forest and Mountain Regions. Terrestrial Ecosystem: are ecosystems that are found anywhere on Earth that is not covered by water; Alberta's terrestrial ecosystems are found within two major biomes: taiga and grassland. Ecosystems of the Taiga Biome: Taiga (Boreal Forest) Biome: Located primarily in northern regions, such as Alberta. Contains mainly coniferous trees (spruce, pine, fir), which have adaptations like wax-coated needles for winter protection.  Snow insulates the ground and prevents tree roots from freezing. Conifer branches are flexible, allowing them to shed snow efficiently. Abiotic and Biotic Adaptations in Taiga: Each forest ecosystem is a mosaic of different communities with various adaptations to abiotic and biotic factors. Example of biotic factors: Seed-eating birds, like crossbills, and small mammals like squirrels, rely on the canopy of trees for food. Canopy: Uppermost layer of forest vegetation where most sunlight is captured. Differences in Forest Floor Light: Taiga Forest (Thick Forest): **Figure 2 Canopy is dense, so little sunlight reaches the forest floor. This limits the types of plants growing on the ground (mostly mosses, ferns, and shade-loving plants). Predators like black bears, grizzly bears, and weasels are common.  Deciduous Forests: Figure 3 Less dense canopy allows more sunlight to reach the forest floor. Supports a variety of undergrowth plants, providing more food sources for herbivores. Adaptations of Forest Species: Animals in the forest canopy (e.g., birds) have specialized feeding mechanisms. Species on the ground (e.g., grouse) are often camouflaged to blend into the shaded forest floor. muskeg: soil above the permafrost Permafrost: permanently frozen soil Understory: below the canopy layer; usually shrubs and smaller trees Muskeg Ecosystems: **Figure 4 Found in cold climates with permafrost (frozen soil). Muskeg is swampy/boggy in summer due to poor drainage. Slow decomposition due to cold temperatures, making soil formation slow. Plants: lichens, mosses, grasses, small shrubs, stunted conifers. Wildlife: Provides habitat for caribou, black flies, and mosquitoes. Grassland Ecosystems: **Figure 5 Fertile soil from deep-rooted grasses. Grasslands have limited layers, reducing biodiversity. Producers: rough fescue, wheat grass. Wildlife: deer, rabbits, sapsuckers, rattlesnakes. Deciduous Forest Ecosystems: Found at the edge of grasslands with moderate rainfall. Trees: Aspen, poplar, birch.  Rich soil from leaf litter and humus. Wildlife: diverse, including insects, insect-eating birds, deer, and moose. **Figure 6### Aquatic Ecosystems Overview: ==Water covers 2/3 of Earth’s surface. 97% is saltwater. ==Oceans control weather and provide freshwater through evaporation. Aquatic ecosystems include ponds, rivers, lakes, and oceans. Alberta has freshwater ecosystems in lakes and rivers. Lake Ecosystems:  Vary in light, temperature, and oxygen at different depths. Littoral zone: shallow, near the shore; most productive zone, with rooted plants like bulrushes and algae. plankton: autotrophic and heterotrophic microorganisms found in the limnetic zone of a lake or pond Limnetic zone: open lake with enough light for photosynthesis; plankton are the main organisms. Profundal zone: deeper, dark zone where no photosynthesis occurs. Organisms rely on detritus (dead matter) from above for nutrients. Decomposition in the profundal zone can reduce oxygen, leaving only species that tolerate low-oxygen environments (e.g., some invertebrates and fish like carp). Lesson 4.3- Factors Affecting Ecosystems Factors Affecting Ecosystems: 1. Soil:  Soil quality is crucial for plant growth and biodiversity. Layers of soil: Litter: Partially decomposed organic matter (leaves/grasses) reduces temperature variations and water loss. - Topsoil: Dark layer with minerals and humus (decayed plant/animal matter), essential for nutrient recycling and plant growth. ==Subsoil: Contains more rock particles, fewer nutrients; composed of rock particles and minerals. == Bedrock: Solid rock beneath the soil. pH of soil influences plant growth. Acidic soil can limit plant diversity. 2. Available Water: Amount and type of precipitation (rain/snow) affects water availability.  Water seeping into the ground forms groundwater. Water table depth determines how much water plants can access. Leaching: Water moves nutrients deeper into the soil, reducing plant access to essential minerals. 3. Temperature: Temperature affects evaporation and growing seasons. Organisms adapt to their region’s temperature (e.g., conifer trees retain leaves to survive shorter growing seasons). Alberta's harsh winters see migration, hibernation, or adaptations like underground biomass in grasses. 4. Sunlight: Latitude affects sunlight levels. Closer to the equator means constant sunlight, while northern regions have seasonal changes. Within ecosystems, canopy layers (tall trees) can limit sunlight reaching lower plants. Factors Affecting Aquatic Ecosystems 1. Chemical Environment: Freshwater vs. Saltwater: Organisms are adapted to one type and cannot usually survive in the other. Dissolved Oxygen: Critical for aquatic life, affected by temperature, pressure, and salinity. Other Substances: Dissolved minerals (e.g., phosphorus, nitrogen) and pollutants also shape aquatic environments. 2. Temperature and Sunlight: Seasonal Variation: In regions like Canada, temperature and light vary with seasons. Depth: Surface waters receive more sunlight and are warmer, while deeper areas are darker and cooler. Some deep-sea ecosystems thrive in complete darkness through chemosynthesis. 3. Water Pressure: Water pressure increases with depth, limiting the range of species.  At 10 meters depth, pressure doubles, and it increases by 100 kPa for every 10 meters. Few species can survive both near the surface and at the deep ocean floor due to extreme pressure differences. 4. Seasonal Variations in Canadian Lakes: Winter: Lakes are stratified by water density, with the coldest water (at 0°C) near the surface and densest water (at 4°C) at the bottom. Ice insulates but limits oxygen exchange, potentially leading to low oxygen levels. Spring Turnover: Ice melts, and surface waters warm to 4°C. Wind-driven mixing distributes oxygen throughout the water column. Summer Layers: Epilimnion: Warm upper layer. Hypolimnion: Cold bottom layer. Thermocline: The middle layer where the temperature drops sharply. During summer, oxygen does not circulate between layers, which can lead to oxygen depletion in deeper waters. Fall Turnover: Surface waters cool, sinking to mix the lake and replenish oxygen levels. Lesson 4.4- limits on Population and Communities in Ecosystems Biotic Potential: the maximum number of offspring that a species could produce with unlimited resources. Biotic potential is regulated by 4 important factors: birth potential- The maximum number of offspring per birth  capacity for survival- The number of offspring that reach reproductive age breeding frequency- The number of times that a species reproduces each year length of reproductive life- The age of sexual maturity and the number of years the individual can reproduce Limiting Factors and Their Effects on Populations 1. Limiting Factors: Abiotic Factors: Favourable Conditions: Light: Adequate light levels Temperature: Optimal temperature range Chemical Environment: Suitable chemical environment (e.g., soil pH, nutrient availability) Unfavourable Conditions: Light: Too much or too little light Temperature: Too cold or too warm Chemical Environment: Unfavourable chemical conditions (e.g., pollution, toxic substances) Biotic Factors: Favourable Conditions: Food: Sufficient food availability Predators: Low number or low effectiveness of predators Diseases and Parasites: Few or weak diseases and parasites Competition: Ability to compete successfully for resources  Unfavourable Conditions: Food: Insufficient food availability Predators: High number or high effectiveness of predators Diseases and Parasites: Many or strong diseases and parasites Competition: Inability to compete successfully for resources 2. Examples and Implications: Fern Population Dynamics: High Spores Production: A fern plant can produce over 50,000 spores annually. If all spores germinated, ferns could potentially cover vast areas quickly. Limiting Factors Impact: Moist Weather: Increases germination and population growth. Dry Weather: Reduces germination and kills plants, leading to population decline. Grazing Animals: High numbers reduce fern population, while fewer grazers allow population growth. Carrying Capacity and Limits of Tolerance 1. Carrying Capacity: Definition: The carrying capacity is the maximum number of individuals of a species that an ecosystem can support sustainably at a given time, based on the availability of essential resources like food and water. Fluctuations: Populations tend to fluctuate due to a combination of biotic (predation, competition) and abiotic (temperature, water availability) limiting factors. However, ecosystems often maintain stability by reaching equilibrium, where none of the populations exceed the carrying capacity. Population Exceeding Capacity: A population can temporarily exceed the carrying capacity. For example, a decline in predators may cause a population surge, but food resources will quickly become scarce, leading to starvation, disease, or increased predation, causing the population to return to or below the carrying capacity. 2. Limits of Tolerance: Law of the Minimum (Liebig's Law): An organism's growth and survival depend on the availability of essential nutrients. The nutrient in the least supply will limit the growth, regardless of the abundance of other resources.  Shelford’s Law of Tolerance: Organisms have a range of tolerance for each abiotic factor (temperature, moisture, etc.). Beyond this range, the organism cannot survive. The optimal conditions within this range allow the population to thrive. Species with a broad range of tolerance can adapt to varying conditions more effectively than species with a narrow tolerance. Density-Independent and Density-Dependent Factors 1. Density-Independent Factors: These factors affect a population regardless of its density (the number of individuals in a given area). Examples: Natural disasters (flood, fire), habitat destruction, climate change** 2. Density-Dependent Factors: These factors influence a population based on its density. As population density increases, the effects of these factors become more pronounced. Examples: Food and water shortages, disease spread, predation, competition for resources (mates, shelter).** Effect: As population density increases, competition intensifies, leading to higher mortality and lower population growth. 3. Population Dynamics: Density-Dependent Regulation: When population density is high, competition for resources increases, leading to higher mortality rates and slower population growth. When the population density decreases, the pressure from these factors eases, allowing the population to recover. Density-Independent Impacts: Events like natural disasters can affect populations regardless of their density, potentially resetting the ecosystem's balance by causing widespread destruction. Competitive Exclusion Principle: Two species competing for the same resource cannot coexist indefinitely. One will outcompete the other, leading to the exclusion or local extinction of the less competitive species. Resource Partitioning: To avoid competitive exclusion, species may evolve different ways of using the same resources (e.g., feeding at different times or using different parts of a habitat), allowing them to coexist in the same ecosystem. Factors That Cause Changes in Populations** Density-Independent Factors: Flood Fire  Pesticide spraying Climate change Habitat destruction Drought Density-Dependent Factors: Food shortage Competition for mates and breeding areas Disease and parasites Introduction of exotic species Predation Competition for water and other resources Lesson 4.5- Changes in Ecosystems Natural vs. Human-Caused Changes Natural Changes: Ecosystems naturally change over time due to shifts in biotic (living organisms) and abiotic (non-living) factors, including climatic changes and natural events (e.g., floods, fires). Human-Caused Changes: Human activities, such as deforestation, pollution, and urban development, are significant drivers of changes in ecosystems. Changes in Terrestrial Ecosystems Deforestation Extent of Deforestation: Before the Industrial Revolution, Earth had approximately 6 billion hectares of forest, now reduced to around 4 billion hectares. About 33% of forests have been cleared for agriculture and urbanization. In Canada, over 60% of virgin forests have been lost to logging since European settlement. Importance of Forests  Ecosystem Services: Forests recycle water and carbon dioxide, which helps regulate climate. Trees act as giant sponges, controlling water runoff, holding groundwater, and preventing soil erosion. Forests provide habitats for wildlife and are crucial for biodiversity. Forestry Practices Types of Deforestation: 1. Slash-and-burn: Used mainly in tropical areas, where forests are cleared by burning to make way for agriculture. It provides temporary soil nutrients but causes long-term damage. 2. Clear-cutting: Removal of all trees in an area, commonly used in Canada for timber or pulp production. It is followed by replanting but leads to soil erosion, biodiversity loss, and increased water runoff. 3. Selective cutting: Only certain trees are harvested, leaving others to regenerate the area, which reduces the environmental impact compared to clear-cutting. Effects of Clear-Cutting Positive Effects: Cheaper and more efficient than selective cutting. Eliminates pest infestations in some cases. Provides benefits to wildlife like moose by increasing low vegetation. Negative Effects: Soil erosion increases, and runoff into streams carries nitrates and sediments, harming fish habitats. Increased water loss and warming due to exposed soil. Replanting monocultures (single species) reduces biodiversity. Negatively affects species like owls that rely on mature forests for nesting. Forest Succession After clear-cutting, herbicides and underbrush removal are used to control the forest regrowth process, creating a monoculture of trees like spruce and fir, which are more vulnerable to diseases and pests. Effects of Fire on Ecosystems Role of Fire in Ecosystems: Fire helps maintain a balance in ecosystems by clearing overgrown vegetation and encouraging new growth. At Elk Island National Park, fires play a critical role in maintaining the grassland, wetland, and aspen parkland. Historically, both natural and human-set fires (by indigenous peoples) controlled forest expansion. Prescribed Burns: Controlled fires are intentionally set in defined areas to maintain ecosystem health, which helps in preventing uncontrolled wildfires and maintaining vegetation balance. Changes in Aquatic Ecosystems Types of Lakes Oligotrophic Lakes: Deep, cold, and low in nutrients. Clear water with fewer organisms due to limited nutrients. Examples: trout thrive in these lakes. Eutrophic Lakes: Shallow, warm, and nutrient-rich, promoting high levels of photosynthetic organisms. Water is often murky due to the abundance of plant life. These lakes naturally evolve from oligotrophic lakes through eutrophication. Eutrophication Process: Natural process where lakes become shallower and more nutrient-rich over time. This process can take hundreds to thousands of years. Human Activities Accelerating Eutrophication: Runoff from fertilizers, sewage, and other waste adds nutrients to lakes, speeding up the eutrophication process. Water Pollution Types of Pollution: 1. Organic Waste: Includes sewage and food processing waste. Decomposition of this waste depletes oxygen in water.  2. Disease-Causing Organisms: Found in sewage and animal waste runoff, leading to waterborne diseases like typhoid. 3. Inorganic Solids: Waste from mining, fertilizers, and road runoff contribute harmful substances to water. 4. Thermal Energy: Waste heat from industries raises water temperatures, reducing oxygen levels. 5. Organic Compounds: Includes oil, pesticides, and detergents. These are toxic to aquatic life and disrupt the food chain. Effects of Water Pollution Dissolved Oxygen (DO): Cooler lakes with fewer pollutants maintain high oxygen levels (8-14 mg/L), supporting healthy fish populations. Pollutants and warming reduce DO levels, which limits the survival of species that need higher oxygen levels (e.g., trout). Biological Oxygen Demand (BOD): A measure of the oxygen required by decomposers to break down organic matter. Higher BOD indicates more pollution, as more oxygen is consumed by bacteria. Indicators of Water Quality 1. Bacteria Count: Coliform bacteria indicate the presence of fecal contamination in water, which suggests that disease-causing bacteria may be present. 2. Dissolved Oxygen: The level of DO is crucial for aquatic life. Lower levels can lead to the death of fish and other organisms. 3. Biological Oxygen Demand (BOD): High BOD levels indicate high levels of organic matter, which can deplete oxygen in water and harm aquatic ecosystems. Human Impact on Lakes 1. Cottages and Shoreline Alteration:  Human activities like creating beaches and planting lawns near lakes increase erosion and nutrient runoff, leading to eutrophication and declining water quality. Removal of shoreline vegetation decreases shade and oxygen levels, accelerating the aging process of lakes. 2. Sewage and Pollution: Sewage from cottages adds nutrients to lakes, promoting plant and algae growth, which eventually leads to oxygen depletion as decomposers break down the organic matter. Climate Change and Lakes Impacts on Lakes: Higher global temperatures increase evaporation rates, reducing water levels in lakes. This raises lake temperatures, affecting cold-water species like trout. Minerals and salts accumulate in lakes, further reducing water quality as nitrogen and phosphorus concentrations increase. These notes are more detailed and include additional concepts from the document. Let me know if you need more information or further adjustments!