Ecology: Ecosystems, Biosphere, and Components

• Ecology studies organisms and their interactions with the environment.
• An ecosystem involves the interaction between living (biotic) and non-living (abiotic) components in a defined area.
• Abiotic factors are non-living physical elements influencing an organism or system within an ecosystem.
• Biotic factors refer to interactions among living organisms.
• The biosphere encompasses all parts of Earth where life exists, from the upper atmosphere to deep within the crust.
• Key components of the biosphere are ecosystems, communities, populations, and individuals.
• Ecosystems consist of living communities and their non-living environments functioning as a single unit.
• The health of ecosystems is assessed by biodiversity, productivity, and the circulation of energy and nutrients.
• Biotic and abiotic components are interconnected through nutrient cycles and energy flows.

Levels of Organisms

• A community is a group of different species populations living and interacting in the same area over time.
• A population comprises individuals of the same species in a specific area, capable of interbreeding; population dynamics influence ecosystem health and evolution.
• An individual is the smallest ecological unit, capable of independent survival.
• A species is a group of organisms that can interbreed and produce fertile offspring.

Population/Community Dynamics

• Interbreeding capability defines populations through the potential for reproduction and genetic exchange, vital for adaptation and survival.
• Populations are confined to specific areas with boundaries that can change.
• A single species can have multiple populations separated by geography, environment, or behavior, leading to evolutionary paths.
• Limiting factors determine the types and numbers of organisms in an ecosystem.
• Temperature impacts the metabolic rates, growth, reproduction, and survival of organisms, thus influencing the geographic distribution of species.
• Light is crucial for photosynthesis in plants and influences the behavior and reproductive cycles of organisms; light availability impacts plant growth.
• Water availability affects species distribution, ecosystem productivity, plant water stress, and water balance.
• Soil properties, including texture, composition, pH, and nutrient content, are essential for plant growth and influencing the types of animals supported.
• The pH level of soil and water influences nutrient availability and toxicity, affecting plant health and microbial communities.
• Soil texture influences water retention and air circulation, affecting plant root growth and nutrient uptake.
• Dissolved oxygen in water affects respiration in aquatic organisms and determines water quality.
• The habitat is where an organism lives, providing food, water, and shelter.
• A niche describes the abiotic and biotic conditions and resources a population responds to.
• A fundamental niche includes the range of conditions and resources a species could theoretically survive and reproduce in.
• A realized niche describes the actual conditions and resources a species exists due to biotic interactions

Niches

• Niches include habitat, food resources, use of abiotic resources (light, CO2, oxygen), influence of abiotic factors (temperature), and interactions with other species.
• Competition involves frogs and small fish competing for aquatic larva.
• Herbivory involves rabbits eating dune grasses.
• Predation involves blue herons eating green frogs.
• Parasitism involves leeches sucking blood from fish.
• Mutualism involves lichens as a cooperative relationship between alga and fungus.
• Commensalism is a symbiotic relationship where one benefits, while the other is neither harmed nor helped.
• Mutualism is a symbiotic relationship where both members benefit.
• Parasitism is a symbiotic relationship where one species benefits, and the other is harmed.
• Predation is how one species consumes another; defenses include plant defenses (spikes, thorns, toxins) and animal defenses (fleeing, camouflage, poisons, mechanical defenses). Population: a same species group of organisms that can live in the same area.

Living Organisms Needs

• Living organisms need movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition.

Exponential Growth

• J-shaped growth demonstrates that populations may crash due to limiting factors, like lack of food or toxin accumulation.
• R-strategists produce large numbers of offspring, colonize new habitats quickly, use short-lived resources, and are competitive in young, changeable habitats.
• S-shaped curves demonstrate exponential growth where a population size slows down and fluctuates when the population reaches its carrying capacity.
• Limiting factors are density-dependent or density-independent.
• K-strategists produce a small number of offspring and give more parental care, investing more energy.

Classification

• Classification (taxonomy) is used to organize and categorize the diversity of life.

Human Population

• Human population growth is high because of technology, medicine, agriculture, mitigated natural predators.

Human Carrying Capacity

• This growth will affect ecosystems worldwide.
• Resource depletion is the increased demand for natural resources.
• Habitat destruction and conversion of land for agriculture reduces biodiversity.
• Pollution from industrial and agricultural activities pollutes the air, water, and soil.
• Human ecological niches are wide and continually evolving due to technological progress.
• Resource mobility: Humans uniquely transport resources globally.
• Technological expansion expanded the human niche by improving resource use and accessing new resources.
• Consumption patterns affect the demand for various resources.
• Changing environments involve rapidly changing habitats due to urbanization, deforestation, and climate change.
• Contested estimates are highly disputed based on resource distribution, consumption patterns, and the impacts of technological interventions.
• Ecosystem equilibrium occurs when populations stabilize at or near the carrying capacity, and natural checks maintain this by predation, disease, and competition.
• Human exceptionalism shows medical advancements, agricultural productivity, and ecological modifications to prevent human decline, which is unique.

Tropical Rainforests

• Tropical rainforests are highly resilient due to their high biodiversity and complex trophic interactions.
• Processes involve intense photosynthetic activity, rapid nutrient cycling, and diverse food web interactions.
• Outputs show high oxygen production, heat energy, and continuous leaf litter, which help soil nutrient content.
• Resilience is the ability of a system to return from a disturbance.
• The tipping point is a threshold at which a system undergoes a rapid and irreversible change.

Human Impact

• Overharvesting is the unsustainable resources, leading to significant biodiversity loss.
• Poaching and illegal wildlife trade poses severe threats to wildlife.
• Habitat loss from land use changes reduces living space.
• Climate change, pollution, and invasive species threaten habitats and shift species geographic ranges.
• Deforestation disrupts the cycle by reducing the forest's capacity for transpiration.
• Reduction in forest cover can lead to a tipping point where the rainforest may irreversibly transform into a savannah-like ecosystem.
• Keystone species are crucial to maintaining the ecosystem.
• Biosphere integrity shows the health and sustainability in species, and the ability for an ecosystem to function correctly.
• A community is a group of interacting species living within the same ecosystem.
• A population has all the same species with a community.
• An individual is one species organism.

Photosynthesis/Respiration Systems

• Respiration equation: Sugar + Oxygen = Carbon Dioxide + Water + Usable Energy
• Photosynthesis equation: Carbon Dioxide + Water + Energy = Sugar + Oxygen
• The 2nd law of thermodynamics describes entropy/disorganizations.
• Trophic levels describes the position that an organism occupies in a food chain.
• Producers show autotrophs and chemosynthetic.
• Consumers are herbivores, omnivores, and carnivores.
• A food chain is a linear sequence through one organism eating another with nutrients and energy transferring.
• Food webs show all the relationships between all plants and animals in a community.
• Ecological pyramids are a graphical representation of biomass/bioreactivity for each trophic level in a given ecosystem.

Pyramids

• Pyramid of number shows the number of organisms; good for giving a simple overview of a community and for comparing changes overtime. Weaknesses include: all organisms are included regardless of size and may be too great to represent correctly/ some animals feed at more than one tropic level
• Pyramid of biomass shows the mass of organic matter; strengths include accuracy and shows solar inputs; weaknesses include difficult data collection and assigning certain species is hard.
• A pyramid of productivity shows a flow of biomass or energy over time.
• Biomagnification shows an increase in concentration of pollutants in a food chain.
• Toxins accumulate along food chains as biomass decreases.
• These substances accumulate in the food chain and can damage organisms.

Flows of Energy and Matter

• Energy in living systems obeys thermodynamics laws.
• The first law shows that energy can be transferred/ transformed.
• The second law shows energy transformations convert matter from a more ordered, less stable form to a less-ordered, more stable form.
• Living systems also obey system laws.
• Food chains, webs, and pyramids ultimately show energy flow.
• Not all solar radiation ends up as biomass. Sunlight will be lost through: reflection, not hitting, wrong wavelength, transmission of light, inefficiency.
• 31% incoming solar radiation is reflected (19% by clouds, 9% by ground, 3% by atmosphere)
• 69% incoming solar radiation is absorbed (49% by land and water, 17% by molecules and dust, 3% by clouds)
• Albedo describes reflectivity of a surface.
• Biomass measures the mass of living organisms in a given area expressed as dry weight.
• Productivity measures the conversion of energy into biomass over time.
• Primary productivity measures of autotrophs.
• Secondary productivity measures of heterotrophs.
• Ecological efficiency measures energy used for growth x new biomass/energy supplied) x 100
• Net primary productivity (NPP): GPP-R

Carbon/Nitrogen Cycle

• Gross primary productivity measures the theoretical amount of biomass or oxygen produced via photosynthesis.
• Respiration is the amount of biomass or oxygen consumed during cellular respiration of a producer.
• Gross secondary productivity (GSP) food eaten - fecal loss
• Net secondary productivity measures the gain by consumers in energy remaining.
• Matter gets recycled through biogeochemical cycles.
• Matter moves between stores (sinks), and energy travels through the food chain and gets lost as heat.
• Nutrients and matter are finite, and flows are either transformations or transfers.
• In the carbon cycle, some processes move carbon from one place to another (ex. storage), and some involve transformations where one form changes over time (ex. fossil fuels)
• Nitrogen is essential for life and is a component of amino acids.
• Nitrogen transformations (ex. gas changing into solid biomass).
• Human impacts have greatly increased carbon dioxide levels in atmosphere.
• Energy is trapped in plants, and available energy has increased.
• Chances in earth energy budgets and increased carbon dioxide levels.
• Carbon cycle regulates climate through atmosphere carbon dioxide.
• Land use changes release carbon from soil and plant biomass.
• The nitrogen cycle can cause urban air pollution and acid rain
• Farmers use inorganic fertilizers and livestock that release ammonia.
• Denitrification is reduced, less nitrogen enters the atmosphere.
• A pioneer community demonstrates the earliest stage of a community.
• A climax community demonstrates the final stage of a community.
• Primary succession occurs on newly created land with no previous life (ex. volcanic eruptions) with bare inorganic surfaces, colonization by r-strategists, and shallow soil. A secondary succession occurs in areas where life has existed but destroyed by disturbances (ex. wildfire)

Succession stages

• Stage 1: Colonization
• Stage 2: Establishment
• Stage 3: Competition
• Stage 4: Stabilization
• Stage 5: Final Community.
• Zonation is the change in vegetation community along the environmental gradient, where species has ecological niches.
• Temperature, precipitations, solar insolation, soil type, and species interactions.
• Succession is change over time.
• Zonation is change over the altitude/distance.