Ecology: Key Terms

• Ecology is the study of interactions between living organisms and their environment

Ecological Terms

• A species is a group of organisms capable of reproducing with each other
• A population is a group of the same species living in a particular area
• A community refers to all the populations living together in a specific area
• An ecosystem includes living organisms and non-living components like soil, air, and water
• The biosphere is the global sum of all ecosystems, including the atmosphere, lithosphere, and hydrosphere
• Organisms occupy specific habitats (where they live) and fulfill niches (what they do) within ecosystems
• A biome is a large area with similar climate, plants, and animals
• An ecotone is the transition zone between two ecosystems

Biotic and Abiotic Factors

• Living (biotic) and non-living (abiotic) factors constantly interact
• Abiotic factors include sunlight, temperature, water, pH, and soil type
• Biotic factors include plants, animals, fungi, and microorganisms
• Every species has a tolerance range for each abiotic factor, which defines the conditions it can survive
• A limiting factor restricts the success of an organism when it falls outside the organism’s tolerance range
• An organism’s fundamental niche is the full range of environmental conditions it could occupy
• An organism’s realized niche is the smaller range of conditions it actually occupies due to competition or other limitations

Biogeochemical Cycles

• Ecological processes are driven by cycles that recycle nutrients and matter
• Biogeochemical cycles include the carbon, nitrogen, phosphorus, and water cycles
• In the carbon cycle, carbon moves through the atmosphere (as carbon dioxide), living things (through photosynthesis and respiration), and soil (through decomposition)
• Human activities like burning fossil fuels add more CO₂ to the atmosphere, contributing to climate change
• The nitrogen cycle includes processes like nitrogen fixation (bacteria turning nitrogen gas into usable compounds), nitrification, assimilation, and denitrification
• The phosphorus cycle moves slowly because phosphorus is usually found in rocks and soil
• Weathering releases phosphorus into soil, which plants absorb
• The water cycle involves evaporation, condensation, precipitation, runoff, and infiltration

Energy Flow in Ecosystems

• Energy flows in one direction: from the sun, to producers (plants), to consumers and decomposers
• Plants convert sunlight into energy through photosynthesis, making them producers
• Herbivores eat plants and are known as primary consumers
• Carnivores that eat herbivores are secondary consumers
• Decomposers like fungi and bacteria break down dead material, returning nutrients to the soil
• Energy moves through food chains and food webs, and organisms exist at different trophic levels
• At each level, about 90% of energy is lost as heat or used up, and only 10% is passed to the next level
• Ecological pyramids (energy, biomass, numbers) illustrate this energy loss

Biotic Interactions

• Within communities, species interact in various ways (biotic interactions)
• Competition occurs when organisms vie for the same resources like food or space
• Predator-prey relationships involve one organism eating another (e.g., hawk eating a mouse)
• Symbiosis refers to close relationships between species
  • Parasitism: one benefits, the other is harmed (e.g., ticks on dogs)
  • Commensalism: one benefits, the other is unaffected (e.g., barnacles on whales)
  • Mutualism: both benefit (e.g., bees pollinating flowers)
• These relationships shape community structure and ecosystem stability

Ecological Succession

• Ecosystems are self-sustaining systems
• Through ecological succession, ecosystems naturally develop and change over time
  • Primary succession: life colonizes bare areas like volcanic rock
  • Secondary succession: life returns to an area that was disturbed, like after a fire
• Eventually, the ecosystem reaches a stable state called the climax community, which is balanced and self-regulating

Adaptation

• Organisms adapt to their environments over generations through natural selection
• Proposed by Charles Darwin, natural selection explains that individuals with favorable traits survive and reproduce, passing those traits on
• Over time, this leads to adaptation, where species become better suited to their environments
• Example: cacti have thick skins to store water in deserts

Population Studies

• Ecologists use various methods to study populations
• Population sampling methods include quadrats, transects, and mark-recapture techniques
• These help estimate population sizes and understand distribution patterns
• Species diversity measures how many species are in an area and how evenly distributed they are
• A diverse ecosystem is usually more stable and resilient
• The Simpson’s Diversity Index is one method of measuring biodiversity

Population Growth

• Population growth in natural ecosystems depends on birth rate, death rate, immigration, and emigration
• If resources are plentiful, populations grow exponentially, but they eventually hit environmental resistance like limited food or disease
• The carrying capacity is the maximum population size an environment can support without damage
• If populations exceed this limit, they may crash

Human Impact on Ecosystems

• Humans are part of ecosystems and depend on them for survival
• Natural ecosystems provide food, water, clean air, medicine, and climate regulation
• Human actions such as deforestation, pollution, and habitat destruction disrupt these ecosystems and reduce biodiversity
• Maintaining the integrity of ecosystems is essential for sustainable development

Environmental Observation and the Scientific Method

• Students of environmental science are encouraged to observe ecosystems firsthand, visiting different environments (terrestrial and aquatic)
• Measuring abiotic factors (temperature, pH, and salinity) and analyzing data using charts, graphs, and tables is essential
• Learning how to apply the scientific method — forming hypotheses, collecting and analyzing data, and drawing conclusions — is also a key skill

Human Population Dynamics

• Humans are deeply connected to the environment biologically, socially, and economically
• Human population growth has exploded in recent centuries, particularly since the Industrial Revolution
• Understanding this growth requires examining demographic trends, environmental impacts, and possible solutions

People and the Environment

• People rely on the environment for food, water, shelter, and clothing
• People have adapted to different environments through agriculture, housing types, and cultural practices
• Abiotic factors like climate and soil, and biotic factors like available food and other humans, affect where and how people live
• Dependence on ecosystems is total, as they provide clean air, water, materials, and spiritual well-being
• Population growth often puts too much pressure on ecosystems

Demographic Indicators

• Population studies use demographic indicators to measure and understand population trends
  • Fertility rate: the average number of children a woman has
  • Mortality rate: the number of people who die per 1,000 each year
  • Life expectancy: the average age a person is expected to live
  • Immigration (coming in) and emigration (leaving) also affect population size
  • Doubling time: the number of years it would take for a population to double at its current growth rate
• Visualize these statistics using population pyramids, graphs showing age and sex distribution

Population Growth Trends

• Historically, the human population grew very slowly
• Industrialization and advancements in medicine, sanitation, and agriculture have caused death rates to fall and populations to grow rapidly
• Today, countries like India and Nigeria continue to grow fast, while others like Japan and Germany have slowed down and even started shrinking
• Geographical distribution of growth affects global resource use and environmental pressure

Calculating Population Growth

• Calculate population growth by subtracting the death rate from the birth rate and adding net migration (immigrants minus emigrants)
• Annual growth rates, percentage increases, and doubling time give a clearer picture
• These calculations help countries plan for the future

Factors Influencing Population Growth Rates

• Women’s education and empowerment generally lead to lower birth rates
• Access to family planning, healthcare, and jobs contributes to smaller families
• In places where children are seen as economic assets or where religious beliefs discourage contraception, populations tend to grow faster
• Economic development, urbanization, and the availability of retirement benefits also affect people’s choices about having children

Population Control Measures

• Governments often use population control measures to manage growth
  • Direct measures: providing access to contraceptives and education
  • Indirect measures: improving women's rights and economic opportunities
• Natural events like earthquakes or pandemics reduce populations but are not controlled

Population Growth and Poverty

• A strong connection exists between population growth and poverty
• When populations grow faster than resources, people struggle to meet basic needs
• Indices of poverty include access to food, clean water, shelter, healthcare, and education
• Economic indicators like GDP per capita, Gross National Product (GNP), the Human Development Index (HDI), and the Gender Development Index (GDI) show how well a country is doing
• Fast-growing populations can stress schools, hospitals, land, and jobs

Consumption Patterns

• People in wealthier nations consume much more than those in poorer nations
• High consumption leads to more waste, more pollution, and greater greenhouse gas emissions
• Current consumption patterns, especially in developed nations, are not sustainable

Environmental Consequences of Overpopulation and Overconsumption

• Overexploitation of resources like forests and fisheries
• Habitat destruction from urban expansion
• Pollution from industries and vehicles
• Introduction of exotic species that can damage ecosystems
• Ecosystems can collapse when too many resources are removed or natural systems change too quickly

Solutions for Reducing Environmental Impact

• Change lifestyles by reducing waste, choosing sustainable products, and conserving energy
• Use substitutes like bamboo instead of plastic, or solar power instead of fossil fuels
• Utilize environmentally friendly technologies like electric cars and water-saving devices
• Emphasize resource efficiency: using only what is needed and reusing or recycling whenever possible

Urbanization

• Urbanization is the movement of people into cities
• Urban areas can improve access to services but also create problems like overcrowding, poor waste disposal, and pollution
• Rapid, unplanned urbanization often results in slums and informal settlements that lack basic infrastructure

Sustainable Development

• Sustainable development means meeting the needs of the present without compromising the ability of future generations to meet theirs
• Balances environmental health, economic growth, and social well-being
• Population growth and rising consumption put pressure on this balance

Global Initiatives for Sustainability

• The 1987 Brundtland Report (Our Common Future) introduced the idea of sustainable development
• Key part of global conferences like the 1992 Earth Summit (Rio Conference) and the 2002 World Summit on Sustainable Development
• Events stressed managing population growth, protecting biodiversity, and reducing poverty

Natural Resources

• Natural resources include everything we use from the environment such as fresh air, water, forests, fish, soil, and minerals
• Understanding and protecting natural resources is essential for a secure and environmentally responsible future

Types of Natural Resources

• Natural resources are materials and features of the environment that humans use for survival, development, and recreation
• Renewable resources replenish naturally over time if managed properly (sunlight, wind, freshwater)
• Non-renewable resources cannot be replaced on a human timescale (coal, oil, natural gas)
• Exhaustible resources can run out if overused (fish and forests)
• Inexhaustible resources are essentially unlimited (sunlight)

Resource Use

• Resources are used consumptively (directly using up the resource) and non-consumptively (benefiting without depleting)
• Responsible management of both types of use is key to sustainability

Caribbean Natural Resources

• A wide variety of valuable natural resources exist in the Caribbean
  • Biodiversity (genetic, species, ecosystem diversity)
  • Water (rivers, lakes, aquifers)
  • Minerals and hydrocarbons (bauxite, oil, natural gas)
  • Landforms (beaches, mountains)
• These resources are essential for food, jobs, health, cultural identity, and economic development

Importance of Natural Resources

• Support livelihoods such as farming, fishing, and tourism
• Major foreign exchange earners through exports and tourism
• Provide food security, raw materials, medicine, recreation, and spiritual or cultural value
• Some resources have intrinsic value, meaning they’re important simply because they exist

Factors Affecting Resource Use

• Political factors: government policies related to development and environmental protection
• Economic factors: foreign investment, national debt, and pressure to export raw materials
• Tourism, agriculture, mining, and manufacturing use up resources and often harm the environment

Environmental Impacts of Poor Resource Management

• Overharvesting and habitat destruction can cause species extinction
• Deforestation removes habitats for birds, insects, and mammals
• Water resources are at risk from pollution, overuse, and poor watershed management
• Mining and oil extraction cause major landscape changes and pollution
• Soil degradation happens when land is overused, leading to erosion and nutrient loss
• Beaches erode due to construction or sand mining
• Coral reefs suffer damage from pollution and climate change
• These issues reduce the long-term productivity and beauty of the Caribbean landscape

Conservation of Natural Resources

• Conservation includes managing, restoring, preserving, and protecting natural areas
• Conservation can happen in situ (on-site) or ex situ (off-site)

Tools for Sustainability

• Sustainable Yield Management: using renewable resources at a rate that allows them to replenish
• Use of substitutes: replacing non-renewables with alternatives (e.g., bamboo instead of plastic)
• Recycling: reusing materials to reduce waste and resource extraction
• Economic tools: governments can charge user fees, offer incentives, or impose penalties
• Environmental accounting: including environmental costs in national budgets and business decisions
• Land-use planning: zoning areas for specific uses
• Integrated Development Planning and Integrated Coastal Zone Management: balancing development and conservation
• Environmental Impact Assessment (EIA): predicting and reducing negative environmental effects before projects are approved
• Protected areas: national parks, marine reserves, and wildlife sanctuaries, with classifications by the IUCN
• Community-Based Natural Resource Management: involving local people in planning and protection Education and awareness: schools, media, campaigns, and training

International Agreements

• UNFCCC: focuses on reducing greenhouse gas emissions and climate change
• CBD (Convention on Biological Diversity): aims to protect species, habitats, and genetic diversity
• UNCCD (Convention to Combat Desertification): works to prevent soil loss and land degradation
• SPAW: protects species and ecosystems in the Wider Caribbean
• Ramsar Convention: protects wetlands of international importance
• MARPOL: prevents pollution from ships

Indigenous Peoples and Natural Resource Management

• Indigenous communities have practiced sustainable methods for generations
• Slash-and-burn agriculture with field rotation
• Collection of non-timber forest products
• Traditional fishing techniques that preserve fish populations
• These practices show us that people and nature can live in harmony