Environmental Science: Ecological Principles

• Environmental Science and Ecological Principles

Objectives

• Key terms to define include: ecosystem, carrying capacity, greenhouse effect, and sustainable development.
• Understanding interactions among organisms within ecosystems is important.
• Key environmental dilemmas need to be identified and explained.
• Population attributes must be described.
• Factors controlling population growth should be listed.
• Key principles of ecosystem management and sustainable development should be explained.

Primary Objective

• "Development must meet the needs of the present without compromising the ability of future generations to meet their own needs."

Ecology

• Ecology is the science that studies the connections between living things and their surroundings, according to the Concise Oxford English Dictionary (2008).
• It focuses on the inter-relationships between organisms and their environment.
• Ecology studies earth's "households," which include plants, animals, microorganisms, and people living together as interdependent components.

Environmental Science

• Systematic study of environment and our place in it

Inter-relationships within the Environment

• An ecosystem is a system of interacting organisms within a specific habitat.
• Flexibility in behavior includes tropism, taxis, reflexes, instincts, learning, and reasoning.
• Interactions within the environment include competition vs. cooperation.
• System regulation can be either "natural or cultural."

Ecosystems

• Ecological units encompassing all biotic and abiotic factors in a specific area.
• Biotic factors include plants, animals, fungi, and bacteria.
• Abiotic factors include sunlight, water, temperature, oxygen, and soil.
• Categories within ecosystems include producers, consumers, and decomposers.
• Examples of ecosystems are coral reefs and rain forests.

Energy Movement Through Ecosystems

• Food chains illustrates the movement of energy through an ecosystem.
• Ecosystem components: plants, herbivores, carnivores, omnivores, decomposers.
• Food webs are a better description of how energy flows because organisms rarely rely on a single food source.

Types of Interactions Among Organisms in Ecosystems

• Predator-prey relationships
• Competition
• Symbiosis:
  • Commensalism (cattle & egrets)
  • Mutualism (legumes & nitrogen fixing bacteria)
  • Parasitism

Biogeochemical Cycling

• The transport and transformation of essential substances through air, water, soil, plants, and animals into useful forms.
• Key cycles include carbon/oxygen, nitrogen, phosphorus, and hydrologic cycles.
• Cycles are driven directly or indirectly by incoming solar energy.

Global Carbon Cycle

• The global carbon cycle is currently imbalanced, increasing the likelihood of climate change.
• Atmospheric CO₂ levels are rising rapidly, currently 25% above pre-industrial revolution levels.
  • CO₂ is a greenhouse gas.
• Factors contributing to the imbalance include the burning of fossil fuels, slash-and-burn agriculture, and land clearing.
• Accidental or intentional fires also increases CO2.
• Unsustainable logging contributes to the imbalance.

Environmental System

• Life support systems include energy, geophysical, biological, built environment, and social components.
• Human activities, such as residential, work, recreation, and transportation, generate residues and wastes.
• Residues and wastes take the form of solids, liquids, gases, and energy.
• Environmental hazards can result from these activities.

Tolerance Limits

• Organisms have optimal ranges for environmental factors, with zones of physiological stress and intolerance outside that range.

Environmental Dilemmas

• Rapid and massive population growth is a key dilemma.
  • Projected growth will be highest in the world's poorest nations.
• Food production struggles to keep pace with population growth, resulting in disparities and food insecurity.
• Fossil fuels currently supply about 80% of energy demand in developed countries.
• CO₂ levels are 18% higher than in 1960.
• 2.8 billion people survive on less than $2 a day.
• 0.5 billion people live in water-stressed or water-scarce countries.
• The water-stressed and water-scarce population is expected to reach 2.5 - 3.4 billion by 2025.
• About 50% of the world's original forest cover has been depleted.
• Approximately 800 million people are clinically malnourished, and 2 million lack food security.
• Sea levels have risen 10-20 cm since the 1950s.

Population Attributes

• Density
• Birth rate
• Death rate
• Growth rate
• Dispersal
• Dispersion (random, uniform, cluster)

Factors Controlling Population Growth

• Fecundity, natality, and fertility
• Immigration and emigration
• Mortality and survivorship
• Age structure

Key Concepts

• Overpopulation: When a population exceeds the carrying capacity of its available resources.
• Optimum population: Population size aligns to efficiently exploit available resources.
• Preventive checks: Factors that reduce population growth (e.g., family planning).
• "Positive checks": Factors increasing the death rate (e.g., famines, wars, disasters).
• Carrying capacity: The maximum population size an environment can sustain.
• Cornucopian vs Neo-Malthusian approaches.
• Sustainable development.

Sustainable Development

• Development that meets present needs without compromising future generations' ability to meet their needs.
• Maintaining a delicate balance between human needs and preserving natural resources/ecosystems.

Principles of Eco-system Management

• Manage across landscapes, watersheds, or regions over an ecological timescale.
• Consider human needs while promoting sustainable economic and community development.
• Maintain biological diversity and essential eco-system processes.
• Utilize cooperative institutional arrangements.
• Integrate science and management.
• Generate stakeholder and public involvement, and facilitate collective decision-making.
• Adapt management over time through experimentation and monitoring.

Summary

• Technology and development have benefits and challenges.
• Advanced or under development can cause environmental problems and illnesses.
• Proper planning and technology can avoid environmental damage.
• Ecosystems must be managed to ensure sustainable development.