Sustainability of Ecosystems Study Notes

Unit 4: Sustainability of Ecosystems

Overview of Ecosystems

• Ecosystems consist of biotic (living) and abiotic (non-living) factors.

• Key concepts include: Organism, Species, Population, Community, Habitat, Niche, Producer, Consumer, Decomposer.

• Energy flow is vital to understanding ecosystem organization.

Sustainable Ecosystems

• A sustainable ecosystem can withstand pressures and support diverse organisms.

• Organisms often rely on multiple ecosystems for survival, e.g., migrating species.

Biotic and Abiotic Components

• Biotic: plants, animals, microorganisms. Interactions like symbiosis, predation, competition affect ecosystem sustainability.

• Abiotic: water, oxygen, light, nutrients, soil; crucial for survival.

Characteristics Affecting Sustainability

• Symbiosis: close interactions between species affecting energy flow (e.g., algae and coral).

• Predation: affects population dynamics; conservation can restore predator populations.

• Competition: both interspecific and intraspecific competition can limit resources and affect population sizes.

Abiotic Factors

• Water: essential for life; quality and availability can be impacted by human activity.

• Oxygen: required by many organisms, can become scarce due to pollution.

• Light: necessary for photosynthesis; affected by ecosystem structure.

• Nutrients: required for growth; can be disrupted by human activity.

• Soil: vital for plant nutrients; erosion and mismanagement can deplete resources.

Soil Composition and Types

• Sandy Soil: Composed of relatively large particles ($0.05$ mm to $2.0$ mm).

  • Pros: Excellent drainage prevents root rot; warms up quickly in the spring.

  • Cons: Low water and nutrient retention; minerals easily leach away.

• Silty Soil: Composed of medium-sized particles ($0.002$ mm to $0.05$ mm).

  • Pros: Better moisture retention than sand; fertile and easy to cultivate.

  • Cons: Prone to compaction and highly susceptible to erosion.

• Clay Soil: Composed of very fine particles (less than $0.002$ mm).

  • Pros: Exceptional nutrient and water retention.

  • Cons: Poor drainage leads to waterlogging; difficult for roots to penetrate when dry.

• Loam Soil: A balanced mixture (approx. $40\%$ sand, $40\%$ silt, $20\%$ clay).

  • Pros: Ideal balance of drainage, aeration, and fertility.

  • Cons: Requires active management to maintain organic matter levels.

Soil Management and Amendments

• Peat

  • Pros: Excellent moisture retention; helps aerate heavy clay soils.

  • Cons: Over-harvesting is environmentally unsustainable; contains very few nutrients.

• Manure

  • Pros: High in organic matter; provides a broad spectrum of nutrients; improves soil structure.

  • Cons: Can introduce pathogens or weed seeds; can "burn" plants if not properly composted.

• Compost

  • Pros: Recycles organic waste; enhances soil microbiome; improves water-holding capacity.

  • Cons: Slow to produce; nutrient levels are generally lower and slower-acting than synthetic options.

• Irrigation

  • Pros: Provides reliable water regardless of weather; increases agricultural productivity.

  • Cons: High water consumption; risk of soil salinization (salt buildup).

• Mulching

  • Pros: Conserves soil moisture; suppresses weed growth; regulates soil temperature.

  • Cons: Can harbor pests (e.g., slugs); may lead to fungal issues if applied too thickly.

• Reduced Tillage

  • Pros: Decreases soil erosion; keeps carbon in the soil; preserves natural soil structure.

  • Cons: Often requires specialized equipment; may increase initial dependence on herbicides.

• Fertilizers

  • Synthetic (Inorganic)

  • Pros: Provide immediate nutrient availability; precise $N-P-K$ ratios.

  • Cons: High energy cost to produce; risk of nutrient leaching and groundwater pollution.

  • Organic

  • Pros: Slow-release of nutrients reduces runoff; improves long-term soil health.

  • Cons: Slower results; nutrient content can be variable and unpredictable.

• Cover Crops

  • Pros: Protects soil from erosion; legumes can fix atmospheric nitrogen ($N_2$) into the soil.

  • Cons: Can compete with cash crops for water; requires management to terminate before planting.

Geographic Ecosystems

• Biomes are large regions with similar climates and plant life; boreal forests characterized by cold temperatures and specific flora and fauna adaptations.

• Ecosystem integrity threatened by industrial development.

Population Dynamics

• Populations are regulated by limiting factors:

  • Density-independent: abiotic factors like storms, pollutants.

  • Density-dependent: biotic factors like disease, predation.

• Carrying capacity: maximum population size sustainable by ecosystem resources.

Nutrient Cycles

• Essential for ecosystem health; human activities can disrupt natural nutrient cycles causing excess nutrients leading to eutrophication in aquatic systems.

• Key cycles include carbon, nitrogen, and phosphorous.

Ecosystem Services

• Benefits provided by ecosystems: supporting (biodiversity), provisioning (food, clean water), regulating (climate control), and cultural (education, recreation).

Biodiversity and Resilience

• Biodiversity refers to species variety in a region; contributes to ecosystem resilience.

• Healthy ecosystems perform better and resist disturbances; more species lead to greater ecosystem efficiency.

Stressors and Recovery

• Ecosystems under stress from physical, chemical, or biological changes; can have lasting impacts.

• Recovery requires identifying and mitigating stressors; human intervention can aid natural recovery processes.

Paradigm Shift in Sustainability

• Growing awareness of interconnected ecosystems and the impacts of human actions on natural processes.

• Conservation efforts and regulations (e.g., phosphorus reduction) demonstrate shifts towards more sustainable practices.