Lecture 25 - Ecosystems and Biomes Part 1

Discusses the foundational topics in ecology relevant to BIOL 1113.
Acknowledges the Mi'kmaq territory and the significance of environmental responsibility.

Key Topics Covered:
- Population Ecology: Dispersal, migration, population growth, reproductive strategies (r & K).
- Species Interactions: Competition, herbivory, plant defenses, top-down & bottom-up processes.
- Community Ecology: Species richness, diversity, stability, and energy flow in ecological networks.

Ecosystem: Combination of biotic communities and abiotic environments.
Study Focus: Energy flows and nutrient cycles (Water, Carbon, Nitrogen, Phosphorus).
Spatial Scales: Ecosystems can vary widely in size and composition based on the species and environmental factors considered.

Energy Flow: Energy eventually lost as heat; nutrients cycle continuously among organisms and abiotic components.
Nutrient Requirements: Organisms need 30-50 different nutrients categorized as:
- Macronutrients: Carbon, hydrogen, phosphorus, potassium.
- Micronutrients: Iron, manganese, zinc, copper.
Acquisition Methods:
- Autotrophs: Obtain nutrients through abiotic sources directly.
- Heterotrophs: Gain nutrients by consuming other organisms.

Importance: Carbon is a crucial component of macromolecules, crucial for energy.
Land Cycle: Carbon cycled between organisms and atmosphere via photosynthesis and respiration.
Water Cycle: CO2 enters water surface where primary producers utilize it. Fossil fuels represent carbon removed from natural cycles during mass die-offs.

Visualizes total terrestrial carbon storage, targeting regions for conservation efforts.
Emphasizes Nature-based Climate Solutions to maintain and increase carbon capture.

Essential for: Proteins, nucleic acids, and chlorophyll.
Forms of Nitrogen: Mostly found as atmospheric N2, unusable directly by most organisms.
Process Steps:
1. Nitrogen fixation (N2 to NH3/NH4+ by bacteria).
2. Nitrification (NH3/NH4+ to NO2- and NO3-).
3. Assimilation (plants use nitrogen, animals obtain secondarily).
4. Ammonification (returns nitrogen to soil through decomposition).
5. Denitrification (NO3- converted back to N2).

Importance: Required for growth, DNA, and metabolic needs.
Sources: Primarily from rocks, absorbed as ionic phosphates by plants.
Trophic Levels: Passage through herbivores to carnivores, returning to soil through decomposition.
Aquatic Effects: Run-off leads to sedimentary formations.

Roles of Water: Solvent, waste elimination, gas exchange, reproduction, structural support, and locomotion.
Distribution Impact: Availability affects life distribution, e.g., timberline phenomenon where trees cease to grow due to insufficient water.

Cohesion & High Surface Tension: Supports small organisms and aids nutrient transport in soils and plants.
Heat Management: High heat capacity and heat of vaporization, supports life thermally.
Density Changes: Expands when freezing making ice buoyant, allows freeze impacts from the top down.

example: Water buffalo rely on grass, determined by rainfall patterns.
case study: Spade foot toads utilize seasonal moisture patterns for survival and reproduction.

Processes: Evaporation, precipitation, driven by solar energy.
Transpiration: Major contributor to atmospheric water.
Cycle Efficiency: Only ~2% of water is held in living organisms or frozen, the rest continually cycles through various states.

Definition: Porous underground deposits of water with differing capacities (confined vs. unconfined).
Water Table: Upper saturated layer of an aquifer vital for water storage.
Human Dependence: Sole freshwater source for significant Canadian populations; threatened by contamination and overuse.

Comparison of Water Storage: Oceans, lakes, swamps, rivers, soil moisture categorized by average depth and time water remains.

Ecosystems can be characterized based on scale of observation and response to seasonal changes.
- Example: Monsoon forests, like in Kakadu, experience extensive wet season flooding.

Definition of Biomes: Distinct habitats with specific plant and animal life influenced by physical characteristics of environment.
Classification Factors: Terrestrial biomes based on temperature and precipitation; aquatic biomes on salinity and depth among others.

Characterized primarily by tree species and classified by respective climate zones.
Example: Acadian forest defining ecotones between boreal and temperate forests.

Dominated by grasses with lower tree presence; classified by climate and geography.
Example: Prairie ecosystems.

Notable for low precipitation (<25 cm), global distribution from tropics to arctic with sparse vegetation.

Characteristics: Snow-covered, treeless, extremely dry with potential for permafrost conditions.

Definitions of ecosystems comprising stagnant or flowing bodies of water (ponds, rivers, swamps).

Saltwater regions, covering the most extensive areas of Earth with rich biodiversity structures.
Example: Great Barrier Reef.