Study Notes on Ecosystems Concept and Dynamics

Definition of an Ecosystem: An ecosystem encompasses all living organisms and the abiotic components of their environment with which they interact. This concept was defined by Tansley in 1935, highlighting the intimate connection between living beings and their physical surroundings.
Ecosystem Dynamics: Determined by various internal and external factors, an ecosystem's dynamics involve the flow of energy and matter linking living organisms and their environment.

Biosphere 2 Overview:
- Purpose: Founded to research and develop technology for self-sustaining space colonization.
- Characteristics: A closed system for matter but an open system for energy.
- Investment: Over $150 million invested, 1.5 hectares under glass; involved missions from 1991-1993 and 1994-1995.
- Design Aspects: Developed by engineers rather than ecologists; aimed to be airtight but proved not to be sustainable.

Diverse Ecosystems:
- Included multiple habitats: Savanna, Ocean and Mangrove, Rain Forest, and Desert.
- Biodiversity: Approximately 3,800 species were introduced into the glass domes of Biosphere 2.

System Components:
- Pressure and Mechanical Systems: Designed to be self-sufficient in food and water while maintaining water and atmospheric conditions.
- Failure: The collapse involved significant loss of biodiversity, decreased pollination, poor crop production, and high organic matter decomposition leading to oxygen drop from 21% to 14.5%, resulting in starvation and suffocation of Biospherians.

Life and Environment Interaction: Emphasizes the dependency of life on and modification of physical surroundings.
Components of Ecosystems: Involves both biotic (living) and abiotic (non-living) components interacting within defined ecosystems.

Scale of Study: Ecosystems can be studied on multiple scales:
- Global (Earth as a whole)
- Continental (like the Amazon)
- Local (such as a first-order stream)
- Specific habitats (forests, rock surfaces).

Lindeman's Influence (1942): Adopted the ecosystem as the fundamental unit in ecology and utilized the food web as a structure to express ecosystem organization, consisting of various trophic levels.

Example: Within a temperate lake, various processes include:
- Radiation absorption
- Photosynthesis
- Predation
- Decomposition
- Nutrient uptake
- Transpiration

Typical Terrestrial Food Web: Representation of energy flow, detailing respiratory losses across different trophic levels:
- Carnivores: 100% (energy intake) leading to a 56% respiratory loss.
- Herbivores: 44% respiratory loss leads to lower energy availability to predators.
- Producers: Provide the primary energy source, with gross primary production losses impacting the food pyramid.

Factors Influencing Ecosystems:
- State Factors (External): Geographic features, climate, parent material, potential biota, and time.
- Interactive Controls (Internal): Include resources, modulators (physical and chemical ecosystem properties), disturbances (fire, storms), and community dynamics.

Feedback Dynamics: Feedbacks may be positive (promoting state change) or negative (stabilizing) within ecosystems, critical for maintaining dynamics and functions.

Examples of Toposequences:
- Miombo woodlands and gallery forests demonstrate variations influenced by soil types, species interactions, and hydrology.

Independent Control Variables: Identify five factors governing ecosystem structure and functioning: climate, parent material, topography, potential biota, and time.

Mapping and Understanding Oceans: Only 23.4% of Earth’s oceans are mapped, presenting challenges for ecosystem exploration. Between 700,000 and 1 million species in the deep sea await discovery. Human activities such as trawling, oil extraction, and plastic pollution pose significant challenges to these ecosystems.

Ecosystems Ecology: Focuses on exploring interactions among organisms and their environment, regulating the movement of energy and materials throughout ecological systems.