Untitled Flashcard Set
Module 1: The Earth's Ecosystem
2. Concept of Ecosystem
- Definition of Ecology: Proposed by German biologist Ernst Haeckel in 1869, it refers to the study of the interactions among organisms and between organisms and their physical environment (such as temperature, soil, water, etc.).
- Ecological Organization Hierarchy: Individual organisms, populations, communities, ecosystems, and the biosphere.
- Biosphere: Includes the atmosphere (air), hydrosphere (water), geosphere (soil, rocks), and biosphere (living things).
- Ecosystem Functions:
- Regulatory Function: Regulates ecological processes, maintains the stability of life systems, cycles nutrients, and provides clean air and water.
- Habitat Function: Provides habitats for plants and animals, and protects biological and genetic diversity.
- Production Function: Produces food and raw materials.
- Information Function: Provides spiritual, cognitive, recreational, and aesthetic experiences.
3. Composition of Ecosystems
- Biotic Components:
- Autotrophs (Producers): Produce food through photosynthesis, such as green plants.
- Heterotrophs (Consumers): Depend on other organisms for food.
- Primary Consumers: Herbivores.
- Secondary Consumers: Carnivores.
- Tertiary Consumers: Apex predators.
- Decomposers: Obtain nutrients by decomposing plant and animal remains.
- Abiotic Components:
- Water, light, soil, temperature, pH, etc., which directly or indirectly affect organisms in the ecosystem.
4. Energy Flow
- Primary Productivity: The production of new organic matter or biomass by producers (plants) over a period of time.
- Secondary Productivity: The production of biomass by heterotrophic consumers through feeding on plants, animals, microorganisms, etc.
- Food Chain and Food Web:
- Food Chain: Energy flows along a linear path, with each organism serving as a food source for the next.
- Food Web: A complex network formed by multiple interconnected food chains.
- Energy Pyramid:
- Energy flow follows the laws of thermodynamics, with an energy transfer efficiency of approximately 10% at each trophic level.
5. Nutrient Cycling
- Biogeochemical Cycle: The cycle of elements between living organisms and the abiotic environment.
- Hydrologic Cycle (Water Cycle): Water cycles through processes such as evaporation, condensation, precipitation, and plant transpiration.
- Nitrogen Cycle:
1. Nitrogen Fixation: Conversion of nitrogen gas into ammonia.
2. Nitrification: Conversion of ammonia into nitrite and nitrate.
3. Assimilation: Plants absorb ammonia and nitrate.
4. Ammonification: Conversion of organic nitrogen into ammonia.
5. Denitrification: Conversion of nitrate into nitrogen gas.
- Carbon Cycle:
- Photosynthesis absorbs carbon dioxide, and respiration releases carbon dioxide.
- Burning fossil fuels increases the concentration of carbon dioxide in the atmosphere.
- Phosphorus Cycle: Phosphorus is released through rock weathering, absorbed by plants, and eventually enters marine sediments.
6. Types of Ecosystems
- Terrestrial Ecosystems:
1. Forests:
- Tropical Rainforest: High temperature and rainfall, with the highest biodiversity.
- Boreal Forest (Taiga): Cold regions, dominated by coniferous trees.
- Temperate Deciduous Forest: Significant seasonal changes.
2. Grasslands:
- Tropical Grassland (Savanna): Wide expanses of grass with sparse trees.
- Temperate Grassland: Suitable for agriculture, such as corn and wheat production areas.
3. Tundra: Cold, with permafrost.
4. Desert: Dry, with plants and animals adapted to arid environments.
- Aquatic Ecosystems:
- Marine Ecosystems: Occupy 70% of the Earth's surface.
- Freshwater Ecosystems: Including rivers, lakes, wetlands, and estuaries.
7. Interactions Among Organisms
- Ecological Niche: The role and function of an organism in an ecosystem.
- Symbiosis:
- Mutualism: Both parties benefit.
- Parasitism: One party benefits, and the other is harmed.
- Commensalism: One party benefits, and the other is unaffected.
- Amensalism: One party is inhibited, and the other is unaffected.
- Predation: One organism preys on another.
- Competition: Organisms compete for limited resources.
- Intraspecific Competition: Competition among individuals of the same species.
- Interspecific Competition: Competition between individuals of different species.
8. Threats to Ecosystems
- Impact of Human Activities:
- Habitat Destruction: Urbanization, agricultural development.
- Pollution: Industrial and domestic waste.
- Invasive Alien Species: Disrupts native ecosystems.
- Overfishing and Overgrazing: Disrupts ecological balance.
- Oil Exploration and Exploitation: Pollutes the environment.