Ecology: Concepts and Related Terms

1. Habitat:

• Concept: A habitat is the natural environment where an organism lives and thrives. It includes all the living and non-living factors that directly or indirectly affect the organism’s survival, growth, reproduction, and other activities.

• Classification:

• Terrestrial Habitat: Includes the atmosphere, soil, and related factors like topography, sunlight, temperature, humidity, etc.

• Aquatic Habitat: Encompasses freshwater (rivers, lakes, ponds), saltwater (oceans, seas), and associated factors like salinity, currents, temperature, pressure, etc.

• Soil Habitat: Encompasses the layers of soil with varying depths, containing nutrients, moisture, and soil structure.

• Biotic Habitat: Includes other living organisms like plants, animals, fungi, bacteria, etc. (which may serve as dwelling places, food sources, or hosts for parasites or symbionts).

Note: The habitat of an organism can change over time and space.

2. Ecological Factors:

• Concept: Ecological factors are all the environmental factors that directly or indirectly affect the life of an organism.

• Classification:

• Abiotic Factors: Include all the physical and chemical factors of the environment, such as:

• Light: Intensity, duration of exposure, wavelength of light, etc.

• Temperature: Optimal temperature, limiting temperature, etc.

• Humidity: Air humidity, soil humidity, etc.

• Water: Water availability, water quality, etc.

• pH: Acidity, alkalinity of soil and water, etc.

• Salt Concentration: Salinity of water, etc.

• Nutrients: Abundance of nutrients in soil, water, etc.

• Topography: Altitude, slope, shape of the terrain, etc.

• Wind: Wind speed, wind direction, etc.

• Biotic Factors: Include:

• Organic World: Other organisms (plants, animals, fungi, bacteria) living in the environment.

• Relationships between Organisms: Competitive, cooperative, symbiotic, parasitic relationships, etc.

• Role of Humans: Humans are a unique ecological factor, exerting a significant influence on the lives of many organisms and causing major changes in their habitats.

Note: Ecological factors can affect organisms independently or in combination with one another.

3. Ecological Limits:

• Concept: Ecological limits are the range of values for an ecological factor within which an organism can survive and thrive over time.

• Classification:

• Optimum Range: The range of ecological factors where the organism performs its life functions best (growth, reproduction, thriving).

• Tolerance Range: The range of ecological factors where the organism can still survive but experiences inhibited development, reduced reproduction, and increased susceptibility to disease.

• Characteristics:

• Every species has its own ecological limits for each ecological factor.

• Ecological limits can vary depending on the age, sex, and physiological state of the organism.

• Narrow ecological limits make organisms more vulnerable to environmental changes.

Note: Ecological limits are crucial for species conservation.

4. Ecological Niche:

• Concept: The ecological niche of a species is its “ecological space,” encompassing all the ecological factors of the environment that allow it to exist and thrive.

• Distinction from Habitat: Habitat refers to the organism’s dwelling place, while ecological niche reflects its way of life in the environment.

• Example: The ecological niche of a house sparrow in a field differs from the ecological niche of a house sparrow in a garden.

Note: Ecological niches can change over time and space due to competition, environmental changes, etc.

5. Population:

• Concept: A population is a group of individuals of the same species living in a defined area at a particular time, capable of interbreeding and producing offspring.

6. Relationships between Individuals in a Population:

• Supporting Relationships:

• Individuals within the same species support each other in their life activities, such as obtaining food, defending against predators, and reproducing.

• Support helps the population adapt well to environmental conditions and exploit more resources.

• It manifests through group efficiency (group efficiency is higher than individual efficiency).

• It enhances the survival and reproduction of individuals.

• Example: Wolves hunting in packs, sparrows working together to protect their nests.

• Competitive Relationships:

• Arises when the population density becomes too high, and the available resources become insufficient for all individuals.

• Individuals compete for resources (food, shelter, light, etc.) or for mates.

• Intense competition leads to antagonism between individuals, forcing some to leave the group, or each group defending a separate living area.

• Competition is an adaptive trait of the population, helping to maintain the number and distribution of individuals at appropriate levels, ensuring survival and development.

• Example: Sparrows competing for food, trees competing for sunlight.

Note: Supporting and competitive relationships are the two fundamental relationships between individuals in a population, contributing to regulating population size and distribution.

7. Key Characteristics of a Population:

• Distinguish one population from another.

• Include:

• Sex Ratio: The ratio of males to females in the population. It varies depending on living conditions, breeding time, species, etc. It is an important characteristic that ensures the population’s reproductive efficiency in changing environmental conditions.

• Age Structure:

• Physiological Age: The maximum lifespan an individual in the population can reach.

• Ecological Age: The actual lifespan of an individual.

• Population Age: The average age of individuals in the population.

• Populations have a specific age structure that can change depending on living conditions.

• Individual Distribution:

• Grouped Distribution: Most common. Individuals gather in groups where living conditions are best. Often observed when living conditions are unevenly distributed in the environment, during hibernation, or wintering.

• Even Distribution: When living conditions are evenly distributed in the environment and there is intense competition between individuals in the population. Reduces competition within the population.

• Random Distribution: An intermediary form. Often observed when living conditions are evenly distributed, and there is no intense competition between individuals.

• Population Density: The number of individuals per unit area or volume of the population. It affects the level of resource utilization in the environment, the population’s reproductive capacity, and mortality rate.

• Population Size: The number of individuals (or the accumulated mass or energy within the individuals) distributed in a certain space of the population. It fluctuates from a minimum value to a maximum value.

• Minimum Value: The minimum number of individuals required for the population to sustain and develop.

• Maximum Value: The ultimate limit on the number of individuals the population can achieve, aligning with the environment’s ability to provide resources.

• Depends on four factors: reproduction rate, mortality rate, immigration, and emigration.

• Population Growth:

• Growth according to Biological Potential: Occurs when environmental conditions are entirely favorable and individuals have high biological potential.

• Actual Growth: In environments that are not entirely favorable.

Note: Population characteristics can change over time and space, reflecting the population’s adaptation to its environment.

8. Fluctuations in Population Size:

• Concept: Fluctuations refer to the increase or decrease in the number of individuals within a population.

• Classification:

• Cyclical Fluctuations: Occur due to cyclical changes in environmental conditions (e.g., fluctuations in the number of field mice with a 3-4 year cycle due to their reproduction cycle).

• Non-cyclical Fluctuations: Caused by unusual changes in the natural environment (e.g., earthquakes, droughts, floods) or excessive human exploitation of resources (e.g., hunting, fishing, logging, etc.).

9. Causes of Fluctuations in Population Size:

• Abiotic Factors: (Density-independent factors) Directly impact organisms regardless of population density (e.g., light, temperature, water, topography, etc.).

• Biotic Factors: (Density-dependent factors) Impact organisms depending on population density (e.g., competition, parasitism, predation, etc.).

10. Population Equilibrium:

• Concept: Occurs when the population size stabilizes, aligning with the environment’s capacity to provide resources.

• Populations tend to self-regulate towards equilibrium.

Note: Population equilibrium is not a static state but a dynamic one, constantly changing within a specific range.

11. Community:

• Concept: A biological community is a group of populations of different species living in a defined area, interconnected and forming a relatively stable structure, creating a unified entity.

12. Key Characteristics of a Community:

• Species Composition:

• Reflected in the number of species within the community, the number of individuals in each species, dominant species, and characteristic species.

• Number of Species and Number of Individuals in each Species:

• Reflects the community’s diversity level.

• Indicates the community’s fluctuation, stability, or degradation.

• Stable communities often have a larger number of species and a higher number of individuals per species.

• Dominant Species: Those species playing a crucial role in the community due to their large population size, substantial biomass, or strong activity.

• Characteristic Species:

• Found exclusively in a specific community.

• Have a significantly larger population compared to other communities and play a significant role in the community compared to other species.

• Individual Distribution:

• Helps reduce interspecies competition and enhance efficient resource utilization of the environment.

• Vertical Distribution: The stratification of trees in a forest (tall tree layer, medium tree layer, low tree layer, understory layer).

• Horizontal Distribution Across the Land: The distribution of organisms from the mountain peak, through the slopes, to the mountain base (changes with altitude, slope, and climatic conditions).

Note: The characteristics of a biological community reflect its adaptation to its environment.

13. Relationships between Species in a Community:

• Two types: Supporting and antagonistic.

14. Supporting Relationships:

• Symbiotic Relationships:

• Close cooperation between two or more species.

• All participating species benefit.

• Example: Lichens (symbiosis between fungi and algae), nitrogen-fixing bacteria in the root nodules of legumes.

• Cooperative Relationships:

• Similar to symbiosis, but the relationship isn’t as close and not necessarily mandatory between species.

• Example: Oxpecker birds cleaning the teeth of crocodiles, birds foraging on the backs of cattle.

• Commensalism:

• Cooperation between two species.

• One species benefits, while the other is neither harmed nor helped.

• Example: Orchids growing on the trunks of trees, remoras attaching to sharks.

Note: Supporting relationships contribute to community diversity and stability.

15. Antagonistic Relationships:

• Competitive Relationships:

• Species compete with each other for resources.

• All species are adversely affected.

• One species will outcompete the others, causing harm to the others, or all species will be harmed.

• Example: Trees competing for sunlight, predators competing for prey.

• Parasitic Relationships:

• One species lives on or in the body of another species.

• Complete Parasitism: Unable to produce their own food (e.g., parasitic worms in human intestines).

• Semi-parasitism: Able to produce their own food but also obtain sustenance from the host (e.g., mistletoe growing on trees).

• Amensalism:

• An organism inadvertently harms another organism during its life cycle.

• Example: Pine trees release chemicals that inhibit the growth of other plants around them.

• One organism eats another:

• Relationship between herbivores and carnivores:

• Example: Wolves hunting deer, sparrows eating seeds.

• Plants catching insects:

• Example: Pitcher plants, sundews.

Note: Antagonistic relationships drive the evolution of species within a community.

16. Direction of Energy Flow in an Ecosystem:

• Originates from the environment (solar energy).

• Absorbed and converted into chemical energy by producers through photosynthesis.

• Energy is transferred through trophic levels (consumers) and eventually returns to the environment during the decomposition process by decomposers.

Note: Energy is gradually lost through trophic levels, with only about 10% of energy being transferred from a lower trophic level to a higher one.

17. Ecological Succession:

• Concept: The sequential transformation of a community over time, corresponding to environmental changes.

• Classification:

• Primary Succession:

• Succession starting in an environment devoid of life (e.g., formation of a community on volcanic rock).

• Pioneer Stage: Organisms disperse to the area, forming a pioneer community (e.g., lichens, mosses).

• Intermediate Stage: Communities change sequentially, replacing each other (e.g., mosses -> grasses -> shrubs -> trees).

• Climax Stage: The final stage, forming a relatively stable community (e.g., virgin forests).

• Secondary Succession:

• Occurs in an environment where a community previously existed but was destroyed due to environmental changes or excessive human exploitation (e.g., community formation after a forest fire, after logging, etc.).

• Initial Stage: The original community is destroyed.

• Intermediate Stage: Includes sequentially changing communities, replacing each other.

• Final Stage: In favorable conditions, a relatively stable community can form, but in reality, a degraded community is often formed.

Note: Ecological succession is a natural process that increases environmental diversity and stability.

18. Causes of Ecological Succession:

• External Causes: Changes in natural conditions (climate, topography, etc.).

• Internal Causes: Intense competition between species, human resource exploitation.

19. Ecosystem:

• Concept: An ecosystem encompasses a biological community and its habitat (the community’s abiotic environment).

• Organisms interact with each other and with the abiotic factors of the environment, creating a complete and relatively stable system.

20. Structural Components of an Ecosystem:

• Abiotic Components (Habitat): Physical environment like soil, water, air, topography, light, temperature, etc.

• Biotic Components (Biological Community): Organisms are categorized into three groups based on their nutrition:

• Producers: Capable of using solar energy to synthesize organic matter (e.g., plants, autotrophic bacteria).

• Consumers: Include herbivores (primary consumers) and carnivores (secondary consumers, tertiary consumers, etc.).

• Decomposers: Break down dead organisms and waste products into inorganic substances (e.g., bacteria, fungi, earthworms, insects, etc.).

21. Material Exchange in an Ecosystem:

• Occurs through food chains and food webs.

22. Food Chain:

• Composed of multiple species linked by their feeding relationships, with each species representing a link in the chain.

• The preceding link is the food source for the subsequent link.

• Example: Grass -> Rabbit -> Fox.

23. Food Web:

• A network of interconnected food chains within a community.

• One species can participate in multiple food chains simultaneously.

• In a food web, species with the same feeding level form a trophic level.

• First Trophic Level: Producers.

• Second Trophic Level: Primary consumers.

• Third Trophic Level: Secondary consumers.

• Final Trophic Level: Highest trophic level.

24. Ecological Pyramid:

• A model illustrating trophic levels within a community.

• Includes:

• Pyramid of Numbers: Shows the number of individuals at each trophic level.

• Pyramid of Biomass: Shows the density of mass (the mass of organisms per unit area or volume).

• Pyramid of Energy: The most complete pyramid, illustrating the amount of energy accumulated per unit area, volume, or time.

25. Biogeochemical Cycle:

• The cycle of material exchange in nature.

• Includes the following parts:

• Synthesis of Materials: From inorganic substances into organic substances (by producers).

• Material Circulation in Nature: Through food chains and food webs.

• Decomposition and Sedimentation of Materials in Soil and Water: By decomposers.

26. Carbon Cycle:

• Carbon enters the cycle as CO2 through photosynthesis.

• Released into the atmosphere through respiration of organisms, industrial production, agriculture, transportation, volcanoes, etc.

27. Nitrogen Cycle:

• Absorbed by plants as salts: ammonium (NH4+) and nitrate (NO3-)

• Formed naturally through physical, chemical, and biological processes.

• Returned to the soil and water from dead organisms through the decomposition of organic matter by bacteria, fungi, etc., and the denitrification process by microorganisms.

Note: Biogeochemical cycles are critical in maintaining ecosystem balance and stability.

Additionally, you can find further information related to ecology, such as:

• Population Ecology: Studies the characteristics, dynamics, and adaptation of populations.

• Community Ecology: Studies the structure, function, and dynamics of biological communities.

• Ecosystem Ecology: Studies the structure, function, and management of ecosystems.

• Applied Ecology: Applies ecological knowledge to address environmental issues, manage natural resources, and promote sustainable development.

To gain a deeper understanding of ecology, consult specialized materials or seek information from teachers and experts in this field.