10- changes in ecosystem Flashcards
colonisation
Where an organism establishes itself in an area.
succession
Where ecosystems develop, starting with colonisation and ending with a climax community.
primary succession
Occurs on newly exposed surfaces where no soil exists, such as after a volcanic eruption or glacier retreat.
secondary succession
Takes place in areas where a disturbance has destroyed an existing
community but left the soil intact, like after a forest fire.
stages of succession
• Early stages → Dominated by fast-growing, opportunistic species (r-strategists).
• Mid-succession → Increased species diversity, more complex interactions, and development of soil.
• Late succession → Stable, long-lived species (K-strategists) become established.
climax communities
• A stable and persistent community that has reached equilibrium with the environment.
• Represents the end point of succession, though it can change with major environmental shifts.
characteristics of climax community
• High biodiversity.
• Complex structure with multiple trophic levels.
• Efficient nutrient cycling and energy flow.
types of climax communities
• Determined by climate, soil type, and other abiotic factors.
• Examples include tropical rainforests, grasslands, deserts, and temperate forests.
biotic factors
- competition
- predation
- disease
- parasitism
- mutualism
- territory
- reproductive partners
competition
Organisms compete for resources like food, light, and space. This limits population size.
interspecific competition
• Members of different species compete for resources.
• Only takes place if the two species have the same niche.
intraspecific competition
• Members of the same species compete for resources.
• More significant than interspecific competition - members of the same species have the same niche and compete for exactly the same resources.
• Tends to have a stabilising influence on population size.
predation
• Predator-prey interactions control population sizes and influence adaptations.
• Predator and prey populations oscillate.
disease
Pathogens can reduce population sizes through mortality and reduced reproduction.
parasitism
• Parasites can weaken hosts, reducing survival and fecundity.
• Parasite and host populations oscillate.
mutualism
Positive interactions between species enhance population growth and survival rates.
abiotic factors
- climatic factors
- edaphic soil factors
- topographic factors
- human factors
- catastrophes
climatic factors
• Temperature.
• Water / humidity.
• Light / shade.
• Current (wind or water).
• Frost.
edaphic (soil) factors
• Soil pH.
• Mineral supply.
• Soil composition and texture.
• Soil moisture.
topographic factors
• Altitude.
• Slope.
• Aspect.
human factors
pollution
catastrophes
• Floods.
• Fires.
