- The type of community that develops during succession is not random.
- It is shaped by a complex interaction of abiotic factors (such as climate, soil, topography, and disturbance events) and biotic factors (such as predation, grazing, and competition).
- These influences determine which species can establish, survive, and dominate during different stages of succession, ultimately shaping the climax community.
Abiotic Factors Influencing Succession
1. Climatic Factors
- Temperature, precipitation, humidity, and seasonality are primary determinants of succession pathways and final community structure.
- These factors influence:
- Rate of soil development
- Plant growth and photosynthetic activity
- Species composition (e.g., tropical vs. temperate vs. arid communities)
- In tropical climates, warm temperatures and high rainfall accelerate succession, where pioneer species are quickly replaced by shrubs and then mature forests.
- In contrast, Arctic tundra experiences extremely slow succession because cold temperatures and permafrost inhibit soil formation and nutrient cycling.
2. Local Bedrock and Soil Properties
- The parent rock and soil characteristics determine nutrient availability, pH, drainage, and texture.
- These influence plant establishment and ecosystem succession.
Soil Depth and Texture
- Deep, loamy soils allow large plants with extensive root systems.
- Thin, rocky soils support only shallow-rooted species like grasses or mosses.
Nutrient Availability
- Rich soils (e.g., volcanic soils) promote rapid succession toward forests.
- Nutrient-poor soils (e.g., sandy or acidic) slow succession, supporting heathlands or shrublands.
Soil pH
- Acidic soils (from granite or sandstone) limit plant diversity, favoring acid-tolerant species such as heather.
- Alkaline soils (from limestone) support calcareous grasslands with unique flora.
Drainage
- Poorly drained areas become waterlogged, limiting oxygen for roots and forming wetlands.
- Well-drained slopes favor drought-resistant vegetation.
Ultra-basic soils (from basalt or serpentine rock) are low in nutrients and may support only specialized plants like chamomile or heathers.
3. Geomorphology
Steep Slopes
- Promote erosion and hinder soil accumulation.
- Support only hardy, shallow-rooted species such as shrubs, lichens, or alpine grasses.
Flat Terrain
- Promotes deep soil formation and accumulation of organic matter, enabling dense forest growth.
Aspect (Slope Orientation)
- South-facing slopes (in the Northern Hemisphere) receive more sunlight and support xerophytic species.
- North-facing slopes are cooler and moister, favoring shade-tolerant species.
Drainage and Waterlogging
- Low-lying areas can accumulate water, creating oxygen-poor conditions.
- These lead to wetlands, bogs, or mangrove swamps with specialized hydrophytic plants.
In mountainous regions, steep gradients prevent thick soil formation, leading to dwarf shrub and grass communities, whereas valley bottoms accumulate nutrient-rich soil that supports deciduous forests.
4. Fire and Weather-Related Events
- Fires, storms, and floods can reset succession by clearing vegetation and releasing nutrients into the soil.
- Some ecosystems are fire-adapted.
- Fires maintain biodiversity by preventing dominance of a few species.
- Extreme weather events (e.g., hurricanes) can knock down trees, opening the canopy and allowing light-demanding pioneer plants to re-establish.
In Mediterranean shrublands and savannas, many plants have fire-resistant bark or fire-triggered seed germination.
