1 Definition and core concepts
Secondary succession is the sequence of ecological changes that occurs after a disturbance removes much of a community but leaves the soil and many biological remnants in place. Because the underlying substrate is already established, recovery often begins with surviving roots, dormant seeds, microbial communities, and nearby colonists. The process is common in forests, grasslands, wetlands, and many other ecosystems.
1.1 Meaning of secondary succession
The term refers to the rebuilding of a biological community on land that has previously supported life. Disturbance may eliminate aboveground vegetation and alter animal populations, yet it does not remove the basic soil framework. As a result, organisms can reappear through regeneration, sprouting, germination, and dispersal from surrounding areas. The sequence of change is usually directional, though not perfectly uniform.
1.2 Distinction from primary succession
Secondary succession differs from primary succession because it begins after an established ecosystem has been disturbed rather than on newly exposed surfaces. Primary succession starts on bare rock, fresh lava, or newly formed deposits with little or no soil. In contrast, secondary succession proceeds more rapidly because nutrients, organic matter, and propagules often remain available. This difference strongly affects the speed and composition of recovery.
1.3 Ecological significance
Secondary succession is one of the main pathways by which ecosystems regain function after disruption. It helps restore plant cover, stabilize soil, support animals, and rebuild nutrient cycles. The process also influences landscape diversity by creating mosaics of habitats at different stages of recovery. In many regions, it is essential for maintaining long-term ecological resilience.
2 Causes and initiating disturbances
Secondary succession begins when a disturbance changes community structure while leaving at least part of the biotic and edaphic foundation intact. The initiating event may remove vegetation, reduce canopy cover, or disturb the soil surface. Disturbances vary in scale, intensity, and duration, which strongly shapes the trajectory of recovery.
2.1 Natural disturbances
Natural events often create openings that reset ecological development to an earlier stage. These disturbances can be localized or widespread, and they may recur at regular or irregular intervals. Their effects depend on climate, topography, and the resistance of the resident community.
2.1.1 Wildfires
Fire is a major natural driver of secondary succession in many ecosystems. It may kill mature plants, stimulate germination, or trigger resprouting from surviving tissues. Some species are adapted to fire and return quickly, while others reappear later from dispersed seeds. The postfire pattern depends on burn severity and fire frequency.
2.1.2 Storms and windthrow
Strong winds, hurricanes, and ice storms can break stems, strip canopies, or uproot trees. Windthrow creates gaps that increase light at the ground surface and alter moisture conditions. Fallen trunks and branches may also serve as habitat and influence seedling establishment. Recovery often begins with fast-growing species that exploit the newly opened space.
2.1.3 Flooding and landslides
Floods may deposit sediments, scour vegetation, or leave behind nutrient-rich silt. Landslides can bury existing plants and expose disturbed soil on slopes. In both cases, the community may recover through surviving roots, buried seeds, and colonization from adjacent areas. The resulting succession can be highly patchy.
2.2 Human-caused disturbances
Human activity frequently initiates secondary succession by removing vegetation or changing land use. Such disturbances may be deliberate, as in farming or logging, or indirect, as in site abandonment following industrial or settlement changes. The outcome depends on how much of the original soil and seed reservoir remains.
2.2.1 Agriculture and land abandonment
Cultivation alters soil structure, nutrient availability, and species composition. When fields are abandoned, weeds, grasses, shrubs, and later woody plants may invade in stages. The rate of recovery depends on prior management intensity, surrounding vegetation, and time since use ended. Abandoned land often becomes a valuable site for studying successional pathways.
2.2.2 Logging and vegetation removal
Timber harvest and other forms of vegetation removal reduce canopy cover but typically leave soil and root systems in place. Regrowth may occur from stump sprouts, advance regeneration, or seeds arriving from nearby stands. The resulting community may resemble the former forest over time, although repeated harvests can alter the trajectory.
2.2.3 Construction and habitat fragmentation
Road building, clearing, and other forms of development can create disturbed patches where succession begins again. Fragmentation also changes dispersal patterns by isolating habitat patches and modifying edge conditions. These effects may favor generalist species and reduce the arrival of some late-successional organisms. Recovery is often shaped by the surrounding land matrix.
3 Successional stages
Secondary succession is often described in stages, although the boundaries between them are gradual rather than fixed. Early communities are typically dominated by fast-colonizing species, while later phases show greater structural and compositional complexity. The exact sequence varies across ecosystems and disturbance types.
3.1 Early stages
The first phase begins soon after disturbance and is characterized by rapid colonization. Light availability is usually high, competition is low, and exposed resources are readily accessible. The vegetation is often patchy but expands quickly.
3.1.1 Colonization by pioneer species
Pioneer species are among the first to occupy the site. They commonly produce many seeds, disperse effectively, and grow quickly under open conditions. Some are annual herbs, grasses, or short-lived shrubs. Their presence helps initiate cover and can modify the site for later arrivals.
3.1.2 Rapid growth and ground cover development
As pioneers establish, they reduce bare ground and help protect the surface from erosion. Root growth begins to stabilize soil, while litter production adds organic material. This stage can proceed quickly when moisture and nutrients are sufficient. Ground cover often increases markedly during this interval.
3.2 Mid-successional stages
Mid-successional communities usually contain a mixture of early colonizers and longer-lived species. Competition for light, water, and nutrients becomes more intense as biomass accumulates. The site begins to show stronger vertical layering and a more diverse set of niches.
3.2.1 Increasing plant competition
As plants grow denser, overlap among canopies and root systems intensifies. Faster-growing species may suppress slower ones, and some early colonists are replaced. Shading becomes a major filter, especially in forests and shrublands. Competitive interactions help determine which species persist.
3.2.2 Changes in soil and microclimate
Developing vegetation alters temperature, humidity, and wind exposure near the ground. Litter and root activity improve soil structure and increase organic matter. Microbial and fungal communities also shift as new plant inputs enter the system. These changes create conditions that favor species adapted to more stable environments.
3.3 Late successional stages
Later phases are often associated with mature vegetation, greater biomass, and more complex habitat structure. Species composition may become more stable, though disturbance can still reset the system. In some ecosystems, these stages persist for long periods.
3.3.1 Establishment of shade-tolerant species
As the canopy closes, species that can grow under low light become more important. Seedlings may remain in the understory for extended periods before reaching the upper canopy. Shade tolerance is a key trait in many wooded ecosystems. These species often replace the initial wave of sun-loving pioneers.
3.3.2 Development of mature community structure
Over time, the community may develop multiple layers, including canopy, subcanopy, understory, and ground cover. Dead wood, leaf litter, and microhabitats become more abundant. Animal communities also diversify as habitat complexity increases. The result is a more structurally elaborate ecosystem.
4 Ecological mechanisms
Secondary succession is driven by biological and physical processes that shape how species arrive, survive, and interact. Soil processes, stored propagules, and species relationships all influence recovery. These mechanisms operate simultaneously and often reinforce one another.
4.1 Soil recovery and nutrient cycling
Disturbance may reduce organic matter, but soil recovery usually begins soon after vegetation returns. Decomposition of litter, microbial activity, and root turnover gradually rebuild nutrient cycling. Nitrogen, phosphorus, and other elements become more effectively retained as plant cover increases. Improved soils often support later-successional species.
4.2 Seed banks and resprouting
Many disturbed sites regenerate from seeds already present in the soil. These seed banks may include dormant propagules that germinate after light, heat, or moisture conditions change. Resprouting from roots, rhizomes, trunks, or stumps is also important. Such persistence mechanisms can greatly speed recovery.
4.3 Species interactions
Interactions among organisms shape the pace and direction of succession. Some relationships slow replacement, while others encourage it. The balance among these effects depends on the species involved and the stage of recovery.
4.3.1 Competition
Competition is common when resources become limited. Plants may compete for light aboveground and water or nutrients belowground. Strong competitors can dominate a site and alter the timing of succession. Competitive hierarchies often shift as the environment changes.
4.3.2 Facilitation
Some early species make conditions more suitable for later arrivals. They may improve soil stability, add shade, or increase moisture retention. This process, known as facilitation, is especially important where the disturbed site is harsh. In such cases, pioneers act as nurses for subsequent species.
4.3.3 Herbivory and predation
Animals can influence succession by feeding on seedlings, seeds, or dominant plants. Herbivory may delay the replacement of early species or create space for others to establish. Predation on seeds can reduce recruitment, while animal dispersal can enhance colonization elsewhere. These effects contribute to patchiness in recovering communities.
5 Factors influencing succession
The trajectory of secondary succession is not identical in every place. It depends on the nature of the disturbance, the environment, and the availability of source populations. Local conditions can accelerate, slow, or redirect recovery.
5.1 Disturbance intensity and frequency
A mild disturbance may leave many survivors and lead to rapid recovery. Severe or repeated disturbance can remove more biological material and favor simplified communities. When events recur too often, later-successional species may fail to establish. The disturbance regime is therefore a major determinant of outcome.
5.2 Climate and weather conditions
Temperature, rainfall, seasonal patterns, and extreme weather influence germination and growth. Warm, moist conditions often support faster plant establishment. Drought, frost, or prolonged wetness may slow succession or favor different species. Climate also affects the timing of dispersal and reproduction.
5.3 Soil characteristics
Soil texture, depth, fertility, and drainage shape which organisms can colonize. Disturbed soils with intact structure often recover more quickly than compacted or eroded sites. pH and mineral content also influence plant establishment. Soil conditions can either support a diverse community or restrict it to a narrower set of species.
5.4 Regional species pool
The species available in the broader region determine what can arrive at the site. A rich regional pool increases the likelihood of diverse recolonization. If potential colonists are absent or rare, succession may be limited by dispersal rather than local conditions. Historical land use can also affect the available pool.
5.5 Landscape context and dispersal
Nearby forests, grasslands, wetlands, or remnant patches provide seeds and animals that aid recolonization. Connectivity improves the movement of propagules, while isolation can delay recovery. Barriers such as roads or large areas of unsuitable habitat may reduce dispersal. Landscape arrangement therefore shapes successional speed and composition.
6 Community and ecosystem changes
As succession proceeds, both the living community and the broader ecosystem change. These shifts are not limited to plants; they include animals, microbes, nutrient flows, and physical structure. The combined effects determine how the site functions over time.
6.1 Vegetation composition
Plant communities typically move from fast-growing pioneers to a more varied mixture of shrubs, trees, or perennial herbs. Species richness may rise, fall, or remain stable depending on the ecosystem. The dominant forms often change as shade increases and competition intensifies. Long-lived species become more important in later stages.
6.2 Animal recolonization
Animals return as food, shelter, and nesting sites become available. Insects may arrive quickly, followed by birds, mammals, amphibians, and other groups. Species that depend on dense cover or mature vegetation often appear later. Animal recovery is closely linked to habitat structure and plant composition.
6.3 Biomass and productivity
Aboveground biomass usually increases as plants establish and mature. Primary productivity may rise during the early and middle stages, then stabilize or vary by ecosystem. Accumulated organic matter contributes to litter layers and soil development. Biomass patterns are important indicators of recovery.
6.4 Structural complexity
Recovering communities usually become more layered and spatially heterogeneous. Canopy gaps, understory patches, dead wood, and plant height variation create a richer physical environment. Such complexity supports more species and ecological interactions. It also affects light, moisture, and movement through the habitat.
6.5 Carbon storage and nutrient dynamics
As vegetation and soils rebuild, the site often stores more carbon in plant tissues and organic matter. Nutrients become more tightly cycled through litterfall, decomposition, and uptake. The efficiency of retention generally improves with community development. These changes link succession to broader ecosystem processes.
7 Examples and case studies
Secondary succession can be observed in many kinds of environments. Examples from different systems illustrate how disturbance type and local conditions produce distinct recovery patterns. Although the details vary, the general progression from early colonization to later stabilization is common.
7.1 Forest regeneration after fire
After forest fire, grasses and herbs often appear first, followed by shrubs and tree seedlings. Surviving roots or seed sources may accelerate regrowth. If fire severity is moderate, many species recover relatively quickly. In some forests, repeated low-intensity fire shapes the structure of the renewing community.
7.2 Abandoned farmland succession
When cultivation stops, fields may pass through a sequence from weeds to grasses, then to shrubs and young trees. Soil conditions and seed sources strongly affect the path of change. In places with nearby forest remnants, woody plants may establish more rapidly. Over time, abandoned farmland can return to a forested or mixed habitat.
7.3 Post-hurricane recovery
Hurricanes and severe storms can strip leaves, break branches, and topple trees. The resulting gaps increase light and allow understory growth to expand. Fast-growing plants often dominate the first phase after damage. Recovery may be rapid in warm, wet climates where regrowth is strong.
7.4 Wetland and grassland recovery
Wetlands and grasslands can also undergo secondary succession after grazing, drainage, flooding, or mechanical disturbance. In wetlands, plant regrowth may depend on water levels and sediment conditions. In grasslands, dominance may shift among perennial grasses, forbs, and shrubs. Local hydrology and soil moisture are especially important.
8 Study and management
Secondary succession is a major topic in ecology, conservation, and restoration. Scientists study it to understand how communities recover, while managers use this knowledge to guide habitat improvement. Because succession is dynamic, long-term observation is often necessary.
8.1 Ecological research methods
Researchers use permanent plots, transects, remote sensing, seed bank studies, and soil analyses to examine successional change. Comparing sites of different ages after disturbance can reveal general patterns. Experimental manipulations may test the effects of light, competition, or soil conditions. These methods help identify the processes driving recovery.
8.2 Monitoring successional change
Monitoring tracks changes in species composition, biomass, structure, and environmental conditions over time. Repeated surveys can show whether recovery is proceeding toward a desired state. Quantitative indicators are useful for comparing sites and evaluating interventions. Long-term datasets are especially valuable because succession may unfold over decades.
8.3 Restoration ecology applications
Restoration projects often use principles from secondary succession to accelerate recovery. Managers may add seeds, reduce invasive species, or protect young vegetation from grazing. In some cases, allowing natural succession is sufficient; in others, active intervention is needed. The goal is usually to support stable, self-sustaining ecosystems.
8.4 Conservation and land management
Understanding secondary succession helps guide decisions about fire management, harvesting, abandonment, and habitat protection. It can inform the timing of interventions and the design of landscape corridors. Managers may also use successional stages to maintain habitat diversity for different species. Because recovery is context-dependent, flexible planning is often most effective.