1. Habitat Changes:
* Pioneer Stages: Early successional stages, like bare rock or sand, offer limited habitat for animals. Only hardy, opportunistic species like insects, spiders, and small, adaptable mammals can survive here.
* Intermediate Stages: As plants establish and grow, more diverse habitats emerge, supporting a broader range of animals. This includes herbivores, insectivores, and predators that feed on the developing plant communities.
* Climax Stages: Mature ecosystems have complex, stable habitats that support a high diversity of animal species. This includes specialized feeders, large mammals, and top predators.
2. Food Web Dynamics:
* Shifting Food Sources: Succession alters the available food sources for animals. Early stages may have limited resources, while later stages provide abundant and diverse food options.
* Competition and Predation: As the ecosystem develops, competition for resources and predator-prey relationships become more intricate.
* Species Interactions: Succession influences the interactions between different animal species, such as mutualism, commensalism, and parasitism.
3. Shelter and Protection:
* Changing Shelter Availability: Early stages offer minimal shelter, while later stages provide more diverse options like trees, burrows, and dense vegetation.
* Predator Avoidance: Succession affects the ability of animals to avoid predators by providing different levels of cover and concealment.
4. Adaptability and Specialization:
* Generalists vs. Specialists: Early stages favor generalist animals capable of adapting to changing conditions. Later stages support specialist species with specific adaptations for their niche.
* Evolutionary Pressure: The changing environment during succession exerts evolutionary pressure on animal populations, driving adaptations and diversification.
5. Dispersal and Migration:
* Habitat Connectivity: Succession can impact the connectivity of habitats, influencing animal dispersal patterns and migration routes.
* Range Expansion: New habitats created by succession may allow animals to expand their geographic ranges.
Examples:
* Dune Succession: As dunes stabilize, grasses and shrubs emerge, attracting insects, birds, and small mammals. Eventually, forests develop, hosting a wide array of species.
* Forest Succession: After a wildfire or clearcut, pioneer species like grasses and shrubs dominate, followed by trees and eventually a mature forest with a diverse animal community.
* Lake Succession: A lake gradually fills with sediment, creating wetlands and ultimately becoming a meadow or forest. This process attracts different animal species adapted to each stage.
In conclusion, succession is a fundamental driver of animal community dynamics. By altering habitat structure, food webs, shelter availability, and evolutionary pressures, it shapes the composition, abundance, and distribution of animal species over time.