Community

• Community structure


  The organization and composition of a group of different species living in the same area
• Main aspects of community structure

  • Species richness
  • Species evenness
• Species diversity


  A combination of the number of species and their relative abundance
• Species richness


  A measure of the total number of different species in a community. Higher species richness indicates greater diversity.
• Communities with the highest species richness tend to be found in areas near the equator, and communities with the lowest species lie near the poles
• Species evenness

  Measures how evenly individuals are distributed among the different species in a community. Communities with more evenly distributed species have greater evenness.
• Trophic structure


  Focuses on the feeding relationships between species in the community. It considers the different levels of the food chain, from producers to herbivores, carnivores, and decomposers.
• Understanding the trophic structure helps predict how changes in one population might impact others
• Trophic structure components

  • Primary producers (plants)
  • Herbivores (consumers of plants)
  • Carnivores (consumers of herbivores)
  • Top predators
• Species composition


  Describes the specific types of species that make up the community. Knowing the mix of plants, animals, fungi, and microbes helps ecologists understand the functional roles within the community.
• Importance of community structure

  • Stability and resilience
  • Indicators of environmental health
  • Provides resources and services
  • Ecosystem functioning
• Community interaction types

  • Competition
  • Predation
  • Mutualism
  • Parasitism
  • Commensalism
• Interactions among species in a community can be categorized into various types, including competition, predation, mutualism, parasitism, and commensalism
• Importance of species interaction

  • Maintaining ecosystem balance
  • Promotes biodiversity
  • Enhancing productivity
  • Pushes adaptation and evolution
• Habitat


  A natural home to an organism wherein it is able to support that organism with shelter, food, water, and space. An organism can only thrive in its habitat if it is suitable for it to live in, and allows it to grow in the area.
• Niche differentiation/niches


  Species within a community often exhibit niche differentiation, where they evolve to occupy different ecological niches to reduce competition for resources. Niches define an organisms role in its environment.
• Types of niches

  • Spatial niche
  • Trophic niche
• Guild


  A guild is a how organisms of different taxonomy extract the same resources in their environment through similar means.
• Ecological succession


  The process of gradual, predictable changes in community structure over time. It typically follows disturbances or colonization of a new habitat.
• Types of ecological succession

  • Primary succession
  • Secondary succession
• Primary succession occurs on lifeless substrates, while secondary succession follows disturbances in established communities
• In an area that was previously occupied by living things is disturbed, then re-colonized following the disturbance, over a long period of time, and assuming no further disturbances, a climax community may form when a community reaches a steady and mature state
• Importance of ecological succession

  • Building soil fertility
  • Habitat creation and biodiversity
  • Resilience and recovery
• Foundation species

  Usually modify the environment so that it can support the other organisms that form the community
• Keystone species


  Species that have a disproportionately large impact on community structure and function relative to their abundance. Their removal can lead to significant changes in the composition and diversity of the community.
• Keystone species generally act in more diverse ways than foundation species and are more likely to belong to higher trophic levels
• Disturbance and stability


  Disturbances, such as fires, hurricanes, or human activities, can disrupt community structure. Some communities are adapted to frequent disturbances, while others are more stable.
• Primary succession involves growth without disturbance, where the soil is not yet fertile. Secondary succession involves growth with disturbance, where the soil is already fertile.