Community Ecology: Population of all species living and interacting in an area.
Keystone species: Species that play roles affecting many other organisms in an ecosystem.
Indicator species: Species that serve as early warning that a community ecosystem is degraded.
Native species: Species that normally live and thrive in a particular ecosystem.
Keystone species examples: Flying fox in Southeast Asian tropical forest – endangered species. They are important for: i) plant species pollination, ii) seed dispersal- droppings, maintain forest biodiversity and regenerate deforested areas. Flying foxes are economically important for many products a) Fruits (such as durians) and wild bananas, c) other foods, d) medicines, e) timber (mahogany), fibers , f) dyes ,g) animal fodder, h) fuel, etc.
Other important role of key stone species are : A) habitat modification- elephant uproot trees and promotes the growth of grasses and other forage plants that benefit smaller grazing species such antelope and deer, and accelerates nutrient recycling, B) population control: - top predator keystone species exert a stabilizing effect on their ecosystem by feeding on and helping regulate the population of certain species e.g. wolf, leopard lion, tiger, etc. The loss of a keystone species can lead to population crashes and extinction other species.
Indicators species examples: Birds are excellent biological indicator, because they are found almost everywhere and respond quickly to environmental change- Decrease in migratory and insect eating song birds is due to habitat loss or fragmentation in the area. Presence or absence of trout species in river water indicates the water quality. Because trout needs clean water with high levels of dissolved oxygen. Similarly toad, frog and salamander are also classified as indicator species.
Species Interaction: Species in a community interact with one another. The members of these species may be harmful or beneficial or unaffected. Five types of interactions viz. 1) interspecific competition, 2) predation, 3) parasitism, 4) mutualism, 5) commensalism.
Ecological niche: to avoid competition – leopard and tiger, Darwin finches, Hawks and Owls, etc
Community Succession: Gradual change in species composition of an area. 2 types.
- Primary Succession: Gradual establishment of biotic communities on nearly lifeless ground.
- Secondary Succession: Re-establishment of biotic communities in an area where some type of biotic community is already present.
Pioneer species: First hardy species , often microbes, mosses and lichens that begin to colonizing a site as the first stage of ecological succession – a)early succession plant species b) mid succession plant species – herbs grasses, and lower shrubs and c) late succession plant species- mostly trees.
Climax: Stable community – self perpetuating and in equilibrium with the physical habitat.
Ecotone: Transition between two or more diverse communities e.g. forest and grassland. Narrow and wide ecotone.
Edge species: Organisms occur primarily or most abundantly or spend the greatest of time in ecotone are called edge species. They increase variety and density at community in junctions in termed the edge effect.
