Community ecology

Community ecology, study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat.

1. Community Ecology Done by :Sumaiah alghamdi Submitted to : Dr . Mai Elobeid

2. Content Introduction & definitions The characteristics Of Communities Elements Of Communities Size & Structure Of Communities Patterns Of Community Structure (Succession) Species interactions Species interactions types References

3. Introduction & definitions Community ecology , study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat. Community ecology represents the population of all species living and interacting in an area at a particular time.

4. Introduction & definitions Each community has its special limit. Sometimes the boundary between two communities may be very sharp or gradual. The transitional zone or junction between two or more diverse communities is called “ecotone”. The ecotone harbors a community termed ecotonal community with organisms of overlapping communities and some of unique types.

5. The characteristics of communities Each biotic community exhibits a number of characteristics, such as diversity, density, dominance, composition and stratification . 1)Species Diversity : A biotic community has producer, consumer & decomposer. Within these species diversities, some populations influenced more than others in the community because the share a higher % of energy flow. 2)Growth & Structure: Community is usually described in term of growth forms.

6. 3) Dominance In each community, one or a few species dominate either in numbers or in physical characteristics or both over the other species. The dominant species are called 'Ecological dominants . 4) Successions Succession is very important in development of community. Community develops as a result of directional change in it with time. The characteristics of communities…cont

7. 5) Trophic levels There are 3 broad trophic levels in a community which are Producers, Consumers & Decomposers. The food produced by the green plants is consumed directly or indirectly by all kinds of animals. So these are known as Consumers. The dead bodies & excreta of both producers & consumers are decomposed by microbes into simple substances, these are called the Decomposers of the community The characteristics of communities…cont

8. Elements Of Communities Trophic pyramids and the flow of energy Autotrophs and heterotrophs All biological communities have a basic structure of interaction that forms a trophic pyramid. The trophic pyramid is made up of trophic levels, and food energy is passed from one level to the next along the food chain . The base of the pyramid is composed of species called autotrophs , the primary producers of the ecosystem. They harness solar energy by photosynthesis to make organic substances from inorganic ones. All other organisms in the ecosystem are consumers called heterotrophs , which either directly or indirectly depend on the producers for food energy.

9. Within all biological communities, energy at each trophic level is lost in the form of heat (as much as 80 to 90 percent), as organisms expend energy for metabolic processes such as staying warm and digesting food. The higher the organism is on the trophic pyramid, the less energy is available to it; herbivores and detritivores ( primary consumers ) have less available energy than plants, and the carnivores that feed on herbivores and detritivores ( secondary consumers ) and those that eat other carnivores ( tertiary consumers ) have the least amount of available energy. Elements Of Communities …cont

10. Elements Of Communities …cont The pyramid structure of communities The organisms that make up the base level of the pyramid vary from community to community. In terrestrial communities, multicellular plants generally form the base of the pyramid, whereas in freshwater lakes a combination of multicellular plants and single-celled algae constitute the first trophic level The trophic structure of the ocean is built on the phytoplankton

11. Transfer of energy through an ecosystem. At each trophic level only a small proportion of energy (approximately 10 percent) is transferred to the next level.

12. Elements Of Communities …cont Food chains and food webs Because all species are specialized in their diets, each trophic pyramid is made up of a series of interconnected feeding relationships called food chains . Species can be grouped according to where in the community they obtain their food, and groups can be linked together by   food chain , where each link comprises a different  trophic level .  Food chains combine into highly complex food webs. Even a simplified food web can show a complicated network of trophic relationships.

13. Generalized aquatic food web.

14. Elements Of Communities …cont Primary Producers – Plants & algae that make food through photosynthesis. Herbivores – Feed on primary producers Carnivores (predators) – Feed on herbivores. Omnivores – Feed on plants & animals

15. Size & Structure Of Communities Size : Communities may be small, consisting a few species populations in a small space, or large, comprising several species populations in a large area. Larger once extend over areas of several thousands of square kms , as forests, other such as deserts etc. Very small sized communities are the groups of microbes in such micro habitats as leaf surface, fallen log, litter, soil etc.

16. Size & Structure Of Communities Structure: The community structures, composition and other characteristics can be readily described by visual observation without actual measurement. Communities usually categories by the ecologists in various ways primarily based of habitat features like water availability, high exposure of light , or other habitat features. For example , depending on the amount of water availability, plant communities may be hydrophytic (aquatic habitats), mesophytic (moderately moist soil habi­tat) and xerophytic (dry or arid habitat).

17. Spatial the way of ultimate distribution of species relative to each other. In a particular habitat shared by several species, each of the species is usually confined to its own microhabitat or spatial. For example the tropical forest trees are stratified into several different levels ,each level is the habitat of distinct collection of species Size & Structure Of Communities…cont

18. Temporal is the timing of appearance and activity of species. These species Called temporal species For example many desert plants and animals are dormant most of the year. they emerge or germinate in response to seasonal rains . other plants stick around year around , having evolved adaptation to resist drought Size & Structure Of Communities…cont

19. Size & Structure Of Communities…cont Scale:   is the size of a community. provided that the area or habitat is well defined, a community can be a system of almost any size, from a drop of water, to a rotting log, to a forest, to the surface of the Pacific Ocean.

20. Patterns Of Community Structure The structure of communities is constantly changing. All communities are subject to periodic disturbances, ranging from events that have only localized effects, such as the loss of a tree that creates a gap in the canopy of a forest, to those that have catastrophic consequences, which include wildfires that sweep across vast landscapes or storms that pound immense stretches of shoreline. In course of very long period of time at many places the communities have reached a peak stage and attained a dynamic balance with the environmental changes. The process of changing in communities and their environment at one place in the course of time is called “ecological succession”

21. Patterns Of Community Structure Succession occurs in predictable stages , at each stage different species plants and animals may be present As succession progresses ,new organisms move in , Others may die or move out The first species to take hold in an area called Pioneer species Types of succession There are two types of succession have been distinguished. Primary and secondary succession

22. Patterns Of Community Structure Primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes.

23. Primary succession

24. Secondary succession occurs in areas where a community that previously existed but has been removed by such as a fire or a storm which create patches of habitat that are colonized by early successional species. Depending on the extent of the disturbance, some species may survive, and other species may be recolonized from nearby habitats, . For example , many plant species in fire-prone environments have seeds that remain dormant within the soil until the heat of a fire stimulates them to germinate Patterns Of Community Structure

25. Secondary succession

26. Patterns Of Community Structure Ecosystem Structure During Early Succesional Stage Small Plants size Low Species diversity Mostly producers, few decomposers Trophic structure Few, mostly generalized Ecological niches low Community organization

27. The process of succession The sequential progression of species during succession is not random. At every stage certain species have evolved life histories to exploit the particular conditions of the community. Initially only a small number of species from surrounding habitats are capable of thriving in a disturbed habitat. As new plant species take hold, they modify the habitat by altering such things as the amount of shade on the ground or the mineral composition of the soil. These changes allow other species that are better suited to this modified habitat to succeed the old species. These newer species are superseded, in turn, by still newer species. A similar succession of animal species occurs, and interactions between plants, animals, and environment influence the pattern and rate of successional change..

28. Patterns Of Community Structure Community equilibrium and species diversity In some environments, succession reaches a climax , producing a stable community dominated by a small number of prominent species. This state of equilibrium, called the climax community, is thought to result when the web of biotic interactions becomes so intricate that no other species can be admitted. Diverse communities are healthy communities. Long-term ecological studies have shown that species-rich communities are able to recover faster from disturbances than species-poor communities. The relationship between species diversity and community stability highlights the need to maintain the greatest richness possible within biological communities.

29. Patterns Of Community Structure

30. Patterns Of Community Structure Characteristic of climax community Mature Communities High occurrence of vegetation patches Contain large plants High species diversity Well-established, efficient nutrient cycles Many, specialized niches High biomass Low Immigration Rate Efficient use of energy

31. Species interactions Structures arise within communities as species interact, and food chains, food webs and other interactive webs are created. As populations of species interact with one another, they form biological communities. The number of interacting species in these communities and the complexity of their relationships exemplify what is meant by the term “biodiversity.”

32. Interspecific Interactions And The Organization Of Communities The interactive relationships that arise between populations of different species form the interactive web of communities. These interactions range from antagonistic to cooperative and have either positive, negative, or neutral effects on the species involved. In antagonistic relationships the interaction is harm to individuals of either one or both species. In commensal relationships (commensalism) one species benefits while the other remains unaffected; and in mutualistic relationships (mutualism) both species benefit.

33. Species interactions…cont The organization and stability of biological communities results from the mix of the different kinds of interaction. These relationships between species are not static; they are a part of the ongoing process of the evolution of interactions. As interactions between species evolve, relationships may shift from antagonism to commensalism to mutualism. As a result, the organization of biological communities is no more fixed than are the characteristics of the species or their environments.

34. Species interactions types There are four major types of species interactions. The four types of species interactions are: antagonism a) Predation b) Parasitism c) Grazing 2) Competition 3) Mutualism 4) Commensalism

35. Species interactions types…cont 1) Antagonism Although mutualisms are common in all biological communities, they occur side by side with a wide array of antagonistic interactions One way of understanding the diversity of antagonistic interactions is through the kinds of hosts or prey that species attack . Carnivores attack animals, herbivores attack plants, and fungivores attack fungi. Other species are omnivorous , attacking a wide range of plants, animals, and fungi. Regardless of the kinds of foods they eat, however, there are some general patterns in which species interact. Parasitism, grazing, and predation are the three major ways in which species feed on one another. .

36. Species interactions types..cont a) Predation is a biological interaction where a predator (an organism, often an animal) kills and eats its prey (another organism). Predators are adapted and often highly specialized for hunting. Specialization in predation Most predators attack more than one prey species. Nevertheless, there are some ecological conditions that have permitted the evolution of highly specialized predators that attack only a few prey species.

37. Types of Predation Herbivores (grass) Fructivores (fruits) Insectivores (insects) Carnivores (meat) Species interactions types..cont

38. b) Parasitism the relationship between the parasite and the host. This interaction involves parasites. Parasitism is thought to be the most common way of life Parasites are organisms that live in or on another organism and feed on it without immediately killing it. Species interactions types..cont

39. Specialization in parasites the parasites often favors extreme specialization to a single host or alternation among small group of hosts. Living for a long period of time on a single host, a parasite must remain attached within or on its host, avoid the defenses of its host, and obtain all its nutrition from that host. Species interactions types..cont

40. Species interactions types..cont c) Grazing Is a method of feeding in which a herbivore feeds on plants such as grasses, or other multicellular organisms such as algae. Grazing differs from true predation because the organism being grazed upon is not generally killed. Grazing differs from parasitism as the two organisms live together in a constant state of physical externality

41. Grazing

42. 2) Competition Competition is a powerful form of interaction in the organization of communities, but it differs from other interactions in that no species benefits from the interaction. In competitive interactions, species evolve either to avoid each other, to tolerate the presence of the other, or to aggressively exclude the other. Species interactions types..cont

43. Species compete for almost every kind of resource, and the same two species may compete for different resources in different environments., but often one resource, called the limiting resource because it limits the population growth of each species. Species interactions types..cont

44. 3) Mutualism a cooperative partnership between two species in which both species benefit where is one species acts as the host, and the other plays the role of visitor or resident. Such as Plants are hosts for insects that pollinate them or eat their fruit and for microorganisms that attach themselves to their roots. The pervasiveness of mutualism Some mutualistic relationships are so pervasive that they affect almost all life-forms. . Mutualistic associations between animals and microorganisms are equally important to the structure of communities. Species interactions types..cont

45. Species interactions types..cont Mutualism

46. 4) Commensalism Commensalism benefits one organism and the other organism is neither benefited nor harmed. It occurs when one organism takes benefits by interacting with another organism by which the host organism is not affected. The commensal organism may depend on its host for food, shelter, support, transport, or a combination of these. Species interactions types..cont

47. A good example is a remora living with a shark. Remoras eat leftover food from the shark. The shark is not affected in the process, as remoras eat only leftover food of the shark, which does not deplete the shark's resources. Species interactions types..cont

48. References http://www.biologydiscussion.com/ecology/community/community-definition-concept-structure-ecology/70721 https://www.britannica.com/science/community-ecology/Effect-on-community-structure https://socratic.org/questions http://ib.bioninja.com.au/options/option-c-ecology-and-conser/c2-communities-and-ecosyste/ecological-disturbance.html https://slideplayer.com/slide/9961964/ https://quizlet.com/63795456/ https://www.nap.edu/read/13393/chapter/4#37   Legendre, P.; Fortin, M.-J. (1989). "Spatial pattern and ecological analysis". Plant Ecology.  80  (2): 107–138.  doi : 10.1007/BF00048036 .

49. Any Question