Terrestrial ecosystem in aquatic one o ecosystem

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terrestrial ecosystem in aquatic one oEcosystem engineerskeystone species that actively shape physical environment, creating other habitat for species
31 Dominant speciesspecies that have a larger effect on a community because it is more numerous or has the highest biomass within that community oi.e. deer Abundant, especially in areas without wolves Graze heavily on young trees large impact on forests with high numbers of deer Not keystone species large impact is due to large numbers of deer Community Succession Following appearance of new habitat, or disturbance that removes species, a community will undergo predictable sequence of changes Pioneer speciesearly colonizers that persist in a community based on their ability to colonize/recolonize after disturbances (opportunistic species) Climax communityfinal stage of succession, mature assembly of best competitors (equilibrial species) that persists until a disturbance leads to local extinction (forming gaps) When gaps are out of phase with one another community becomes mosaic of patches at different successional stages, allowing more species (especially worse competitors) to persist in area Primary successioncolonization following disturbance that eliminated all species from an area (i.e. volcanic eruptions, emergence of new islands) Secondary successionrecolonization following a disturbance that only partially removed species from area oSome species persist as either adults or in seedbank oi.e. forest fire, flood Clements-Gleason Dichotomy & Succession Based on succession: oClements argued that succession provided strong evidence that his view was correct oGleason argued that succession was based on individual movement of species, so his view was correct Climate change & the dichotomy oSpecies respond individually to climate change oMany long-term species associations are being broken apart because of climate change oEvidence in favour of Gleason’s view
32 Ecosystems Ecosystemconsists of all organisms living in a community as well as the abiotic factors with which they interact oPredatory-prey interaction do not occur in isolation, but as a part of a larger community of interacting species (community ecology) oCan model interactions based on how energy/nutrients move through the community (modeling trophic structure), which brings in the abiotic component 2 important processes: oEnergy flow oChemical/nutrient cycling Reliance on Autotrophs Autotrophprimary producers; form organic molecules through reduction of inorganic carbon (nitrogen, phosphorous) obtained from physical environment oi.e. photoautotrophs, chemoautotrophs Heterotrophsconsumers; obtain organic carbon & other elements needed for growth from other organisms oCan obtain this from autotrophs or other heterotrophs oDecomposers special class of consumers that break down molecules of primary producers/consumers & return carbon (& other elements) to ecosystem in inorganic forms Trophic Structure

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