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Assembly © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT for SALE OR DISTRIBUTION NOT for SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC 5 © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ASSEMBLY © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chapter Outline 5.1 Equilibrium Theory of Island Biogeography 5.2© JonesEcosystem &Resilience Bartlett and Stability Learning, LLC © Jones & Bartlett Learning, LLC NOTResilience FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Resistance Stability Ecological Constraints 5.3 Alternative Stable States © Jones & BartlettRegime Learning, Shift LLC © Jones & Bartlett Learning, LLC NOT FOR SALE RestoringOR DISTRIBUTION Alternative Stable States NOT FOR SALE OR DISTRIBUTION 5.4 Assembly Rules Sequence Introduction Species Compatibility Ecosystem Thresholds © Jones & Bartlett Learning,Ecosystem LLC Filters © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION5.5 Unified Neutral Theory of Biodiversity NOTand Biogeography FOR SALE OR DISTRIBUTION Case Study 5.1: Resilience and Ecosystem Restoration Case Study 5.2: Phylogenetic Structure of Plant Communities Provides Guidelines for Restoration © Jonesacilitating & Bartlett succession Learning, or assembly LLC of a functional and integral© Jones eco- & Bartlett Learning, LLC NOTF FORsystem SALE after disturbances OR DISTRIBUTION is an important task of ecologicalNOT restora- FOR SALE OR DISTRIBUTION tion. Various ecological models have been used in these restoration processes. These models can predict changes in community composition with time and therefore aid in the restoration work. Some models have background in community ecology, whereas others are derived from © Jones & Bartlettbiogeography. Learning, These LLC include the deterministic© Jones model &of Bartlett succession Learning, LLC NOT FOR SALE(sensu OR DISTRIBUTION Clements), the individualistic model of successionNOT FOR (sensu SALE Gleason), OR DISTRIBUTION and assembly models (sensu McArthur and Wilson and Diamond). © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 102 Chapter 5 ■ Assembly © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Succession models in particular have provided the theoretical frame- NOTwork FOR for SALE restoration OR DISTRIBUTION of plant communities, as discussed inNOT Chapter FOR 4. SALE OR DISTRIBUTION These models have mainly been applied on terrestrial ecosystems. On the other hand, restoration of aquatic ecosystems has put much more emphasis on assembly models, which consider the possibility of alterna- © Jones & Bartletttive Learning, ecosystem LLCstates instead of only one ©final Jones “climax” & Bartlett community. Learning, LLC Recently, assembly models have been applied successfully in the resto- NOT FOR SALE ORration DISTRIBUTION of terrestrial ecosystems. Many basicNOT aspects FOR underlying SALE ORassem- DISTRIBUTION bly models, such as the importance of arrival time of species to a new site in determining an alternative ecosystem state, are already incorpo- rated in various succession models. The emphasis of succession models, © Jones & Bartlett Learning, LLChowever, is on the trajectory© Jonesleading to& Bartletta climax community,Learning, orLLC final state whereas assembly models demonstrate the possibility of various NOT FOR SALE OR DISTRIBUTIONdifferent endpoints. NOT FOR SALE OR DISTRIBUTION Restoration ecology benefits from using assembly models to con- sider the possibility of multiple stable states instead of one final state. Another practical aspect of assembly models in restoration work is to © Jonesconsider & Bartlettecological Learning, constraints andLLC especially what actions© are Jones needed & Bartlett Learning, LLC to relie degraded states to move along an assembly trajectory toward a NOTdesirable FOR SALE ecological OR endDISTRIBUTION state. NOT FOR SALE OR DISTRIBUTION 5.1 Equilibrium Theory of Island Biogeography © Jones & BartlettThe equilibrium Learning, theoryLLC of island biogeography© Jones was proposed& Bartlett by Learning,Robert LLC MacArthur and Edward O. Wilson in 1967 and has since had a profound impact NOT FOR SALEon ecology,OR DISTRIBUTION biogeography, and conservation biology.NOT The FOR equilibrium SALE ORtheory DISTRIBUTION also has strong implications for restoration ecology. MacArthur and Wilson used the gradual colonization of offshore islands derived from a mainland source as a model system for community assembly. In essence, their work predicts that the number of species on offshore islands is based on a balance between the rate of © Jones & Bartlett Learning,random LLC dispersal of colonizing species© Jones from & the Bartlett mainland Learning, and the rate LLC of random NOT FOR SALE OR DISTRIBUTIONlocal species extinction on the islandsNOT (FigureFOR SALE5.1). The OR model, DISTRIBUTION therefore, describes community assembly mainly as a result of random immigration and random local extinction. An important aspect of the model is that it assumes all species have the same probability of dispersal to an offshore island as they do to facing local extinction. The main parameters of the model are © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT1. Distance FOR SALEof the islands OR DISTRIBUTION from the mainland determining the dispersalNOT FOR rate SALEof OR DISTRIBUTION new species 2. Size of an island determining the rate of species extinction In practice, large islands close to the mainland are more likely to experience © Jones & Bartletthigher Learning,numbers of LLCimmigrating species and lower© Jones extinction & Bartlett of species Learning, than LLC NOT FOR SALEsmall OR islands. DISTRIBUTION The opposite effect increases theNOT farther FOR the SALE small ORislands DISTRIBUTION are from the mainland. The size of these islands and distance from the mainland, © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Equilibrium Theory of Island Biogeography 103 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Immigration Extinction © Jones & Bartlett Learning,Rate LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC Number© Jones of species & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Figure 5.1 Model of equilibrium theory. Equilibrium in community assemblages is formed by the rate of immigration and extinction. therefore,© Jones determine & Bartlett the Learning, number of LLCspecies that exist there in ©a Jonesflux. Such & Bartlett Learning, LLC randomNOT FOR community SALE assembly OR DISTRIBUTION does not imply that these colonizingNOT species FOR are SALE OR DISTRIBUTION necessarily coadapted or preadapted to specific niches on the new site. The equilibrium theory does provide, however, a powerful insight into community assembly by emphasizing a few factors such as random dispersal and coloniza- tion resulting in random assemblages of species derived from the mainland © Jones & Bartlettsource. It Learning, is assumed LLCthat random dispersal processes© Jones alone &play Bartlett an important Learning, LLC NOT FOR SALErole inOR structuring DISTRIBUTION communities. NOT FOR SALE OR DISTRIBUTION The prediction of the equilibrium theory is similar to Gleason’s individual- istic model of succession. The “individualistic model” of succession assumes that community composition is the result of a random process influenced by the availability of vacant niches and species dispersal. The individualistic model © Jones & Bartlett Learning,is analogous LLC to a carousel where ©seats Jones become & Bartlett vacant randomly Learning, and areLLC filled NOT FOR SALE OR DISTRIBUTIONby nearby passengers (that representNOT different FOR SALEspecies). OR DISTRIBUTION Practical uses of the equilibrium theory have been extended to conservation biology, especially to predict extinction rates of species in parks or nature reserves. At the same time the model has been used to predict the necessary size of reserves and need for restoration, buffer zones, and connectivity between fragments© Jones to & facilitate Bartlett species Learning, dispersal LLC into parks and reserves where© Jones the goal & Bartlett Learning, LLC isNOT to avoid FOR species SALE extinctions. OR DISTRIBUTION These factors (size and connectivity)NOT are probably FOR SALE OR DISTRIBUTION more important to avoid species extinction than protection alone. In fact, most nature reserves are too small to fully support biodiversity conservation in the long run. Large nature reserves are needed to inhabit large predatory animals that roam over huge territories. Such animals are often keystone species that influence © Jones & Bartlettfunctioning Learning,
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