Geography 1001: Climate & VegetationLecture 12: Wednesday June 28Slide 3Slide 4Slide 5Ecosystem Stability, Dynamics, and DiversitySlide 7Population Controlling Factors Growth interaction Reduction factorsSlide 9Ecosystem Stability and DiversityAgricultural EcosystemsCommunity Ecology & Ecological SuccessionSlide 13Slide 14Community change: conceptsSlide 16Ecological SuccessionSlide 18Mount St. HelensSlide 20Mount St. Helens: primary or secondary succession?Forest fires: primary or secondary?Other examples of primary & secondary succession?Slide 24Vegetation dynamics & Scale: a brief review of the basic concepts of forest dynamicsVegetation dynamics conceptsSlide 27The role of disturbances across scalesSlide 29Patch Dynamics“Shifting Mosaic”Climax conceptGeography 1001:Climate & VegetationInstructor: Andrés HolzTeaching Assistant:Eungul LeeLecture 12: Wednesday June 28•Review lecture 11–Chapter 20•Tundra: Properties–Arctic vs. Alpine Tundra–Chapter 19•Basic terms–Ecology & Biogeography–Ecologies of »Individual»Population»Community definition & characteristics»Habitat & niche –Role of scaleLecture 12: Wednesday June 28•Review lecture 11•Ecosystem Components–Plants essential component–NPP–Abiotic & Biotic components–Life zones–Limiting factors •Biotic Ecosystem Operations–Producers, Consumers, and Decomposers–Food Chains and (Complex) Food Webs»Biomass consumption & Efficiency»Toxins accumulationsLecture 12: Wednesday June 28•Lecture 12–Chapter 19•Ecosystems and Succession–Ecosystem Stability, Dynamics, and Diversity –Community Ecology & Ecological Succession»Historical views of a community»Conceptual issues»Clements versus Gleason•Changes of a community–Initial Floristic Composition versus Relay Floristics•Primary and Secondary successionLecture 12: Wednesday June 28•Lecture 12–Chapter 19•Ecosystems and Succession–Vegetation dynamics & Scale–Patch dynamics– role of disturbances (Historical shift…“catastrophic” versus normal process; e.g. fires, floods, etc…) –“Climax” concept–Vegetation dynamics »Terrestrial SuccessionEcosystem Stability, Dynamics, and Diversity•Stability–Inertia stability and resilience•resistance of an ecosystem to change •ability of an ecosystem to return to normal after a disturbance –What increases the stability of an ecosystem?•Diversity•Dynamics•Growth interaction reduction factorsEcosystem Stability, Dynamics, and Diversity•Diversity –(Bio) Diversity = richness*abundance*genes*habitat diversity•Dynamics (dynamic balance)–Biotic & abiotic factors enhancing growth–Disturbances & its regime•Size, frequency, intensity, severity, etc…Population Controlling Factors Growth interaction Reduction factors Figure 19.21Ecosystem Stability, Dynamics, and Diversity–(Dynamic) equilibrium, and non-equilibrium•Various aspects of the ecosystem change from day to day, season to season, and year to year •Changes are within limits and are usually small•Only mature ecosystems are stable and in dynamic equilibrium •Mature ecosystems have resilience and inertiaEcosystem Stability and Diversity•The more diverse a community, the more or less stable the community?•The more stable a community, the higher/lower its inertia & resilience?•The higher the species diversity the greater the inertia and resilience of the ecosystem is.Agricultural EcosystemsFigure 19.23Increase or decrease the resilience and general stability?At the short-term? At the mid- & long-term?Community Ecology & Ecological Succession•Historical views of a community–Conceptual issues•Clements versus Gleason•Changes of a community–Initial Floristic Composition versus Relay Floristics•Primary and Secondary succession•Vegetation dynamics & Scale•Patch dynamics– role of disturbances (Historical shift…“catastrophic” versus normal process; e.g. fires, floods, etc…) •“Climax” concept•Conceptual Issues–What is a community (Clements v Gleason)•Individualistic responses versus super-organismany environmental gradientDOWNCommunity as super-organism (Clements)AbundanceUPComm. A B C•Conceptual Issues–Community integrity (Clements v Gleason)•Individualistic responses versus super-organismany environmental gradientUPDOWNINDIVIDUALISTIC RESPONSES (Gleason)AbundanceCommunity change: conceptsInitial Floristic Composition Relay FloristicsTimeEarlyAbundanceLateComm. A B CCommunity change: conceptsInitial Floristic Composition Relay FloristicsThe idea is that all species enter early on, but dominate at different points along the wayEarlyAbundanceEcological SuccessionFigure 19.26Ecological Succession•Def.: Succession refers to a directional change in species composition across space and time, •which usually include a change in spatial structure –(e.g. spruce fir regeneration within a lodgepole pine forest)–Primary–SecondaryMount St. HelensMount St. HelensMount St. Helens: primary or secondary succession?Forest fires: primary or secondary?Figure 19.27Other examples of primary & secondary succession?Other examples of primary & secondary succession?Vegetation dynamics & Scale: a brief review of the basic concepts of forest dynamics•Vegetation dynamics –Is less deterministic than succession Patch dynamics  “Shifting Mosaic”–includes succession and regeneration/maintenance dynamicsVegetation dynamics concepts•Regeneration/maintenance dynamics refers to:–a spatio-temporal change in structure–keeping the species composition constant (e.g. spruce fir regeneration within a spruce fir forest)Vegetation dynamics concepts•The dynamic part of the concept is emphasized by frequent occurrence of disturbances, which interrupt the successional pathway to a dynamic endpoint, and promote spatial heterogeneityThe role of disturbances across scales •Spatial heterogeneity: At a stand scaleThe role of disturbances across scales •Spatial heterogeneity: At a landscape scale  patch dynamics & the “shifting mosaic”Patch Dynamics“Shifting Mosaic”Climax concept–Largely viewed as a dead concept (but still in many books!)–Communities rarely reach a pre-determined “equilibrium” –Disturbances promote a constant change, and heterogeneous