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Geography 1001: Climate & Vegetation. Instructor: Andr é s Holz Teaching Assistant: Eungul Lee. Lecture 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
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Geography 1001:Climate & Vegetation Instructor: Andrés Holz Teaching Assistant: Eungul Lee
Lecture 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 scale
Lecture 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 accumulations
Lecture 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 succession
Lecture 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 Succession
Ecosystem 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 factors
Ecosystem 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 19.21
Ecosystem 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 inertia
Ecosystem 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 Ecosystems Increase or decrease the resilience and general stability? At the short-term? At the mid- & long-term? Figure 19.23
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
Comm. A B C UP • Conceptual Issues • What is a community (Clements v Gleason) • Individualistic responses versus super-organism Community as super-organism (Clements) Abundance DOWN any environmental gradient
Conceptual Issues • Community integrity (Clements v Gleason) • Individualistic responses versus super-organism INDIVIDUALISTIC RESPONSES (Gleason) Abundance UP DOWN any environmental gradient
Comm. A B C Late Community change: concepts Initial Floristic Composition Relay Floristics Abundance Early Time
Community change: concepts Initial Floristic Composition Relay Floristics Abundance Early The idea is that all species enter early on, but dominate at different points along the way
Ecological Succession Figure 19.26
Ecological 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 • Secondary
Forest fires: primary or secondary? Figure 19.27
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 dynamics
Vegetation 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 heterogeneity
The role of disturbances across scales • Spatial heterogeneity: At a stand scale
The role of disturbances across scales • Spatial heterogeneity: At a landscape scale patch dynamics & the “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 heterogeneousenvironment