Great Smoky Mountains Robert H. Whittaker Vegetation gradients - - PowerPoint PPT Presentation

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Sep 22, 2023 359 likes •564 views

Great Smoky Mountains Robert H. Whittaker Vegetation gradients Environmental tolerance determines distribution Iverson and Prasad 1998, Distributions of 80 sp. of trees Iverson and Prasad 2001 Current Potential forest change under

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Robert H. Whittaker Vegetation gradients Environmental tolerance determines distribution Great Smoky Mountains

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Iverson and Prasad 1998, Distributions of 80 sp. of trees

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Iverson and Prasad 2001 Potential forest change under alternative climate change scenarios based on species specific tolerance and environmental optima. Current

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Crozier 2003 Range change in Atalopedes campestris

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What is microclimate?

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Stream microclimates

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Temperature optima in ectotherms

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Evolution of thermal tolerance homeotherms What is this range of temperatures called?

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Heat balance equation HS = Hm ± Hcd ± Hcv ± Hr - He

HS = Total heat stored in an organism Hm = Gained via metabolism Hcd = Gained / lost via conduction Hcv = Gained / lost via convection Hr = Gained / lost via electromagnetic radiation He = Lost via evaporation

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Metabolic thermoregulation in verdins (Aureparus flaviceps) Wolf and Walsberg, 1996

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Not all plants are ectotherms: Symplocarpus foetidus

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Thermoregulation by environmental manipulation Fungus-growing termites (Macrotermes bellicosus) Korb and Linsenmair, 1998

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Thermal tolerance - a virus in a fungus in a plant Marquez et al. 2007 Science Dichanthelium (a tropical grass) Soil heated to 65 C 10 hrs per day That is HOT!

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97.7% Oceans 2% Ice 0.02% Fresh 0.00002% Living

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Water Travels on Gradients

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Ψplant = Ψsolute + Ψmatric + Ψpressure Ψsoil ≈ Ψmatric Water potentials are NEGATIVE and water flows from less negative to more negative potential.

Ψmatric represents water’s tendency to adhere to surfaces. Ψpressure is the reduction in water potential due to negative pressure created by water evaporating from leaves. As long as Ψplant < Ψsoil, water flows from the soil to the plant.

Water movement from soil to plant

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In plants, water flows in a continuous stream from root to leaf

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Plant Wip= Wr + Wa - Wt - Ws Wip= Internal water Wr =Root uptake Wa = Absorbed (air) Wt = Transpiration Ws = Secretions Animal Wia= Wd + Wf + Wa - We - Ws Wia= Internal water Wd = Drinking Wf = Food (as source) Wa = Absorbed (air) We = Evaporation Ws = Secretion / Excretion