Geographic Template Environmental variables exhibit non- random patterns Patterns of spatial...
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Transcript of Geographic Template Environmental variables exhibit non- random patterns Patterns of spatial...
Geographic Template
• Environmental variables exhibit non-random patterns
• Patterns of spatial variation comprise the geographic template, forms the foundation of all biogeographic patterns
• Biota and interactions of biota form gradients in response to geographic template
Geographic Template
• Energy driving spatial and temporal dynamics– Earth’s core and gravity– Sun – heat transfer, angle and seasons
Local to Global Effects(S-facing slopes in N.Hemisphere (opp in S. Hem.
Elevational Effects
• Why glaciers at tropics?
• Properties of Air
• Density and pressure of air decreases with elevation
• Air moving up a mountain loses heat due to reducing density
• Loses heat energy (adiabatic cooling) as molecules move apart
Greenhouse Effect
• Water vapor and carbon dioxide (as well as methylated metals) trap longer energy wavelengths
• Holds heat
• Moist environments – limited diel temp fluctuation
• Dry environments – diel temp flux
Wind and Rainfall
• Climatic cells – differential heating
• Coriolis effect – wind patterns
• Surface winds create ocean currents
• Temperature + Winds + Ocean Currents = global pattern of precipitation
•Predictable general trends•Rainy season in tropics tied to equinox•Horse latitudes (30 – 35° N and S) – descending air absorbs moisture•Mediterranean climate – west side of continents – hot, dry summer; mild, wet winter
Rain Shadow
Climate and Scale
• Climate scales down to millimeters
• Creates patchy distribution
• Inhospitable environment can contain hospitable meso- and microclimates
Soils
• Distinct pedogenic regimes
• Close correlation with global climate cycles (compare Figures 3.7 and 3.12)
• Soil types can range from limited (Great Plains) to complex mosaic (mountains)
• Tell story of temporal development of global geographic template (and a time-travelling map)
Aquatic Environments
• Main points to get are diversity of space and time
• Patchiness (clinal zones in lakes, intertidal to abyssal in oceans)