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)