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The Physical Setting
Biogeography (ENVR333)9/5/07
Environmental Gradient
Operational Environment(Abiotic Factors)
• Terrestrial Systems– Light– Temperature (soil and
air)– Moisture (soil and air)– Chemistry (soil and air)– Mechanical force– Fire
• Aquatic Systems– Salinity– Temperature– Depth (pressure &
light)– nutrients
Fig. 2.5 (MacDonald 2003)
Relationship between light intensity
and rate of photosynthesis
Fig 3.2 (MacDonald 2003)
• C3 – CO2 to 3-carbon 3-phosphoglyceric acid molecules
• C4 – CO2 to two 4-carbon malic and aspartic acid molecules
• CAM – CO2 absorbed at night and stored as malic acid then used in C3 process during day
Photosynthetic Pathways
Relationship between temperature and rate of photosynthesis
Fig 3.3 (MacDonald 2003)
The northern limits ofspruce in North Americais limited in part by the cool and short summers of the arctic
White spruce (Picea glauca) at treeline in the Northwest Territories of Canada
Relationship between northern limits of spruce and July temperatures in
Canada
Fig 3.4 (MacDonald 2003)
Brown and Lomolino 1998
Relationship between January temperature and northern limits of the Eastern phoebe
Fig 3.8 (MacDonald 2003)
http://soils.usda.gov/use/worldsoils/mapindex/str.html
Moisture - Some Keywords
• Xerophyte• Mesophyte• Hydrophyte• Transpiration• Sclerophyllous leaves
Cacti exhibit a number of adaptations helpful in arid environments
Cacti of Baja California, MexicoBarrel cactus n Baja California, Mexico
Some plants loose their leaves in the dry season and/or have dimorphic leaves with smaller leaves produced and retained in the dry season
Sclerophyllous leaves are associated with a number of trees and shrubs in dry regions
The enlarged trunk of some trees (Baobabs) can hold up to 120,000 liters of water
The distribution of pinyon pines in California and otherparts of the southwestern United States is in part explained by moisture
Pinyon pine (Pinus monophylla) near the desert limits in southern California
Altered chemical conditions, such as decreased pH and increased concentrations of heavy metals caused by industrial pollution can severely limit the distribution of plants and animals. Acid and metaldeposition from the smelter at Monchagorsk, Russia has destroyed forest and aquatic life in a large region around the city
Increased levels of ozone have caused damage and mortality to some pines in the mountains surrounding Los Angeles, California. Acid deposition has caused similar symptoms to conifers in eastern NorthAmerica and Europe
Allelopathy - Allelotoxins
Ice
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Catastrophic and Local Land Movement
Operational Environment(Abiotic Factors)
• Terrestrial Systems– Light– Temperature (soil and
air)– Moisture (soil and air)– Chemistry (soil and air)– Mechanical force– Fire
• Aquatic Systems– Salinity– Temperature– Depth (pressure &
light)– nutrients
Brown and Lomolino 1998
Major Ocean Currents
Environmental Gradient
The Niche Concept takes into account the fact that many environmental variables control species’ distributions