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)

C 3 – CO 2 to 3-carbon 3-phosphoglyceric acid molecules C 4 – CO 2 to two 4-carbon malic and aspartic acid molecules CAM – CO 2 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 of spruce in North America is 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)

Moisture - Some Keywords Xerophyte Mesophyte Hydrophyte Transpiration Sclerophyllous leaves

Cacti exhibit a number of adaptations helpful in arid environments Cacti of Baja California, Mexico Barrel 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 other parts 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 metal deposition 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 North America and Europe

Allelopathy - Allelotoxins

Ice

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