Lecture 9 Biomes

Growth Form

Refers to the physical structure of a plant.

Relyea’s definition

A Biome is a geographic region that contains communities composed of organisms with similar adaptations.

Convergent evolution

A phenomenon in which two species that descended from unrelated ancestors have similar adaptations because they have evolved under similar selective forces.

screlophyllous vegetation

Which has small, tough leaves that resist desiccation.

Ecotone

region where two communities or ecosystems overlap

Lotic

Characterized by flowing water

Riparian zone

terrestrial vegetation alongside rivers and streams that is influenced by season flooding and elevated water tables.

Upstream

often shaded and nutrient poor, which limits primary productivity.

allochthonous

organic matter that is inputted from outside forces.

Autochthonous

organic matter produced by algae and aquatic plants - produced w/in the ecosystem.

Ponds and Lakes

An aquatic biome characterized by non-flowing fresh water with some area of water that is too deep for plants to rise above the water’s surface

Littoral zone

the shallow area around the edge of a lake or pond containing rooted vegetation

Limnetic (pelagic zone)

The open water beyond the littoral zone, where the dominant photosynthetic organisms are floating algae

Profundal zone

the area in a lake that is too deep to receive sunlight; typically has low concentrations of oxygen

Benthic zone

the area w/ sediments at the bottom of lakes, ponds, and oceans; is habitat for burrowing organisms

Stratification

the condition of a lake or pond when the warmer, less dense surface water floats on the cooler, denser water below

Epilimnion

the surface later of water in a stratified lake

Thermocline (or metalimnion)

a middle depth of water in a lake that exhibits a rapid decline in temp. over a relatively short distance in depth

Hypolimnion

The deeper layer of water in a lake

Freshwater wetland

an aquatic biome containing standing fresh water, or souls saturated with fresh water for least part of the year; shallow enough for emergent vegetation throughout all depths.

Swamps — contain emergent trees

Marshes — contain emergent non-woody vegetation

Salt marshes

a saltwater biome that contains non-woody emergent vegetation

mangrove swamps

a biome that occurs along a tropical and subtropical coasts and estuaries

Intertidal zones

a biome consisting of the narrow band of coastline between the levels of high tide and low tide.

Coral reefs

marine biome found in warm, shallow waters that are above 20* C year-round. Greatest species diversity of all aquatic biomes

Neritic zone

the ocean zone beyond the rang of the lowest tidal level and which extends to the edge of the continental shelf; generally a region of high productivity because it has both abundant light and nutrients

oceanic zone

the ocean zone beyond the neritic zone; nutrients are sparse and production is limited

photic zone

the area of the neritic and oceanic zones the contains sufficient light for photosynthesis by algea

aphotic zone

the area of the neritic and oceanic zones where water is so deep that sunlight cannot penetrate; Low productivity. food web largely dependent on rain of detritus from above.

Chemosynthesis sustains some productivity around hydrothermal vents and cold seeps