Communities and Biomes Chapter 3 Communities and Biomes

3.1: Communities Limiting factors- any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution, of organisms Examples?

Sunlight Climate Atmospheric gases Temperature Water Nutrients or food Fire Soil chemistry Space Competition, predation, parasitism

Tolerance Ability of an organism to survive changes in biotic and abiotic factors

Section 3.1 Summary – pages 65-69 Ranges of tolerance Limits of Tolerance Organisms absent Organisms absent Organisms infrequent Organisms infrequent Greatest number of organisms Zone of Physiological stress Zone of Physiological stress Population Zone of intolerance Zone of intolerance Optimum range Range of tolerance Lower limit Upper limit Section 3.1 Summary – pages 65-69

Biological Succession Succession- the process of change as it occurs to communities in an ecosystem Species that can be found in a particular ecosystem change over time

Primary Succession Colonization of barren land by organisms Pioneer species-first species to inhabit an area Lichens, algae, bacteria, protists colonize bare rock, lava flows

Climax community A stable community that remains relatively unchanged for a period of time Represents by a variety of ecosystems- mature forest, grassland, coral reef, tundra, etc.

Secondary Succession A sequence of changes that takes place after an existing community is disrupted Disruption could be natural (fire, hurricane, flood) or human-influenced (farming, controlled burn, construction)

3.2: Aquatic & Terrestrial Biomes Regional climate influences the distribution of biological communities Latitude and ocean currents influence the climate on different parts of the Earth

Section 3.2 Summary – pages 70-83 Latitude describes your position in degrees north and south of the equator. North pole Sun’s rays 66.5o 23.5o o Sun’s rays O Equator 23.5o Sun’s rays 66.5o South pole Section 3.2 Summary – pages 70-83

Saltwater Ecosystems Estuary- area where different types of water merge (temperatures, pH, salt/fresh) Intertidal zone- area where salt water and land meet, alternately submerged and exposed

Oceanic Zones The oceans can be separated into a variety of zones based on depth and proximity to the shoreline

Oceanic Zones

Intertidal zone- alternately submerged and exposed Continental shelf- submerged edges of continents, relatively shallow water, high diversity Pelagic zone- open water, motile populations Benthic zone- sea floor of both continental shelf and pelagic zone

Light Availability Photic zone- portion of the water column which can be penetrated by light, from the surface to a couple of meters down Aphotic zone- portion of the water column beneath the photic zone where light cannot penetrate Phytoplankton- plant-like plankton, base of aquatic food chains, perform photosynthesis Zooplankton- animal-like plankton

Oceanic Zones

Section 3.2 Summary – pages 70-83 Freshwater biomes Greatest Greatest species diversity Warmer layer Oxygen and light penetration Colder layer Least Section 3.2 Summary – pages 70-83

Terrestrial Biomes Biome- major type of terrestrial ecosystem characterized by similar climate and resulting types of organisms

Tropical Forests Clustered near the equator Can be tropical rain forests or tropical dry forests Relatively poor soil due to rapid decomposition and recycling of materials

Savannas & grasslands Biome dominated by grasses and small scattered trees Lack of water limits the size and number of trees

Deserts Desert biomes are defined by lack of water, not by temperature Deserts can be both hot and cold Rain shadow- dry area on sides of mountains opposite prevailing winds

Desertification- conversion of other biomes into desert Results from growing human populations, overgrazing, changing climate

Temperate Forests Dominated by hardwood trees which require sufficient moisture Deciduous trees- lose their leaves

Coniferous Forests Principal trees are coniferous Needle-like leaves can remain all winter Many adaptations to periodic fire Taiga- northern boreal forest- fewer trees and harsher winters than coniferous forests, located just south of tundra

Tundra Arctic areas and tops of mountains Permafrost- soil that is permanently frozen year round Plant life is very low-lying, no trees