© 2011 Pearson Education, Inc. AP Environmental Science Mr. Grant Lesson 31 Ecological Communities

© 2011 Pearson Education, Inc. Mastery Check What is meant by the term keystone species, and what types of organisms are most often considered keystone species? A species might be considered a keystone species if its removal from the ecosystem causes pervasive ripple effects throughout the food web. Removal of predators at high trophic levels can result in increased prey abundance, which may cause decreased abundance of their food as they overgraze. Other species that have major effects because they physically modify the environment shared by community members (as beavers and their dams do) are more often considered “ecosystem engineers.”

© 2011 Pearson Education, Inc. Objectives: Define the term trophic level. Characterize feeding relationships and energy flow, using them to construct trophic levels and food webs. Distinguish characteristics of a keystone species. Characterize disturbance, succession, and notions of community change. Perceive and predict the potential impacts of invasive species in communities. Explain the goals and the methods of restoration ecology.

© 2011 Pearson Education, Inc. Trophic Level: Rank in the feeding hierarchy of a food chain. Organisms at higher trophic levels consume those at lower trophic levels. Define the term trophic level.

© 2011 Pearson Education, Inc. Characterize feeding relationships and energy flow, using them to construct trophic levels and food webs. Energy is transferred among trophic levels in food chains. -Explain… Lower trophic levels generally contain more energy, biomass, and individuals. -Explain… Food webs illustrate feeding relationships and energy flow among species in a community. -Explain…

© 2011 Pearson Education, Inc. Ecologists organize species hierarchically by trophic level. Someone explain this figure…

© 2011 Pearson Education, Inc. Lower trophic levels generally contain more organisms, energy content, and biomass than higher trophic levels. Someone explain this figure…

© 2011 Pearson Education, Inc. Food webs represent feeding relationships within a community.. How does a food web differ from food chain?

© 2011 Pearson Education, Inc. Distinguish characteristics of a keystone species. Keystone species exert impacts on communities that are far out of proportion to their abundance. -Explain… Top predators are frequently considered keystone species, but other types of organisms also exert strong effect on communities. -Explain…

© 2014 Pearson Education, Inc. Sea otters are a keystone species. What is a trophic cascade?

© 2011 Pearson Education, Inc. Characterize disturbance, succession, and notions of community change. Disturbances are varied, and communities respond to disturbance in different ways. o Explain… o What is a resistance response? o What is a resilience response? Succession describes a typical pattern of community change through time. o Explain… Primary succession begins with an area devoid of life. Secondary succession begins with an area that has been severely disturbed but where remnants of the original community remain. o Explain…

© 2014 Pearson Education, Inc. Primary succession begins as organisms colonize a lifeless new surface. What are pioneer species?

© 2014 Pearson Education, Inc. Primary succession occurs after a disturbance (such as a fire, landslide, or farming) removes most vegetation from an area. What is a climax community?

© 2011 Pearson Education, Inc. Characterize disturbance, succession, and notions of community change. Ecologist today view succession as being less predictable and deterministic than they did in the past. o Explain… If a disturbance is severe enough, communities may undergo phase shifts involving irreversible change – or novel communities may form. o Explain…

© 2011 Pearson Education, Inc. Perceive and predict the potential impacts of invasive species in communities. People have introduced countless species to new areas. Some of these no-native species may become invasive if they do not encounter limiting factors on their population growth. o Explain… Invasive species such as the zebra mussel have altered the composition, structure, and function of communities. o Explain… We can respond to invasive species with prevention, control, and education measures. o Explain…

© 2014 Pearson Education, Inc. The zebra mussel and the quagga mussel are modifying ecological communities. What is an invasive species? What is an introduced species?

Zebra Mussels… another view... are invasive species all bad?

© 2011 Pearson Education, Inc. Explain the goals and the methods of restoration ecology. Restoration ecology is the science of restoring communities to a previous, more functional or more “natural” condition, variously defined as before human or before recent industrial impact. -Explain… The growing practice of restoration ecology, informed by the science of restoration ecology, helps us restore ecological systems. -Explain…

© 2011 Pearson Education, Inc. Ecological restoration is being used to restore prairies. Prairie restoration involves replanting native species, controlling invasive species. Nearly all tallgrass prairie was converted to agriculture by the 19th century