Food webs are extensions of the concept of trophic levels- the compartmentalized view of how energy flows through ecoystems from primary producers to primary, secondary and tertiary consumers. The food web concept clarifies that individual species can influence energy flow in more than one of these trophic levels. These and related topics are the subject of the next video in a lecture series related to the AP Environmental Science national curriculum. The video also reviews the concept of trophic efficiency- the percent of energy that is passed from one trophic level to the next, and compares the productivity of a variety of ecosystems on planet Earth.
The focus of the video then shifts to that of biological diversity. It compares a system with few species in which some reach great abundance with a system housing many species in which no one assumes dominance. It also examines the components of diversity- richness and evenness. The video concludes by considering the patterns of diversity that may be viewed at large geographic scales. This and other videos in this series are produced by the publishing partner of Bird Conservation Research, Inc.- Arts and Academic Publishing.