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Sunday, January 29, 2017

SPECIES DIVERSITY

The wet, high elevation limestone forests of Rota in the tropical Pacific are characterized by epiphytic ferns, fern allies and orchids.

The topic of species diversity is focused upon in this next episode of a video series designed to complement the AP Environmental Science curriculum.  It begins with an exploration of the scale at which diversity is considered,  discussing the concepts of alpha, beta and gamma diversity.  It also considers the components of diversity- species richness and species evenness.  

The video then goes on to examine methods of computing diversity.  It evaluates the uses and pitfalls of diversity characterization, including the loss of information that occurs by computing diversity indicies.

Still another diversity-related issue is the edge effect.  The video examines how diversity responds to the boundary between habitats and how certain species are edge specialists.  It also notes, however, that edges can have reduced habitat quality as well as higher rates of predator activity.

The video concludes by examining the species-area effect.  It considers the phenomenon of minimum habitat size and the role of chance in the accumulation of species by virtue of area.


This and other videos in this series are produced by the publishing partner of Bird Conservation Research, Inc- Arts and AcademicPublishing.


Tuesday, January 10, 2017

FOOD WEBS AND SPECIES DIVERSITY



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.