Community Ecology

Question 1

Describe Simpson’s diversity Index

Answer 1

Simplest measure of the character of a community:
Takes into account both abundance (or biomass) patterns and species richness
Simpson’s Index, D = 1/(∑_(𝑖=1)^S 𝑃𝑖^2 )

Question 2

Describe Equitability

Answer 2

Equitability can itself be quantified (between 0 and 1) by expressing Simpson’s index, D, as a proportion of the maximum possible value D would assume if individuals were completely evenly distributed amongst the species.

Question 3

Describe the Shannon Index

Answer 3

The Shannon Index (sometimes called Shannon-Weaver or Shannon-Weiner) is a measure of community diversity that takes into account both abundance and species richness patterns

Question 4

Describe other commonly used indices

Answer 4

Hill numbers or the effective number of species are increasingly used to quantify species diversity of an assemblage. Recently extended to phylogenetic diversity, which incorporates species evolutionary history, as well as to functional diversity, whichconsiders the differences among species traits.

For a landscape of habitat patches containing different sets of species,

total species richness of the region, γ‐richness
average species richness within patches (α‐richness) and
between‐patch component of regional richness (β‐richness)

Question 5

Describe the national vegetation classification

Answer 5

‘Phytosociological classification’ used to assign the vegetation to a community
Generalisations are possible when some details (minor variations) don’t matter.
Like species, associations are grouped together in higher or lower taxa—that is, alliances, orders, and sub-associations.

Question 6

Describe the roots of community

Answer 6

biocœnose
First used* by zoologist Möbius in 1877, between 1868 and 1870 he studied oyster banks to determine their potential for commercial exploitation.
Each species is represented by the greatest number of individuals which can grow to maturity subject to the conditions which surround them

Question 7

Describe succession

Answer 7

SUCCESSION: ‘The developmental study of vegetation rests upon the assumption that the unit or climax formation is an organic entity.’

As an organism the formation arises, grows, matures, and dies.

Question 8

Describe the modern definition of community

Answer 8

an [interactive] assemblage of species populations that occur together in space and time
‘The end of the process of stabilization is a climax [community].
The essential cause of stabilization is dominance.