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Measurements of Ecological Diversity How to measure Diversity in an ecological system Laila, Vimal, & Rozie. Diversity-Stability Hypothesis McArthur (1955). WHY ?. Ecologists describe distribution of diversity on a spatial scale in three classifications.
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in three classifications.
The diversity of organisms within a
selected habitat or sample.
Index of the rate of increase of alpha
as new habitats are sampled.
The full species diversity/ species richness.
Alpha, Beta, and Gamma diversity measures are Scale Dependent.
What’s that mean?
One acre of land
and calls this
Ecologist two studies microbial organisms,
therefore one acre of land would contain
an infinite amount of microhabitats under
his consideration. The one acre of land would
be measuring Gamma Diversity.
can be measured to indicate its alpha diversity?
functions to describe diversity indices by encapsulating
different aspects of the balance between richness and balance.
The Shannon Index
The Simpson Index
of a Population Proportion Pi
3.3219 x H’(base 10)
Both the indices mentioned do not come with estimates of variability.
Why would a scientist be interested in estimates of variability?
Jack-Knifing is an extension of the resampling process,
performed by a computer using the completed final dataset.
It obtains estimates of the variability within
parameter estimates in a wide range of
settings, including diversity indices.
stabilizing of values due to dominance
of one species.
The species richness diversity index
shows a clear pattern: increases
consistently every year.
Five experimental plots:
Brachypodium pinnatum was
present, not dominant.
* different concentrations of
nitrogen, phosphorus, &
* increase in biomass,
decrease in number of
Data summarized using
Interest: the effects of
pollution on the growth of
Problem: high levels of
nitrogen deposits due to
Effect: stimulates coarse
grasses in preference to
the rich community of low-
growing, less vigorous herbs.
Brachypodium pinnatum is able to flourish on high levels of
nitrogen & low levels of phosphorus. The coarse grass was
able to use its height to shade out other species therefore
1. Reducing Biodiversity
2. Reducing conservation value of habitat.
The Macintosh Index of Diversity
D= [N-(∑ni2)1/2] / N-N1/2