Soil Microorganisms and Nematodes for Bioremediation and Amelioration

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TABLE 1.5 Various Ecological Indices to Study Community Changes of Nematode Under Stress

Parameters/Ecological Index Calculation/Definition

Purpose

References

Colonizer–persister (cp) values The cp scale corresponds to r–K strategy: cp

1 (colonizers, opportunists) are r-strategists,

cp 5 (persisters) are K-strategists.

Categorization of nematode taxa

Bongers &

Ferris (1999)

Maturity index (MI)

Plant parasitic index (PPI)

Weighted mean of the c-p values for all

individual nematodes in a representative soil

sample excluding plant parasite nematodes.

Weighted mean of the c-p values for all

individual plant parasite nematodes in a

representative soil sample.

Monitor colonization and subsequent

succession after disturbances, measure

xenobiotic-induced stress, differentiate

between tillage practices, aftereffects of

liming an acid soil

Bongers &

Ferris (1999)

Modified maturity index

(mMI)

Weighted mean of the c–p values for all

individual nematodes in a representative soil

sample

PPI/MI ratio

–

Assessment and monitoring of the status

recovery of disturbed habitats.

Yeates &

Bongers (1999)

Shannon-Weaver’s diversity

index

H´ = –Σ pi log2 p

where; pi is n/N, n being the number of

organisms of the ith species and N the total

number of organisms in the sample

Characterize nematode diversity under

stress

Shannon &

Grieve (1998)

Simpson’s diversity index

Ds = 1 – Σ(pi)2

–

Hurlbert (1971)

where; pi is the percent of genus ‘i’ in the total

abundance.