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Usually expressed as relative values, relative density is the number of a given species expressed as a percentage of all species present, relative frequency is the frequency of a given species expressed as a percentage of the sum of frequency values for all species present, and relative dominance is the basal area of a …

## What is relative density in biodiversity?

Relative density is calculated by dividing the density by the sum of the densities of all species, multiplied by 100 (to obtain a percentage). Dominance is calculated as the total basal area of a species.

## What is the relationship between density and frequency environmental science?

Remember that density measures how many of a species are present, while frequency measures how often that species occurs. Determining the frequency can help researchers define the distribution of species in a community.

## How is ecological importance value calculated?

The importance value is calculated as the sum from (i) the relative frequency; (ii) the relative density; and (iii) the relative dominance. The importance value ranges between 0 and 300. Frequency is calculated as the number of plots where a species is observed divided by the total number of survey plots.

## How do you find frequency in ecology?

Local frequency is easiest to measure if you have a gridded quadrat of 10 x 10 squares. For each species, count the number of squares which are at least half-occupied. The final figure (which will vary between 1 and 100) is the local frequency.

## Why is relative abundance important?

The relative abundance of each species is more evenly distributed than Community 1. While both communities have the same species richness, Community 1 would have greater diversity due to the relative abundance of each species present.