The number of different species present within a given area is known as the species richness. Through sampling or a census, one can determine a region's species richness. In order to account for differences in spatial scale, species richness has been further divided into three components. They are alpha diversity, beta diversity, and gamma diversity. This article will explain to you about Species Richness which will be helpful in preparing the Environment Syllabus for the UPSC Civil Service exam.

Species Richness

Number of Species on Earth

• Despite many efforts, there is little known about the species that live on the planet.
• There have been about 1.5 million species described, however, there are still many unknown species.
• There are an estimated 3 million to 100 million species on Earth, with more recent estimates often falling between 8 and 11 million species.
• According to a 2011 survey, just 13% of eukaryotic species—which include plants, animals, fungus, and algae—have been named.
• Although bacterial species numbers are primarily speculative, biologists agree that science has just recently started to document their variety.
• There are actually between 1 and 6 billion species on Earth, with at least 70% of them being bacteria, according to a 2017 study by Brendan Larsen and colleagues.

Species Richness - Sampling Considerations

• Depending on the purposes of assessing species richness, the individuals might be selected in different ways.
• They can be, for example, trees located in an inventory plot, birds observed from a monitoring station, or insects gathered in a pitfall trap.
• If the species-level taxonomy of the creatures of interest is sufficiently understood, it is possible to precisely measure the species richness of a group of individuals once it has been defined.
• For the same group of individuals, applying various species delimitations will result in various species richness values.
• People are typically interested in the species diversity in places that are so huge that not every individual can be observed and assigned to a species.
• When alternative sampling techniques are used, multiple sets of individuals will be seen for the same area of interest, and each set's species richness may vary.
• A new member of a set may introduce a species that wasn't previously represented in the set, increasing the set's species richness.
• As a result, sets with a large number of people are likely to contain more species than sets with a smaller number of individuals.

Species Richness - Measurement

Alpha Diversity

• Alpha diversity is a metric for species diversity within a given ecosystem or geographic region.
• The number of species found in the area of concern is how alpha diversity is expressed.
• As a result, species richness in that particular ecosystem is provided by alpha diversity.
• Compared to beta and gamma diversity, alpha diversity is a small-scale indicator.
• When compared to species diversity within different ecosystems, species richness is a useful metric.
• The number of species is calculated based on the species we observe along the survey.

*To know more about the topic, click this link Alpha Diversity

Beta Diversity

• When species diversity varies between groups or ecosystems, it is referred to as beta diversity.
• Therefore, beta diversity enables the comparison of ecosystem biodiversity.
• The number of species that are particular to each system is measured in beta diversity.
• Example: If the beta diversity between ecosystems A and B is 10, this indicates that a total of 10 different species exist between the two ecosystems.
• While ecosystem B has two unique species that are not present in environment A, ecosystem A may have up to eight distinct species that are not present in ecosystem B. Consequently, the two ecosystems' beta diversity is equal to 10.

*To know more about the topic, click this link Beta Diversity

Gamma Diversity

• Gamma diversity is a measurement for assessing a large area's total biodiversity.
• As a result, it calculates the total diversity of all the ecosystems in that area.
• The average species diversity in an ecosystem and the variation in species diversity between those habitats are the two factors that determine total diversity.
• Geographic-scale species diversity is one sort of gamma diversity.
• When referring to biodiversity hotspots, gamma diversity, the level of species diversity, is most frequently discussed, with tropical regions, particularly the Neotropics, displaying the highest gamma diversity values globally.

*To know more about the topic, click this link Gamma Diversity

Species Richness - Example

• Consider a mountainside for the landscape.
• There will be a variety of diverse sections of grasses and trees on this slope.
• Alpha diversity is the variety of species found inside each patch of forest or grassland on the slope.
• The species diversity between any two patches and their communities serves as a proxy for beta diversity.
• The species richness along the full length of the mountain slope is known as the gamma diversity of the terrain.

Species Richness - Trends

• The observed species richness is influenced by the sample's heterogeneity as well as the total number of individuals.
• The species richness of the resulting set can be expected to be higher if individuals are collected from various environmental circumstances (or habitats), as opposed to if all individuals are taken from the same environment.
• A species accumulation curve can be used to illustrate how new species are added with increased sampling effort.
• Such curves can be built in a variety of ways.
• Because more individuals are included in the sample as the region sampled grows and because larger areas have greater environmental diversity than smaller ones, reported species richness increases.
• There are latitudinal variations in species richness since many organism groups have most of their species in the tropics.
• The connection between productivity and species richness has been the subject of extensive discussion.
• No universal agreement has been reached on the pattern or its potential explanations as a result of the disparate findings from different investigations.

Conclusion

Species richness is frequently employed as a criterion when evaluating the relative conservation values of ecosystems or landscapes. However, species richness is oblivious to the species identity. An area with a high concentration of endemic or uncommon species is typically thought to have more conservation significance than an area with a similar species richness but where every species is widespread and ubiquitous.