Biodiversity measurements biodiversity higher biology. Chapter 17 indices of association and species diversity indices. Shannon diversity index was used to calculate the species diversity. Difficult to define because definition consists of two distinct components. According to the encyclopedia of earth, species diversity is a measurement of an ecosystems species richness and species evenness. Details of genetic diversity, species diversity and ecosystem diversity are given. Threats to biodiversity have adverse effects on the ecosystem. A biologist is comparing species diversity at two sites within traethygoes sand dunes. Species diversity is marked by some interesting factssuch as larger areas have more species, and diversity is particularly high near the equator. Difference between species richness and species diversity.
The number means the total hits per species per site. Alpha, beta, and gamma diversity biology libretexts. In this video we look at aqas version of an index of species diversity. For example, species richness usually noted s of a dataset is the number of different. List of books and articles about biodiversity online.
Much has been written on species diversity but it remains hard to define. We discuss what is meant by biodiversity, and calculate an example. Species diversity is defined as the number of species and abundance of each species that live in a particular location. This accessible and timely book provides a comprehensive overview of how to measure biodiversity. A total of 158 bird species belonging to 52 different families and 20 orders were identified. The diversity measure is maximal for a fixed number of species s when all species. Practical handbook of the biology and molecular diversity of trichoderma species from tropical regions fungal biology 9783319649450.
Correlation r between species richness, diversity and evenness on the one hand, and. Species diversity is an essential part of an ecosystem since each species fulfills a role of the ecosystem. Scientists have variously estimated that there are from 3 to 30 million extant species, of which 2. The number of species that live in a certain location is called species. Evenness is a measure of the relative abundance of the different species. There are numerous reasons why species diversity is essential.
Species diversity indicates whether most of the individuals of the community belong to one species or not, and how the species are distributed. Other factors to consider are what reduces diversity in ecologically productive places and across what scales of space and time diversity patterns hold. A diversity index is a quantitative measure that reflects how many different types such as. If an ecosystem has poor species diversity, it may not function properly or efficiently. Download species diversity and biogeography of ants pdf 295p download free online book chm pdf. A diverse species assemblage also contributes to ecosystem diversity. Species richness an index based on the number of species i. Indices n1 and hadj have not been included in the dendrogram. In the example in table, the total number of species for the three ecosystems 14, which represent the gamma diversity. We will then consider one measure used to compare diversity among communities, jaccard.
The importance of species diversity to the ecosystem. Horn h 1966 measurement of overlap in comparative ecological studies. Biodiversity is the total variation between all living things and can be measured to help identify species that need to be supported. Shannon index the idea behind this index is that the diversity of a community is similar to the amount of information in a code or message. Ncert class 12 biology biodiversity and conservation. Species richness variety of species or the number of different species or genera, families, etc.
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