If you were to measure the species richness of a forest, you might find 20 bird species, 50 plant species. Imagine chasing a horned lizard, and it uses a bizarre tactic to deter you, squirting blood at you out of its eye. A large proportion of the species waiting to be discovered are in the tropics. Details of genetic diversity, species diversity and ecosystem diversity are given. Pdf an unequivocal, precise, and generally accepted definition of biodiversity does not exist. As with h, evenness assumes that all species are represented within the sample. Sampling and estimation procedures for the vegetation. Genetic diversity is all the different genes contained in all the living species, including individual plants, animals, fungi, and microorganisms. The relationship between species diversity richness and community stability is quite complex. Species diversity takes into consideration species richness, which is the total number of different species in a community. The objective of the study was to identify avian diversity and main threats to them in the sanctuary.
Patterns of tree species diversity in relation to climatic factors on. It has been estimated that more than 50 million species of plants, animals and microorganisms are. Microbial diversity an overview sciencedirect topics. In 2002, governments set 2010 as a deadline to achieve a significant reductionin the rate of loss of biodiversity for reducing poverty.
A new hypothesis, based on differences in the rates at which populations of competing species approach competitive equilibrium reduction or exclusion of some species, is proposed to explain patterns of species diversity. Difficult to define because definition consists of two distinct components. An overview of plant biodiversity is provided in this chapter. Biological diversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. However, conservation biologists often use the term species diversity even. The information theory formulae can also be used to measure habitat diversity and differences between communities or habitats. This global definition makes monitoring biodiversity a. Information and translations of species diversity in the most comprehensive dictionary definitions resource on the web. Ecosystem diversity is the the variety of different ecosystems within an area. Main focus is on the difference in taxonomic abundance. One of the fundamental tenants of diversity is that the number of species found in a given sample is strongly dependent upon the size of that sample. B based on the species richness the number of species present and species abundance the number. However the need for such a definition that is both scientifically sensible and universally applicable is imperative to help guide the design of policy and programs for the future, as well as to make critical decisions in. Structure is the physical organization or pattern of a system, from habitat complexity as measured within communities to the pattern of habitats or patches and other elements at a landscape scale.
Specifically termed as biodiversity, its scope includes but not limited to the following. Alpha diversity refers to the diversity within a particular area or ecosystem, and is usually expressed by the number of species i. It also takes into account evenness, which is the variation of abundance in individuals per species in a. Microbial diversity addresses biological diversity at three levels. It occurs within a species as well as between species. Species diversity is a measurement of species richness combined with evenness, meaning it takes into account not only how many species are present but also how evenly distributed the. Biodiversity definition biological diversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. Biodiversity acronyms areas countries marine terms definition biological diversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. A keystone species is an organism that helps maintain species diversity within an ecosystem by keeping the numbers of other species in an ecosystem constant. Ecosystem diversity is all the different habitats, biological communities and. Species richness an index based on the number of species i.
Biodiversity is not evenly distributed, rather it varies greatly across the globe as well as within regions. To reflect on the definition, impact, and possible vulnerabilities of the concept of biocultur. The objectives of this study were to model how tree species diversity is related to. Species diversity is the number of different species that are represented in a given community a dataset. Species richness the number of species that live in a certain location. Species density or the number of species per m 2 is most commonly used to measure species richness. Simpsons index of diversity national institute for. The intrinsic, ecological, genetic, social, economic, scientific, educational, cultural, recreational and aesthetic values of biological diversity and its components. Species diversity is a measurement of biological diversity to be found in a specific ecological community. The effective number of species refers to the number of equally abundant species needed to obtain the same mean proportional species abundance as that observed in the dataset of interest where all species may not be equally abundant. The plant community data analysis section provides background information on plant community analysis for analysts who are.
Pdf concepts of species diversity by charlie laman unimas. The methods on offer range from the familiar, such as the calculation of various diversity indices and the fitting of common distributions, to more recentlydeveloped techniques such as total species complement estimators. Among other factors, the diversity of all living things depends on temperature, precipitation, altitude, soils, geography and the presence of other species. Species diversity is most commonly meant by biodiversity. Biological diversity or biodiversity is that part of nature which includes the differences in genes among the individuals of a species, the variety and richness of all the plant and animal species at different scales in space, locally, in a region. Human society depends on biological resources, their diversity and the ecosystems that sustain them to provide essential goods and services. Whittaker 1972 described three terms for measuring biodiversity over spatial scales. Do we have species evenness similar abundance level or do some species dominate others. Definition, classification, threats to biodiversity and its conservation. An area with four different ecosystems say boreal, tundra, temperate grasslands, and temperate forests has greater ecosystem diversity than the same size. The evenness of the sample is obtained from the formula. Finally, gamma diversity is the full diversity species richness of an entire sampled landscape or gradient. Species richness variety of species or the number of different species or genera, families, etc.
A diversity index also called phylogenetic indices or phylogenetic metrics is a quantitative measure that reflects how many different types such as species there are in a dataset a community and that can simultaneously take into account the phylogenetic relations among the individuals distributed among those types, such as richness, divergence or evenness. In biology, diversity may pertain to the variation of life forms present in different ecosystems. For example, if we are monitoring the effect that british farming practices have on the. Species diversity is defined as the number of species and abundance of each species that live in a particular location.
The number of species that live in a certain location is called species richness. A general hypothesis of species diversity the american. Species diversity is a measurement of species richness and species evenness. It represents the species richness or number of species found in an ecological community, the abundance or number of individuals per species, and the distribution or evenness of species. Genetic diversity the genetic material of microorganisms, plants and animals contains information that. It is not the diversity of species within an ecosystem. Species diversity is all the differences within and between populations. Species diversity is all the different species, as well as the differences within and between different species.
The hypothesis assumes that most communities exist in a state of nonequilibrium where competitive equilibrium is prevented by periodic population reductions and. Genetic diversity is all the different genes contained in all individual plants, animals, fungi, and microorganisms. Alpha, beta, and gamma diversity biology libretexts. An unequivocal, precise, and generally accepted definition of biodiversity does not exist. The variety and variability of organisms and ecosystems is referred to as biological diversity. A a diversity index is a mathematical measure of species diversity in a given community. Species richness is the number of species present in a sample, ecological community, ecosystem, landscape, region, or any defined spatial unit. Species diversity and richness 4 is designed for professional ecologists and their students. Biodiversity, besides its ecological significance provides a socioeconomic and monetary asset to the nation. Estimates place the global species diversity at several million. Usually three levels of biodiversity are discussedgenetic, species, and ecosystem diversity. What is the difference between species diversity and. Since by definition the pis will all be between zero and one, the. According to iucn 2004, the total number of plant and animal species described so far is slightly more than 1.
Evenness hhmax hlns by definition, e is constrained between 0 and 1. The complete disappearance of a species from the earth. Biodiversity, ecosystems and ecosystem services 7 biodiversity at a suitable scale, e. The importance of species diversity to the ecosystem. B based on the species richness the number of species present and species abundance the number of individuals per species. Biological resources includes genetic resources, organisms or parts thereof, populations, or any other biotic component of ecosystems with actual or potential use or value for humanity. Ecological theory and nature conservation have tradi tionally relied solely on observed local diversity. Species richness is the number of species found in a community or ecosystem. We can compare the actual diversity value to the maximum possible diversity by using a measure called evenness. The smallest sample size may be 1 km and the largest may be the entire region or country. Beta diversity shows the different between microbial communities from different environments.
The study of the spatial distribution of organisms, species and ecosystems, is the science of biogeography. However, species richness increases with sample size. Species diversity refers to the measure of diversity in an ecological community. However, this is not to say that such measures are mutually exclusive. Diversity definition and examples biology online dictionary. Ecological concepts, principles and applications to. Species richness, as measure of diversity, has been used by ecologists. C the more species you have, the more diverse the area. By not allowing one species or another to become overly dominant, a keystone species maintains species diversity and ecosystem integrity. Species diversity species diversity refers to the variety of different types of species found in a particular area.
The year 2010 has long been seen as an end goal, a time when we could look back and say, yes, weve done it that biodiversity, life on earth, is no longer threatened. It is sometimes confused with ecological diversity which is the number of species within a community. This makes good intuitive sense in that the more quadrats one samples in a plant community, the more likely you are to pick up more and more rare species. The study was conducted to measure bird species diversity at taunsa barrage wildlife sanctuary from 2009 to 2011.
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