Species diversity is a measure of diversity within an ecological community that encompasses both species richness and evenness of species abundance hamilton, 2005. A diversity index is a quantitative measure that reflects the number of different species and how evenly the individuals are distributed among those species. Typically, the value of a diversity index increases when the number of types increases and the evenness increases. Aug 25, 2014 species diversity concepts for high school students or freshman and sophomore students depends on the curriculum. Index, diversity, fractal theory, species abundance distribution. The summation of all the organisms of the same species or species group that live in a particular geographical area and have the capability of interbreeding. The reciprocal form of simpsons index ensures that the value of the index increases with diversity. The proposed index incorporates an importance weight to each species of organisms found in an ecosystem. For example, in the image below, we can see that these two communities are. Species richness refers to the number of species in an area. Cousins species are by definition different from each other. Species diversity takes into consideration species richness, which is the total number of different species in a. This fact favours ranking rather than additive indices.
We discuss what is meant by biodiversity, and calculate an example. If you have a list of smaller forest components you need to combine them to calculate the total area for each species, we provide two methods for doing this using excel. Food web complexity and species diversity robert t. A rich ecosystem with high species diversity has a large value for the shannon diversity index h, while an. After determining the number of each species car, in each parking lot, the shannon diversity index will be calculated separately for the student lot and the staff lot. There are over 12 000 species of plants in costa rica. At the outset, let us be clear why the prob lem of understanding species diversity is com plicated. Diversity all species diversity indices show a significant degree of positive kurtosis, but no skewness except for sib. 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. This paper is concerned with the estimation of shannons index of diversity when the number of species and the species abundances. Patterns of plant species diversity during succession. Simpsons diversity index apply simpsons reciprocal diversity index and outline its significance.
We provide step by step instructions for calculating the following in microsoft excel. A healthy forest might have a diversity index of 0. A diversity index also called phylogenetic or simpsons diversity index 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. Pdf measuring species diversity for conservation biology. A new importance diversity index is proposed as an enhancement to the traditional shannons diversity index. He also propounds that if a diversity index is to be used, then a variancebased index is preferable i. Shannon weiner diversity index was used to calculate plant species diversity index. Species diversity refers to species richness and how evenly species abundance is distributed. It is a scale independent indicator of diversity, but can be underestimated in communities where clustered distribution of species is found. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext.
The variability of the species diversity indices is extremely low for sib. Simpsons diversity index is a calculation of variety which takes into records both richness and evenness. Evidence of the effects of postharvest practices on vascular plant diversity is limited by an absence of communitylevel studies in older, managed forests. The basic idea of a diversity index is to obtain a quantitative estimate of biological variability that can be used to compare biological entities, composed of direct components, in space or in time. The index was resolved into its components, species richness and relative abundance, to determine which components played a larger role in the determination of diversity patterns.
Similar trends can be observed in the landcover change for related habitats between 1990 and 2000, especially for heaths and scrubs as well as mires, bogs and fens, which are specific wetland habitats. Therefore, index is usually expressed as 1 i or li. A rich ecosystem with high species diversity has a large value for the shannon diversity index h, while an ecosystem. Diversity indices provide more information about community composition than simply species richness i.
A a diversity index is a mathematical measure of species diversity in a given community. Dominance indices are weighted toward the abundance of the commonest species. Measurements of biodiversity marinespecies introduced. B based on the species richness the number of species present and species abundance the number of individuals per species. Endemic species is one whose habitat is restricted to a particular area. Application of diversity indices and an index of biotic integrity to a basin area.
Paine department of zoology, university of washington, seattle, washington though longitudinal or latitudinal gradients in species diversity tend to be well described in a zoogeographic sense, they also are poorly under stood phenomena of major ecological interest. Species diversity and equitability species density and relative importance have been combined in the concept of species diversity, sometimes also known as biodiversity, which increases with both increasing species richness and with increasing equality of importance among members of an assemblage, known as equitability. A diversity index is a mathematical measure of species diversity in a community. Species diversity is the number of different species that are represented in a given community a dataset. Nonparametric estimation of shannons index of diversity. Species diversity considers both the number of species richness in the community and their relative abundance evenness or equability. Species richness an index based on the number of species i. Kathryn morris1,2, tancredi caruso3, franc ois buscot4,5,6, markus fischer7, christine hancock8. The index is normally used in studies of vegetation but can also be applied to comparisons of animal or even all species diversity. A book on biodiversity and community ecology analysis is available for free download from the website.
Do the factors controlling species diversity just constitute a laundry list, a catalog without. It is a parametric diversity index which assumes that species abundance follows log distribution. Application of diversity indices and an index of biotic integrity to a. Correlation r between species richness, diversity and evenness on the one hand, and. May 04, 2015 in this video we look at aqas version of an index of species diversity.
The impact of wetlands on avian diversity and species. Statistics shannon wiener diversity index in the literature, the terms species richness and species diversity are sometimes used interchangeably. In 2008, we measured richness and diversity considering all. The present study was conducted in the subtropical vegetation stands in the suburban areas of muzaffarabad city to study the diversity and distribution of invasive alien species ias of plants and assess the factors responsible for their spread. It is between 20 and 30% for the number of species sand margalevs index ma, both indices which. A community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance. It is sometimes incorrectly referred to as the shannon weaver index krebs, 1985. Studies of species diversity are a major component of community ecology and. We apply the condition that evenness should be independent of species richness help.
Difficult to define because definition consists of two distinct components. Species richness the number of species that live in a certain location. This is a very simplified version of diversity index. Jan 30, 2016 this website and its content is subject to our terms and conditions.
Hothorn, 1 christiane fischer, 2 heiko nacke, 2 kai u. C the more species you have, the more diverse the area. The index is most often used for ecological studies that measure species diversity, but the same analysis can also be applied to other principles, such. Explain how this has resulted in a high species diversity of animals. The number of a species within a given sample, community or area usually from a particular taxa, e. Pdf biodiversity, a multidimensional property of natural systems, is difficult to quantify partly. Species diversity is a benchmark that can be used to evaluate the health of ecosystems.
Communities in which such large patches are rare are characterized by a large number of species that reach the canopy through small gaps and realtively few which regenerate in the large clearings. Species abundance refers to the number of individuals per species. Diversity increases during succession following a large scale disturbance. Species richness and evenness can be combined into a single indicator, and in ecology the shannon index is commonly used. Diversity, inclusion, people development and news controversies. A total of 5 plant species were recorded, 122 species belonging to 39 families were identified to species level, 8 species were identified to genus level while 5 were unidentified. In addition, new methods show how the degree of difference between species can be included in an index.
Scribd is the worlds largest social reading and publishing site. There are numerous reasons why species diversity is essential. The relationship between species richness s, the number of species. Assessing group differences in biodiversity by simultaneously. By not allowing one species or another to become overly dominant, a keystone species maintains species diversity and ecosystem integrity. It has been a useful tool to understand the profile of biodiversity across study area.
A variety of objective measures have been created in order to empirically measure biodiversity. Species diversity refers to the measure of diversity in an ecological community. The simplest of whittakers original definitions of beta diversity is. Species diversity can be used to determine whether conservationist measures and interventions are required in a particular area. 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. May 19, 2005 butterfly and bird species occurring in different habitat types across europe show population declines of between 2% and 37% since the early 1970s. Here gamma diversity is the total species diversity of a landscape and alpha diversity is the mean species diversity per habitat. Simpsons diversity index a community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance.
Brief outlines of the two types of diversity indices of biodiversity are discussed in this article. A relationship between species richness and evenness that. Natural resources managers and policy makers may use species richness and diversity indices to describe the status of ecological. Gamma diversity and alpha diversity can be calculated directly from species inventory data.
Tes global ltd is registered in england company no 02017289 with its registered office at 26 red lion square london wc1r 4hq. The diversity index we will use is the shannon diversity index. Diversity and distribution of invasive plant species in. My examples will be drawn mostly from the other papers of this sym posium. The document is still incomplete and does not cover all diversity methods in vegan. Community dynamics, or interactions between species, can be modeled using path analysis to describe direct and indirect interactions between species and to quantify the strength of these interactions. Statistics shannon wiener diversity index tutorialspoint. Simpsons diversity index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species.
The more accurate versions are called the simpson and shannon. Indices n1 and hadj have not been included in the dendrogram. In a healthy ecosystem, a diverse and balanced number of species exist and maintain the equilibrium of the ecosystem. Dbh and height relationship was determined using regression graph of dbh as the independent variable and height as the response variable.
Assessing group differences in biodiversity by simultaneously testing a userdefined selection of diversity indices philip pallmann, 1 frank schaarschmidt, 1 ludwig a. Species richness variety of species or the number of different species or genera, families, etc. Measuring forest tree species diversity forest research. 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. As a measure of species diversity, we will calculate the shannon index. In the first place, species diversity is surely not determined in all cases by the same single factor but is the outcome of many contributing factors. The main difference between species diversity and ecosystem diversity is that the species diversity is the variety of species in a particular region whereas the ecosystem diversity is the variety of ecosystems in a particular area species diversity and ecosystem diversity, along with genetic diversity, are the three levels of biodiversity on the earth. Diversity indices usually used as biodiversity as in species, but can apply to other data where you count the number of times a particular category occurs e. We suggest that at the very least, authors should define.
The maximum number for a location is equal to the total number of species present. It is used to measure the local members of a set, and many fields can be studied to evaluate the diversity of any population. Dbh and height distribution was plotted using histogram. Fishers alpha index it is a tool to measure the diversity within a population. A widely used dominance index is simpsons diversity index. Weighting effective number of species measures by abundance. The importance of species diversity to the ecosystem. What is the difference between species diversity and. Species diversity species diversity differs from species richness in that it takes into account both the numbers of species present and the dominance or evenness of species in relation to one another. May 19, 2010 environmental stress affects species richness and diversity in communities, but the precise form of the relationship is unclear. View species diversity research papers on academia. Species and biological diversity choices of diversity.
For example, communities with a large number of species that are evenly. The impact of wetlands on avian diversity and species richness at brookhaven national laboratory long island, new york. The index independently derived by shannon and wiener from the application of information theory is known as the sharmon index of diversity. However, diversity may remain depressed for more than two decades on severely burned sites, and some species may experience local extinction.94 1301 1524 985 885 523 125 728 1252 489 389 618 293 764 639 1161 521 448 20 990 229 918 1386 165 173 804 1335 253 785 1084 416 685 586 342 1066 441 1342 1208 951 1274