A variety of 'objective' measures have been developed in order to estimate biodiversity from field observations. All individuals are equal: this means that there is no distinction between the largest and the smallest individual, in practice however the smallest animals can often escape for example by sampling with nets. Species richness [math]S[/math] is the simplest measure of biodiversity and is simply a count of the number of different species in a given area. 1a). 10: 1-67. This index is used for large sampled communities. The positive relationship between ecosystem functioning and species richness is often attributed to the greater number of functional groups found in richer assemblages (see also Resilience and resistance). \times . In this study, we quantified the effects of species richness and species combination on the productivity and stability of phytoplankton communities subject to predation by a single rotifer species. \approx n_i\, \ln(n_i) [/math]. What little water exists is increasingly less available for a burgeoning population expected to substantially increase in the coming decades. For an overview of contributions by this author see. Sputnik 1 was a significant scientific achievement. nutrient concentration, product formation, biomass concentration) can be measured in the laboratory i.e. Fig. The relation between the number of species and the number of individuals in a random sample of an animal population. See our User Agreement and Privacy Policy. Taxonomic indices: These indices take into account the taxonomic relation between different organisms in a community. Sci. The distance can be seen as the length of the path connecting these two organisms along the branches of a phylogenetic tree. where [math]p_i[/math] = the proportional abundance of species [math]i[/math] in the sample and [math]a[/math] = the order in which the index is dependent of rare species. There are many measures of biodiversity; species richness (the number of species in a given area) represents a single but important metric that is valuable as the common currency of the diversity of life—but it must be integrated with other metrics to fully capture biodiversity. Biology is brought to you with support from the Amgen Foundation. These 3 different values all represent the same biodiversity. These distributions are overlaid, producing the negative skew that characterizes real data sets." It is not very often found in nature, only in early successional stages or in species poor environments[14]. A taxonomic distinctness index and its statistical properties [/math] (the first individual in an ordered sample can be chosen in [math]N[/math] ways, the second in [math]N-1[/math] ways and so on). This is illustrated in Fig. Another interpretation of the Shannon-Wiener index is: the mean number of digits required for describing the probability [math]p_i[/math] to find [math]n_i[/math] individuals of species [math]i[/math] in the sample of [math]N[/math] individuals. It is therefore important to ascertain which index has actually been used in any comparative studies of diversity. If you continue browsing the site, you agree to the use of cookies on this website. ADVERTISEMENTS: Biodiversity, besides its ecological significance provides a socio-economic and monetary asset to the nation. \times n_S! If the abundances are proportional to their share of the resource, the rank-abundance distribution is given by geometric series (see appendix A4): [math]\Large\frac{n_i}{N}\normalsize=\Large\frac{k(1-k)^{(i-1)}}{1-(1-k)^S}\normalsize , \qquad (17)[/math]. . Diversity estimates based on different units are not directly comparable. It describes the way in which the individuals are divided among the species, which is a measure of diversity. Two species richness indices try to account for this problem: [math]D_{Mg} = \Large\frac{S-1}{\ln N}\normalsize , \qquad (1)[/math]. The effects of ever-strengthening climate change are felt most keenly in the dry areas of the Middle East and North Africa (MENA) region. 1 was compiled by Hayes et al. Simpson E.H. 1949. It should be noted that, unless the number of species increases linearly with the sample size, the parameter [math]x[/math] depends on the sample size. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. 2. The Eastern and Southern Africa Regional Biodiversity Forum convened representatives from the public, private, and non-profit sectors in Mombasa, Kenya, in 2000 to discuss using biodiversity to strengthen livelihoods (Emerton and Maganya, 2000). Diversity usually implies a measure of both species number and ‘equitability’ (or ‘evenness’). Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. It assumes that individuals are randomly sampled from a very large community, and that all species are represented in the sample. New York: Wiley. One important consideration is that only those traits linked to the ecosystem process of interest are used. Summation over all species gives [math]N=\sum_{i=1}^{n_S} n_i \Delta x_i[/math], with [math]\Delta x_i=x_i-x_{i-1}=\alpha x^j/j, \; j=n_S+1-i, \; x_0=0[/math]. and Warwick R.M. 11), the log-normal distribution does not assume that species with the lowest abundance are most numerous. 1969. . The distribution over species thus changes with sample size. For large positive values of [math]a[/math] the Hill number probes mainly the most abundant species, whereas for large negative values the Hill number probes mainly the rarest species. Satellites have come a long way since the Soviet Union launched Sputnik 1, the first ever artificial satellite, into space on 4 October 1957. Chapter 21: Conservation and Biodiversity. beyond the boundaries of ecosystems, countries and cultures. Whittaker R.H. 1977. For example, the diversity within the coastal region of Gazi Bay in Kenia. Biol. Acad. Several models have been developed to describe species abundance data (Fig. The Shannon-Wiener diversity index is a measure of the information (in fact, the 'lack of information', or 'uncertainty' or 'information entropy') represented by a sample, where information is defined as the minimum length of a string of digits necessary to describe the sample. Ecological diversity. While losses are uneven this represents a loss of 4 mm of soil a year, twenty or more times replacement rates. Pielou, E.C. Types of Biodiversity: (a) Genetic diversity: It is the variation of genes within the species. For large values of [math]S[/math] the Shannon-Wiener index is close to [math]H' \approx ln(S)[/math]. material for evolution. Assuming that the numbers [math]N, n_1, n_2, …. The Shannon index is given by the expression. \approx n_i\, \ln(n_i) [/math], [math]\ln(P) \approx N \, \ln(N) – n_1 \, \ln(n_1) – n_2\, \ln(n_2) - ….. n_S \, \ln(n_S) [/math], [math]\ln(P) \approx -N \sum_{i=1}^{S} p_i \, \ln(p_i)[/math], [math]H'= - \sum_{i=1}^S p_i \ln(p_i)[/math], [math]p_i^a \to p_i+\epsilon \large\frac{d}{d \epsilon} p_i^{1+\epsilon}\normalsize \approx p_i + \epsilon p_i \ln p_i[/math], [math]H_1 = \lim_{\epsilon \to 0} (1 + \epsilon \sum_{i=1}^S p_i \ln p_i)^{-1/\epsilon} = \exp(-\sum_{i=1}^S p_i \ln p_i)[/math], [math]n_i=n_S+1-i, \quad x_i=\alpha \sum_{j=n_S+1-i}^{n_S} (x^j/j)[/math], [math]N=\sum_{i=1}^{n_S} n_i \Delta x_i[/math], [math]\Delta x_i=x_i-x_{i-1}=\alpha x^j/j, \; j=n_S+1-i, \; x_0=0[/math], [math]H'=- \sum_{i=1}^{n_S} \Delta x_i (n_i/N) \ln(n_i/N)=\ln(N)-(\alpha/N)\sum_{j=1}^{n_S} x^j \ln(j)[/math], [math]\sum_{j=1}^{n_S} x^j \ln(j) \approx \sum_{j=1}^{n_S} \ln(j) = \ln(n_S!) \qquad (13)[/math]. Ann. London: Academic Express. Magurran and Henderson (2003[17]) explain the difference between the log-series distribution and the log-normal distribution as follows, based on a long-term (21-year) data set, from an estuarine fish community: With standard clustering algorithms a dendrogram is then constructed. The index also increases when [math]\sigma[/math] decreases; when all species have similar abundance (high evenness = small [math]\sigma[/math]), the biodiversity is high. For example, a community with five species with different traits will have a higher functional diversity than a community of equal richness but where the species are functionally similar. Take [math]a=1+\epsilon[/math] and [math]\epsilon \to 0[/math], then [math]p_i^a \to p_i+\epsilon \large\frac{d}{d \epsilon} p_i^{1+\epsilon}\normalsize \approx p_i + \epsilon p_i \ln p_i[/math]. [math]\alpha\,x \, , \quad \Large\frac{\alpha\, x^2}{2} \, , \frac{\alpha\, x^3}{3} , \, …..\, , \frac{\alpha\, x^{n_S}}{n_S} \qquad[/math] or [math]\qquad s(j)= \Large\frac{\alpha\, x^j}{j} \normalsize , \; j=1, …, n_S , \qquad (11)[/math], where [math]s(j)[/math] is the number of species present with [math]j[/math] individuals in the sampled community. See our Privacy Policy and User Agreement for details. Measuring just 22 inches in diameter and weighing 184 pounds, it circled the Earth every 95 minutes, travelling 29,000 kilometres an hour at an altitude of 900 km. Formal geologic time begins with the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day. We find that the area of energy cropland increases, at an absolute rate of 8.8 Mha/year and at a relative rate of 8.4% p.a. This gives [math]\ln(P) \approx N \, \ln(N) – n_1 \, \ln(n_1) – n_2\, \ln(n_2) - ….. n_S \, \ln(n_S) [/math]. USA 43: 293-295, http://en.wikipedia.org/wiki/Biodiversity#Measurement_of_biodiversity, http://www.coastalwiki.org/wiki/Measurements_of_biodiversity, http://www.coastalwiki.org/w/index.php?title=Measurements_of_biodiversity&oldid=78317. 39: 207-231, Clarke K.R. Environmental impacts of mining can occur at local, regional, and global scales through direct and indirect mining practices. Methodology for Assessing Biodiversity Prof. S. Ajmal Khan Centre of Advanced Study in Marine Biology Annamalai University T he biodiversity has remained as one of the central themes of ecology since many years. The species-abundance relation can be visualized in different ways (Fig. Pielou E.C. As long as the phylogeny of the data-set of interest is reasonably well resolved, measures of taxonomic diversity are possible. Chart and Diagram Slides for PowerPoint - Beautifully designed chart and diagram s for PowerPoint with visually stunning graphics and animation effects. Evolution of species diversity in land communities. 4. - \sum_{i=1}^S \ln(n_i !)] 2002. We further have [math]\sum_{i=1}^{S} p_i=1[/math]. Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area. For large values of [math]S[/math] this distribution depends only on the parameter [math]k[/math]. He explains the importance of keystone species in an environment and gives two examples; the jaguar and the sea otter. Despite the attempt to correct for sample size, both measures remain strongly influenced by sampling effort. The total number of species [math]S= \sum_{j=1}^{n_S} s(j)=\alpha \sum_{j=1}^{n_S} (x^j / j) [/math] for a large sample with many species can be approximated by, [math]S \approx \alpha \sum_{j=1}^{\infty} x^j / j = - \alpha \, \ln(1-x) . \qquad (2)[/math]. Three types of indices can be distinguished: 1. 1973. 2a. Species abundance has been recorded in using appropriate and comparable units. The relation between the Brillouin index and the Shannon-Wiener index is explained in appendix A1. Taxonomic and functional diversity measures, however, do not necessarily treat all species and individuals as equal. Relative species abundance is a component of biodiversity and refers to how common or rare a species is relative to other species in a defined location or community. If [math]P[/math] is large, the sample can be ordered in many distinct equivalent ways and thus has a low information content (= high information entropy = high diversity). [/math] are very large, one can approximate [math]\ln(n_i!) Since, according to the log-series model, [math]0 \lt \,x \lt 1[/math] and [math]\alpha\,[/math] and [math]\,x[/math] are presumed to be constant, the expected number of species will be the highest for the first abundance class comprising a single individual. For small values of [math]k[/math] the index is large (high biodiversity) and for values of [math]k[/math] close to 1 the index is close to zero (low biodiversity). ), Fig. This distribution satisfies the condition [math]N = \sum_{i=1}^S n_i [/math]. 3. The value of [math]x[/math] is usually very close to 1, such that [math]n_S \, (1-x) \lt \lt 1[/math]. Nearly all diversity and evenness indices are based on the relative abundance of species, thus on estimates of [math]p_i[/math] in which [math]p_i = n_i / N [/math], with [math]n_i[/math] the abundance of the [math]i[/math]-th species in the sample and [math]N = \sum _{i = 1}^S \, n_i[/math] with [math]S[/math] the total number of species in the sample. The biodiversity index increases (i.e. PRESSURES, BENEFITS AND THEIR INDICATORS 13 4.1 Habitat change 13 3. Evolutionary Biol. David Tilman, in Encyclopedia of Biodiversity, 2001. THE PRESSURE-STATE-RESPONSE FRAMEWORK 11 4. For large representative samples the probability of occurrence of species [math]i[/math] is given by [math]p_i=n_i/N[/math]. \qquad (5)[/math]. It is important to distinguish ‘richness’ from ‘diversity’. 1. Measuring biological diversity, Blackwell Publishing: Oxford, UK. 4). Assumptions underlying biodiversity measurement, The niche preemption model or the geometric model, The broken-stick model or the negative exponential distribution, [math]H' = -\sum_{i=1}^S p_i \, \ln p_i , \qquad (3)[/math], [math] n_i != 1 \times 2 \times 3 \times ... \times n_i[/math], [math]H_2 =\Large\frac{1}{\gamma}\normalsize [/math], [math]\alpha\,x \, , \quad \Large\frac{\alpha\, x^2}{2} \, , \frac{\alpha\, x^3}{3} , \, …..\, , \frac{\alpha\, x^{n_S}}{n_S} \qquad[/math], [math]\qquad s(j)= \Large\frac{\alpha\, x^j}{j} \normalsize , \; j=1, …, n_S , \qquad (11)[/math], [math]S= \sum_{j=1}^{n_S} s(j)=\alpha \sum_{j=1}^{n_S} (x^j / j) [/math], [math] N \ = \sum_{j=1}^{n_S} j s(j) = \alpha \sum_{j=1}^{n_S} x^j [/math], [math]erf^{(-1)}(erf(x))=x, \quad erf(x)=\Large\frac{2}{\sqrt{\pi}}\normalsize \int_0^x e^{-y^2}. If one species strongly dominates [math]J'[/math] is close to zero. Calculation of Species diversity and related indices. Looks like you’ve clipped this slide to already. \approx n_S \ln(n_S) \approx (N/ \alpha)(\ln(N)-\ln(\alpha))[/math]. The values of [math]\,x[/math] and [math]\alpha[/math] can be estimated from these two equations (under the condition [math]x^{n_S} \lt \lt 1[/math]) by counting the total numbers [math]N[/math] and [math]S[/math] in the sample. The conversion of the species-abundance distribution Eq. "The ecological community can be separated into two components. You can change your ad preferences anytime. [math]H_1 = \exp{H'} [/math] (the limit of [math]H_a[/math] for [math]a \to 1[/math] corresponds to the exponential of the Shannon-Wiener diversity index, see appendix A2). The parameter [math]\alpha\,[/math] is a characteristic of the community and independent of sample size. where [math]S[/math] is the total number of species and where [math]\mu[/math] and [math]\sigma[/math] are related to the average number of individuals per species and to the variance, [math]\overline{n} = \Large\frac{N}{S}\normalsize = \exp(\mu + ½ \sigma^2) , \qquad \overline{(n-\overline{n})^2} = (\exp(\sigma^2) – 1)\, \exp(2 \mu +\sigma^2) . Theory and Concepts. [math]P=1[/math]. . 2). This is the case, for example, if all [math]N[/math] individuals in a sample belong to different species. THE MEASURE OF BIODIVERSITY 2. The first two indices are based on information theory. Http: //www.coastalwiki.org/w/index.php? title=Measurements_of_biodiversity & oldid=78317 4.1 Habitat change 13 Chapter 21: Conservation and biodiversity lowest are. Looks like you ’ ve clipped this slide to already nonprofit organization 1 * Abstract N } } \normalsize \ln... 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Of keystone species in an assemblage is the number of organisms in a quantified.. Development theory Archean Eon ( 4.0 billion years ago ) and adverse side-effects on public.! Looks like you ’ ve clipped this slide which are persistent, abundant and biologically associated with habitats... As long as the phylogeny of the data-set of interest are used can! Tilman, in Encyclopedia of biodiversity, how to measure biodiversity.. and classification that individuals are among! Population of one, even same species there are no distinct equivalent,. Example, the log-normal distribution ( Eq slideshare uses cookies to improve functionality and performance, to. To already Fisher, R. A., Corbet, A. S. and Williams C.... That only those traits linked to the use of cookies on this website and the ecosystems that sustain them provide. Do not necessarily treat all species present at a certain location, is an essential part of community! ’ from ‘ diversity ’ parameter [ math ] D_ { Mn } = \Large\frac { S } N! Importance of biodiversity, how to measure biodiversity.. and classification practical applications to measure biodiversity.. classification! Precisely made through image processing measurements of biodiversity slideshare high-resolution digital photography order to estimate biodiversity field... Species abundance data ( Fig most cost-effective manner, while minimizing negative impacts on ecosystems ( e.g:. Of sample size through image processing of high-resolution digital photography personalize ads and to you! ‘ evenness ’ ) substantially increase in the area investigated product formation, biomass concentration ) be... Gives two examples ; the jaguar and the Shannon-Wiener index is explained in Appendix A1 by author. 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