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field_methods:estimate_population_size [2009/09/21 16:04]
jasonkarl
field_methods:estimate_population_size [2012/03/08 15:34]
jgillan
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 +<​sup>​[[:​bug_reporting|Report a bug, broken link, or incorrect content]]</​sup>​[[http://​methods.landscapetoolbox.org|{{ field_methods:​methodsguide3.png?​220x120|}}]]
 ====== Estimate of Population Size ====== ====== Estimate of Population Size ======
- ​[[http://​www.rangelandmethods.org/​about/​get_involved|{{:​abstract_in_dev.gif|}}]]+ ​[[http://​www.landscapetoolbox.org/​about/​get_involved|{{:​abstract_in_dev.gif|}}]]\\ 
 +written by Jason Karl
  
 ===== Method Type ===== ===== Method Type =====
  
 +Abundance - Qualitative
  
 ===== Other Names ===== ===== Other Names =====
  
 +Estimated population count, population estimate
  
 ===== Description and Uses ===== ===== Description and Uses =====
  
 +This technique involves making rapid assessments of the number of individuals in a population at a site by visual estimate. A quick, gross indicator of the size of a population, this technique can sometimes be used for coarse assessments of population trends over time if the change is large. Often, population size can be estimated while collecting presence/​absence data. The establishment of protocols and size classes can help remove some of the subjectivity of this method and increase repeatability. Size and visibility of the plants being counted need to be considered as this method breaks down if many individuals are not detected.
  
 ===== Advantages and Limitations ===== ===== Advantages and Limitations =====
  
 +The main advantage of this method is that it is a quick way to collect information on population abundance. The disadvantages to this method are:
 +  - it is highly subjective and repeatability is low
 +  - there can be a large amount of variation between observers
 +  - cryptic species or those difficult to see due to surrounding vegetation can cause significant underestimation.
  
 ===== Manuals/​Instructions ===== ===== Manuals/​Instructions =====
Line 19: Line 28:
  
 ===== Technical and Application References ===== ===== Technical and Application References =====
 +  * Muir, P. S. and R. K. Moseley. 1994. Responses of //Primula alcalina//, a threatened species of alkaline seeps, to site and grazing. Natural Areas Journal 14: 269-279.
  
 ===== Similar Approaches ===== ===== Similar Approaches =====
 +Quantitative estimates of population size can be obtained using frequency or density methods like [quadrat frequency], [nested frequency], or [density quadrats].
  
 ===== Additional Information ===== ===== Additional Information =====
  
 +===== Web Search Results =====
 +<​html>​
 +<script src="​http://​www.google.com/​jsapi"></​script>​
 +
 +    <script language="​Javascript"​ type="​text/​javascript">//<​![CDATA[
 +      google.load('​search',​ '​1.0'​);​
 +      ​
 +      function OnLoad() {
 +
 +        var searchString = '"​estimate population size monitoring"';​
 +        // create a tabbed mode search control
 +        var searchControl = new google.search.SearchControl();​
 +        options = new google.search.SearcherOptions();​
 +        options.setExpandMode(google.search.SearchControl.EXPAND_MODE_OPEN);​
 +        options.setRoot(document.getElementById("​web_results"​));​
 +        searchControl.addSearcher(new google.search.WebSearch(),​ options);
 +
 +        var drawOptions = new google.search.DrawOptions();​
 +
 +        options2 = new google.search.SearcherOptions();​
 +        options2.setExpandMode(google.search.SearchControl.EXPAND_MODE_OPEN);​
 +        searchControl.addSearcher(new google.search.BookSearch(),​ options2);
 +        searchControl.draw(document.getElementById("​book_results"​),​ drawOptions);​
 +
 +        // execute searches
 +        searchControl.execute(searchString);​
 +
 +      }
 +      google.setOnLoadCallback(OnLoad,​ true);
 +    //]]>
 +    </​script>​
 +
 +    <table border="​0">​
 +       <​tr><​td width="​50%">​ <div class="​search-control"​ id="​book_results">​Loading...</​div>​
 +           </​td>​
 +           <​td width="​50%">​ <div class="​search-control"​ id="​web_results">​Loading...</​div>​
 +           </​td>​
 +       </​tr>​
 +    </​table>​
 +</​html>​
 +
 +===== Discussion/​Comments =====
 +<​sub>​**You must have an account and be logged in to post or reply to the discussion topics below. [[http://​abstracts.rangelandmethods.org/​doku.php/​Home?​do=login&​sectok=db3676cff5bcd873b609b4e582432d73|Click here]] to login or register for the site.**</​sub>​
 +~~DISCUSSION| ~~
  
field_methods/estimate_population_size.txt · Last modified: 2012/03/08 15:34 by jgillan