Landscape Ecology - Eric B. Peterson <link rel="stylesheet" href="../styles.css" /> </head> <body> <table width="98%"> <tr> <td class="TitleSide"></td> <td class="TitleMain"> <br /> <p class="title">Landscape Ecology - Eric B. Peterson</p> <br /> </td> </tr> <tr> <td class="MainSide"></td> <td class="MainMain"> <p class="PageDescription"><u>Abstract of oral or poster presentation:</u></p> <p class="AbstractTitle">Evaluating indicator species: a case study with epiphytic lichens.</p> <p class="AbstractAuthor">PETERSON, ERIC B.* AND B. MCCUNE. Oregon State University, Corvallis, OR 97339-2902.</p> <p class="AbstractText">TWINSPAN and discriminant functions are often used to determine indicator species. TWINSPAN yields indicators only for groups that it finds in the data, which may be difficult to relate to a priori groups. Discriminant Analysis (DA) requires problematic assumptions. Recently, Dufr[E-HAT]ne and Legendre developed Indicator Species Analysis (ISA) for directly evaluating species as indicators of a priori groups. ISA evaluates species independently. A randomization procedure tests for significance. All three methods were used with a data set of epiphytic lichen communities in Western Oregon to search for and evaluate indicators of forest structures and habitat types. ISA and DA agreed more closely than they did with TWINSPAN. The Dufr[E-HAT]ne and Legendre method was the most effective for elucidating indicator value (IV) of species for site characters such as the presence of old-growth conifers. The method also revealed negative indicators where low abundance of a common species indicates the presence of a site character. IVs varied slightly depending on the number of groups analyzed. A perfect indicator needs to be present in maximum abundance at all sites within a group and at no sites outside the group. A broad variation in IVs was present among the lichens but no perfect indicators were found.</p> <p class="AbstractMeeting">For Presentation at the 1997 meeting of the <a href="http://www.esa.org">Ecological Society of America</a></p> <br /> <font size="-1"><a href="http://www.landscapeecology.com">HOME</a> : <a href="http://www.landscapeecology.com/Info/">Info</a></font> <br /> <br /> </td> </tr> </table> <hr width="97%" /> <font="-1"><a href="http://www.landscapeecology.com">LandscapeEcology.com</a> - contact the webmaster, Eric Peterson, <a href="http://non-parametric.com/contact.php?return=http://www.landscapeecology.com">here</a>. </body> </html>