|Scientific Name:||Dioon holmgrenii|
|Species Authority:||De Luca, Sabato & Vázq.Torres|
|Red List Category & Criteria:||Endangered A4c; B1ab(iii,iv)+2ab(iii,iv) ver 3.1|
|Assessor(s):||Chemnick, J., Gregory, T. & Morales S.|
|Reviewer(s):||Donaldson, J.S. & Bösenberg, J.D.|
Classified as Endangered based on an estimated ongoing decline of >50% over three generations. Also qualifies under criterion B due to very small extent of occurrence, small number of locations and ongoing decline.
|Previously published Red List assessments:||
|Range Description:||This species is restricted to state of Oaxaca, Mexico. Plants occurs to the south west of San Gabriel Mixtepec.|
|Number of Locations:||2|
|Lower elevation limit (metres):||650|
|Upper elevation limit (metres):||850|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Plants are known only from two (500 and 10,000 plants) colonies.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This species grows mainly in humid forest dominated by species of Pinus and Quercus. They are found on slopes with a north eastern exposure. Plants often grow in ravines in humus-rich soil.|
|Generation Length (years):||500|
|Major Threat(s):||These plants are affected by habitat destruction due to agriculture (corn, pastures) and also as a result of over-collecting.|
|Conservation Actions:||This species is listed on Appendix II of the CITES Appendices. Plants are protected by local communities.|
Chemnick, J., Gregory, T. and Morales, S. 2007. Email received in response to request for information.
Donaldson, J.S. (ed.). 2003. Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.
Hill, K.D. and Stevenson, D.W. 1998-2006. The Cycad Pages. Available at: http://plantnet.rbgsyd.gov.au/PlantNet/cycad/.
IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.3). Available at: http://www.iucnredlist.org. (Accessed: 2 September 2010).
Jones, D.L. 1993. Cycads of the World. Reed, New Holland, Frenchs Forest, N.S.W., Australia.
Whitelock, L.M. 2002. The Cycads. Timber Press, Portland, Oregon.
|Citation:||Chemnick, J., Gregory, T. & Morales S. 2010. Dioon holmgrenii. The IUCN Red List of Threatened Species 2010: e.T42129A10660365. http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T42129A10660365.en . Downloaded on 07 October 2015.|
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