|Scientific Name:||Hamadryas argentea|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Upson, R., McAdam, J.H., Clubbe, C.P. & Lewis, R.|
|Reviewer(s):||Hilton-Taylor, C. & Bilz, M.|
The Silvery Buttercup (Hamadryas argentea) has an extent of occurrence (EOO) of about 13,209 km² and an area of occupancy (AOO) of 192 km². Subpopulation sizes are generally small and the population as a whole is severely fragmented. The distribution of this species suggests that there is a threat from grazing as it is limited to ungrazed sites or areas where grazing levels are reduced; this in turn suggests that there has been a decline in numbers of this species over time, however, it is not clear whether this decline is continuing or not. Hence the Silvery Buttercup is assessed as Near Threatened as it is close to qualifying for a threatened category under criteria B1a and B2a.
There appears to be a large amount of vegetative spread within subpopulations which makes estimation of the number of individuals difficult; some populations appear to consist of a single male and female plant which is merely spreading via rhizomes. If future genetic work shows that the majority of subpopulations comprise only several individuals, with extensive vegetative spread, this species may warrant a much more threatened status.
|Previously published Red List assessments:||
|Range Description:||Endemic to the Falkland Islands. H. argentea is widespread but scarce across the islands, occurring in 25 ten km UTM grid squares.|
Native:Falkland Islands (Malvinas)
|Estimated area of occupancy (AOO) - km2:||192|
|Continuing decline in area of occupancy (AOO):||Unknown|
|Extreme fluctuations in area of occupancy (AOO):||No|
|Estimated extent of occurrence (EOO) - km2:||13209|
|Number of Locations:||21|
|Upper elevation limit (metres):||600|
|Range Map:||Click here to open the map viewer and explore range.|
There is a large amount of vegetative spread within subpopulations which makes estimation of the number of individuals difficult; some populations appear to consist of a single male and female plant which is merely spreading via rhizomes. There are >2,000 leaf rosettes of H. argentea across the Falkland Islands, with the largest subpopulations composed of about 500 leaf rosettes.The population as a whole is severely fragmented.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||H. argentea grows predominantly where gazing pressure is low or absent: in maritime cliff and slope habitats, inland rock, Poa alopecurus acid grassland (upland), dwarf shrub heath, Fachine scrub, cushion heath (upland) and fern beds.|
|Continuing decline in area, extent and/or quality of habitat:||Unknown|
|Use and Trade:||There is no known use.|
|Major Threat(s):||The distribution of this species suggests a threat from grazing as although not limited to ungrazed sites, where grazing occurs it is present as a highly reduced form that may rarely or never produce seed. The suppression of reproductive activity under grazing indicates that there has probably been a decline in numbers of this species over time.|
Ex situ Conservation:
A seed collection is held at Kew's Millennium Seed Bank. Leaf material has been collected from several subpopulations and is held at the Royal Botanic Gardens Kew for future genetic research and DNA banking.
A plant is currently being propagated from vegetative material at Royal Botanic Gardens Kew and another plant cultivated from vegetative material is growing in Falkland Conservation's small botanical garden.
In situ Conservation:Three Important Plant Areas have been identified which cover subpopulations of this species including the largest yet recorded (in terms of number of leaf rosettes) (Upson 2012).
The species occurs in a protected area.
A species identification guide is available for free download from Falkland Conservation's website.
|Citation:||Upson, R., McAdam, J.H., Clubbe, C.P. & Lewis, R. 2012. Hamadryas argentea. The IUCN Red List of Threatened Species 2012: e.T44039A15245607. . Downloaded on 10 February 2016.|
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