COSEWIC Assessment and Status Report on the Tiny Cryptantha Cryptantha Minima in Canada
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COSEWIC Assessment and Status Report on the Tiny Cryptantha Cryptantha minima in Canada THREATENED 2012 COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows: COSEWIC. 2012. COSEWIC assessment and status report on the Tiny Cryptantha Cryptantha minima in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 37 pp. (www.registrelep-sararegistry.gc.ca/default_e.cfm). Previous report(s): COSEWIC. 2000. COSEWIC assessment and status report on the tiny cryptanthe Cryptantha minima in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 18 pp. Smith, B. 1998. COSEWIC status report on the tiny cryptanthe Cryptantha minima in Canada, in COSEWIC assessment and status report on the tiny cryptanthe Cryptantha minima in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-18 pp. Production note: COSEWIC would like to acknowledge Sue Michalsky for writing the status report on the Tiny Cryptantha Cryptantha minima in Canada, prepared under contract with Environment Canada. This report was overseen and edited by Bruce Bennett and Erich Haber, Co-chairs of the COSEWIC Vascular Plants Specialist Subcommittee. For additional copies contact: COSEWIC Secretariat c/o Canadian Wildlife Service Environment Canada Ottawa, ON K1A 0H3 Tel.: 819-953-3215 Fax: 819-994-3684 E-mail: COSEWIC/[email protected] http://www.cosewic.gc.ca Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur la Cryptanthe minuscule (Cryptantha minima) au Canada. Cover illustration/photo: Tiny Cryptantha — Source: Environment Canada 2010. Her Majesty the Queen in Right of Canada, 2012. Catalogue No. CW69-14/207-2012E-PDF ISBN 978-1-100-20726-1 Recycled paper COSEWIC Assessment Summary Assessment Summary – May 2012 Common name Tiny Cryptantha Scientific name Cryptantha minima Status Threatened Reason for designation This small herbaceous annual plant is limited in Canada to a small area of grassland habitat in southeastern Alberta and adjacent southwestern Saskatchewan. Though a larger range and population size are now known due to greatly increased search effort, the species remains under threat from residential and industrial development, agricultural activities, altered hydrological regimes, and a lack of fire and grazing which allows encroachment of competing vegetation, such as invasive species. The species’ extent and quality of habitat continue to decline and it is subject to extreme fluctuations in population size, which increases its vulnerability. Occurrence Alberta, Saskatchewan Status history Designated Endangered in April 1998. Status re-examined and confirmed in May 2000. Status re-examined and designated Threatened in May 2012. iii COSEWIC Executive Summary Tiny Cryptantha Cryptantha minima Wildlife Species Description and Significance Tiny Cryptantha is a small, bristly-haired annual plant that has tiny white flowers with yellow centres. The Canadian populations are the most northern occurrences of this species, and because these populations are disjunct from more southern populations, they could carry unique genetic variability that may contribute to adaptations and long-term persistence of the species. Distribution Tiny Cryptantha is native to North America. In Canada, the species is associated with river systems, mainly the South Saskatchewan River valley in the eastern half of Alberta and into western Saskatchewan. It also occurs near the lower Red Deer, lower Bow, Oldman and Lost rivers in Alberta and the Red Deer River in Saskatchewan. The closest occurrence outside Canada is a historical collection from Great Falls, Montana approximately 200 km from the southernmost Alberta population at Onefour. The species’ range in Canada represents less than 1% of its total range. Habitat Tiny Cryptantha is found within about five kilometres of river systems, typically in sandy, level to rolling upland areas and sand dunes near valley breaks, valley slopes with up to 50% slope, and level or gently sloping terraces in valley bottoms, particularly in meander lobes where flooding provides more frequent disturbance. It requires habitats with low litter levels and a minimum of 10% bare soil for establishment. Periodic soil disturbance by wind, water, erosion or animals is required to open up the canopy and provide spaces for germination and establishment. However, areas that have repeated intense disturbance, such as actively eroding slopes, dunes and sandbars do not appear to support Tiny Cryptantha. iv Biology Tiny Cryptantha is an annual that spends a large portion of its life cycle as a seed. It lacks a dormancy mechanism, but exhibits conditional dormancy in which germination is temperature and moisture dependent. The proportion of seeds deposited into the seed bank and the period of viability of seeds remains unknown. Seeds are likely dispersed passively, with most falling close to the parent plant. There may also be dispersal by animals, wind and water. There is no means of asexual reproduction for this species. Population Sizes and Trends Twenty-five extant populations of Tiny Cryptantha exist in Canada. There are 22 in Alberta, two in Saskatchewan and one straddling the Alberta-Saskatchewan border. A third Saskatchewan population may have been misidentified or may be extirpated. Due to its annual life cycle, the timing of various surveys throughout the growing season, and a limited number of resurveys of known populations, population trends for the species cannot be fully assessed. Threats and Limiting Factors Availability of suitable habitat is limiting. Identified threats to Tiny Cryptantha include habitat loss and degradation as a result of residential development and oil and gas exploration. Cultivation and sand/gravel extraction have also been identified as threats. Additional threats include modifications to natural processes through altered hydrological regimes and lack of grazing and/or fire, invasion by alien species, and the effects of climate change. Protection, Status, and Ranks Tiny Cryptantha is designated as Endangered under Schedule 1 of the federal Species at Risk Act. It is also listed as Endangered under the provincial species at risk legislation in Alberta and Saskatchewan, the two provinces where it occurs in Canada. A large part of the Canadian population occurs in the Suffield National Wildlife Area where legal protection exists but ongoing petroleum exploration and development threatens the species. v TECHNICAL SUMMARY Cryptantha minima Tiny Cryptantha Cryptanthe minuscule Range of occurrence in Canada: Alberta, Saskatchewan Demographic Information Generation time. Plants are annual, and the half-life of seeds in the seed Unknown bank or the median time to germination is unknown. Generally speaking, Possibly 5 years seed bank half-lives commonly range between <1 and 10 years (IUCN 2010). Is there an [observed, inferred, or projected] continuing decline in number Probably of mature individuals? Continuing decline in some populations can be inferred and projected based on urban development in the Medicine Hat region and impacts of petroleum development. The trends in other populations are unknown. Estimated percent of continuing decline in total number of mature Unknown individuals within [5 years or 2 generations] [Observed, estimated, inferred, or suspected] percent [reduction or Unknown increase] in total number of mature individuals over the last [10 years, or 3 generations]. [Projected or suspected] percent [reduction or increase] in total number of Unknown mature individuals over the next [10 years, or 3 generations]. [Observed, estimated, inferred, or suspected] percent [reduction or Unknown increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future. Are the causes of the decline clearly reversible and understood and No ceased? Though a decline has not been demonstrated, an ongoing decline which is not reversible, and has not ceased may be inferred. Are there extreme fluctuations in number of mature individuals? Yes Extent and Occupancy Information Estimated extent of occurrence. It is expected that though more sites may 15,726 km² be found, new sites are expected to be found within the current extent of occurrence. Index of area of occupancy (IAO) >284 km² (2x2 grid). The IAO is expected to increase through increased search effort. Is the total population severely fragmented? No More than half of the mature individuals are in large viable populations consequently, by definition, the total population is not severely fragmented. Number of “locations” >10 Some populations are > 1 km2 in extent; therefore number of locations may be several for a single population depending on type of threat. There are 25 extant populations separated by 2 km or more. The number of locations is therefore not defined but is likely greater than 10 (a threshold number for COSEWIC’s B criterion) Is there an [observed, inferred, or projected] continuing decline in extent of No occurrence? Is there an [observed, inferred, or projected] continuing decline in index of Unknown area of occupancy? See definition of location. vi Is there an [observed, inferred, or projected] continuing decline in number Unknown of populations? Is there an [observed, inferred, or projected] continuing decline in number Unknown of locations? Is there an [observed, inferred,