Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 4 accessions of Poa atropurpurea in orthodox seed collection. There are as many as 2055 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.
Known wet meadow habitats within the San Bernardino, Palomar and Laguna mountains in southern California. There are currently about 12 populations known extant. Only 2 sites, each with about 50 plants, are known in the Laguna Mountians; in the San Bernardino Mountains, most sites are small and the total area of available habitat remaining is estimated to be less that 40 ha. Extensive habitat was probably lost with the construction of a dam and reservoir in the late 1880s. Habitat has also been destroyed or degraded by recreational and airport development, livestock grazing and trampling, and the invasion of non-native plants. Much of the habitat is on unprotected lands subject to development within the next 15 years.
A common greenhouse study to look at factors that might affect reproduction and the sex ratio of seedlings.
An assessment of whether introducing more male plants to populations with skewed sex ratios would improve cross-fertilization and support population survival.
Development of a seedbank for future reintroduction and restoration efforts.
Habitat Loss and degradation urban and recreational development
Fragmentation from off-road vehicle traffic
Grazing by livestock and feral burros (affecting seed consumption and exacerbating the invasion of non-native species).
Hybridization with K
According to survey information recorded in the California Natural Diversity Database, (CNDDB) 21 occurrences of Poa atropurpurea are currently known (CNDDB 2007). However, surveyor information submitted to the CNDDB comes from surveyors using various methods to record species occurrence information, therefore, the status and distribution of this species is considered in terms of the number of meadow areas currently occupied this species. The listing proposal (1998) cited less than 20 known occurrences. According to occurrence information from the SBNF (SBNF 2000; SBNF 2002) and the CNDDB (2007), P. atropurpurea has been documented in 15 meadow areas in the Big Bear area, and four meadow areas in the Laguna and Palomar mountains of San Diego. According to the final listing rule, population sizes of P. atropurpurea typically range from two to 300 individuals, although 3,000 individuals were reported from Belleville Meadow in 1999 (SBNF 2000).
No herbarium specimens of male plants of Poa atropurpurea had been reported from the southern end of its range (San Diego County) until quite recently. During a study on the Cleveland National Forest (San Diego County) a total of just four male plants were discovered, two at each of two different populations (Hirshberg, 1994). It has been suggested that it is possible the San Diego County populations have turned apomictic (not needing fertilization). This would be evident by a seed set of 20 percent or higher (USDA FS 2007). Much more research is needed on the fertilization processes and natural history of this species
Of the known Poa atropurpurea occurrences, 81 % are currently under claim for mining, or on private lands with limited protection (USDA FS 2007). An estimated 91% of meadow habitat has been eliminated since 1900, of the remaining land 70% of the meadows in the Big Bear area are currently without protection (FWS 1998). Two management guides are published by the US Forest Service, that address conservation of this species: the Cleveland National Forest habitat management guide for four sensitive plant species in mountain meadows; and the San Bernardino National Forest Meadow Habitat Management Guide.
There have already been proposals for the individual management of each occurrence and sometimes significant implementation of management practices to conserve Poa atropurpurea. Examples include seasonal cattle exclosures in Laguna Meadow (CNF 1991), and recreational trail closures in Belleville Meadow near Big Bear Lake (SBNF 2002a). Burro removal in the San Bernardino National forest has also been effected after livestock were seen grazing in P. atropurpurea meadows (USDA FS 2007).
It should be noted that habitat management guides and plans are voluntary guidelines and do not provide protection or long-term conservation of the species on US Forest Service lands. A recovery plan for this species is being developed but is not yet complete (USDA FS 2007). Some recommended practices include monitoring fence lines (repairing as necessary), continuing to survey for Poa atropurpurea on NFS lands and visiting populations to update information on populations that have not been visited for ten years of more (USDA FS 2007).
Sound management practices in the National Forest lands will be crucial to the recovery of this species, through protection of known populations, habitat restoration, acquisition of lands that support other occurrences, plus additional monitoring and research to guide future management practices (USDA FS 2007) Poa atropurpurea needs non-compacted, non-eroded soils, a perennial water source, relatively intact meadow systems and limited invasion of exotic species for its reproduction, growth and survival (Curto 1997; Eliason 2007). In order to maintain wet meadows and forest openings to enable the survival of this species invasive and exotic species will need to be monitored and controlled as appropriate.
A population level study to assess genetic diversity throughout the range of this species would provide a basis for determining future management descisions. For the genetic diversity of this species it may be necessary to encourage seed set through special management considerations (Eliason 2007). Protection and possibly propagation of male P. atropurpurea plants may be required to maintain P. atropurpurea populations in the future (Eliason 2007). Seed set in plants at the southern end of the range should be investigated to assess apomictic (clonal seed) reproduction. A genetic study to assess whether hybridization between Poa atropurpurea and P. pratensis is occurring, and to what extent, would also help to elucidate the genetic status of this species.
Be the first to post an update!