Photo Credit: USFWS: John Martin
Goal: Maintain or enhance existing San Diego ambrosia occurrences to ensure multiple conserved occurrences with self sustaining populations to increase resilience to environmental and demographic stochasticity, maintain genetic diversity, and ensure persistence over the long term (>100 years) in chaparral vegetation communities.
Management units: 3, 4, 6, 8
Beginning in 2017, annually inspect San Diego ambrosia occurrences on Conserved Lands in (see occurrence table) using the regional rare plant IMG monitoring protocol to record abundance and collect habitat and threats covariate data to determine management needs.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Based upon occurrence status and threats, determine management needs including whether routine management or more intensive management is warranted. | some occurrences are in progress | |
| IMP-2 | Submit project metadata, monitoring datasets and management recommendations to the MSP Web Portal. | some occurrences are in progress |
| Criteria | Deadline year |
|---|---|
| Surveys Completed Annually with Management Recommendations | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3, 4, 6, 8
Beginning in 2017, conduct routine management actions identified through the IMG monitoring at San Diego ambrosia occurrences on Conserved Lands in (see occurrence table). Depending on the type and level of threat, management should only be conducted as needed, not necessarily every year, and using BMPs with precautions to do no harm.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Perform routine management activities such as protecting occurrences from disturbance through fencing, signage, and enforcement. | available for implementation | |
| IMP-1 | Perform routine management activities such as protecting occurrences from disturbance through fencing, signage, and enforcement. | available for implementation | |
| IMP-2 | Submit project metadata and management data to the MSP Web Portal. |
| Criteria | Deadline year |
|---|---|
| Routine Management Completed as Needed Based Upon Monitoring Recommendations | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3, 4, 6, 8
In 2020, begin preparing a section for San Diego ambrosia in the MSP Rare Plant Management Plan that prioritizes management actions to maintain large occurrences and expand at least 3 small occurrences on Conserved Lands (see occurrence table) based upon an assessment of data on occurrence status, habitat, threats, genetic data, and results of existing restoration efforts. Minimum criteria for enhancement are to reduce invasive annual nonnative plants and thatch to less than 20% absolute cover within the occurrence.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| PRP-1 | Consult the San Diego County Rare Plant Working Group made up of plant ecologists, geneticists, rare plant experts, land managers, restoration practitioners, seed banking and bulking practitioners, wildlife agencies, and other stakeholders to provide input and recommendations for San Diego ambrosia in the MSP Rare Plant Management Plan. | on hold | |
| PRP-2 | Develop a conceptual model that identifies management actions to effectively reduce threats to San Diego ambrosia occurrences. | on hold | |
| PRP-3 | Prioritize occurrences for management based upon an assessment of occurrence size, the potential for management to significantly reduce identified threats, and the availability of adjacent suitable habitat for occurrence expansion. | on hold | |
| PRP-4 | Develop an implementation plan for San Diego ambrosia that prioritizes management actions for the next 5 years and details tasks, lead entities, responsibilities, and timelines, budgets. | on hold | |
| PRP-5 | Submit project metadata, management datasets and the MSP Rare Plant Management Plan to MSP web portal | on hold |
| Criteria | Deadline year |
|---|---|
| By 2021, Completed San Diego Ambrosia Section in the MSP Rare Plant Management Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3, 4, 6, 8
In 2021, begin implementing highest priority management actions identified for San Diego ambrosia in the MSP Rare Plant Management Plan.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Using BMPs, conduct invasive plant control annually until success criteria are met and then as needed thereafter. | waiting for precedent action | |
| IMP-2 | Submit project metadata, management data and monitoring data to MSP web portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| By 2025, >1 High priority Management Actions for San Diego Ambrosia initiated from the MSP Rare Plant Management Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3, 4, 6, 8
In 2021, monitor the effectiveness of highest priority management actions for San Diego Ambrosia in the MSP Rare Plant Management Plan.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Submit metadata, management effectiveness datasets, analyses, and report to the MSP Web Portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| Effectiveness of High Priority Management Actions Determined | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3, 4, 6, 8
In 2020, begin preparing a section for San Diego Ambrosia in the MSP Seed Collection, Banking and Bulking Plan to preserve genetic diversity and rescue occurrences in case of catastrophic disturbance. The plan should incorporate best science and management practices (e.g., Wall 2009, KEW 2016) and provide guidelines for collecting and storing seeds over the long term at a permanent, established conservation seed bank (e.g., Institute for Conservation Research Native Plant Seed Bank, Rancho Santa Ana Botanic Garden Seed Conservation Program) and for providing a source of seeds for management purposes. The plan should include recommendations for: collecting and storing seeds for conservation banking; management oriented research; rescuing occurrences after catastrophic disturbances; and seed bulking and out-planting to augment extant occurrences or to establish new occurrences with consideration of genetic implications for population sustainability.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| PRP-1 | Consult the San Diego County Rare Plant Working Group made up of plant ecologists, geneticists, rare plant experts, land managers, restoration practitioners, seed banking and bulking practitioners, wildlife agencies, and other stakeholders to provide input and recommendations for San Diego Ambrosia in the MSP Seed Collection, Banking and Bulking Plan. | On hold | |
| PRP-2 | Prepare a seed collection plan to collect seeds over multiple years, collect seeds several times within a season, accumulate seeds across populations, and to sample among habitats and ecological niches. Include guidelines for collecting and storing seeds along maternal lines from small occurrences (<1,000 plants) and to provide propagules to be used in management experiments, enhancement of existing occurrences, and establishment of new occurrences. | On hold | |
| PRP-3 | The seed collection plan should include guidelines for collecting seeds from occurrences of sufficient size to accommodate harvest and based on genetic studies as available. Include provisions for collecting seed from unconserved populations planned for development. | On hold | |
| PRP-4 | Include protocols and guidelines for collecting voucher specimens and submitting to the San Diego Natural History Museum (McEachern et al. 2007). | On hold | |
| PRP-5 | Include guidelines for testing seeds for viability and to obtain information on dormancy and germination rates. | On hold | |
| PRP-6 | Submit project metadata and MSP Seed Collection, Banking and Bulking Plan to the MSP Web Portal. | On hold |
| Criteria | Deadline year |
|---|---|
| By 2021, Completed San Diego Ambrosia section in the MSP Seed Collection Banking and Bulking Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3, 4, 6, 8
In 2021, begin implementing the San Diego Ambrosia section in the MSP Seed Collection, Banking and Bulking Plan to collect and store seed at a permanent seed bank and to provide propagules as needed for management oriented research, existing population enhancement and establishment of new occurrences.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Bulk seed at a qualified facility for enhancement, expansion, establishment or transplantation projects using seed from genetically appropriate donor accessions in the propagation seed bank collection. | waiting for precedent action | |
| IMP-2 | Maintain records for collected seed to document donor and receptor sites, collection dates and amounts. Submit seed collection, storage and bulking data to the MSP Web Portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| By 2025, >1 San Diego Ambrosia Seed Collection, Banking and Bulking initiated | 2021 |
| Threat Name | Threat Code |
|---|---|
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
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2021-2026 Rare Plant Regional Discovery Surveys
Starting in 2021, surveys were conducted on suitable habitat on Conserved Lands to document whether historic plant occurrences were extant and to discover new occurrences for rare plant species. The purpose of these surveys is to refine and update the distribution of these plants in the Management and Monitoring Strategic Plan Area. Voucher specimens and photographs are taken for each occurrence. Some species are already part of the Rare Plant Inspect and Manage Program and any new occurrences for these species will be included in future monitoring. In the next update of the Management and Monitoring Strategic Plan (2027), species not formerly monitored will be evaluated and potentially added to the Rare Plant Inspect and Manage Program. Botanists surveyed for four rare plant species in 2021: San Diego coastalcreeper (Aphanisma blitoides), Blochman’s dudleya (Dudleya blochmaniae), coast wallflower (Erysimum ammophilum), and Orcutt’s bird’s-beak (Dicranostegia orcuttiana). In 2022, botanists surveyed for: San Diego coastalcreeper (Aphanisma blitoides), Baja California oat grass (Sphenopholis interrupta ssp californica), San Diego ambrosia (Abrosia pumila), Wiggins’ cryptantha (Crytantha wigginsii). In 2023, botanists will survey for five rare plant species: Deane’s milkvetch (Astragalus deanei), Parish brittlescale (Atriplex parishii), Mexican flannelbush (Fremontodendron mexicanum), Jennifer’s monardella (Monardella stoneana ), and small-leaved rose (Rosa minutifolia).
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Rare Plant Inspect and Manage Monitoring 2014-2026
From 2014-2026, a Management and Monitoring Strategic Plan (MSP Roadmap) monitoring objective for 30 rare plant species is to inspect occurrences to determine management needs. The inspect and manage (IMG) objective is implemented to document the status of rare plant occurrences and assess habitats and threats to develop specific management recommendations. IMG monitoring is implemented by a combination of land managers and contracted biologists in coordination with the SDMMP. Available rare plant data is posted below. New annual updates are typically posted in March. Based upon an evaluation of these data, a 2014-2026 monitoring schedule has been developed for the 30 rare plant species (attached below). Coordinating data collection across the region allows analyses of species and population trends over time and provides a better understanding of the association between habitat and threat covariates and population dynamics.
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Distributed from western Riverside County and western San Diego County, California south in widely scattered populations along the west coast of Baja California, Mexico, to the vicinity of Cabo Colonet [1,2]. Majority of U.S. populations in San Diego County, with 12 occurrences on Conserved Lands in the MSPA [3].
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Occurs in open floodplain terraces in variety of ruderal associations or in openings in coastal sage scrub and chaparral [1,2,4]. In San Diego County most occurrences associated with sandy loam soils5. Disturbance, such as flood plain scouring, helps to keep openings that are colonized by this species [6].
Member of the Asteraceae. Species variability is common within Ambrosia genus because of the presence of polyploid races and dysploidy [7]. San Diego ambrosia gametic (haploid) chromosome number is 72, in its vegetative stage it is an octoploid with 144 chromosomes. Recent genetic study [8] found Mission Trails Regional Park, San Diego National Wildlife Refuge, and Skunk Hollow (Riverside Co.) occurrences were genetically distinct with 31 different genotypes. No spatial genetic structure at short distances and different clones occupy the same plots. However, at larger distances there is spatial structure with different genotypes and no overlap. This indicates that clones have a limited spatial distribution and that genetic diversity is maintained by some level of sexual reproduction. Patches within 480m of each other at San Diego National Wildlife Refuge did not appear to be interbreeding. The Mission Trails occurrence had low genetic variability that may be a result of a non-native invasive grass overstory limiting wind pollination.
Clonal, herbaceous, perennial plant species1. Reproduces mainly be vegetative resprouting from underground rhizomes [6]. MSCP populations do not appear to produce many seeds [9]. Presumed to be able to self-pollinate like other species of Ambrosia, however it remains to be determined if self-pollination produces viable seeds.
Amount of above ground biomass fluctuates annually and likely depends on seasonal conditions, such as amount and timing of rainfall [5]. Flowers usually present from June through September1.
Thought to be primarily wind pollinated, although the role of insects is not known9. Mode of seed dispersal is unknown, does not have specialized structures for dispersal by wind or animals. May disperse in flooding events.
Non-native plants are a significant threat to San Diego ambrosia [9,10]. Mowing and discing for fuel modification can impact populations, although mowing if done at the right time of year can help to reduce non-native plant cover. Trampling by humans, bikes, horses, and off-highway vehicles can damage plants. Fragmentation of occurrences can reduce wind pollination and result in smaller populations that are more vulnerable to loss of genetic diversity and environmental and demographic stochasticity. Altered hydrology may reduce flood scouring events that maintain open habitats colonized by San Diego ambrosia. Feral pigs were introduced into the upper San Diego River in 2006 [11] and could pose a threat if they move downstream.
Special considerations: Large occurrences are necessary to maintain genetic diversity [8]. Based on genetic results, it was estimated that at a minimum unique genets represent one order of magnitude less than the total number of stems growing in a population with the San Diego National Wildlife Refuge Par 4 occurrences estimated at 5,000 genets and the Mission Trails Regional Park at 1,000 genets. Because of the localized nature of genets, it is recommended that seed collection and removal of transplants for establishing new occurrences be done widely across a population to obtain the greatest number of different genets. However, caution is needed as potential differences in chromosome numbers could cause problems with reduced fitness and sterility if individuals from one population are transplanted with individuals from another population if there is chromosome incompatibility [12]. Work has been conducted to determine BMPs for controlling non-native plants with some success from Fusilade herbicide and hand weeding [13,14] although Vulpia myurus increased with Fusilade. Further testing of methods is needed and is ongoing at Mission Trails Regional Park [15]. There have been seven translocation projects but it is uncertain whether environmental conditions at translocation sites are suitable for sustained populations, so further research on viability of translocated populations is needed. [9]
[1] Munz, P.A. 1974. A Flora of Southern California. University of California Press, Berkeley, California.
[2] Reiser, C. 1994. Rare Plants of San Diego County. http://sandiego.sierraclub.org/rareplants/ Accessed 2012 and 2013.
[3] MSP-MOM. 2013. Management Strategic Plan Master Occurrence Matrix. http://www.sdmmp.com/Home.aspx
[4] County of San Diego. 2010. North County Plan Conservation Analysis. Draft.
[5] Dudek & Associates, Inc. August 26, 1999. City of San Diego Mission Trails Regional Park, San Diego Ambrosia Management Plan. Unpublished report, 36 pp. + appendices.
[6] McEachern, K., B. Pavlik, J. Rebman and R. Sutter. 2006. San Diego Multiple Species Conservation Program (MSCP) rare plant monitoring review and revision. Final report prepared for the City of San Diego.
[7] Payne, W. W., Peter H. Raven and D. W. Kyhos. 1964. Chromosome Numbers in Compositae. IV. Ambrosieae. American Journal of Botany 51:4 pp 419-424.
[8] McGlaughlin, M.E. and E.A. Friar. 2007. Clonality in the endangered Ambrosia pumila (Asteraceae) inferred from RAPD markers; implications for conservation and management. Conservation Genetics 8:319-330.
[9] USFWS. 2010. Ambrosia pumila (San Diego Ambrosia) 5-Year Review: Summary and Evaluation. Prepared by the U.S. Fish and Wildlife Service Carlsbad Fish and Wildlife Office, Carlsbad, California.
[10] Hierl, Lauren A., Janet Franklin, Douglas H. Deutschman, and Helen M. Regan. 2007. Developing Conceptual Models to Improve the Biological Monitoring Plan for San Diego’s Multiple Species Conservation Plan. Prepared for the California Department of Fish and Game.
[11] USFS and BLM. 2012. Environmental Assessment: Feral Pig Damage Control Project on Cleveland National Forest and Bureau of Land Management Lands. http://a123.g.akamai.net/7/123/11558/abc123/forestservic.download.akamai.com/11558/www/nepa/72857_FSPLT2_148901.pdf
[12] Severns, P.M. and A. Liston. 2008. Intraspecific chromosome number variation: a neglected threat to the conservation of rare plants. Conservation Biology 22:1641-1647.
[13] Kelly, Mike, Cindy Burrascano, and Melanie Johnson Rocks. 2008. Spraying over the top of Ambrosia pumila, a federally listed species to control weeds. Powerpoint presentation.
[14] Hasselquist, Niles, Eliza Maher Hasselquist, and Deborah Rogers. 2009. Final Report: Comparison of Vegetation Management Techniques to Support Recovery of the Federally Endangered Ambrosia pumila. Prepared by the Center for Natural Lands Management.
[15] City of San Diego. 2013. Mission Trails Regional Park Sensitive Habitat Field Notes.