Photo Credit: USFWS: John Martin
Goal: Maintain or enhance existing Otay tarplant 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 native and non native grassland vegetation communities.
Management units: 3
In 2017, begin annual inspections of extant occurrences of Otay tarplant on Conserved Lands (see occurrence table) using the regional rare plant IMG monitoring protocol to record spatial extent, estimate abundance, and collect habitat and threat covariate data to determine management needs.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Based upon occurrence status and threats, determine if 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 |
|---|---|
| Altered fire regime | ALTFIR |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Urban development | URBDEV |
Management units: 3
Beginning in 2017, conduct routine management actions identified through the annual IMG monitoring at Otay tarplant occurrences on Conserved Lands (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 as needed, such as protecting occurrences from disturbance through enforcement and controlling invasive non-native plant species to =20% absolute cover. | available for implementation | |
| IMP-2 | Submit project metadata, monitoring and management recommendations to the MSP web portal. | available for implementation |
| Criteria | Deadline year |
|---|---|
| Routine Management Completed as Needed Based Upon Monitoring Recommendations | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Urban development | URBDEV |
Management units: 3
In 2017 continue the collaboration with the South County Grasslands Project initiated in 2014 to develop BMPs for landscape-scale restoration of Otay tarplant habitat in MU3 that includes testing methods of seeding and invasive plant control so that nonnative plants and thatch are reduced to less than 20% relative cover and thatch to <5 cm tall and native plants to at least 25% relative cover. These percent cover criteria could be revised based on data collected from an acceptable reference site.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| DEV-1 | Conduct experiments using mowing, prescribed burns herbicide and potentially grazing to control invasive non-native grasses and forbs at a landscape-scale and to compare drill seeding versus hand broadcast seeding in order to determine economical and effect. | in progress | |
| DEV-2 | Based upon experiment results, develop explicit BMPs for the restoration of Otay tarplant. Submit project metadata, monitoring datasets and BMP report to MSP web portal. | in progress |
| Criteria | Deadline year |
|---|---|
| BMPs Developed for Restoration of Otay tarplant by 2017 | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2017, continue a study begun in 2016 to characterize the population genetic structure, gene flow, and genetic diversity for Otay tarplant occurrences (see occurrence table). The study will determine if there is evidence of mixed ploidy levels within or among occurrences; evaluate vulnerability of occurrences to genetic drift and loss of genetic diversity; assess the level of gene flow among occurrences; identify if there are signatures of genetic bottlenecks or low genetic diversity in occurrences that have undergone recent reductions; and look for evidence of local population adaptation. Based on the results of the genetic analyses, management recommendations will include whether common garden and reciprocal transplantations are necessary before proceeding with population enhancement or restoration and will provide specific recommendations for collecting, bulking and distributing seed to enhance existing occurrences or establish new occurrences.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| RES-1 | Use BMPs to collect plant material for genetic samples at conserved Otay tarplant occurrences (Table 2-3.3). | in progress | |
| RES-2 | Evaluate the overall long-term genetic trajectory for Otay tarplant | in progress | |
| RES-3 | Hold a workshop of scientists, rare plant experts, and land managers to develop management recommendations based upon the results of genetic analyses. | waiting for precedent action | |
| RES-4 | Submit project metadata, genetic datasets and analyses, and report with management recommendations to the MSP Web Portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| By 2018, Completed Genetic Study for Otay Tarplant with Management Recommendations | 2021 |
| Threat Name | Threat Code |
|---|---|
| Loss of connectivity | LOSCON |
Management units: 3
Beginning in 2018, and continuing for 3 years at the 3 Otay tarplant restoration sites initiated under the South County Grasslands project, use BMPs to maintain the maximum occupied extent and a surrounding buffer area equal to 25% of this extent by preventing ground disturbance and reducing nonnative plants and thatch to less than 20% total cover and thatch to <5 cm tall.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Conduct invasive plant control annually using BMPs until success criteria are met and then as needed thereafter. | waiting for precedent action | |
| IMP-2 | Submit project metadata and management data to the MSP Web Portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| By 2021, 3 Otay Tarplant Occurrences Enhanced/Established and Reports Submitted | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2018, begin preparing an Otay tarplant section in the MSP Rare Plant Management Plan that prioritizes management actions to maintain and expand conserved occurrences based upon an assessment of data on occurrence status, habitat and threats. Minimum criteria for enhancement are to reduce invasive annual nonnative plants and thatch to less than or equal to 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 Otay tarplant in the MSP Rare Plant Management Plan. | some occurrences are in progress | |
| PRP-2 | Develop a conceptual model that identifies management actions to effectively reduce threats to Otay tarplant occurrences. | some occurrences are in progress | |
| 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. | some occurrences are in progress | |
| PRP-4 | Develop an implementation plan for Otay tarplant that prioritizes management actions for the next 5 years and details tasks, lead entities, responsibilities, and timelines, budgets. | some occurrences are in progress | |
| PRP-5 | Submit project metadata, project datasets, and the MSP Rare Plant Management Plan to the MSP Web Portal. | some occurrences are in progress |
| Criteria | Deadline year |
|---|---|
| By 2019, Completed Otay Tarplant Section in the MSP Rare Plant Management Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2019, begin implementation of highest priority management actions for Otay tarplant identified in the MSP Rare Plant Management Plan.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Submit project metadata and management datasets, report to MSP web portal | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| By 2023, =1 High Priority Management Action Implemented for Otay tarplant from the MSP Rare Plant Management Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2019, begin monitoring the effectiveness of implementation of highest priority management actions identified in the Otay tarplant section 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 |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2018, begin preparing a section for Otay tarplant 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 the Otay tarplant section in the MSP Seed Collection, Banking and Bulking Plan. | some occurrences are in progress | |
| 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. | some occurrences are in progress | |
| 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. | some occurrences are in progress | |
| PRP-4 | Include protocols and guidelines for collecting voucher specimens and submitting to the San Diego Natural History Museum (McEachern et al. 2007). | some occurrences are in progress | |
| PRP-5 | Include guidelines for testing seeds for viability and to obtain information on dormancy and germination rates. | some occurrences are in progress | |
| PRP-6 | Submit project metadata and MSP Seed Collection, Banking and Bulking Plan to the MSP Web Portal. | some occurrences are in progress |
| Criteria | Deadline year |
|---|---|
| By 2019, Completed Otay Tarplant Section in the MSP Seed Collection, Banking and Bulking Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2019, begin implementing the MSP Seed Collection, Banking and Bulking Plan for Otay tarplant to collect and store seeds 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. | some occurrences are in progress | |
| 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. | some occurrences are in progress |
| Criteria | Deadline year |
|---|---|
| By 2023, > 1 Highest Priority Action Implemented for Otay Tarplant from the MSP Seed Collection, Banking and Bulking Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Human uses of the Preserves | HUMUSE |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 3
In 2017, continue field research into soils and habitat relationships and development of habitat suitability and climate change models for Otay tarplant and other edaphic endemic plants to better understand habitat requirements and to identify and prioritize geographic areas important for connectivity, restoration, and range shifts due to climate change and other threats.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| RES-1 | Test soils at potential expansion sites and compare to occupied reference sites to determine site suitability based on soils. | In progress | Enhancing the Resilience of Edaphic Endemic Plants |
| RES-2 | Prepare habitat suitability models under current environmental conditions and for different scenarios of climate change to delineate potential future habitat. | In progress | Enhancing the Resilience of Edaphic Endemic Plants |
| RES-3 | Collect covariate data on vegetation composition and cover (alliance and association-level mapping), soils, invasive plants and other threats for selected populations. | In progress | Enhancing the Resilience of Edaphic Endemic Plants |
| RES-4 | Prioritize locations for conservation, management, and future surveys based on predicted distributions and environmental correlates. | In progress | Enhancing the Resilience of Edaphic Endemic Plants |
| RES-5 | Submit project metadata, monitoring data, habitat models, analyses, and report to MSP web portal. | In progress | Enhancing the Resilience of Edaphic Endemic Plants |
| Criteria | Deadline year |
|---|---|
| Refined Models and Prioritized Future Survey Locations for Otay Tarplant by 2018 | 2021 |
| Threat Name | Threat Code |
|---|---|
| Climate change | CLICHN |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
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Dennery Canyon Rare Plant Restoration
The goal of this project is to restore and enhance populations of four Management Strategic Plan (MSP) plant species and vernal pool habitat over a three-year period. Species directly benefiting from this effort include: San Diego thornmint (Acanthomintha ilicifolia), Otay tarplant (Deinandra conjugens), San Diego ambrosia (Ambrosia pumila), Orcutt's bird’s beak (Dicranostegia orcuttiana). The proposed project area encompasses approximately 8.68 acres. It provides a unique setting where the fours species co-exist with vernal pools not previously documented in the Vernal Pool Habitat Conservation Plan (VPHCP). Annual inspect and manage (IMG) monitoring results indicate increasing threats (primarily non-native weeds) are impacting MSP species populations in this area, and an intensive restoration effort is needed to ensure the long-term persistence of these species. Activities will consist of weed management, seed collection, seed bulking and redistribution, trash removal, vegetation monitoring, photo monitoring, and IMG monitoring. The proposed project will utilize the most current state of management knowledge along with Best Management Practices (BMPs) that have been successfully implemented in the region. This project is consistent with management objectives and actions in the MSP Roadmap, the MSP Framework Rare Plant Management Plan, and the MSP Seed Collection, Banking, and Bulking Plan.
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Enhancing the Resilience of Edaphic Endemic Plants
The Management Strategic Plan for San Diego County requires prioritization and management for edaphic endemic plants, including the five rare plants addressed in this study. These species face low genetic diversity due to reduced population sizes, geographic isolation, and loss of pollinators. To enhance the resilience of these species across their ranges, we must manage threats to increase population sizes, identify potentially suitable habitat to connect existing populations, find or restore new populations, and provide opportunities for shifting distributions due to climate change.
This study identifies and describes geographic areas that support the five edaphic endemic species and their habitat in a design that enhances resilience and provides opportunities for shifting distributions. We developed conceptual models to inform field studies and management, refined soils and vegetation attributes, and assessed regional population structure and threats. We used results to suggest prioritized locations for surveys, management, potential translocation, and additional conservation or acquisition. Project partners (U.S. Geological Survey and San Diego Management and Monitoring Program) modeled suitable habitat for the target species under current and future climate scenarios; we reference models as appropriate.
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Population Genetic Analysis of 6 Rare Plant Species in San Diego County
The first phase (years 1-2) of this research task focused on genetic and cytological screening to determine potential ploidy and population genetic differences among occurrences within species. Upon completion, an expert panel convened to review results of the genetic studies and develop specific recommendations for each species relative to the MSP management objectives planned for that species. These recommendations included designing appropriate common garden or reciprocal transplant studies to determine the fitness consequences of using seed from different populations to increase population size or establish new occurrences. The recommendations also addressed MSP objectives involving seed banking and seed bulking needs for each species. The expert panel also made recommendations on genetic management of populations, including whether genetic connectivity needs to be enhanced or restored to maintain or increase genetic diversity. Recommended and approved studies will be added in the second phase (beginning in year 3). The following questions were specifically addressed in phase 1:
1. What is the status of documented occurrences?
2. Is there evidence of mixed ploidy levels among or within occurrences?
3. What is current genetic structure among and within occurrences in the MSPA? How vulnerable are the occurrences to genetic drift and loss of genetic diversity and is there gene flow between occurrences?
4. Are there signatures of genetic bottlenecks or lower genetic diversity in populations that have undergone recent reductions due to fire, drought, or other causes, or evidence of local adaptation?
5. Based on the cytological and genetic analysis, what are the recommendations for common garden and reciprocal transplantations, for collecting, bulking and distributing seeds for enhancing existing occurrences, and for establishing new occurrences?
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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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Rare Plant Management and Seed Plan
MSP Roadmap 2019 and 2020 objectives include developing a “Management Strategic Plan Framework Rare Plant Management Plan for Conserved Lands in Western San Diego County” and a “Management Strategic Plan Seed Collection, Banking, and Bulking Plan for Conserved Lands in Western San Diego County”. These plans include general sections with background information and rationale for prioritizing and developing management recommendations with separate chapters and specific recommendations for priority species. In 2019, general framework sections were developed along with species chapters for San Diego thornmint, Nuttall’s acmispon, salt marsh bird’s-beak and Otay tarplant (CBI, AECOM and SDMMP 2020 a,b). In 2020, chapters will be developed for short-leaved dudleya, Orcutt’s spineflower, and willowy monardella. These plans are developed with input and guidance provided by the Rare Plant Management Group Steering Committee and species working groups. Participants in these groups include landowners and managers, scientists, species experts, restoration specialists, seed collection and banking practitioners, and representatives from non-profit organizations and wildlife agencies. These plans are based on the latest scientific information for species on habitat relationships, ecology, genetics, seed collection guidelines, and best management practices. Occurrence-specific management recommendations are based on working group input and multiple years of Inspect and Manage monitoring data on population status, habitat associations and threats. These are living documents as new species chapters are added as they are developed and existing chapters are revised when new information becomes available or management actions are completed, and new recommendations are needed.
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South San Diego County Grassland Project
The purpose of the project was to to develop landscape-scale, collaborative strategies for managing target grassland species in the South County MSCP. Phase I involved grasslands assessments, target selection, and experimental design while Phase II was the experimental design implementation. Develop BMPs for restoring native grassland and forbland habitat for Otay tarplant and Quino checkerspot. The native grassland habitat restoration experiment compared the effectiveness of seeding full extent vs. Desimone strip seeding method, determined whether recent fall burn impacts success of two seeding approaches, and evaluated whether hand weed control and seeding methods are as effective as mechanized methods. The research goal for forblands was to assess the effectiveness of two mechanized site preparation techniques that limit soil disturbance while reducing weed cover in sites with good access and low native forb cover.The research goal for Quino checkerspot butterfly was to assess the effectiveness of two seeding techniques in establishing Plantago erecta and other QCB forb species on difficult to reach sites and sites with sensitive soil crusts. The research goals for Otay tarplant were to evaluate the effectiveness of establishing OTP populations using hand broadcast seeding or two-way drill seeding and to determine if calcareous soils are limiting the establishment of OTP populations.
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SR 94 Wildlife Infrastructure Plan
Proposed road improvements to SR 94 provide an opportunity to mitigate the potential barrier effects of the highway. This project identifies where improvements to existing infrastructure on SR-94 could improve connectivity across the South County preserves, using Best Management Practices from the scientific literature; recommends wildlife movement monitoring to identify where new crossings are needed; and identifies where additional conservation would enhance the integrity of South County linkages. The review prioritizes infrastructure improvements of 35 existing undercrossings inspected by wildlife experts in the field along 14.6 miles of SR-94 where the highway bisects conserved lands. The majority of the recommendations for infrastructure improvement focus on increasing the diameter, and thus the openness ratio (cross-sectional area divided by length), of the undercrossing itself, removing vegetation and debris blocking the undercrossing, restoring habitat in the approach to the undercrossing, and installing fencing to both (1) keep animals off the highway and (2) funnel wildlife to the undercrossings.
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Restricted to southern San Diego County and Baja, Mexico [1, 2]. In 2009, USFWS recognized 34 extant occurrences in southwestern San Diego County [2].
Twenty-two occurrences in the MSPA in MU3 and a single small isolated occurrence in MU2 [3]. Large occurrences (>5,000 individuals) at Otay Mesa/Moody Canyon, Dennery Canyon, Otay River Valley, Johnson Canyon, Salt Creek, Proctor Valley, Bonita Meadows/Trimark, Rice Canyon, Rancho Jamul Ecological Reserve, Mother Miguel grasslands and Sweetwater Reservoir.
FT, SE
Elevation 25-300m [4]. Typically associated with clay soils supporting grasslands, open coastal sage scrub, or maritime succulent scrub vegetation [2]. Strongly associated with clay and clay loam soils (but not exclusively) in the Diablo, Linne, and Olivenhain series [5].
Known as Hemizonia conjugens when originally listed as threatened. Reclassified in Deinandra to better reflect phylogenetic and cytogenetic relationships [6]. Genetic analysis indicated substantial genetic diversity resides within individual populations, making each remaining population potentially valuable for this diversity [7].
Annual herbaceous plant in the Asteraceae (sunflower family). Plants less than 40cm (16 in) tall, lobed leaves, yellow flowers in heads of 8-10 ray flowers and 13-21 disk flowers [2]. Number and location of standing plants in a population of annual plant species varies each year, due to a number of factors, including amount and timing of rainfall, temperature, soil conditions, and extent and nature of seed bank [8]. Large annual fluctuations in the number of standing plants of Otay tarplant in a given population have been documented [8]; two examples include from 1 to >5,400 standing plants at a site on Otay Mesa, and from ~100 to 50,000 at a site in Rice Canyon. In a given year, the observable plants are only the portion of the individuals from the seed bank that germinated that year.
Blooming period May to June.
Asteraceae family produce one-seeded fruits (achenes). Species relies on sexual reproduction (self-incompatible) [2]. In one study bees most common putative pollinators; additional potential pollinators from 12 insect families [5]. Same study found < 10% of disc florets produced matured achenes, whereas 60% of ray florets did. In addition, germination of ray achenes generally unsuccessful, whereas disc achenes germinated readily. Seeds of this species potentially dispersed by small and large mammals and birds based on the sticky nature of flower parts attached to fruits [8]. In late summer, dried plants may be blown by wind [A. Davenport in litt. 2004; cited in 2] thereby moving seeds. Need for additional information on seed dispersal and seed bank longevity identified in the federal recovery plan [8].
Aside from loss of suitable habitat (e.g., loss to development and agriculture), threat from invasive nonnative plants (annual grasses, tocalote, and mustard species) identified as most widespread significant threat, affecting known occurrences [2; see references therein]. On-going threats include urbanization (including development, road construction and maintenance), utility construction, maintenance, and access; Caltrans projects; OHV impacts; Border Patrol activities; habitat fragmentation, and agricultural activities [2].
Species occurs within the range of fasciculated tarplant (Deinandra fasciculata) and San Diego tarplant (Deinandra paniculata); can be distinguished from others in genus by ridged phyllaries, black anthers, and number of disk and ray flowers [8]. Clay soils tend to crack during dry season, the same time that seeds of this species are typically released; thus seeds may fall into cracks and also become mixed deeper in the soil column [8]. The Recovery Plan [8] states it is anticipated that gene flow is achieved primarily through pollen movement (more so than seed dispersal), and that some of the smaller populations of this species are believed to be important to its conservation because they may facilitate gene flow among larger populations. The federal 5-year annual review for this species identified a need to develop, implement, and monitor effective invasive species management actions for all conserved occurrences [2]. Competition experiments done under controlled conditions indicate high density of the weed Centaurea melitensis reduces biomass, height, number of branches, and number of capitula (inflorescences) [2]. Additional information on Threats: Otay tarplant was assigned a Risk Group 1 ranking in an assessment of sensitivity status and threats to San Diego MSCP species [9]. It was ranked as high risk of habitat loss, fragmentation and moderate risk of impacts from invasive nonnative plant species. Lower-ranked threats included recreation/human disturbance, off-road vehicles, and grazing. Fragmentation of populations may further reduce connectivity between populations and potentially limit suitable pollinators, and hence gene flow between populations [2]. Climate change has the potential to negatively affect populations in a variety of ways; hotter and/or drier conditions may reduce germination rates and increase fire frequency, and the phenology of pollinators may become mismatched to plant phenology.
[1] Reiser, C.H. 1994. Rare Plants of San Diego County. Aquafir Press, Imperial Beach, CA. Available online: http://sandiego.sierraclub.org/rareplants/
[2] U.S. Fish and Wildlife Service (USFWS). 2009. Otay tarplant (Deinandra conjugens) 5-year review: Summary and evaluation. Prepared by the Carlsbad Fish and Wildlife Office, Carlsbad, California.
[3] MSP-MOM. 2014. Management Strategic Plan Master Occurrence Matrix. http://sdmmp.com/reports_and_products/Reports_Products_MainPage.aspx
[4] CNPS, Rare Plant Program. 2014. Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant Society, Sacramento, CA. Website http://www.rareplants.cnps.org [accessed 14 July 2014].
[5] Bauder, E. T., J. Snapp-Cook, and J. Sakrison. 2002. Ecology and management of Deinandra conjugens (D.D. Keck) B.G. Baldwin (Otay tarplant); Final Report. Prepared for California Department of Fish and Game, Region 5, Natural Community Conservation Planning Program, San Diego, California.
[6] Baldwin, B.G. 1999. New combinations and new genera in the North American tarweeds (Compositae-Madiinae). Novon 9:462-471.
[7] Bauder, E.T. and D. Truesdale. 2000. A comparison of Hemizonia conjugens (Otay tarplant) with two closely related tarplant species using enzyme electrophoresis and soil textural analysis. Final report prepared for California Department of Fish and Game Region 5. Available at: https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentVersionID=3624
[8] U.S. Fish and Wildlife Service (USFWS). 2004. Recovery Plan for Deinandra conjugens (Otay Tarplant). Portland, Oregon. vii + 65 pp. Available at: http://ecos.fws.gov/docs/recovery_plan/041228.pdf
[9] Regan, H.M., L.A. Hierl, J. Franklin, and D.H. Deutschman. 2006. Draft MSCP Covered Species prioritization for Task B of Local Assistance Grant #P0450009. Prepared for the California Department of Fish and Game (Grant Coordinator: Dr. Brenda S. Johnson). January 2006.