Project Title: Renewing and refining the Tahoe yellow cress Conservation Strategy: incorporating new science and
management tools
Primary theme & subtheme: Integrating Science Subtheme 4b: Identifying environmental indicators and
development of approaches for monitoring and evaluation
Principal Investigators and institutions:
Alison E. Stanton, Consultant
3170 Highway 50 Suite # 7 South Lake Tahoe, CA 96150
p: 415.990.2269 f: 530.600.1281; alisonestanton@sbcglobal.net
Dr. Bruce M. Pavlik
Jodrell Laboratory, Royal Botanic Gardens Kew
Richmond, Surrey, TW9 3 DS UK
44 0208 332-5367 b.pavlik@kew.org
Collaborators and their institutional affiliations: the Tahoe yellow cress Adaptive Management Working Group
(Tahoe Regional Planning Agency, U.S. Fish & Wildlife Service, U.S. Forest Service, Nevada Division of Forestry,
Nevada Division of State Lands, Nevada Division of State Parks, Nevada Natural Heritage Program, California State
Lands Commission, California Department of Fish & Game, California Department of Parks & Recreation, California
Tahoe Conservancy, Tahoe Lakefront Owners’ Association, and de facto members including Natural Resources
Conservation Service, Tahoe Resource Conservation District, Nevada Tahoe Conservation District).
Grants contact person: Alison Stanton, p:415.990.2269; f: 530.600.1281; alisonestanton@sbcglobal.net
Total funding requested: $ 76,320
Total cost share (value of financial and in-kind contributions): $46,377
Staff time for participation in the Tahoe yellow cress Adaptive Management Working Group (AMWG) is estimated in
the annual reports. Members attend quarterly meetings, review documents and projects, implement management,
provide comment on research and technical reports, and participate in the annual lake-wide survey. Recent yearly
cost estimates for total staff time spent on AMWG duties ranges from a high of $133,963 in 2005 to $64,509 in 2007.
The average of five years (2004, 2005, 2007-2009) is $92,755. It is not easy to estimate a percentage of time that
staff might contribute specifically to this project, but since the importance of the MOU renewal and CS update will be
a high priority, we conservatively estimate 50%, or $46,377.
ll. Proposal Narrative
Project abstract
Tahoe yellow cress will always be a rare plant because it occurs only on the shores of a single lake, Lake Tahoe. The
degree of endangerment to the species in this high profile habitat depends on a host of factors, many of which can be
managed on some level. Since the adoption of the Tahoe yellow cress Conservation Strategy (CS) in 2002, the
Adaptive Management Working Group has worked together to address threats to Tahoe yellow cress and coordinate
efforts to manage and protect the species. A central emphasis has been the implementation of a field based research
program conducted between 2003 and 2010 testing the role of genetic, hydrologic, and logistical factors in population
restoration using container-grown Tahoe yellow cress plants. Yearly analyses have been conducted and most
recently we have tested the effectiveness of translocation (moving naturally occurring plants from one site to
another). We propose to 1) conduct a synthesis and meta-analysis of this existing dataset (2003-2010); and 2)
incorporate resulting protocols for outplanting and translocation into a series of new management tools in the CS for
restoration and mitigation. We further propose to utilize the existing survey record from 1979-2011 to 3) update the
conceptual model of TYC population dynamics; 4) valuate and update indicators in the CS, and 5) develop a geodatabase for data management and analysis. The Memorandum of Understanding uniting 13 signatories in the cause
to implement the CS is set to expire on January 29, 2013, ten years after the last signature date. The main
consequence of failure of the signatories to continue to implement the CS is reconsideration by the US Fish and
Wildlife Service to list the species under the Endangered Species Act. Federal listing would significantly increase the
regulatory burden on all projects located in or near the shorezone around Lake Tahoe. In response to the apparent
success of the CS, recent regional planning efforts are specifically referencing the strategy in sensitive species
sections that address Tahoe yellow cress. From a regulatory standpoint agencies will be relying on continued
implementation of an updated CS that incorporates new science and management tools.
Justification statement
Tahoe yellow cress (Rorippa subumbellata Rollins) is a small perennial plant in the Brassicaceae (Mustard) family. It
has small yellow flowers and is characterized by fleshy leaves and a spreading growth form. Tahoe yellow cress
(TYC) only occurs on the sandy shores of Lake Tahoe and nowhere else in the world. The species is listed as
Endangered in California, Critically Endangered in Nevada, and has been a candidate species for listing under the
federal Endangered Species Act (ESA) since 1999. It also has special status as a Sensitive Plant Threshold Indicator
for the Tahoe Regional Planning Agency. This high level of protection is the greatest of any plant occurring in the
Tahoe Basin.
In response to near extinction of the species between 1995 and 2000, the Tahoe yellow cress Conservation Strategy
(CS) was adopted in 2002 (Pavlik et al. 2002a). The overarching purpose of the CS is to sufficiently protect and
promote the persistence of the species to prevent listing under ESA. A total of 13 entities (Table 1) united behind this
purpose and signed the MOU agreeing to implement the CS. The CS provides an operational example of an adaptive
management framework to coordinate efforts and incorporate new information on methods to successfully manage
and protect the species. Embedded in this framework are the necessary elements of a comprehensive monitoring
and evaluation plan that are addressed by Subtheme 4b including: 1) a conceptual population dynamic model, 2)
quantitative indicators, 3) a standardized monitoring approach, 4) an applied research program, 5) data analysis,
reporting, and management protocols, and 6) management actions, including an Imminent Extinction Plan.
Since 2003, the TYC Adaptive Management Working Group (AMWG) has worked together to implement the
elements of the CS (members are listed in Table 1). However, the MOU is set to expire on January 29, 2013, ten
years after the last signature date. The main consequence of failure of the signatories to continue to implement the
CS is reconsideration by the US Fish and Wildlife Service to list the species. Federal listing would significantly
increase the regulatory burden on all projects located in or near the shorezone around Lake Tahoe. To preclude
federal listing and to keep the momentum of that last nine years of adaptive management moving forward, the
AMWG recommends that key elements of the CS should be updated and the MOU renewed (August 18, 2011
AMWG meeting minutes). This proposal addresses that need.
2
Concise background and problem statement
Tahoe yellow cress was first described as a species in 1941 (Rollins 1941) and quantitative monitoring began in 1979
(Knapp 1979). Survey effort has varied over the years, but standardized surveys for Tahoe yellow cress have been
conducted in the first week of September at up to 62 population sites around Lake Tahoe. Survey data is presented
in Annual Reports which also provide a record of all the conservation activities related to Tahoe yellow cress (Stanton
and Pavlik 2005 -2010). The monitoring sites are distributed around the entire lake and each is known to have
supported Tahoe yellow cress at some point since the species was first described (Figure 1).
In 2002, the Conservation Strategy presented a conceptual model of Tahoe yellow cress population dynamics that
emerged from the analysis of the presence/absence data from 1979 to 2000. Some sites were occupied in all or most
years, other sites experienced gaps in occupancy, and a few sites were found to have been occupied only in the
distant past. These temporal and spatial gaps suggested the occurrence of fundamental metapopulations events
(local extirpation, colonization, and recolonization). There are at least five types of metapopulations that vary
depending on the relative size, longevity, and dispersal frequency of component populations (Harrison and Hastings
1996). One of those, the “mainland-island” type, may best describe what is observed in Tahoe yellow cress (Pavlik et
al. 2002a). This model of metapopulation dynamics refers to spatio-temporal changes in distribution and abundance
where “mainland” subpopulations persist over long periods of time while other “island” subpopulations come and go
through the processes of local colonization and extirpation.
The analysis of the long term survey record in the CS further illustrated that the distribution and abundance of Tahoe
yellow cress is closely linked to the level of Lake Tahoe, such that the greatest number of sites is occupied when the
lake is low (Pavlik et al. 2002a). Lake Tahoe is regulated as a reservoir between the natural rim at 6,223 feet (Lake
Tahoe Datum, LTD) and the maximum legal limit set at 6,229.1 ft LTD. Tahoe yellow cress habitat occurs solely on
sandy beaches within this zone. With respect to Tahoe yellow cress, the lake is considered low (6,223-6224 ft), in
transition (6,225-6226 ft), or high (>6226 ft) as measured in the first week of September when the surveys are
conducted. According to the metapopulation model, “mainland” populations of Tahoe yellow cress are those which
can persist despite periodic high water levels and human-related impacts.
While the potential for sustained high water level appears to pose the greatest threat to Tahoe yellow cress, high
levels of recreational activities that can cause trampling of plants on both public and private beaches pose a
significant threat (Knapp 1980). Beach raking to remove debris and vegetation and construction of piers, jetties, and
other structures can directly destroy plants and decrease the amount of suitable habitat (Ferreira 1988). These
human-caused impacts are intensified when the level of Lake Tahoe is high (>6,226 ft LTD) and less sandy beach
habitat is available due to the geometry of the filling basin. Successive years of high lake level have the potential to
seriously reduce the presence and abundance of Tahoe yellow cress as was observed between 1995 and 2000
when the number of occupied Tahoe yellow cress sites declined from 37 in 1993 to only 9 in 1995-96, prompting
concerns of imminent extinction of the species (Pavlik et al. 2002a). Climate change may also adversely affect Tahoe
yellow cress populations through altered levels of runoff into the lake. The potential for sustained high water levels
and increased recreation pressure continue to pose a threat to the long-term, persistence of Tahoe yellow cress.
Adoption of the CS launched an adaptive management process to address these threats to TYC and coordinate
efforts to manage and protect the species. An adaptive management framework was created to structure information
flow and to develop and evaluate management actions. A Key Management Questions (KMQ) framework was
developed to focus the research agenda to better assist land and resource managers to meet the habitat needs of
the species (Pavlik and O’Leary 2002). The KMQ framework has guided our field-based research program of
experimental plantings conducted at various beaches around the lake testing the role of genetic, hydrologic, and
logistical factors in population restoration using container-grown Tahoe yellow cress plants. Our field research
program has also tested the effectiveness of translocation (moving naturally occurring plants from one place to
another). From 2003 to 2009, over 9,000 container-grown TYC were planted at 14 sites and from 2005 to 2009 a
total of 525 plants were translocated at 7 sites. Currently, the analysis of these data are contained in 8 technical
reports (Pavlik and O’Leary 2002, Pavlik et al. 2002b, Pavlik and Stanton 2004, 2005, 2006, 2007, Stanton and
3
Pavlik 2009) and 7 annual reports (Stanton and Pavlik 2005 -2010). A preliminary meta-analysis of the 2003 to 2006
data container-grown plant data has been conducted along with an analysis of the pilot-scale translocations.
However, there is a critical need to incorporate additional data from 2008 to 2010 into the analysis and translate all of
this data into a series of protocols for outplanting and translocation. The analysis and synthesis of the research work
proposed here will generate needed peer reviewed publications
There is also a critical need to incorporate these outcomes into the CS. Recent planning efforts at the USFS and the
TRPA are specifically referencing the CS in sensitive species sections that address Tahoe yellow cress. From a
regulatory standpoint these agencies will be relying on continued implementation of the CS. The main indicator of the
success of the CS itself is the number of sites around Lake Tahoe occupied by Tahoe yellow cress. The long term
survey record indicates there has been a rapid improvement in this parameter since the adoption of the CS in 2002
(Stanton and Pavlik 2010.) During the period from 1979 to 2001, an average of 39 sites was surveyed each year and
19 of those sites were occupied. From 2002 to 2011, the average number of surveyed sites climbed to 59 and 39 of
those were occupied. Already the U.S. Fish and Wildlife Service has downgraded Tahoe yellow cress from a priority
2 to a priority 8 Candidate because of “continued commitments to conservation demonstrated by regulatory and land
management agencies participating in the Conservation Strategy” (69 FR 77167, 2005).
Goals, objectives, and hypotheses
Our primary goal is to ensure that the critical work of the Tahoe yellow cress AMWG can continue and that the MOU
to implement the Conservation Strategy is renewed by January, 2013. To reach these goals we propose the following
objectives:
1)
2)
3)
4)
5)
Synthesize results of field based research conducted between 2003 and 2010
Update the conceptual model of TYC population dynamics
Evaluate and update indicators in the CS
Develop a geo-database for data management and analysis
Recommend new management tools including restoration and mitigation tools
Objectives 1-3 directly address tasks set forth in subtheme 4b. Development of a geo-database (Objective 4)
addresses the need to consolidate the long term dataset (currently 26 years) into a more user friendly and
assessable format that can be used for project evaluation, conservation, and management. Recommendation of
new management tools (Objective 5) arises directly from the extensive field research on restoration and mitigation
methods using container-grown and naturally occurring plants and from our involvement in the Tahoe yellow cress
Stewardship Program addressing conservation on private lands. The details of our approach for achieving these
objectives are discussed in the next section.
Cost savings can be achieved on two tasks specified in subtheme 4b; 1) preparation of a monitoring and
evaluation plan, and 2) pilot implementation of protocols specified in the monitoring plan. Monitoring protocols for
the annual surveys were established early on (Baad 1979, Knapp 1980) and the CS developed a series of
evaluation protocols for the indicators (Pavlik et al. 2002a). In 2010, the Tahoe yellow cress Adaptive Management
Working Group (AMWG) shifted from an annual survey to an adaptive survey strategy where the lake-wide
monitoring effort is now linked to lake level (Stanton and Pavlik 2011). Surveys are conducted every year that the
lake is at or above 6,226 ft LTD and every other year when the lake is lower. There has been a continual desire on
the part of the AMWG to expand the survey to cover the entire lake in order to more fully assess colonization and
extirpation ratios, but despite multiple efforts, private property issues have not been resolved. Any expansion of
monitoring on private property, particularly in Nevada where there is no public trust, will need to be pursued
through the Stewardship Program, currently being administered by the Nevada Tahoe Resources Conservation
District. Absent the need to develop a new monitoring and evaluation plan for the species there is no need to
conduct any pilot implementation of associated protocols.
4
Approach, methodology and location of research
All research will be conducted from our local office in South Lake Tahoe. Below we discuss our approach and
methodology for each of the objectives specified above.
Synthesis of results of field based research conducted between 2003 and 2010
Experimental plantings of container-grown plants from 2003 to 2009 addressed Key Management Questions focused
on the role of genetics (maternal seed source), hydrological habitat conditions (measured as planting elevation
above the water table), inundation ( lake level), logistical factors (planting time), and site factors (proximity to a creek
mouth, annual precipitation) for restoration efforts. During this period over 9,000 container-grown plants were
installed at 14 sites around the lake. In most cases a block design was utilized within a fenced enclosure where
plants were spaced one meter apart and marked with a wooden stake. Plant phenology was monitored over the
growing season and plant canopy area measured in September. Sexual reproductive output was estimated based on
an equation that links canopy size (area) to seed output by individual plants (y=3.609x – 109.542, r = 0.81, where y is
the number of seeds per individual and x is canopy area in square centimeters) (Pavlik and O’Leary 2002).
In addition to the container-grown plant experiments, we also tested the effectiveness of translocation (moving
naturally occurring plants from one location to another). After small pilot tests in 2005 and 2006, translocation
experiments were installed in 2008 and 2009 using a paired design with one container-grown and one naturally
occurring Tahoe yellow cress plant. Translocation results for each year have been presented in the annual reports
and in an additional technical report to the California Department of Fish and Game (Stanton and Pavlik 2009b).
The primary experimental factors tested include maternal seed source, planting elevation, and planting time (JuneSeptember). The only quantitative variable that was measured was canopy area. Analyses to date have utilized
simple t-test, ANOVA, and multiple comparison tests such as Tukey Kramer on canopy area and the derived
estimate of seed output (# of seeds per plant). Going into the study, we expected that planting elevation (relative to
lake level) would be the single most important predictor of both survival and seed production. However, plantings
failed at some sites so a number of categorical variables describing site and habitat conditions will be included in the
proposed analysis. Results from these experiments are contained in a series of seven technical reports (Pavlik and
O’Leary 2002, Pavlik et al. 2002b, Pavlik and Stanton 2004, 2005, 2006, 2007, Stanton and Pavlik 2009b). Beginning
in 2007, experimental results were included in the Tahoe yellow cress annual reports (Stanton and Pavlik 2008,
2009, 2010, 2011).
Since our dataset has such a large number of categorical variable our analytical approach will use classification and
regression trees analysis (CART) using the freeware statistical software called R (Dalgaard 2008). This is a method
that looks at a rather wide collection of piecewise-constant models for predicting an outcome, defined so that
recursively it splits the predictor space along one of the predictors in order to minimize the variability in response
within each of the resulting subgroups. It’s a good exploratory tool for a dataset with many factors where logical cutoff
points are not apparent and it is not clear whether the same cutoff points are appropriate for different levels of a
second factor. It also has a few disadvantages. Piecewise constant models doesn’t mesh well with a regression
approach and such a wide class of models are considered that it’s hard to compute reliable p-values for the models.
However, the same can be said of stepwise model-building approaches that might be used as an alternative. With
both approaches there are so many predictors and so many ways to express them that the significance of any one
predictor is minimized.
The output of CART is a decision tree that gives the probability of particular outcomes i.e. survivorship at different
elevations above the lake at sites located in California vs. Nevada. The years of data collection have spanned the full
range of ecological conditions from very low lake levels to near-record high levels. Therefore any consistent patterns
that develop are apt to be valid over a wide range of conditions, and inconsistencies in the patterns can probably be
attributed to year to year differences.
5
Updating the conceptual model of TYC population dynamics
The mainland–island metapopulation model proposed in the CS (Pavlik et al. 2002) emerged from an analysis of
presence/absence data in the long term survey record. The CS adopts this metapopulation model as a conceptual
framework and includes goals that promote conditions for reestablishing a positive dynamic (colonizations > extirpations)
for self-maintenance of the species into the indefinite future. No scientific inventory of unoccupied sites with appropriate
habitat has been conducted and therefore extirpation probabilities can only be estimated. Private property issues make it
unlikely that such an inventory will be conducted in the future. However, the metapopulation dynamic is still a useful model
for prioritizing our thinking about recovery efforts and identifying critical attributes and processes for restoration. Therefore
we are not proposing to update the metapopulation model presented in the CS. Instead we will focus on the role of lake
level and site ownership in determining population persistence.
In the CS, a cyclic pattern emerged in the presence/ absence dataset when mean presence (mean % of occupied sites of
three ownership categories, USFS, State/County, and private) was plotted against survey year (Fig 2). A simple
regression analysis revealed that lake level accounted for 75% of the variation in mean presence (Fig 3). This analysis
utilized 31 sites with “high quality” records (USFS n=5, State/County n=8, and private n=18) and the maximum survey
record for a site was 16 years. Site and ownership designation have changed since adoption of the CS and that dataset in
that analysis was skewed toward high lake level years. The current dataset from 1979 to 2011 includes 26 years where
>50% of the known population sites were monitored and is balanced with a nearly equal number of years of low (10) and
(11) high lake level years, with 5 transition years. We will use this improved data and the same methods employed in the
CS to reevaluate the role of ownership in mean presence and the strength of the relationship between lake level and
presence. If the relationship has weakened it heightens the importance of developing and implementing on the ground
management actions that protect and enhance the species.
Evaluate and update indicators in the CS
Priority ranking index
The CS used persistence and stem count data to evaluate known Tahoe yellow cress sites for purposes of
conservation and restoration. An index of viability (Index = Ra + -1(CoVar) + Pr) was calculated for each site with
sufficient data based upon three components:
Where:
Ra
the relative abundance (mean stem count at a site/sum of mean stem counts of all sites
X100
-1(CoVar)
the negative coefficient of variance (-1 X the coefficient of variance of
mean maximum stem count at a site multiplied by 100)
Pr
persistence (number of occurrences at a site/record years multiplied by 100
Sites that support relative large, invariant, and persistent populations had a high, positive index value and were
classified as “Core” or “High” priority restoration sites. Sites with small, variant, and ephemeral populations had a low,
possibly negative value (if the CoVar term is large) and were classified as “ Medium” or Low” priority restoration sites.
Sites with low quality occurrence/absence data or that lack stem count data could not be assigned an index and were
simply designated as “unranked”. The CS specifies that ranking should be maintained for every site and we propose
to use the same methodology and re-rank all sites with sufficient data using the current, balanced dataset. In
addition, the component scalars (++,+,o) and the relative scalars (light, moderate, heavy) for development and
recreation impact are probably no longer accurate and need revision.
We expect that the number of Core (6) and high priority (6) sites will increase, partially because the total number of
surveyed sites has increased, but also because the CS dataset was skewed toward high water levels. This has
important management implications for planning and project review.
6
Minimum Viable Population (MVP) size
Also in the CS, the relationship between presence (% of years in the survey record from 1979-2000 where a site was
occupied by TYC) and mean stem count (Figure 4) was used to estimate values for the minimum stem count per site
(population size) required for varying probabilities of persistence (Table 2). In some ways these represent
demographically based minimum viable population (MVP) estimates widely used in conservation biology (Shaeffer
1981), with the following caveats: 1) These estimates were obtained retrospectively from field data, rather than as
projections from population models; and 2) they apply to the 20-year monitoring period, not to the 100, 500, or 1000
year timeframe simulated by modeling.
We propose to use the same methods and recalculate MVP. In the CS, an MVP of 1,200 stems is required to insure
a 90% probability of persistence over 20 years. The intended purpose of these estimates is to define the target sizes
of native, created and managed populations and thus provide indicators of biological and project success (Pavlik
1996). At the time that the CS was written there was only limited evidence about how to create or enhance
populations (Etra 1994). Based on the more recent survey data we expect that this minimum mean stem count will
decline. Once the synthesis of the experimental plantings has been completed and prescriptions for restoration and
mitigation are available, accurate targets will be needed to guide future projects.
Develop a geo-database for data management and analysis
Currently, the survey data is housed at the Nevada Natural Heritage Program in an Oracle database called Biotics.
The database is one used for all rare and endangered species in the national network of Heritage Programs but it
does not adequately catalog the Tahoe yellow cress survey data because data is stored in text fields, it is ArcGIS
incompatible, and it cannot be queried. We propose to collaborate specifically with the US Fish and Wildlife Service
to develop an ArcGIS database for Tahoe yellow cress with the following component layers: 1) site indicators (Priority
ranking index and MVP) 2) annual survey data, 3) public protection measures (fence locations), 4) experimental
plantings 5) restoration plantings, 6) stream mouths entering Lake Tahoe, 7) shoreline topography, and 8) beach use.
An ArcGIS database will enable users to query the annual stem count data, habitat descriptions, and information on
disturbance by year or any other parameter and also to do cumulative queries across all monitored sites. This
database plan was presented and approved at the August 18, 2011 AMWG meeting. Upon completion, the US Fish
and Wildlife Service Reno Office has agreed to assume responsibility for maintenance and upkeep of the database.
Recommend new management tools including restoration and mitigation tools
Essential components of the CS for Tahoe yellow cress include protection, restoration, monitoring, research, and
ongoing adaptive management. The CS explicitly intends that adaptive responses to monitoring and research will
inform and direct future management action. Many of the actions contained in the CS relating to monitoring and
research have been implemented. However, protection on public lands is still limited to fences at the high water line
that fail to protect plants within the entire range of their habitat from high water line down to the lake (see Figures 7
and8 in Stanton and Pavlik 2008). When the CS was written there was no knowledge on how to implement any
restoration and the only available option in project impact review and analysis was avoidance.
Prescriptions on how to conduct restoration outplantings with container-grown plants are embedded in the results of
the technical reports on the field experiments. Likewise, translocation has been proved to be a feasible and effective
(Stanton and Pavlik 2009b, 2011). There is a critical need to incorporate additional data from 2008 to 2010 and
translate all of this data into a series of protocols for the following:
1) seed collection and storage procedures,
2) propagation techniques and timing,
3) outplanting protocols based on seed source, container plant vigor, elevation, habitat suitability, lake level,
and planting month
4) translocation protocols based on habitat suitability, elevation, lake level, and planting month.
7
Several Environmental Improvement Projects (EIP) that are in the planning stage including the California Tahoe
Conservancy Upper Truckee Marsh Restoration and the City of South Lake Tahoe Bijou Erosion Control Project,
have the potential for unavoidable impacts to Tahoe yellow cress. The above protocols will be needed in project
review and will likely become components of mitigation. To ensure regulatory compliance and uniformity these
protocols need to be incorporated into the Management Actions that are contained in the CS
Relationship of the research to previous and current relevant research
The proposed research to update the conceptual model of Tahoe yellow cress population dynamics and the
associated indicators (Priority ranking index and Minimum Viable Population size) leverages the presence/ absence
and stem count data from the annual surveys and builds upon analytical methods developed in the CS (Pavlik et al.
2002b). Likewise, the majority of the data needed to populate the proposed ARC database is already contained in
annual survey reports or can be mined from the Nevada Natural Heritage Program Biotics database.
The experimental field plantings of container-grown Tahoe yellow cress plants was initiated because of the
documented success of greenhouse propagation and plantings by Western Botanical Services (Etra 1994). The
synthesis and analyses proposed here leverage the large dataset generated by pilot and experimental plantings
conducted from 2003 to 2009.
Our field research and successful participation in the AMWG has been supported by a variety of funding sources
including the Tahoe Regional Planning Agency, U.S. Fish & Wildlife Service, Nevada State License Plate Fund,
California Department of Fish & Game, the US Bureau of Reclamation, and the U.S. Forest Service. Currently there
are no active funding sources and this is the first time a request for funding is being sought for Tahoe yellow cress
through the SNPLMA science themes (USFS funds were provided by SNPLMA capital improvement funds).
Strategy for engaging with managers and obtaining permits
We have participated as technical consultants in the AMWG since its inception in 2000 and our continued
engagement with the group would leverage this relationship. Beginning in August 2010 we functioned as facilitator of
the group to provide continuity with a heightened level of staff turnover. Our funding was exhausted in September
2011. Facilitation of the AMWG is not included in this proposal, but we plan to attend the quarterly meetings in 2012
as soon as funding is available to gather input and feedback on the CS update process. We will convene a meeting
of the Executive Committee to present key findings prior to the renewal of the MOU. The funding timeline under this
proposal with an earliest start date of June 2012 is likely to delay renewal of the MOU beyond the expiration in
January 2013. However, securing funding will preserve the momentum of the AMWG and facilitate the process.
No permits will be required for this research.
Description of deliverables; include a data plan and a description of how deliverables will be reviewed and
made available to end users
As soon as funding becomes available we will be able to resume our collaboration with the Tahoe yellow cress
AMWG by attending quarterly meetings to get input on elements of the CS update and solicit review of all
deliverables. This funding will also enable us to resume collaboration with the US Fish and Wildlife Service to
develop a GIS database that contains eight layers relevant to Tahoe yellow cress management and conservation.
We expect to convene a meeting of the Executive Committee as early as January 2013 in order to present preliminary
updates to the Conservation Strategy that would be required prior to the renewal of the MOU. At that time we also expect
to present at the Northern California Botany conference. Our close collaboration with the AMWG will make it necessary to
allow sufficient time for them to conduct iterative review of drafts of updated sections of the CS. The members of the
AMWG are the end users of the CS and it is already designed to address stakeholder needs. Finally, the development of
at least two peer reviewed manuscripts is a central part of the data analysis plan and these publications will benefit the
wider conservation community.
8
lll. Schedule of Major Milestones and Deliverable The proposed project is scheduled to begin in June 2012. We
expect the majority of work will be completed within one year by June 2013, but additional time for manuscript
preparation may be required through December 2013.
Deliverable
Quarterly Reports
Start Date
July 2012
End Date
October 2013
Attend quarterly AMWG meetings
August 2012
November 2013
ARC database
June 2012
December 2012
Present at 2013 Northern
California Botany conference
Tahoe yellow cress Executive
Committee Meeting in January
June 2012
January 2013
June 2012
January 2013
Draft Conservation Strategy
June 2012
March 2013
Draft manuscript on role of
genetics and hydrologic factors in
outplanting success
Draft manuscript on translocation
and timing
Final Conservation Strategy
June 2012
March 2013
June 2012
March 2013
March 2013
May 2013
Final manuscripts
March 2013
December 2013
9
Description
Submit brief progress report to Tahoe
Science Program coordinator by the
1st of July, October, January, and April
Quarterly AMWG meetings are
generally scheduled for February, May,
August, and November
Collaborate with the US Fish and
Wildlife Service to develop a GIS
database
Present preliminary synthesis of
experimental planting results
Present preliminary updates of the
Conservation Strategy including the
conceptual model and indicators
Submit draft CS with updates to
conceptual model, indicators, and
management tools to AMWG for review
and comments
Submit draft to AMWG for review and
comments
Submit draft to AMWG for review and
comments
Incorporate AMWG comments and
finalize
Peer reviewed journal articles
lV. Literature Cited
Baad, M. 1979. Rare Plant Status Report for Rorippa subumbellata. Report prepared for California Native Plant
Society, CA.
California Native Plant Society. 2001. Inventory of Rare and Endangered Plants of California (sixth edition). Rare
Plant Scientific Advisory Committee, David P. Tibor, Convening Editor. California Native Plant Society.
Sacramento, CA. 388 pp.
Peter Dalgaard (2008), “Introductory Statistics with R”, 2nd edition. Springer, ISBN 978-0-387-79053-4,
http://www.biostat.ku.dk/~pd/ISwR.html.
DeWoody, J. and V.D. Hipkins. 2004. Expanded evaluation of genetic diversity in Tahoe yellow cress (Rorippa
subumbellata). USDA, Forest Service, National Forest Genetic Electrophoresis Laboratory. Placerville, CA.
DeWoody, J. and V.D. Hipkins. 2006. Genetic Monitoring of Rorippa subumbellata (Tahoe yellow cress): Analyzing
Northeast Populations and Monitoring South Shore Populations. USDA, Forest Service, National Forest Genetic
Electrophoresis Laboratory Project #194. Placerville, CA.
Etra, J. 1994. Third Annual Mitigation Monitoring Report: Rorippa subumbellata Rollins. Pump House Relocation
Project, Kahle Beach. Western Botanical Services, Reno, NV.
Ferreira, J.E. 1988. The Potential Effects of Pier Removal and Construction on Rorippa subumbellata Roll. at Ward
Creek, Placer County, CA. Tahoe Regional Planning Agency, Zephyr Cove, NV. 35pp.
Ferreira, J.E. 1987. The Population Status and Phenological Characteristics of Rorippa Subumbellata Roll. at Lake
Tahoe, California and Nevada, M.A. Thesis. California State University, Sacramento. Sacramento, CA.
Ingolia, M. 2006. Germination Ecology of an Endangered Endemic Plant in the Lake Tahoe Basin, Rorippa
subumbellata Roll. (Tahoe Yellow Cress). M.S. Thesis. University of California, Davis.
Knapp, C.M. 1980. Rorippa subumbellata Roll. Status in the Lake Tahoe Basin. USDA, Forest Service, Lake
Tahoe Basin Management Unit. South Lake Tahoe, CA.
Knapp, C.M. 1979. Rorippa subumbellata Roll.: Its Status on Historical and Potentially New Sites. USDA, Forest
Service, Lake Tahoe Basin Management Unit. South Lake Tahoe, CA.
Menges, E.S. 1990. Population viability analysis for an endangered plant. Conservation Biology 4, 52-62.
Pavlik, B.M. 1996. Defining and measuring success. In D.A. Falk, C.I. Millar, and M. Olwell (eds.), Restoring
Diversity: Strategies for Reintroduction of Endangered Plants. Island Press, Washington, D.C.
Pavlik, B.M. 2001. Developing an ecosystem perspective from experimental monitoring programs II. Physiological
responses of a rare geothermal grass to soil water. Environmental Management 28:243-253.
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Pavlik, B.M. and A.N. O'Leary. 2002. Implementation of the Conservation Strategy for Tahoe yellow cress (Rorippa
subumbellata). II. Key Management Questions as a Framework for Research. Prepared for the Tahoe yellow
cress Technical Advisory Group and the Tahoe Regional Planning Agency.
Pavlik, B., D. Murphy, and Tahoe yellow cress Technical Advisory Group. 2002a. Conservation Strategy for Tahoe
yellow cress (Rorippa subumbellata).Unpublished report prepared for the Tahoe Regional Planning Agency.
Zephyr Cove, NV. 106p.
Pavlik, B., A. Stanton, and J. Childs. 2002b. Implementation of the Conservation Strategy for Tahoe yellow cress
(Rorippa subumbellata): I. Seed Collection, Assessment of Reproductive Output, and Propagation for
Reintroduction. Unpublished report prepared for the Tahoe yellow cress Technical Advisory Group and the
Tahoe Regional Planning Agency. Zephyr Cove, NV.
Pavlik, B., and A. Stanton. 2004. Implementation of the Conservation Strategy for Tahoe yellow cress (Rorippa
subumbellata): III. Pilot Project to Support Reintroduction Experiments. Unpublished report prepared for the
Tahoe yellow cress Technical Advisory Group and the Tahoe Regional Planning Agency. Stateline, NV.
Pavlik, B., and A. Stanton. 2005. Implementation of the Conservation Strategy for Tahoe yellow cress (Rorippa
subumbellata): IV. Experimental Reintroductions: Year One. Unpublished report prepared for the Tahoe yellow
cress Technical Advisory Group and the Tahoe Regional Planning Agency. Stateline, NV.
Pavlik, B., and A. Stanton. 2006. Implementation of the Conservation Strategy for Tahoe yellow cress (Rorippa
subumbellata): V. Experimental Reintroductions: Year Two. Unpublished report prepared for the Tahoe yellow
cress Technical Advisory Group and the Tahoe Regional Planning Agency. Stateline, NV.
Pavlik, B., and A. Stanton. 2007. Implementation of the Conservation Strategy for Tahoe yellow cress (Rorippa
subumbellata): VI. Experimental Reintroductions: Year Three. Unpublished report prepared for the Tahoe yellow
cress Technical Advisory Group and the US Fish and Wildlife Service, Reno, Nevada.
Reed, S. 1982. Sensitive Plant Interim Management Prescription for Rorippa Subumbellata, Roll. USDA, Forest
Service, Lake Tahoe Basin Management Unit. South Lake Tahoe, CA.
Rollins, R.C. 1941. Some new or noteworthy North American crucifers. Contributions of the Dudley Herbarium 3,
174-184.
Saich R.C. and V.D. Hipkins. 2000. Evaluation of genetic diversity in Tahoe yellow cress (Rorippa subumbellata).
USDA, Forest Service, National Forest Genetic Electrophoresis Laboratory. Camino, CA.
Shaffer, M.L. 1981. Minimum population sizes for species conservation. Bioscience 31, 131-134.
Stanton, A., and B. Pavlik. 2005, 2006, 2007, 2008, 2009, 2010. Implementation of the Conservation Strategy for
Tahoe yellow cress (Rorippa subumbellata): Annual Reports 2004-2010. Unpublished reports prepared for the
Tahoe yellow cress Adaptive Management Group and Executive Committee.
Stanton, A., and B. Pavlik. 2009. Mitigation options for Tahoe yellow cress (Rorippa subumbellata). Unpublished
report prepared for the California Department of Fish and Game
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V. Figures
Table 1. Membership of the Tahoe yellow cress Adaptive Management Working Group (AMWG) in 2011 * denotes
de facto member, not a signatory on the MOU.
Agency or Entity
TRPA
USFWS
USFS LTBMU
NDSP
NDF
NNHP
CDFG
CSP
CTC
CSLC
TLOA
NRCS*
NTCD*
TRCD*
BOR*
CONSULTANTS
AMWG Representative
Mike Vollmer, Vegetation Program Manager
Sarah Kulpa, Botanist
Cheryl Beyer, Forest Botanist
Peter Maholland, Conservation Staff Specialist
Roland Shaw, Forester
Jennifer Newmark, Administrator/Program Biologist
Tim Nosal, Environmental Scientist
Dan Shaw, Environmental Scientist
Adam Lewandowski, Conservancy Program Analyst II
Eric Gillies, Environmental Scientist
Jan Brisco, Executive Director
Rachel Kozlowski, Resource Conservationist
Gretchen Huie, Environmental Scientist
Gretchen Eichar, Environmental Scientist
Myrnie Mayville, Wildlife Biologist
Dr. Bruce Pavlik, Principal, BMP Ecosciences
Alison Stanton, Research Botanist
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Figure 1. Tahoe yellow cress monitoring sites at Lake Tahoe and results from the survey, September, 2009.
13
Tahoe Yellow Cress
MEAN PRESENCE (%)
100
80
60
40
20
0
1978
1982
1986
1990
1994
1998
2002
SURVEY YEAR
Figure 2. Mean presence+ SE of three ownership categories (USFS n=5, State/County n=8, and private
n=18) for 31 total sites with long-term, high quality records for Tahoe yellow cress, 1979 to 2000.
Tahoe Yellow Cress
MEAN PRESENCE (%)
100
80
60
40
20
y = 5.1244e+4 - 8.2206x R^2 = 0.751
0
6220
6222
6224
6226
6228
6230
LAKE ELEVATION (feet LTD)
Figure 3. Relationship of mean presence as a linear function of mean lake elevation for Tahoe yellow
cress, 1979 to 2000.
14
Tahoe Yellow Cress 1978-2000
PERSISTENCE (% of record years)
Taylor Creek
Upper Truckee E
100
Blackwood S
Edgewood
80
Logan Shoals
Baldwin Beach
60
Glenbrook
Timbercove
40
Regan/Al Tahoe
20
y = 13.436 + 24.760*LOG(x) R^2 = 0.633
El Dorado
0
0
500
1000
1500
2000
MEAN STEM COUNT (#/site)
Figure 4. Relationship between mean stem count (for each site in all record years) and persistence (% of
record years the site was occupied) for Tahoe yellow cress, 1978 to 2000.
Table 2. Calculated values of minimum viable population size (minimum mean stem count/site) for
Tahoe yellow cress with different probabilities of persistence after 20 years. Data collected from 29
sites between 1978 and 2000. See Figure 4 for relationship.
Probability of
persistence after
Minimum mean
20 years (%)
stem count/site
________________________________________
99
2800
95
1900
90
1200
75
300
50
30
________________________________________
15