Range-wide status assessment of Houghton’s goldenrod (Oligoneuron houghtonii) with a
special emphasis on niche limits, demographic transitions, and population stability
Justine Weber
SUNY College of Environmental Science and Forestry
Final Report to the Edna Bailey Sussman Foundation, 2015
Introduction
Humans are changing Earth’s landscape, and thus exerting substantial impacts on
biodiversity and the function of ecological communities (Barnosky et al. 2011). Rare species,
especially, may have more difficulty adjusting to climate change if narrow environmental limits
are driving their rarity (Bartholomeus et al. 2011; Broennimann et al. 2006; Schwartz 2006).
Additionally, species with small, specific ranges and high population densities are more
vulnerable to extinction (Pimm and Raven 2000). Although rare organisms often get
considerable attention in conservation, the ecology and distribution of less charismatic rare
species are not well understood.
Houghton’s goldenrod (Oligoneuron houghtonii) is perennial plant of hybrid origin
(Laureto and Barkman 2011) that has a geographically restricted range with approximately 80
populations found in Michigan and Ontario, and one population in New York (USFWS 1997). O.
houghtonii is federally- and Michigan state-listed as threatened, is endangered in New York
State, and is a species of concern in Canada (USDA 2014, COSEWIC 2005). Although it is a
species of conservation concern and has a limited range, Houghton’s goldenrod is locally
abundant in some interdunal wetlands, rocky shorelines, wet limestone pavements, and marl fens
(USFWS 1997).
a
b
Figure 1. Houghton’s goldenrod occurrences in its core range (a) and the disjunct population in
New York (b). Images from USFWS 5-year Review, 2011.
Due to its narrow range, it faces extinction or extirpation of unprotected populations.
Habitat loss and fragmentation in the main Michigan coast populations are the most pressing
threats (USFWS 1997), but general succession and invasive species also appear to play a role in
outcompeting what appears to be an early successional plant (COSEWIC 2005; personal
observation). Additionally, many populations of O. houghtonii occur in highly dynamic habitats;
without a persistent seedbank, extirpation of adjacent populations could result in major losses
across the species (USFWS 1997).
The Federal Recovery Plan for O. houghtonii recommended protecting 30 of the most
viable elemental occurrence records (EORs, loosely populations) and their habitats as the sole
delisting criteria (USFWS 1997). Currently, 42 EORs are located partially or fully on State,
Federal, or land conservancy properties (USFWS 2011). While threats to this species still exist,
the current status of HOGO suggests that delisting due to recovery may be appropriate. However,
limited and often outdated information available for HOGO has prevented this evaluation
(USFWS 2011).
a
b
Figure 2. Houghton’s goldenrod flowering stems (a) and a marl “room” at Bergen Swamp, NY,
in which the only population of NY O. houghtonii is found (b).
Completed Work
Continued monitoring of the Bergen Swamp population of Houghton’s goldenrod
occurred during summer 2015. A survey of O. houghtonii flowering stems in NY revealed far
fewer (~ 10%) flowering individuals than the past two years (Table 1). This was likely due to an
unusually cold winter; other marl plants at Bergen Swamp (e.g. small white lady’s slipper,
Cypripedium candidum and pitcher plant, Sarracenia purpurea) also had very low flower counts
for the year.
Table 1. Number of O. houghtonii flowering stems at Bergen Swamp, NY.
Year
2013
2014
2015
Number of flowering stems
3400
3000
375
Additionally, in early summer 2015, a cooperative project between SUNY-ESF, the U.S.
Fish and Wildlife Service (USFWS), and Michigan Natural Features Inventory (MNFI) was
started to assess the status of O. houghtonii across its U.S. range. This new project will be
completed and funded through the Great Lakes Restoration Initiative (GLRI), and shifted the
timeline of the originally proposed Houghton’s goldenrod research. My initial objectives for the
Sussman internship were to 1) investigate habitat characteristics of multiple populations to
determine the drivers of species abundance and to 2) investigate the conditions necessary for
Houghton’s goldenrod seed germination and establishment. These objectives will now be
completed in 2016, though groundwork to fulfill these objectives was laid during summer 2015.
In order to achieve such a broad status assessment, comprehensive surveys of population
numbers were initiated in summer 2015. Around 50 populations of Houghton’s goldenrod were
visited in August; at each location, number of flowering stems (often rounded, as per past MNFI
surveys), percent of individuals flowering, and likely threats to the population were recorded.
Example data is provided in Table 2. This data will help MNFI update Houghton’s goldenrod’s
state ranking, and the surveys provided valuable field observations that will guide further work.
In October 2015, seeds were collected from 28 O. houghtonii populations. These seeds will be
used for in situ and ex situ germination trials and viability tests.
Table 2. Example data from Houghton’s goldenrod population surveys, August 2015.
Population
Summerby Fen
Grass Bay Preserve
Belonga Road Fen
Flowering Stems
100
>5000
300
Percent Flowering
30
20
20
Probable Threats
deer herbivory, succession
fluctuating lake levels
deer herbivory, road
runoff, cattail competition
Fox Point
10,000
30
Cheboygan SP Beach
>3000
<10
fluctuating lake levels,
recreational beach use,
Phragmites
fluctuating lake levels,
recreational beach use
a
b
Figure 3. Interdunal wetland at Wilderness State Park, MI (a) and recreational beach use
impacting shoreline habitat (b).
Additional field observations:
 Houghton’s goldenrod in northern Michigan was most often found in interdunal swales
along Lake Michigan and Lake Huron shorelines. Moreover, it typically occurred on the
upslope of the first backdune.
 Though water levels in the Great Lakes are controlled throughout the lake system, there
is some fluctuation of lake levels from year to year. In August 2015, water levels in Lake
Michigan and Lake Huron were close to 8 inches higher than average – a significant
change when applied horizontally along shorelines. This would certainly have
implications for species that depend on the narrow interdunal habitats between the lake
and conifer forests nearby.
 Several Michigan sites had O. houghtonii in most disturbed locations – such as around
trails or roadsides.
Future Work
Seed viability tests and greenhouse germination experiments will begin during winter
2016 and in situ germination experiments in Michigan and NY Houghton’s goldenrod
populations will begin in summer 2016. Habitat data will be collected in Michigan and New
York during summer 2016. These data – germination success and habitat data – will be
combined using mixed models to assess what habitat variables are most associated with
flowering and germination success. These results will be provided to USFWS and MNFI to
update the federal and state listing status of Houghton’s goldenrod, and to assess whether it is
appropriate to delist O. houghtonii from federal protection. Population surveys will also continue
in summer 2016, in conjunction with MNFI botanists. Further genetic work on the species –
dealing with population stability across the range – is being considered as well.
Acknowledgements
My major professor, Don Leopold, has contributed much support and advice to my
continuing work. John Wiley, USFWS, aided in developing the larger range-wide project with
Houghton’s goldenrod relative to federal recovery goals. Baylee Earl, my undergraduate
assistant during 2015, contributed many hours and thoughtful insights in the field. And the
Bergen Swamp Preservation Society, especially Steve Locke, has provided significant support
and encouragement, as well as supervising this internship and providing access to Bergen
Swamp and the NY Houghton’s goldenrod population. The Edna Bailey Sussman Foundation
provided funding that allowed for expansion of a significant and applied conservation project,
and will be recognized in my dissertation as well as in all posters, publications, and presentations
wherein this work is referenced.
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