Horse Rock Ridge Restoration and Monitoring

Grass meadows and Douglas fir forests create a mosaic landscape at Horse Rock Ridge

Horse Rock Ridge is a unique mosaic habitat located in the Coburg Hills that has received dual designation from the Bureau of Land Management as an Area of Critical Environmental Concern and a Research Natural Area.  Areas that receive such designations are managed to provide for scientific research and protection of key natural attributes through short and long term studies, education, and restoration.  An ACEC can serve as a baseline reference for measuring human impacts on native ecosystems and for studying the effectiveness of restoration efforts.  IAE has been involved with experimentation and restoration on Horse Rock Ridge since 2006 and has developed research projects that include experimental seeding and treatment plots, seed collection and redistribution, plant community mapping, and invasive species management. This area is considered to be the best, and largest, remaining example of a "grassy bald" meadow located west of the Cascade Range.  The high botanic value can be attributed to the abundance of native Willamette Valley  species interspersed with species that are more prevalent in the mountainous Cascade region.  Douglas fir and western hemlock forests surround the grassy meadows creating a distinct mosaic landscape. 

IAE staff next to the dike at Horse Rock Ridge

Many of the geologic features found on Horse Rock Ridge are a result of basaltic-andesite flows that were deposited approximately 24 million years ago.  The Coburg Hills were formed as molten lava from the flows rapidly cooled  at the surface.  Long after flows cooled, a large crack formed cutting through older layers of rock and creating a dike as molten lava rose up through it.  The rock forming this dike is more resistant to erosion than the rock around it, so it can now be seen protruding above the present rock layer.  Soil within the meadows remains extremely shallow due to the steep and actively eroding slopes.  The soil type found here shows very little development, which is typically found in young landscapes, because it is not able to establish the depth required to create horizons.  These shallow soils inhibit the establishment of roots from larger plants and trees, effectively halting ecosystem succession in the meadows.  

Monitoring of experimental seeding plots

Restoration activities were initiated in 2006 with the creation of maps detailing the existing plant communities. In 2008, researchers established experimental plots in both xeric and mesic meadow areas to test the effects of a variety of restoration treatments. Xeric areas have very shallow soils and retain low amounts of moisture while mesic areas tend to occur near seeps and have moderate moisture levels and soil depth.  Restoration treatments included combinations of seed addition, solarization, and carbon addition. Seed addition appeared to be the most successful and can be used as a future tactic for augmenting the native plant populations. Seed collection for restoration purposes began in 2008 and has focused on collection of aggressive forbs such as Oregon sunshine (Eriophyllum lanatum), grassy tarweed (Madia gracilis), and Clarkia spp. that tend to germinate quickly and produce copious amounts of seed.  Several native grass species, including blue wildrye (Elymus glaucus), California oatgrass (Danthonia californica), and prairie Junegrass (Koeleria cristata) have also been collected and reseeded in an effort to reinforce the ecosystem’s resistance to invasion.  In 2010-2012, research expanded to include experimental outplantings of plugs, and bulbs in order to measure the establishment abilities of several native species and improve habitat quality.  Plant establishment can be difficult on Horse Rock Ridge due to harsh environmental conditions such as extreme erosion, exposure to high winds and rains, and steep slopes limiting water retention.  The Bureau of Land Management currently manages for potential habitat threats, namely illegal access by off-road vehicles and spread of invasive species.  The agency continues to support restoration, conservation research, and  habitat monitoring at the site.

The meadows on Horse Rock Ridge exhibit spectacular wildflower displays in early summer.  Some of the most prevalent wildflower species are Oregon sunshine, Indian paintbrush, and darkthroat shooting star.

Pink sand verbena monitoring on the Oregon Coast

Abronia umbellata ssp. breviflora

Pink sand verbena (Abronia umbellata ssp. breviflora) is a short-lived perennial in the Nyctaginaceae family that is native to the Pacific Coast.  Individuals of this species only reproduce by seed and many individuals act as annuals, flowering and dying in their first year of growth.  Given their placement on dynamic dune systems, most populations are obliterated during winter storm events but seeds persist and are able to reestablish in the following years.  This pattern leads to highly variable populations (in both size and distribution) from year to year, but shows that a long-lived, persistent seed bank is possible and necessary for survival.   Historically found in widespread populations between British Columbia, Canada and Northern California, the species is now sparsely distributed throughout the range.  Pink sand verbena was thought to be extinct in the northern part of its range until 2 plants were found on Vancouver Island in 2000 and another two plants were found in Washington in 2006.  Existing populations are geographically isolated to the extent that there is little possibility of genetic exchange.  The greatest threat to the verbena habitat is competition with invasive European beachgrass (Ammophila arenaria), which has become widespread throughout pink sand verbena’s range and easily outcompetes native forbs.  The beach grass was introduced to the U.S. coast in the early 1900s and, once established, began stabilizing foredunes and disrupting the dynamic, hummocky dune habitat that pink sand verbena thrives in.   

Staff collected sand for substrate analysis

Research has been conducted since the mid-1990s about methods for reintroduction.  In extensive seeding experiments, over 3.8 million seeds have been distributed across more than 23 Oregon Coast sites.  The sites that had the most successful plant establishment rates were ones where the beach grass populations had been disturbed by bulldozing the top layer of sand and vegetation off the dune.  Following reintroduction in 1997, population numbers were steadily increasing until 2010.  Population surveys by IAE began in 2000 and have extended across lands owned by the US Forest Service, the Bureau of Land Management, the State of Oregon, and private land owners.  In 2012, monitoring occurred at nine populations near Bandon, Coos Bay, and Florence.  Researchers found that the number of plants at several sites had increased since the previous year.  Oregon's largest population of pink sand verbena occurs on the Coos Bay North Spit and is entirely a product of seeding efforts.  Seed was collected from a population in Port Orford in the mid-1990s and was spread across an area identified as ideal sand verbena habitat in 1997.  Seeding at the site resulted in a population of over 185,000 plants in 2011.  In addition, a trip was taken to Floras Lake and the survey crew discovered 67 plants (8 reproductive) at the site, which hasn’t had plants documented since 2006.  This site was last seeded in 2000, so the current population could indicate a small, but long-lived seed bank.

A mat of pink sand verbena sprawls across the dune on the Coos Bay North Spit.  Now the largest population in Oregon, this is entirely a result of seeding by IAE and its partners.

The pink sand verbena produces flowers June through September, but the surveying and monitoring window is limited due to protection of the western snowy plover’s nesting habitat.  The western snowy plover is a small shorebird that has been listed as threatened at the federal level.  It is native to the beaches of the Pacific Coast, but has experienced a drastic decline in numbers over the past several decades, primarily due to habitat degradation and destruction.  The state of Oregon recognized the decline and has included the plover on the state threatened species list since 1975.   The Pacific Coast population of snowy plovers inhabits the same area in which pink sand verbena is found, and their population decline has coincided with the decline of the verbena and several other native beach species.  According to the Western Snowy Plover Recovery Plan there used to be 20 nesting sites along the Oregon Coast, but that number has dwindled to just seven areas that are consistently used.  One of the steps taken to work towards delisting the species is restricting access to known breeding areas during the nesting season, typically between March and late September.  Ideal nesting sites such as dune-backed beaches, sand spits, and sparsely vegetated dunes with active sand movement coincide with ideal habitat for pink sand verbena populations.

Western snowy plover and chick.  Photo source: www.duneguide.com

Kincaid's lupine in Douglas County, Oregon

Lupine leaves and racemes

Lupinus oreganus, commonly known as Kincaid’s lupine, is a perennial forb native to the Pacific Northwest ecoregion.   It is found in wet prairie habitats and open oak woodlands, both of which are habitat types that have experienced extreme degradation and fragmentation due to urban and agricultural development.  Although Kincaid’s lupine is listed as a threatened species by the U.S. Fish and Wildlife Service, approximately 90% of occurrences are located on private land making management and protection difficult.  There are 161 known populations in Oregon, 94 of which cover less than one acre.  Kincaid’s lupine is a member of the legume family (Fabaceae) and has clumping, palmate basal leaves and numerous unbranched stems.  Reproductive stems produce 4-7 inch racemes (flowering stalks) with flowers arranged in a whorled pattern.  This species can be seen flowering between April and June.  There are several other lupine species that exist within the same range as Kincaid’s lupine and hybridization between species can cause difficulty in proper identification.

IAE staff use a grid to census the lupine plants

Ten years ago, IAE began monitoring several lupine populations in Douglas County (the southernmost occurrences of the species) in order to look at trends in population size and reproductive vigor.  Given that Kincaid’s lupine is the obligate larval host plant for the federally endangered Fender’s blue butterfly, researchers conducted butterfly surveys in 2007 at all monitoring locations.  To date, there are no known occurrences of Fender’s blue butterfly within Douglas County.  Current monitoring focuses primarily on measuring foliar cover (translating to abundance) and counting the number of racemes on the individuals monitored (translating to reproductive vigor).  Transects or monitoring grids have been established at six independent sites within the Roseburg BLM district.  Four of the sites are monitored with a full census of the plants, while the remaining two use sub-sample monitoring.

One of the monitoring locations, Callahan Meadows, has a unique population that appears unable to produce successful reproductive individuals.   Plant samples from Callahan Meadows were genetically tested and 100% of the individuals tested were polyploidy and from one maternal haplotype, meaning that the plants are effectively sterile.  Individuals are able to continue reproducing vegetatively but not sexually.  So, while the foliar cover of the plants in this population has continued to increase, the implications of decreased genetic diversity are concerning.  The failure of pollination experiments has reinforced researchers' theories that the population has reached a genetic dead-end and is unable to produce viable seed. This population is the only known Kincaid's lupine population in the Roseburg BLM district that does not occur along a roadside and it also hosts enough nectar species to theoretically be habitat for Fender’s blue butterfly.  Unfortunately, given the chronic reproductive failure, the lupine population would not be able to provide stable reproductive habitat for the butterfly.

Monitoring methods: grid in forest clearing (l), transect on roadside (r)

Aside from concerns about low genetic biodiversity, these lupine populations are vulnerable to encroachment of invasive species, disturbance and competition for resources from associated vegetation.  Kincaid's lupine thrives in areas that receive high levels of sunlight, so decreasing canopy cover can have a positive effect on the populations' health.  In 2010, the BLM treated four of the sites monitored by IAE by significantly thinning small shrubs and trees to open up the canopy around established plots.  At three of the four sites it appears that plants have responded positively, as evidenced by an overall increase in foliar cover and number of inflorescences. Continued monitoring will provide more information about the success of this experimental treatment.   

Point Reyes bird's beak: Population monitoring and disturbance evaluation

Cordylanthus maritimus ssp. palustris (Point Reyes bird's beak) 

Point Reyes bird’s beak (Cordylanthus maritimus ssp. palustris) is a unique hemiparasitic halophite native to salt marshes on the coasts of Oregon and California.  It is only found in tidal salt marshes, leaving many of the populations exposed to the threats of filling, tidal manipulation, and water pollution.  The US Fish and Wildlife Service lists this species as a Species of Concern and the Oregon Department of Agriculture considers it to be Endangered.  There are 18 known occurrences of Point Reyes bird's beak within the state of Oregon, with the colonies’ populations averaging 2,000 individuals.  The population that is currently monitored by the Institute for Applied Ecology (IAE) is located on the North Spit of Coos Bay within a BLM Area of Critical Environmental Concern (ACEC).  Monitoring began in 2010 and has continued annually in an effort to track changes in population size and location.  IAE also collects plant community data to analyze Point Reyes bird's beak's preferred habitat.

Point Reyes bird’s beak is an annual that blooms June through September and produces fruits August through November.   This species reproduces from seed, but requires very specific levels of salinity in the marsh in order for the seeds to germinate.  There is some evidence indicating that Point Reyes bird’s beak is a self-pollinator, unlike similar species which require pollinators.  This plant is a member of the Orobancaceae family, which consists of holoparasitic and hemiparasitic plant species.  Hemiparasitic plants, such as Point Reyes bird’s beak, can produce some of their own energy through photosynthesis, but also utilize underground root connections to derive resources from neighboring plants.  While this particular species lacks host specificity, it is commonly found in association with Virginia glasswort (Salicornia depressa), marsh rosemary (Limonium californicum) and marsh jaumea (Jaumea carnosa).

IAE crew members (L to R: Erin, Eddie, Charlotte, Guy) monitoring community composition and population density along transect.

In recent years, the BLM took action to protect a portion of the North Spit population by diverting an access road around the largest grouping of plants.  In the first several years of monitoring on the North Spit, the primary research objectives were mapping population size and testing the effects of interspecific competition between Point Reyes bird’s beak and its associated species.  After it was determined that there was no competition effect presented by surrounding species, research shifted to focusing on population mapping and, starting in 2012, comparing population size and success of protected versus unprotected areas.  Ten transects within the protected area were monitored in order to collect data on community composition and species density.  Data on the density of Point Reyes bird’s beak, the associated plant community, and habitat type were recorded within each meter sampled, and were used to estimate the number of individuals present within the entire population.  This year, four new transects were established within the unprotected portion of the population to provide a functional comparison of the effects of human disturbance (e.g. ORV use). 

ORV tracks through the C. maritimus population

The primary threat to this specific population continues to be human disturbance, but additional threats include water pollution.  Individual populations can be affected by changes in microtopography of the marshes due to sand accretion, changing tidal patterns, or recreational and industrial uses in close proximity to the habitat. Continued monitoring of the population size and habitat will provide information about how the North Spit population responds to disturbance pressures and can be used to inform future decisions about management and protection. 

Population monitoring of Cusick's lupine in Baker County, Oregon

Cusick's lupine inflorescence

Lupinus lepidus var. cusickii (Cusick’s lupine) is a narrow endemic forb inhabiting eroding volcanic ash deposits in eastern Oregon’s Baker County.  Given its extremely limited geographic distribution, the Oregon Department of Agriculture has listed it as a state endangered species.  The BLM considers it to be a special status species, meaning that management actions must be taken in order to avoid having the plant listed as threatened or endangered on the federal level.  All populations fall within the Blue Mountains physiographic region, part of the Columbia Plateau geologic formation.

Herbarium specimen collected

Cusick’s lupine was originally discovered in 1886, but very little information existed about its range and population extent.  Over the past several decades, field surveys have been conducted using the Intuitive Controlled survey method to determine where populations currently exist.  Potential habitat was first identified by analyzing aerial photos and topographic maps. To date, there are five small populations of Cusick’s lupine found on BLM land in Baker County.  Although the plant was uncommon throughout the survey area, locations that did contain Cusick’s lupine were fairly densely populated.  The known populations were found on eroding hillsides where competition from other plants species was low.  Surveys will continue to be conducted throughout areas of interest to provide accurate information about the full extent of the population and to help prioritize management actions.

BLM Botanist, Roger Ferriel, assisting IAE crew

Cusick’s lupine is a low-lying perennial, often found growing in dense clusters. Short purple and white racemes, which flower in July, are generally surpassed by the plant’s foliage.  Stems are branched at the base and leaves are mainly basal.  There are four other varieties of Lupinus lepidus occurring in eastern Oregon, but variety cusickii can be distinguished by its low raceme position, short stature (up to 11 cm tall), and erect growth.  Seed production is vital for population maintenance since Cusick’s lupine does not reproduce vegetatively.

Population monitoring on permanent transects began in 1993 and has continued to occur intermittently.  Fences were erected at three populations to exclude human disturbance from portions of the population.  This season, Vale District BLM Botanist Roger Ferriel joined the IAE crew to assist at several monitoring sites.  At each monitoring location, data was recorded regarding plant height, diameter and perpendicular width, the number of inflorescences and evidence of herbivory.  Population density and plant health have varied considerably over the years, most likely due to climatic variation.  Threats to the Cusick’s lupine populations include small population size, invasive species, and human disturbance (off-road vehicle use and illegal dumping).  Although the populations do not appear to be in immediate danger, continued disturbance by humans could potentially degrade the limited habitat available to this lupine species.  Since little information exists about cultivation of this species, seeds were collected from three populations to be used in future germination trials. A subset of these seeds will be sent to the Rae Selling Berry Seed Bank to be stored in case reintroduction projects are needed to mitigate unforeseen anthropogenic or natural population disturbances.

Cusick's lupine habitat (foreground) at ORV Hill monitoring site

Population dynamics of Mulford's milkvetch

Population monitoring at the South Alkali population. Vale, Oregon

Although Oregon is well known for its coniferous forests, low valley prairies, and coastline that receive high amounts of rainfall, nearly two thirds of the state exhibits semi-arid habitat conditions.  Oregon’s eastern desert region experiences greater seasonal fluctuation than the western portion of the state and is inhabited by plants and animals that can tolerate extreme differences in weather.  The high desert receives significant amounts of snow in the winter, but quickly dries out in the spring.  The characteristic plant community in eastern Oregon consists of juniper and sagebrush scrublands with bunchgrasses such as needle-and-thread grass (Hesperostipa comata) and Indian rice grass (Achnatherum hymenoides).

Astragalus mulfordiae (Mulford’s milkvetch), listed as a Species of Concern by the US Fish and Wildlife Service, is a member of the legume family (Fabaceae) native to the Snake River Plain of Oregon and Idaho.  In 1995, only 38 populations of Mulford’s milkvetch were known to occur in Oregon, in addition to 34 populations in Idaho.   It was estimated that, in total, there were less than 12,000 living individuals.  Mulford's milkvetch only occurs in desert shrub communities on sandy substrates, such as lacustrine and alluvial sediments.  The plant relies on environmental cues to initiate regrowth, but it can generally be seen flowering between April and June.  Flowers are yellowish to white in color and measure 6-8 mm in length.  Fruits usually mature in June and July.      

Astragalus mulfordiae

IAE has tracked Mulford's milkvetch populations in the BLM’s Vale district since 2008, beginning with the establishment of monitoring plots to determine the effects of ungulate and rodent grazing on the populations.  Large animal exclosures and unfenced control plots were established at five different sites around Vale, Oregon.  In the second year of monitoring, transects were established in order to collect data on the plant community associated with Mulford’s milkvetch.   The monitoring protocol used by IAE is consistent with the methods being used to monitor the populations in Idaho, allowing for comparable data sets.  During annual monitoring, data regarding plant life history stage (reproductive, non-reproductive, seedling) and evidence of herbivory and disturbance were documented, as well as quantitative data on plant size and number of inflorescences (flowering stems).  Population trends were difficult to discern after the first few years of monitoring, but continued monitoring may provide more information about the effects of mammal grazing on the size and health of the Mulford's milkvetch populations.  Currently, there appears to be high turnover of individual plants.  The community sampling transects have revealed ubiquitous invasive and non-native plants that could potentially compete with the native milkvetch.  IAE will continue to monitor these populations to increase understanding of population dynamics for this rare species, and to analyze the potential threats of cattle grazing, rodent activity, encroachment of invasives, and ground disturbance.

Evidence of cattle activity adjacent to mammal exclosure

The Effects of Fire on Parish's horse-nettle

Beginning in 2009, IAE, in cooperation with the Medford BLM, has been conducting a fire ecology experiment in Jackson County in order to create a better understanding of the effects that fire has on the growth and reproduction of Parish’s horse-nettle (Solanum parishii).  Prior to this study, very little experimental research had been conducted looking specifically at this species' response to periodic burning. Controlled burning was conducted on two BLM locations, Hukill Hollow and Woodrat Mountain, with known populations of Parish’s horse-nettle. Fire suppression has occurred in the area since the beginning of the 20^th century when much of the native grassland and oak savannah landscape was converted into pasture and urban space.  However, it is possible that recruitment and survival of S. parishii, along with several other natives could benefit from periodic natural disturbance. 

Parish's horse-nettle is a small perennial in the Solanaceae (potato) family found in dry chaparral communities.  Its native habitat ranges from southern Oregon into Baja California at elevations of less than 2000 feet.   Approximately thirty populations have been documented within the Medford BLM district occurring in Jackson, Josephine, and Curry counties.  In mid-summer the plant produces umbel-like infloresences with white to purple flowers.  After fertilization, the plant produces berries that change from green to purple in color.  Individuals measure less than one meter in height and grow in a branching formation.  The lanceolate leaves exhibit wavy margins and measure between 2 and 7 centimeters long.

In 2009, IAE established 40 sample plots at two locations outside Jacksonville, each plot measuring 3 meters by 6 meters.  Half of the plots were assigned to receive a burn treatment and half were left alone to be control plots.  All S. parishii plants located within the plots were mapped and measured to establish baseline population data.  Data collected included the maximum and perpendicular widths of the plant, the total number of fruits and flowers, and the presence or absence of insect and mammal herbivory.  Controlled burns were conducted in the fall of 2010 and annual monitoring has continued through this year.  Based on 2011 data, there was no evidence of fire effects on reproductive effort (calculated by the sum of fruits and flowers within the population).  However, one of the two sites did exhibit an increase in the mean size of S. parishii plants within burn treatment plots.  Both sites appeared to experience a high level of mammal herbivory.  The final data analysis conducted this year will provide valuable information about whether periodic controlled burning is an effective management tool in areas that host Parish’s horse-nettle populations. 

Demography plot markers at Hukill Hollow

View from Woodrat Mountain