Conservation assessment for Cypripedium fasciculatum and Cypripedium montanum

Purpose

The impetus for developing the Conservation Assessment for Cypripedium fasciculatum and Cypripedium montanum arose from the Sierra Nevada Forest Plan Amendment Environmental Impact Statement, 2001. While, the primary goal of this document is to determine the conservation status of these species throughout the Sierra Nevada, the document’s scope also includes discussion of both species throughout Region 5, and in the context of the species’ range as a whole.

This conservation assessment addresses the biology, management and conservation of Cypripedium fasciculatum (clustered lady’s slipper) and C. montanum (mountain lady’s slipper). Conservation assessments may cover one to several species, where life history characteristics, habitat and distribution, and management concerns make grouping more effective and efficient. Due to the similar nature of these two species of lady’s slipper, they are treated together in this document. This conservation assessment provides the foundation for guiding the development of management and monitoring plans for these species.

Management Status

Given the relatively wide geographic distribution of clustered and mountain lady’s slipper in the western U.S, at the national level, Natural Heritage Programs give these species a global ranking of G4 (up to G5 for mountain lady’s slipper) indicating that these species are apparently secure throut their range. Both of these lady’s slipper species are listed as Sensitive Species by the U.S Forest Service Region 5, which encompasses the National Forests in California. They are also Sensitive Species in Region 6, Oregon and Washington. The Bureau of Land Management lists clustered and mountain lady’s slippers as a Bureau Sensitive Species.

The California Native Plant Society ranks these species as a List 4 or watch list species. This ranking indicates that these species are of limited distribution in California and are also considered to be rare outside the state. Rankings by state agencies for clustered lady’s slipper (S3.2 in California, and S3 in Oregon and Washington) also indicate that this species is rare, threatened or uncommon on a statewide basis. The state ranking for mountain lady’s slipper is S4 in California, and S3S4 in Oregon and Washington. These orchids were formerly treated as Survey and Manage Species under the Northwest Forest Plan (Record of Decision 2004, www.or.blm.gov/nwfpnepa/index.htm#Survey_and_Manage).

Range and Habitat

Clustered and mountain lady’s slipper have large geographic ranges and similar habitat requirements. Clustered lady’s slipper occurs in widely disjunct locations from north central Washington south to California and east to the mountains of Idaho, Montana, Colorado, Wyoming, and Utah. The species has high concentrations of populations in the Sierra Nevada (e.g., Plumas National Forest), northern California and southwestern Oregon. Mountain lady’s slipper is found from southern Alaska, British Columbia, and western Alberta south to Montana, Idaho, Wyoming, and California. Its greatest abundance in California is on the Klamath National Forest, but it is widely distributed throughout National Forests (except Tahoe) of the Sierra Nevada.

These species are most often found on north facing slopes in mixed coniferous forests of >60% canopy closure. Douglas-fir is the most common associated tree, but other frequently noted forest components include white fir, mountain dogwood, sugar pine, and incense cedar. Clustered lady’s slipper is known to occur at elevations of 600-5800 feet, and mountain lady’s slipper at 1300-6350 feet. Both species have complex life-histories and depend on specific mycorrhizal fungi (Tulasnellaceae) for seed germination and growth. These mycorrhizal fungi may determine where and in which specific habitats these lady’s slipper species can grow and how they respond to disturbance, but little information is available on the fungi, their requirements, associated tree species, and their function in forest ecosystems.

Threats

These orchids are sensitive to disturbances that damage their current year’s growth, rhizomes, soil surrounding their root systems, and forest canopy (too much light appears to negatively affect them). The primary project related threats to clustered and mountain lady’s slipper species include mechanical disturbances and alteration of forest and understory canopy by timber harvest activities, construction of fire lines, power/gas transmission line construction and maintenance, culvert relocation, and other ground disturbing activities. High intensity wildfires which remove canopy and incinerate the soil organic layers, also rank very high as a widespread threat to both species. Other threats include plant collectors, road building and maintenance, recreation, livestock grazing, fuel reduction practices, fire suppression, erosion, prescribed burns, alteration of local hydrology, mining, and invasive species. More than half of the populations of both species have fewer than 10 plants, placing them at high risk. Population declines and losses of both species have been significant over the last two decades, and population extinction has occurred at a high rate (44%-55%) for small populations (<10 plants).

Conservation

Tools and practices to conserve lady’s slipper orchids in the Sierra Nevada and throughout the National Forests in Region 5 emphasize maintaining habitat elements for the species, including:

• sufficient forest canopy cover and stand structure to provide shade and filtered light which influences understory temperatures and humidity for plant establishment and growth, as well as suitable habitat conditions for vascular plant associates,
• decayed down logs as well as snags for future log recruitment to favor habitat conditions for mycorrhizal fungi, which may attract fungus gnats that in turn play a role in the pollination of lady’s slipper orchids (i.e. clustered lady’s slipper),
• adequate cover and depth of the forest floor organic layer (e.g. duff and litter) for retention of soil moisture that affects both the lady’s lipper orchids and their fungal associates.Treatment of areas with high concentrations of fuels to reduce the risk of high intensity fire will protect some populations, but some fuel reduction actions also may damage or compromise these species. Site management that includes entire populations plus surrounding areas to capture dormant plants as well as minimizing edge effects will conserve the species more effectively than partial or unbuffered population protection.

  Actions that benefit these species at a regional scale may also help with their overall conservation. Region-wide coordination among public agencies would improve conservation for clustered and mountain lady’s slippers to alleviate the cumulative impacts of such activities as timber harvest and grazing, as well as high intensity wildfire. Coordinated approaches that consider habitat connectivity to allow for the spatial and temporal (e.g. dormancy) variations inherent to these species would provide for movement of genetic material among populations and perhaps accommodate the meta-population dynamics of these species.