Pine Hill Preserve

Rare plants on the western slope of El Dorado County: The Pine Hill Plants

Centering around Green Valley Road in El Dorado County and extending north to Salmon Falls and south to Durock Road is a soil complex called the Pine Hill Intrusive Complex (Fig.1)—or more generally gabbro rocks—that covers approximately 30,000 acres. The rocks from which the soil is made were originally formed deep in the earth’s crust from molten rock. These rocks were then lifted up to the earth’s surface as the rest of the Sierra Nevada was being formed over the last 150 million years. The soil that is formed from this material as it weathers is generally red, mildly acidic, rich in iron and magnesium, and often contains other heavy metals such as chromium. Outcrops of serpentine rocks also occur in the Pine Hill area. The soils that result from the weathering of serpentine are similar to the soils from gabbro rocks.

Growing on these gabbro and serpentine soils are a suite of eight rare plants that are found almost exclusively in El Dorado County. These plants are commonly referred to as the Pine Hill Plants and are associated with black oak woodland and chaparral plant communities scattered from Cameron Park north to Folsom Lake. The rare plants are:
Figure 1. Click image to enlarge.
Pine Hill intrusive complex orgin of gabbro soils. Map courtesy of Department of Mines and Geology, State of California, 1981.

All eight species are included in the California Native Plant Society list as Rare, Threatened or Endangered.
For a complete list of plants at the preserve, click here.

Protection for the Pine Hill Plants

Housing and commercial development have threatened the continued existence of the Pine Hill endemics. Loss of the habitat that is important to their persistence and the periodic fires to which they are adapted have contributed to declines in the number of plants present. The concern about these plants became so extreme that in 1996 five of the eight species were listed as either threatened or endangered by extinction under the Endangered Species Act.

A preserve system (Fig. 2) is being created to protect these species and their habitat in perpetuity. Managed by the Bureau of Land Management, the Pine Hill Preserve contains a total of 4,746 acres with a high diversity of native plants; however, only 3,276 of these acres are included in an area designated for the recovery of five federally listed plants.

Separated into five areas, the Preserve is made up of the:

  • Cameron Park Unit (to the south)
  • Pine Hill Unit (centrally located)
  • Penny Lane Unit (east of Pine Hill)
  • Martel Creek Unit (west of Pine Hill), and
  • Salmon Falls Unit (to the north).

Though the units are physically separated, they are managed together as a single preserve. An important part of the Preserve’s overall management includes wildfire risk reduction and control of the amount of vegetation, or “fuels,” present. Having larger units allows management actions like prescribed fire that cannot be attempted with small parcels surrounded by developed private lands. See the Pine Hill Preserve website for additional information of these rare species and their history.

Read more about the development of the preserve system and other conservation actions on our Current Issues page.

Figure 2. Click image to enlarge.
Pine Hill Preserve location map, courtesy of Bureau of Land Management at BLM Mother Lode Field Office, Pine Hill Preserve

Why is it important to conserve these rare species?

Wild plant species are the source of many medicines, industrial products, and improvements to agricultural and horticultural species. They are a bank of chemical and genetic information that humans may be very grateful to have available in the future. Furthermore, native plants are integral to the function of ecosystems. The air we breathe, the water we consume, and landscape we live within are linked in a fundamental way to the native plants that surround us. The Pine Hill endemics are an important part of the natural heritage of El Dorado County. Their intrinsic value as species besides our own and their aesthetic value as a part of an intact natural landscape also are important considerations for their conservation.

Vegetation and flora of a biodiversity hotspot: Pine Hill, El Dorado County

Video from the California Department of Fish and Wildlife (CDFW) Conservation Lecture Series Archive of a presentation given on January 22, 2015, by Debra Ayres, PhD, who has been studying the rare plants in the Pine Hill area for over 20 years. Dr. Ayres presents new analyses showing that two chaparral communities are present here. Recognition and preservation of both types of chaparral will be necessary to conserve this diverse flora. Original video: Vegetation and Flora of a Biodiversity Hotspot: Pine Hill, El Dorado County from Margaret Mantor on YouTubeThe slides from the presenation can be downloaded from the CDFW website here.

Additional Reading

Pollinator Report for Pine Hill Preserve: Part 1 and Part 2 (Burge and Eldredge 2020)