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Ben Lomond Wallflower
Ben Lomond Wallflower

Mount Hermon June Beetle
Mount Hermon June Beetle

Silverleaf Manzanita
Silverleaf Manzanita

Band-winged Grasshopper
Band-winged Grasshopper

Ben Lomond Spineflower
Ben Lomond Spineflower

Ben Lomond buckwheat
Ben Lomond buckwheat
Zayante Sandhills Conservation Bank

Sandhills Threats
The endemic species and communities of the Santa Cruz Sandhills are extraordinarily rare naturally. This is because they occur only on Zayante Soils within the central portion of Santa Cruz County, in central California. Unfortunately, the persistence of Sandhills endemic species and communities is threatened by:

  • Habitat loss, which reduces the area of habitat available
  • Habitat fragmentation, which reduces the size of remaining habitat patches
  • Habitat degradation, which reduces the ability of the habitat to support persisting populations
  • Genetic erosion, which can reduce the genetic diversity and integrity of sandhills species, subspecies, and ecotypes

    These factors often interact to impact Sandhills species. For example, development of a residential subdivision within the Sandhills removes habitat. Many populations cannot persist within the small, isolated habitat patches around the subdivision, where habitat quality is often degraded by a variety of anthropogenic factors, including the invasion and spread of exotic plants, use of habitat for recreation, and suppression of natural wildfires which maintain habitat for many sandhills species. These factors cause population extinctions (extirpations) or dramatic declines which can reduce genetic diversity required for species to persist. Genetic erosion also results when non-Sandhills genetic material is introduced and swamps the locally adapted genetic complexes of the native populations.

    To conserve the endemic species and communities of the Santa Sandhills, conservation measures will need to address these factors, which threaten biodiversity at the ecosystem, community, species, and genetic level.

    Sandhills Habitat Loss
    Habitat loss is the leading threat to the persistence of the endemic Sandhills species and communities. Naturally rare, the Sandhills historically covered and estimated 6,000 acres. However, approximately 40% has been lost due to conversion for human uses, including:

  • Sand quarrying (mining)
  • Development
  • Agriculture (including viticulture)

    The conversion of Sandhills habitat fragments and degrades remaining habitat, thus further impacting the native species and communities. Much of the remaining habitat is not currently protected, and instead is vulnerable to future development.

    Sand Quarrying
    The marine deposits of the Santa Margarita formation that give rise to the Sandhills communities also produce sand that is highly valued commercially. The sand deposits are very deep and loosely consolidated, so they provide abundant sand that is readily removable. The sand itself is desireable for several reasons including:

  • It is well-worn and rounded, so it is less abrasive to machinery during construction.
  • It has a neutral pH, and thus is less corrosive than beach sand.
  • Some locations have high aluminum content, and thus are valued for manufacturing glass products, including fiberglass, bottles, windshields, and optics.

    In sand quarrying, Sandhills vegetation, soils, parent material, and some bedrock are removed. As a result, it is difficult to re-establish vegetation during reclamation. Despite extensive efforts, it has not been possible to recreate Sandhills communities following mining.

    Since its inception in the early part of the 20th century, sand quarrying in the Sandhills has occurred in six quarries, which have removed an estimated 450 acres of habitat and fragmented remaining habitat.

    Sandhills habitat has been lost due to residential and commercial development in the several towns and cities in central Santa Cruz County, including Scotts Valley, Felton, Ben Lomond, Boulder Creek, and Bonny Doon.

    In addition to reducing Sandhills habitat, development impacts Sandhills species and communities in adjacent undeveloped habitat by:

  • Facilitating the invasion and spread of non-native plants and animals which impact native Sandhills plants and animals
  • Increasing recreation, which causes erosion and reduces native plant and animal populations
  • Decreasing the size of remaining Sandhills habitat patches, thus reducing their ability to support native populations.

    Despite the alteration of habitat conditions, several native Sandhills plant and animal species persist in developed areas, including the Mount Hermon June beetle. These populations may contribute to long term species persistence, by linking the otherwise small and isolated populations that persist in Sandhills habitat patches adjacent to development. Sandhills property owners can help facilitate global biodiversity by implementing a few simple steps in their own backyards.

    Though the Zayante soils are unsuitable for most crops, Sandhills habitat has been converted to vineyards and orchards, which can tolerate the well-drained soils. Agricultural conversion is the cause of less than 10% of Sandhills habitat loss. However, given the overall rarity of the Sandhills, even such small losses can have significant impacts on the endemic species and communities.

    As a result of their rarity and the ongoing threats to persistence, the endemic species and communities of the Santa Cruz Sandhills have been recognized as endangered by the Federal, State, and Local agencies. Their special legal status affords them some protection from future habitat loss, which greatly threatens their persistence.

    Though legal protection is essential, long term conservation will require proactive measures to address the multiple threats to biodiversity at the genetic, species, and community level. Developed in 2004 to inform and guide Sandhills conservation, the Sandhills Conservation and Management Plan describes important elements of a comprehensive conservation strategy for the Santa Cruz Sandhills.

    Three key components of the conservation strategy for Sandhills Conservation are:

  • Preservation, to protect remaining Sandhills habitat
  • Management, to maintain biodiversity within Sandhills habitat preserves
  • Education, to enhance awareness of the biological treasure in our backyard

    Several projects with important implications for regional Sandhills conservation are currently being conducted.

    More Information:

    Sandhills - Rare & Unique
    Overview of Benefits

  • * McGraw, J. M. 2004. Sandhills Conservation and Management Plan: A Strategy for Preserving Native Biodiversity in the Santa Cruz Sandhills. Report prepared for the Land Trust of Santa Cruz County. June 2004. 354 pages. ** Method for Determining the Number of Available Credits for the Zayante Sandhills Conservation Bank. Prepared by Richard A. Arnold, Ph.D. 2004. *** U.S. Fish and Wildlife

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