Premises on the conservation challenge

  1. The southern California CSS planning region has been severely degraded by past urbanization and agricultural land conversion. Certain subhabitats, such as those at low elevation, those close to the coast, and those with lesser slope, have been disproportionally affected and many have experienced local losses of some species.

  2. Threats to CSS habitat are more than losses of total habitat area alone. Threats also include losses of distinct CSS subtypes and losses of the special conditions needed to maintain the broad suite of CSS-resident species. (Attachment A .)

  3. Conversion of natural land has also severed connections among remnant habitat patches resulting in their increased isolation. Connections among habitat patches are critical to the long-term survival of CSS species.

  4. Because CSS is found naturally admixed with other vegetation communities, the best conservation strategy for CSS is to protect large areas of native vegetation that include biologically significant patches of CSS.

  5. Under present conditions, few CSS-dominated lands are of sufficient extent to be self-sustaining. A status quo strategy of "benign neglect" management likely will result in substantial further losses of CSS biodiversity. Habitat areas large enough to be self-sustaining should not be significantly reduced in size and they should be actively managed in ways responsive to pertinent new information as it accrues.

  6. The CSS community is inherently dynamic and should be managed to retain its capacity to support the broad range of CSS species over the long term. Under an adaptive management regime that provides for natural successional dynamics, a reserve system that consists of smaller habitat areas that are appropriately managed could have a greater likelihood of maintaining CSS biodiversity than a system of larger habitat areas that are unmanaged. The techniques associated with such a management regime, however, have not been fully developed.

  7. CSS conservation will require appropriate levels of participation by public agencies responsible for publicly owned land that contains CSS or that serves as linkages between reserves. State and local government can participate through the NCCP process and federal agency land owners can participate through federal programs coordinated with NCCPs. Although important to the integrity of regional conservation efforts, not enough CSS exists in public ownership for public land to be the sole basis of a reserve network.

  8. Within the southern California region as a whole, roughly a dozen biologically defined subregions, designed around extensive habitat areas can be identified based on geography, the ecological characteristics of CSS species, and patterns of past land use. Each subregion exhibits distinct local conditions that will affect the conservation approach to be used.

  9. Each subregion will need to meet explicit conservation objectives to promote ecosystem stability at both subregional and regional levels. Each subregion will need to provide for conservation of the three target species.

  10. Despite the extent of current threats, the majority of the species inhabiting the CSS do not appear to be in imminent danger of regional extinction. Some small amount of short-term habitat loss can be tolerated as long as it is ultimately counter-balanced by adequate long-term enhancement efforts.

  11. A few, small-scale efforts at CSS restoration and enhancement have been attempted; these examples indicate that net enhancement of habitat quality may be attainable. Furthermore, ecological studies of CSS show natural recovery from disturbance suggesting that active restorative projects may be successful.

  12. Information available to the SRP supports a conservative estimate of 5% habitat quality enhancement potential for existing CSS habitat. This potential for mitigation leads to a corresponding estimate of 5% short-term habitat loss that can be tolerated in any subregion. A level of enhancement beyond 5% may be possible and with adequate scientific information, improved prospects for enhancement can be the basis for allowing a greater than 5% loss of habitat.

  13. Land of high priority for inclusion in a reserve system can be identified based on a combination of size, location, and quality criteria. The impact of an overall 5% loss of CSS habitat area can be further reduced by avoiding losses of higher priority habitat.

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