Diverse Habitats on District Lands

Habitats -- the conditions and locations in which plants and animals live and reproduce -- are the critical components of naturally functioning ecosystems. The District, with lands in much of the northern portion of the Santa Cruz Mountains, encompasses a region characterized by diverse habitats, including freshwater streams, redwood forests, oak woodlands, coastal grasslands, chaparral, and many others. These habitats provide ideal conditions for a broad assemblage of plants and animals.

Wildlife Corridors Maintain Population Health

In the San Francisco Bay region and elsewhere, wildlife habitats are frequently intersected by roads, houses, and development -- a consequence of a growing human population in an area of limited living space. This high degree of habitat fragmentation isolates populations of plants and animals living within the Santa Cruz Mountains both locally as well as state-wide as populations are cut off from other habitats within the Santa Cruz Mountains bioregion and the rest of the state. Ultimately, such isolation threatens the long-term preservation of biodiversity within District lands.

Many of the plants and animals living in the Santa Cruz Mountains also occur in mountain ranges and other habitats throughout the state. Connecting these separate populations is important for maintaining the overall population health of species: plants and animals living in small, isolated patches of habitat are more susceptible to disease, population pressures, predation, and other stresses. In addition, isolation can result in inbreeding, which compromises genetic diversity and contributes to instability of species' populations.

Consequently, "wildlife corridors," or routes of migration and dispersal that connect otherwise isolated habitats, effectively extend the range of a species from one small location to many interconnected locations. Such corridors, or linkages, commonly follow watercourses into and out of the foothills and valleys. Typically, the most resilient and diverse habitats are large connected areas along which:

• wide-ranging animals can travel
• plants can propagate
• genetic interchange can occur
• populations can move in response to environmental changes and natural disasters
• species at risk can be replenished from other areas

The need for habitat connectivity is particularly true of wide-ranging animals like mountain lions in the Santa Cruz Mountains that need corridors to allow lions from the surrounding areas, such as the Diablo range to the east or the Gabilan and Santa Lucia mountain ranges to the south, to travel into the Santa Cruz Mountains. Habitat connectivity is also important for animals with very restricted habitat requirements; for example, steelhead trout. Steelhead require uninterrupted stream corridors where they have access to spawning gravels and deep pools within which the young of the year can spend the summer months.

District Prioritizes Habitat Connectivity

Recognizing that habitat fragmentation and land use conversion are increasingly detrimental to the viability of the Santa Cruz Mountains ecosystem, District resource management staff recommended in May 2008 the addition of habitat connectivity policies to its existing resource management policies. The revisions incorporate policies and implementation measures that address the issues specific to managing the District's habitats and biogeography.

MROSD Presentation: Habitat Connectivity