Spotlight on Diversity

Floristic Provinces

Look at a map and find the intersection of Kern, Tulare, and Inyo Counties you will be looking at a transition zone of amazing diversity.

The Holarctic Kingdom of North America contains ten Floristic Provinces which are defined as regions where at least 50% of the species are endemic. “Endemic” signifies that a species has a limited geographic distribution. The terms floristic provinces, biotas and biomes are virtually the same. All are defined as unique assemblages of floras and faunas associated with a specific climate and geographic region. Bioregions are more narrowly defined regions that are restricted by specific types of plants and animals although the number and description keeps changing depending on which group you speak with (which is why I choose not to use the term).

Our area falls within the Madrean Subkingdom of the Holarctic Kingdom with three provinces: Great Basin Province, Californian Province, and the Sonoran Province. The desert portions of Kern County fall mostly within the Mojavean Subprovince of the Sonoran Province.

North America has between 18,000 - 20,000 native species of plants. California has more than one quarter of the national total at 5,500 species. The three counties, Kern, Inyo and Tulare each have between 2,375 and 2,505 native species. There is an overlap of up to 75% of species between counties, but at least 588 species are endemic to small regions within each county.

The Californian Floristic Province is the largest region in the state with most of the varied habitats. The Californian province has grasslands, shrublands, woodlands and forests all of which occur in Kern County. Considered a Mediterranean climate, the winters are relatively cool and wet with rain falling at low elevations and snow at high elevations. Summers are relatively warm to hot and dry depending on elevation. The coastal region is the exception with cool moist summers due to an onshore fog belt. Rain varies from less than 5 inches in the Southern San Joaquin Valley to over 100 inches in the rainforests of Siskiyou County.

The Mojave Desert Subprovince includes all of eastern Kern County, most of San Bernardino County and the southeastern portion of Inyo County. The subprovince is characterized by relatively cool, dry winters and relatively hot, dry summers with 2-12 inches of mostly winter rain and some summer monsoonal rain. The growing season is  from early spring to late fall (March to November

Although the Great Basin Desert Province only touches Kern County by its transitional influence, it allows for an interesting mix of plants and animals in northeastern Kern. The province is found in California East of the Cascade Range and Sierra Nevada, and north of the Mojave Desert. It is characterized by relatively cold, dry winters and hot, dry summers. The precipitation amounts to between 2-15 inches and falls mostly as winter snow. The growing season runs from late spring to late summer (May to September).