California's biodiversity is remarkable, holding significant percentages of US species richness:
Vascular Plants: 5,047 species (6,272 varieties), making up 32% of US species.
Amphibians: 51 species, 22% of US species.
Reptiles: 84 species, 30% of US species.
Birds: 433 species, 56% of US species.
Mammals: 197 species, 47% of US species.
Freshwater Fish: 67 species, 8% of US species.
California's biodiversity ranks highly among US states in:
Richness: 1st
Endemism: 1st
Rarity (percentage at risk): 2nd
Endemic species numbers and rankings:
Vascular Plants: 2,153 (Rank 1)
Amphibians: 17 (Rank 1)
Reptiles: 5 (Rank 1)
Birds: 2 (Rank 2)
Mammals: 17 (Rank 1)
Freshwater Fish: 20 (Rank 1)
Topography
California features a long coastline and a series of mountains and valleys in close proximity.
There are rapid transitions in elevation, soil type, rain harvest/shadow, and solar exposure.
This leads to isolated populations and communities.
Snowpack provides year-long water supply.
The highest and lowest points in the continental US are within 80 miles of each other, and 200 miles of the coast.
Factors such as aspect (angle of sun exposure), elevation, slope, temperature, wind exposure, precipitation, soil depth, runoff & groundwater, and air pressure & gas partial pressures all contribute to the unique ecology.
Geology
Igneous rock forms volcanic mountains.
Metamorphic rock is found at plate boundaries.
Sedimentary rock originates from old seabed.
California Ecology
California is a long, narrow region bordered by mountains on the east and a long coastline on the west.
Its climate is greatly affected by ocean conditions, leading to "Seasons of the Sea".
Climate fluctuations are reduced by proximity to bodies of water.
Great Ocean Current Gyres
Gyres rotate clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere.
Eastern Boundary Currents
Draw cold, nutrient-rich water from sub-polar regions toward the tropics.
The North Pacific Eastern Boundary Current is the "California Current".
North Pacific Gyre
Waters from the California Current flow to the North Pacific Equatorial Current.
They warm and lose nutrients as they flow westward across the tropics.
Warm, oligotrophic (nutrient-poor) water flows north with a western boundary current.
Water cools and picks up nutrients.
Some North Pacific Equatorial Current flow reflects back as a countercurrent.
Water crosses the tropics twice.
California Current
Regional variations: Eddy currents produce local cells.
Seasonal variations: Intensity, depth, and distance from shore vary.
California Seasons of the Sea
Determined and defined by dominant nearshore ocean conditions:
Upwelling season
Oceanic season
Davidson season
Upwelling Season: mid-spring to summer
High atmospheric pressure system develops offshore.
Air is pushed away from high pressure.
The Coriolis effect deflects wind clockwise.
Prevailing wind along CA is north to south.
Maximum nutrients and maximum sunshine lead to high primary productivity, amplifying all trophic levels from the bottom up.
Typical daily pattern:
Hot, summer sunshine
Offshore surface water warms
Cold, upwelled water rises
Warm, moist air mass
Land heats up
Air warms and rises
Cold air mass
Cool, onshore seabreeze
Air cools; moisture condenses, leading to cool, windy, foggy summers in coastal areas.
Oceanic Season: late summer to autumn
High pressure system weakens and moves onshore.
Low pressure system develops offshore.
Air is pulled toward low pressure.
The Coriolis effect deflects wind counter-clockwise around the low.
Prevailing wind along CA is south to north.
Southerly winds cause nearshore downwelling.
Warm, oligotrophic oceanic waters move nearshore.
The weather is mild with low ocean productivity.
Davidson Season: winter to early spring
Low pressure system intensifies, marking the storm season.
Strong southerly winds intensify the very warm, very oligotrophic Davidson countercurrent.
Extreme subarctic cold generates storms.
Storm weather is pulled counterclockwise around the low.
Storms travel south, warming and absorbing more moisture.
They continue counterclockwise and approach California from the south as the "Pineapple Express", resulting in warm, wet winters.
El Niño Effect
Occurs during the Davidson Season
Warm, oligotrophic currents flow to the Americas.
This leads to decreased nutrients, productivity, and fish populations.
Westward equatorial current weakens and Eastward equatorial counter current intensifies.
This phenomenon is part of the El Niño Southern Oscillation (ENSO).
Climate
Major climate types in California:
Mediterranean
Steppe
Cool interior
Highland
Desert
Vegetation
California Floristic Province (CA-FP) is located west of the Sierra Nevadas.
Much of the Mediterranean climate lands have been converted to urban and agricultural areas.
Geographical Information Systems (GIS)
Used to map diversity, specifically species (taxon) richness.
Also used for Rarity-weighted Richness Index (RWRI), an "index of irreplaceability" for "species of special status" which have, very limited distribution, low population levels, and/or are under immediate threat, especially from habitat loss.
The state is divided into equal hexagonal grid cells (250.4 mi2 each).
The number of cells a species occupies determines its rarity rank.
The RWRI for each cell is the sum of (special species x its rarity rank).
Diversity Maps
Maps are shown for plant, mammal, amphibian, and reptile diversity.
Maps are shown for Bird Diversity for both Summer and Winter Distribution, as well as Human Population Density.
Example numbers from the Coastal Atlas of Bird Richness: