The Big Sur coast of California in central Monterey County is situated precisely where the wet colder climate of the northern Pacific region meets the dry hotter climates of the southern region. Big Sur is one of the few places on Earth where giant redwoods grow within sight of cacti. Hence, this central coastal area of California is at the nexus of modern climate change geography in the western United States.
The topography of Big Sur is dominated by the steepest coastal gradient in North America. The highest mountains form a wall behind coastal hillsides which effectively traps cooler marine air. This sets up a steep elevation gradient in air temperature regimes, humidity and other climate factors. Coastal temperatures vary little during the year, ranging from the 50s (Fahrenheit) at night to the 70s (Fahrenheit) by day from June through October, and in the 40s (Fahrenheit) to 60s (Fahrenheit) from November through May. Farther inland, away from the ocean's moderating influence, temperatures are much more variable.
Annual precipitation in the Big Sur River valleys is about 100 cm, diminishing further to the south to about 60 cm. More than 70% of the rain falls from December through March, while the summer brings drought conditions. Snow is uncommon during the winter months on the coast, although the mountaintops can receive heavy snowfalls. Strong winter storms can pack winds in excess of 80 mph, and heavy rains can cause rock and mud slides. Fog is an essential summer water source for many Big Sur coastal plants. Most plants cannot take water directly out of the air, but the condensation on leaf surfaces slowly precipitates into the ground like rain water.
The varied topography and micro-climates of Big Sur result in high biodiversity, including many rare and endangered species. Arid, dusty chaparral-covered hills exist within easy walking distance of dense riparian woodland. The Santa Lucia mountains trap the moisture out of coastal clouds; fog in summer, rain and snow in winter. This creates a favorable environment for coniferous forests, including the southernmost habitat of the coast redwood (Sequoia sempervirens), which grows only on lower coastal slopes. The rare Santa Lucia fir (Abies bracteata), as its name suggests, is found only in the Santa Lucia mountains of Big Sur. There are many broadleaf trees in Big Sur as well, such as the tanoak (Lithocarpus densiflorus), coast live oak (Quercus agrifolia), and California Bay Laurel (Umbellularia californica). In rain shadows, the forests disappear and the vegetation becomes open oak woodland, and then transitions into the more fire-tolerant California chaparral scrub.
Sites for on-going climate change studies on the California central coast currently include the University of California Santa Cruz Campus Natural Reserve, the US Forest Service Brazil Ranch, and the University of California Big Creek Reserve. We are conducting research at each of these sites to better understand possible impacts of climate change, including: (1) biological and physical capacity of soils to capture carbon and retain plant-essential nutrients; (2) rates of plant-soil water and carbon cycling and energy flow; and (3) recovery mechanisms for disturbances such as invasive weed species, grazing, and wildfire.