Climate of Uncertainty : The county’s weather is a complex matter--moist air from the ocean, dry air from the interior, high mountains, deep valleys and the sun. The result is a flourishing variety of plants and animal life.

Ventura’s Camino Real Park could hardly be considered a wilderness area. The sunny suburban park bordering the Arundell Barranca is as benign as the monarch butterflies that winter there.

So why is biologist Walter Sakai tromping through the eucalyptus early on a winter morning with a compass and a pair of binoculars as if he’s on some kind of jungle safari? He’s going to all the effort because he’s looking for specific places that monarchs pick to roost.

“They look for deep groves of eucalyptus that have a southern or eastern exposure,” said the Santa Monica College teacher. “The morning light warms them up after a cool evening, and being on the east side of the trees means they’re protected from Santa Ana winds. It’s a very specific microclimate they look for.”

Farther up the barranca, near Telegraph Road, Sakai finds a roosting site matching those conditions. Several clusters, each containing 1,000 or more insects, hang motionless and barely noticeable until the morning light reaches the branches and warms them to the point that they explode in an orange and black flurry.

Butterflies, it turns out, know more about local climate than we do. Sure, everybody’s familiar with such big climate topics as global warming, ozone depletion and El Nino, the periodic rise in ocean temperature implicated in the recent rains.

But few people can identify the local climatic variations that explain where rare plants and animals can be found, how to landscape your home and, to some degree, why different crops are located the way they are.

“People seem to think that the Southern California climate, particularly the coastal climate, is all the same,” said Suzanne Goode, an ecologist for the state park service. “It’s actually quite diverse.”

All of the factors that create microclimates bump up against one another here. Moist air from the ocean, dry air from the interior, high mountains, deep valleys and the sun. Always the sun. Without the coastal fogs, north-facing slopes or shady canyons for delicate plants to escape solar radiation, Ventura County would be a biologically less diverse place . . . a sort of Bakersfield by the sea.

The combination of climate and weather that creates such variety can be confusing. Weather describes what happens day to day; climate is what happens year to year.

The torrential rains that have scoured the county are considered weather. Maybe it will rain next week, maybe not. Precipitation varies. Although the pelting of raindrops at times seems ceaseless, the occurrence of storms can vary.

The Pacific Ocean is an example of a climate influence. The ocean is always present and its effect on air temperature is largely what defines the nine climatic zones in the county.

Microclimate, on the other hand, refers to the barely perceptible temperature and moisture variations within a single climatic zone. It might not seem like a big deal to humans, but if you’re a butterfly or a banana plant, it makes a huge difference.

The variation is usually caused by some physical feature. That can be created by something as large as the 300-foot cliff that keeps the Seaside Banana Garden from freezing in the winter to the coolness a shade tree provides on a sunny day.

“Anytime you have a new factor that doesn’t exist in the surrounding area, you have a microclimate,” Goode said.

Here’s a distilled version of what experts consider the three basics of microclimate: warm air is wet; the sun is hot; cold air goes downhill.

It sounds ridiculously simple, but those three factors, like the three primary colors, can produce an almost limitless variety. Hikers with acute senses say they can discern different microclimates along the trail, within an area of 100 square yards.

The county’s best-known microclimate, the Seaside Banana Garden, is somewhat larger at 16 acres.

Doug Richardson, a La Conchita resident turned banana impresario, had been warned that the banana trees wouldn’t yield fruit in areas where the winter low temperature regularly dips below 50 degrees. But after he had great success with some bananas planted around his home, he started keeping records of high and low temperatures.

“I kept temperature records for four or five years, and I was able to compare that with the readings from surrounding areas. I found that La Conchita has consistently warmer nighttime temperatures--10 to 15 degrees warmer on cold nights.”

Richardson deduced that the cliff was the main reason. It faces south, so it radiates heat collected during the daylight hours. But the most important factor is that the vertical wall traps air coming off the ocean.

“The ocean temperature is in the mid- to high 50s, so it’s giving off heat into the air directly above. Since the predominant wind during the winter is onshore, that air gets trapped against the bluff. That’s what keeps the nighttime temperature moderated and inhibits frost.”

Inhibits, but doesn’t prevent it. Shortly after Richardson planted the first commercial banana plantation in the continental United States, a killer 1990 frost destroyed 30% of his crop.

Production has since bounced back to 10 tons per acre.

Of course it’s not only bananas and butterflies that are choosy about climate. There are a host of wild plants that demand specific conditions.

THE SUN IS HOT

Rick Burgess, an environmental planner for the city of Thousand Oaks and a board member of the local branch of the California Native Plant Society, is practiced at identifying climatic variations and the wild plants that are likely to thrive within them.

For the last 10 years, Burgess has been compiling a field guide on plants in the county. There are several rare or endangered species that exist only in particular microclimates.

Pentachaeta, a rare member of the sunflower family, occurs usually in sparse grassland areas where it gets the full, drenching sunlight that most other plants can’t tolerate. In contrast, most unusual plants here are found in microclimates comparatively lacking sun.

“The easiest way to find a microclimate in the chaparral is to look for pockets of trees,” Burgess said. “Whether they’re oak, ash, maple, sycamore or alder, trees create a microclimate that’s cooler in the summer. There’s an entire under story of plants, mugwort, poison oak, blackberries.

“We have some brown dogwood that grows in a stream here in Thousand Oaks underneath large sycamores. You usually find that plant farther north up around the Oregon border where it’s common,” Burgess said, “but we have a few here in the Conejo Valley taking advantage of those wet, shady conditions.”

Another species that likes moisture is the Big Cone Douglas Fir. “You’ll see them on steep northern slopes and deep canyons, both of which get less direct sunlight, and therefore have less evaporation,” Burgess said. “Lots of those steep northern slopes, the only thing you’ll see on them are Big Cone Douglas Fir. You can recognize them because they look sort of like a candelabra.”

Sun and shade are of no small concern to gardeners. Anybody who’s ever cracked the cover of the Sunset “Western Garden Book” knows southern exposure is good in the winter, but hard on plants during the summer.

But landscape architect Owen Dell of Santa Barbara said examining back-yard sun patterns can be more complicated than taking note of where the shadows fall. He’s seen cases where sunlight reflected from a window creates a superheated microclimate on the opposite side of the yard, leaving gardeners with no idea why a 4-by-5-foot patch of ground is turning brown and dying.

WARM AIR IS WET

Among the best places to find unusual plants is Divide Peak, an east-west ridge that separates the coastal bluffs from Matilija Creek, above Ojai. Burgess said amateur naturalists can find tan bark oak, madrone (a large evergreen), and sword fern, a plant that’s typically found in redwood forests.

“Divide Peak area is one of the wettest in the county,” he said. “It’s much cooler.”

During the recent storms, Old Man Mountain just north of Divide Peak got 11 inches of rain in 24 hours, according to the National Weather Service.

Joel Michaelsen, a professor of geography at UCSB, said the soggy microclimate is a result of orthographic effect. Warm, rain-heavy clouds come off the ocean and encounter mountains. As the air travels up the slope of Divide Peak, it cools and, because cool air holds less moisture than warm air, the clouds release their moisture resulting in rain.

COLD AIR GOES DOWNHILL

Here is where some readers might get confused: If cold air sinks, then why is air colder on the tops of high mountains than air in the valley below.

Air is warmed, not by direct sunlight, but by radiant heat reflected from the ground, said Lanny Kaufer, an Ojai herbalist. Because there’s less real estate at high altitudes, it’s colder. But if you travel only a few hundred feet up from the valley floor, Kaufer said it will actually be warmer, because the cool air flows downhill just like water.

Santa Paula grower Mike Shore has witnessed the effect.

“It’s beautiful up there in Wheeler Canyon. Aliso and Matilija too. But it gets cold as anything at the mouths of those canyons, because it’s a huge air drainage.”

The resultant bands of warm air are called thermal belts. That’s where Kaufer said an astute observer can find the rare Checker Lilly, a chocolate-colored flower with purple and yellow spots that is unique to the Ojai district of Los Padres National Forest.

“It grows in shady canyons that get a western exposure on their slopes--not so far up the slope as to dry out, but far enough up from the floor to get some warm air.”

Thermal belts are also part of the reason you frequently see avocados, a frost-sensitive subtropical species, planted on hillsides, Shore said. They’re not planted there, as some suggest, so the fruit will roll downhill for easy collection.

Thermal belts, cold air basins and evaporation rates are all factors that Shore and other growers pay extremely close attention to.

“I was recently out evaluating some property we’re thinking about buying, and the sumac and sage was really thick. That’s a good sign. Sumac and sage are indicators because they’re sensitive to frost,” he said. “You see healthy sumac, you can be sure the property is frost-free.”

Of course there are limits to a microclimate’s role in determining planting patterns in the county. Rex Laird, director of the Ventura County Farm Bureau, said there are often more obvious factors to consider.

The reason you see row crops on the Oxnard plain is that if you try to grow them on a slope, the irrigation water runs off, he said. And if you tried to cultivate them, the tractor would tip over.

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Ventura County’s Climate Zones

The county has a number of distinct climate zones. Changes in temperature, humidity and sunshine are usually caused by altitude and air flow from the ocean or inland sources.

Climate Zones

High elevation

Zones 1,2 and 3

Snowy climates with growing seasons less then 180 days. The top of Mt. Pinos is classified as among the coldest winter climates in the West. In Zone 1 frost can occur any time of the year. Zone 2 and 3 also get snow, the difference being that average low temperatures aren’t as severe.

Interior valleys

Zones 18 and 19

The major influence is continental airmass. Marine air dominates no more than 15 percent of the time. Zone 19 is favorably located in thermal belts (slopes that are warmer in winter because colder, heavier air drains off of them). Zone 18 is more typically located in basins where the cold air collects or elevations above the thermal belt where altitude creates colder temperatures. Zone 18 favors apricots, peaches, apples and other varieties that need a winter chill. Zone 19 typically grows citrus and other subtropicals like avocados.

Mixed Marine and Continental Air

Zones 20 and 21

Marine air is more of a factor, but otherwise these zones are similar to Zones 18 and 19. Zone 20 is a cold air basin, like the Ojai Valley where several canyons empty cool air onto the valley floor. Zone 21 is more akin to Zone 19 in that it lies in a warmer thermal belts. Winter lows in Zone 20 can dip below 20 degrees, but the mercury in Zone 21 rarely drops to freezing. That’s why towns like Fillmore and Piru, both in Zone 21, produce so much citrus.

Coastal Climates

Zones 23 and 24

Typical image people get when they think of Southern California climate. Marine air influences conditions 85% of the time. Only 15% of the determining influence is from the interior and a significant portion of that comes in the form of Santa Ana winds. Zone 23 is roughly coterminous with the coastal mountains, while Zone 24 is the mild, moist climate that dominates the beaches and marine bench leading to the hills.

Source: Sunset “Western Garden Book.”

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Guided Hikes to Wild Things

So you want to apply some of the principles of microclimate to find out where the wild things are? Well, it might help to have a guide. Here’s a list of hikes on which knowledgeable leaders will point out unusual plant life and the specific areas they thrive in.

Sunday: The Sespe chapter of the Sierra Club will do an afternoon hike through Wildwood Canyon. Leader Eric Rose will point out dudleyas, chocolate lilies, pentacheata and such other rare plants as Conejo buckwheat. Call 522-7344.

Feb. 25: The Native Plant Society will conduct a field trip through Rattlesnake Canyon at the base of the Santa Ynez Mountains. The trip will focus on the abundant ferns, annual shrubs and spring foliage in the verdant canyon. For information on this and other Native Plant Society field trips throughout the year, contact 564-1165.

Feb. 26: The Santa Monica Mountains Conservancy has a docent-led hike to Happy Camp. For information, call (800) 533-PARK.

March 5: The Sespe chapter of the Sierra Club will hike through Santa Paula Canyon. A featured plant along the trek will be big cone spruce, which grows on a shelf above the canyon at the aptly named Big Cone Camp. Call 642-8512.

The Santa Monica Mountains Conservancy will conduct a wildflower walk at Sage Ranch. For information, call (800) 533-PARK.

Also: Herbalist Lanny Kaufer leads half-day herb walks in the canyons around Ojai. During the walks, Kaufer points out plants with medicinal or nutritional value. The walks start in March. For specific dates and times, call 646-6281.