Dripping My Way Through the Forest

For anyone interested in water, a rain-gauge is not only an essential tool and toy, but a great topic for cocktail party chit-chat. Did you know, for example, that one can actually overlook 30 to 60 inches of "rain"?

I live on a high ridge dividing a hotter, dryer inland plain from the more temperate, wetter Pacific Ocean climate some five miles to the west. The non-drought average rainfall on top of my cloud-scraping ridge is about 60 inches per year.

Shortly after moving here, I noticed that a foggy summer evening produced the sound of steady rain beneath the tallest trees—even though a meadow 20 feet away remained bone-dry. I soon learned that in my Mediterranean coastal zone, summer "rain," consisting of droplets of condensed fog, is a frequent occurrence

In this climate, with its summer fogs and winter rains, moist air condenses on the leaves of plants and forms droplets like the hot-weather "sweat" on a bottle of cold soda. The collective needles of the Douglas fir trees near my house offer an immense surface area for this condensation.

I set up a rain-gauge beneath the tallest (125 -foot) Douglas fir tree, and over six years I've discovered that this single tree gathers one or more inches of "rain" each summer night during heavy fogs, and half-again to twice the year-round "rain" of the adjacent open meadow. The month of August usually produces six inches of summer fog drip, or an amazing 163,000 gallons per acre of tree foliage!

To utilize nature's original "drip irrigation" and take direct advantage of this free rain, I plant beneath the dripline of the Douglas firs near my patio The difficulty is finding plants that are somewhat drought-tolerant, shade-loving and deer-resistant. So far my list includes most of the varieties of Daphne (Daphne spp.); wild ginger (Asarum caudatum); native Western ferns; foxgloves (Digitalis spp.); huckleberry (Vaccinium ovatum); Forget-me-nots (Myosotis scorpioides); salal from Northern CA, OR and WA (Gaultheria shallon); the native thimbleberry (Rubus parviflorus); Euryops pectinatus (gets leggy, must have late evening light); and various ornamental grasses. Soon to be infiltrated by Rhododendrons spp., Azaleas spp., and bear berries (Mahonia spp.)

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Spring & Summer Moisture

Last night there was a very gentle rain that lingered for only a short time. It announced the coming of spring and the dry months ahead. 

The peach, plums, plumcots, and quinces are the early-blooming fruit trees in my garden; the first to announce spring is here, no matter how briefly before the yearly drought of summer. Even a gentle rain can affect the pollination and bring disease such a fire blight and scab. So I watch the clouds dissipate and the fog slip back to the shoreline so the sun can dry the flowers to prevent such diseases of fruit trees. The warm, sunny days also bring forth pollinating bees (what few are left) and insects that flutter about in the warmth of the sun and "do their thing". 

The rain was typical for late winter, the roads were wet along my lane, but the asphalt was dry beneath the larger trees. The shadows of dryness follow light mists and gentle rains. In the dry times of the summer, the pattern is reversed. Fog laden with moisture often roll up the hills to my house and the trees 1200 feet above the ocean. The trees gather the fog and condense the moisture into "rain". Then the roads in the open, next the to meadows, are dry and the lane is wet with "rain" beneath the larger, taller trees. 

Many people assume only the roots absorb moisture for the plant's growth. Not always true. Both spring rains and summer fog drip directly feed the needles of the nearby redwoods. It has been discovered that the stomata under the leaf can actually absorb tiny amounts of moisture. This amazing process is but one part of the puzzle about how the forest surrounding my home passes through each summer's dry cycle.

More to follow on future postings.

I'd like to hear about the special micro climates at your home and in the garden. 

Please post a comment - I want to know what you think.

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