The short days and chill nights have arrived, and there is much more about Nature’s Fall to take a moment to appreciate.
Mediterranean Fall
Mediterranean fall is the transition between the hot, dry season and the cool, wet season. We must thank the Rocky Mountains and the Sierra Nevada, and a variety of other factors for the lack of summer rainfall in much of California, including right here on the Central Coast. Mediterranean spots are very rare on Planet Earth, and their unique climates make for very interesting, species-diverse places. The “rainfall season” starts October 1st. If you manage property, your target date to be prepared for significant rain is October 15: if you are prepared by that date, you will almost always be in time for the first big storm.
Now is Dry
The rain-carrying wintertime storms are starting to sneak our way, but we aren’t quite there. Meanwhile, it is the driest time of year. The tiny rains we’ve seen so far have only wet the soil surface; the soil is bone dry as deep as it goes over most of our landscape. The last significant rains were from a storm that ended on May 3rd and, prior to that, a wetter storm on March 21st!
To Wet Things
The first significant rain is one inch of precipitation, which usually wets the soil enough that it won’t dry out again until Spring. Although there are many soil types across our region, one of the dominant ones is sandy loam. Each inch of rain saturates about 1 foot of soil. I count the inches and imagine the soil getting saturated deeper and deeper, eventually pouring through to the bedrock and recharging the water table, raising the level of groundwater, feeding the springs, streams, and rivers.
When it Keeps Raining
If we are fortunate enough to have a rainy winter, the rain brings so much life. First comes the petrichor, the smell of the newly soaked ground, a chemical that has been shown to be akin to cedar scent, but you know it when you smell it. Fungus gatherers delight in the seasonal parade of edible treats from boletes to oyster mushrooms to chanterelles (and many more). The mosses and lichens brighten, coating and dangling from every limb of every tree. The dust settles and the seeds produced last Spring start to germinate, the golden hills blushing with green.
Fall Bugs
The dry summer means few biting insects, but there are lots of other interesting insects around in Fall. Over the summer, dragonflies went through metamorphosis in streams and ponds and now the young adults are hunting in the uplands, far from their watery birthing places. Watch for them in meadows, over farms, and even in towns. They are gobbling up flying insects, including the rafts of flying ants that came out when it rained a bit a week or so ago.
Ants!
Each of the first rains triggers some insect or another to explode. This last rain produced millions of flying ants on the North Coast. The air was thick with them as they floated on the breeze, more like tiny butterflies than the bees that they are closely related to. One of these early rains will also trigger termites to fly. Both ants and termites nurture winged males and females that disperse to new territories. Different species seem to prefer to take wing with different cues.
Rain Beetles
Another insect flies with the first rains: rain beetles. These are extremely hard to see, but especially rewarding. Many of us celebrate the season’s first significant storm by going outside and getting soaking wet. Rain beetles are no exception. The male beetles make a loud humming-buzz as they seem to float around during the first big storm of the season, right at dusk, and always near chaparral with manzanitas and pines.
Pests
The first rain obliterates the very annoying canyon flies but also sets in motion the birthing of the season’s first mosquitoes. Canyon flies, aka ‘face flies,’ are the miniature flies that invade your eyes and ears and somehow make it into your throats, hack hack! They like the dry summer and even that last small rain made them disappear. However, whenever the soil gets wet, the soil-borne mosquitoes will hatch.
Newts and Salamanders Ahoy!
The first big storm also brings out amphibians. And here’s something you can do to help. I believe we are all pretty attuned to the first big rainfall, either by following the weather report or relying on a friend that does. As the forecast settles on the first storm of the season, stock up on your groceries and cancel your evening appointments. You’ll be safer and the critters that move around for the first deluge won’t die under your vehicle’s tires. Newts and salamanders await the first big rain and then they move around at night. They’ve been holed up in some burrow complex, pacing back and forth all summer eating beetles and grubs along a set of tunnels they have become quite familiar with. The night with the downpour means that they can move out of that familiar territory towards their breeding pools. And, move they do: in mass, across roads, in straight lines to their favorite pond.
First Flush
The first few rains also set loose a host of pollutants that have been concentrating during the dry season. Another reason to not drive on those first few nights of the Big Rain is that the roads are particularly slippery due to the concentration of oils that have leaked out of cars and plastered themselves to the roadways. After making the roadway treacherously slippery, those vehicle fluids then wash into the streams and rivers and flow out to the ocean. I have a habit of looking at the water flowing down the sides of roads in the City of Santa Cruz during the first rains and noting the continuous normally iridescent, oil sheen that is destined to the San Lorenzo and our precious Bay….so sad. If it is your job or you have any means of cleaning up the roads or other pollutant areas for that first flush of rain, I wish you luck in preparing for that, which is right around the corner. This also means you must pay attention if you have made any bare soil by gardening or farming- sediment loss is soil loss, and soils are a non-renewable resources, taking a long, long time to create.
-this column appeared in Bruce Bratton’s blog BrattonOnline.com, a place you should bookmark for the best coverage of local, regional, and international news.