By Marcia Wolfe
Valley Ag Voice
Well, it’s finally cooling off. Around us big winter storm fronts have been moving across the state, the Southwest, the Midwest and into the Northeast, bringing freezing temperatures and snow, and recently as I am writing this, a whole lot of tornadoes to the Southeast too. Along with the cool-off, we have received a few rain showers and had a couple misty days. The moist air also resulted in a bit of mild fog around town the last couple weeks. Our Bakersfield average precipitation is 5.5-6.5 inches each year, and it goes up and down, depending upon whether it’s a wet year or a dry year. This year so far, we are at about 122% above normal for total rainfall. Since I have lived here, that is very unusual. The summers here are very hot, but the heat generally starts in February and March.
Having been born and raised in Washington state and starting my professional career on Mount Rainier, for the US National Park Service of the Department of Interior, I was not used to heat or low amounts of precipitation. One of the years I worked there, The Mountain, as we used to call it (and they still do), broke the world’s record snowfall with over 1023 inches of snow. That record was since beat by Mount Baker to the north with 1140 inches (that’s a lot) of snow in 12 months.
Nearby about 80 miles distant (depending on which side you drive to), Seattle has about 152 rainy days a year; can you imagine that? It rains there almost half of all the days in a year! Precipitation there averages about 37 inches of rain annually. Being born and raised there, I was anything but used to hot and dry! In fact, upon moving here and starting to work in the field in February and March in the oil fields at Elk Hills, according to the doctor, I got heat sickness. I had to climb up and down many trail-less, steep slopes digging and collecting soil samples. It was grueling. As apparently heat sickness mimics morning sickness when a woman is pregnant, the doctor asked me if I could be. Nope I told him, not unless it’s an immaculate conception. I survived, but it wasn’t easy. People kept telling me that you get used to the heat. Then one day, years later, someone told me, “The truth is, you never get used to the heat.” And that’s the truth!
Interestingly, living here has changed the whole concept of what the seasons are for me, as what happens in a season is not the same here as in Washington. The seasons here do not even correlate with the definitions. It is winter now, right? It’s the middle of December for all practical purposes. But while doing a biological field survey last week, we found annual plants in rangeland and riparian habitats germinating and growing from seed. December is defined as the beginning of winter. But the vegetation is germinating and growing like it’s Spring. In most locations, winter is typically the coldest part of the year. Winter often has frosts, if not freezing rain or snow (though not much snow here and its rare). Winter is not when one generally thinks about planting most species. The ground can be frozen, frost can kill seedlings beginning to sprout. It’s generally cool during winter months
Here winter is generally also the wettest part of the year. In some years, precipitation will start in the Fall in September, but not always. Although small amounts of rain often fall in October and November, most of the precipitation doesn’t come until later. Then by the middle to the end of March, which is Spring by definition and where I came from, the annual plants here already have bloomed and gone to seed. If it’s a dry year, the seeds may already be shattering and the leaves starting to dry up and die. Now, this year was a bit unusual. Total rainfall was significantly above normal, and we got a lot of that rain in March (two inches). Heavy rainfall in March is unusual, but good for the rangelands, for everything really. Plants help this extra moisture percolate into the groundwater, whether it be shallow alluvial groundwater or deep groundwater.
So, what does this discussion have to do with anything? The timing of the seasons and what happens during the seasons is somewhat different than most people experience and seems somewhat different even than the common definitions of the seasons. The timing of the seasons affects us all. The timing affects germination and plant growth, of both annual and perennial species. Overall the timing is important relative to the timing of habitat restoration and revegetation. It’s important to crop planting. Crop timing for various species can be as different as it may be for native and non-native habitat species. Properly designed, the timing of these activities may also improve groundwater recharge. The timing of vegetative growth also affects wildlife of all types, ranging from browsers to seed collectors and root eaters. Interestingly as well, over the years we have found that planting and managing road and canal shoulders and other open areas with native and non-native vegetation also reduces the number of squirrels, other pesky small mammals and weeds for which millions of dollars are spent on herbicides and pesticides in attempts try to control them every year. However, the disturbed status of the vegetation actually encourages further rodent invasion.
So, Winter really being Spring here, you want to plant your native and non-native plant species mixtures in the Winter, rather than Spring, when the already established species go to seed and die. Further, here during an average Spring, March-May, the natural vegetation goes to seed or goes to seed and dies. If heavy bird and rodent predation is not an issue, one can plant here in the Fall. Fall plantings capture the maximum amount of precipitation possible. 2019 may not have been a bad year to do that, as we got about an inch of rain in November, but September and October we basically got none (.02) inches. Consequently, this year if one planted in September, the seed would have been in the ground for a full two months before it would receive moisture to germinate. All that time it would be available for bird and small mammal foraging which can make a dent in the amount of seed planted. If one could predict rainfall timing with certainty, it would be a perfect world. Based on our 30+ years here, planting around the beginning of November has been a good time to plant native species. It helps to maximize moisture while at the same time minimizing seed predation risk,
Planting native habitats can also enhance groundwater recharge by maintaining water percolation pathways with their roots. In addition, they help slow the water flow off site, so that it has time to percolate down to the groundwater instead of running off downstream. So, when thinking about planting native species in Bakersfield, think plant in the Fall (November) or early Winter, which is Spring in the southern San Joaquin Valley, believe it or not.