Showiness of the Bloom vs. Time
This page contains up-to-date plots of the number of plants in bloom and the showiness of the bloom for 2005, but contains only a brief analysis of that data set up to 3/10/05.
For an introduction to the quantities plotted below and discussed here, see Analysis of Plants Blooming on the Santa Rosa Plateau Vs. Time in 2001.
In 2001, I attempted to keep detailed track of the entire bloom on the older section of the Santa Rosa Plateau Ecological Reserve, the part east of Clinton Keith and Via Volcano Roads. Beginning in 2002, I keep detailed track only of the bloom on the Vernal Pool Trail. Thus all the plots and analysis here pertain only to that trail. (I kept separate records of the bloom on the Vernal Pool Trail in 2001, and hence the 2001 values in this page also pertain only to that trail.)
The time sampling is very different in 2002 and beyond as well. In 2001, I sampled the early and peak bloom every 2-4 days, extending the sampling interval to 6-7 days near the end of the bloom. Using that data set, I was able to determine that the data have only a very small variation with periods shorter than a week or two. In 2002 and 2003, I sampled the bloom once every week or two, which should be sufficient to follow the bloom well.
In 2004, I only have a single data point because I mostly botanized elsewhere.
In 2005, my intent was to botanize the SRP heavily, but the wonderful rains resulted in two separate almost month-long closures of the SRP, preventing sampling in January and March.
In the following, all rainfall references are to the rainfall season from July 1 to June 30. For brevity, a referenced year refers to July 1 of the previous year to June 30 of the referenced year. Thus 2001 refers to the rainfall year from July 1, 2000 to June 30, 2001.
The last five years have had essentially the full range of weather expected in a hundred year period, condensed into only five years:
- 2001 was a fairly normal year for rainfall, with the first rain that germinated annuals on 11 January 2001, with rain continuing throughout the growing season at fairly regular intervals. The temperatures were below normal all winter until the beginning of April.
- 2002 was the worst drought for Southern California in recorded history (some locations) or the worst drought for over 50 years (other locations). We never got a good enough rain to germinate all the annuals. The first rain that germinated some annuals was 1 inch on 24 November 2001. Every single rainfall after that was never more than a half inch at a time, and typically a quarter inch or less. Worse, every single one of those rainfalls was immediately followed by significant winds or heat that dried up the rainfall. Hence the soil never got wet beyond a depth of a few inches.
Temperatures were essentially normal overall.
- 2003 began with an early rainfall, with over two inches from 8-10 November 2002. Rainfall continued until 21 December, but then no further rainfall was received through 9 February 2003. Temperatures were much above normal the entire month of January. Rain resumed in February, and overall we had normal rainfall.
- 2005 began with even earlier rainfall, with five inches from 17-21 October, and the rains just kept coming. It looks like 2005 may be the heaviest rainfall in recorded history, or close to it.
As a direct result of the weather summarized above, in 2001 the blooms were all pushed later in the year (see plots below). In 2003 and 2005, the blooms were so early for many species than some species were blooming before the earliest dates reported in floras.
Someday, I'll make a plot of bloom times in 2003 vs. bloom times in 2001, and analyze the results.
These years are so different that though only four years are analyzed here, it is likely that they already show most of the possible variation in bloom times.
Showiness of the Bloom vs. Time
Each year, I assign a different showiness factor to each species, based on the display for that year. For example, in 2001 blue-eyed grass produced many patches of blue color along the Vernal Pool Trail that were very impressive. As a result, I assigned this species a showiness factor of "10" on a scale of 1-10 in 2001. In 2002, the number of individual plants blooming at a given time was down by a factor of 10 to 100, and there were no patches of blue color evident anyplace along the Vernal Pool Trail. Sometimes one even had to hunt for the handful of plants blooming at any given time. As a result, the showiness factor was only a "2" in 2002. In 2003, the blue-eyed grass started in January, stopped in February, and resumed in March. This resulted in the bloom being dragged out in time, so that even though the same number of plants bloomed in 2003 as did in 2001, the bloom at its peak was never as showy. Thus I gave it a "5" in 2003.
The above was an extreme example; 90% of the species receive the same showiness factor each year, since they aren't nearly as variable.
Analysis of 2001-2003 shows the following:
- Some plants that normally bloom before ~May, especially annuals, can bloom earlier or later than normal, depending on rainfall and temperatures. See Analysis of Plants Blooming on the Vernal Pool Trail Vs. Time in 2003 for a discussion of how the early rains, and especially the drought and heat of January 2003, moved up the bloom that year in the early months.
- Plants that normally bloom in May and later stick to their schedules no matter what the weather was like in the winter and early spring.
This separation seems reasonable. There isn't much difference between a December day and a February day in terms of the amount of sunshine (length of day and intensity of sunlight) and the temperatures. So early rainfall, and especially early heat and drought, can induce plants that normally bloom in February through April to bloom as much as two months earlier, since they can't really tell the difference.
But a day in February or March simply can't masquerade as a day in May through September. The length of day and intensity of sunlight is very different, and the temperatures are strikingly different when averaged over an interval of a month. So no amount of rainfall or even early heat is going to persuade a plant that normally blooms in June to bloom any earlier. In particular, for their bloom times, these plants just don't care about any rainfall in October or November, seven to eight months before they normally bloom.
For the 2005 bloom, although I was not able to collect data in January and February 2005, my impression is that we did not get as much of an early bloom in 2005 as we did in 2003. Of course, the bloom in 2005 was still way ahead of that of 2001.
As of 3/10/05, we are almost exactly on track for the number of species in bloom and for the "fullness" of the bloom as was recorded in 2001. We are a bit ahead on the showiness of the bloom, which is what I predicted in 2003 would happen in a heavy rainfall year. That is, all the rain in 2005 did not move up the bloom any more than it did in 2003, but it definitely increased the number of plants and flowers that are blooming, making the bloom more "showy".
My prediction for the next few months is that the absolute peak of the bloom will occur in its usual mid-April. Note that we are already at over 80% of peak bloom, and should stay above 80% until ~1 May.
Copyright © 2005 by Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Updated 12 March 2005.