Analysis of Plants Blooming on the Vernal Pool Trail, Santa Rosa Plateau, Vs. Time in 2003

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 2003, but contains only a brief analysis of that data set up to 4/30/03.

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. Hence in 2002 and later I am sampling the bloom once every week or two, which should be sufficient to follow the bloom well.

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 three years have had very different weather:

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, the blooms were so early for many species than some species were blooming before the earliest dates reported in floras.

Later in the year, 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 three years are analyzed here, it is likely that they already show most of the possible variation in bloom times. The only weather not represented here is a heavy rainfall year, but such a year is unlikely to produce blooms any earlier than 2003, with its very early heavy rain. However, it is likely that a heavy rainfall year would produce more abundant bloom that represented in any of these three years.

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.


Beginning in February 2003, a number of species began flowering as much as six weeks earlier than they did in 2001. As a result, all the bloom plots show a shift to earlier bloom times by about a month. (Some species stubbornly kept their normal bloom time, so the curve did not shift forward by a full six weeks.)

As of 4/30/03, we are now back to tracking the 2001 number of species blooming, as well as the extent of bloom for each species. We are probably at the peak of the number of species blooming at one time. The showiness of the bloom has definitely declined, both due to the loss of some showy species like ground pinks and chocolate lilies, and to the tall annual grasses obscuring the shorter flowers.

The main effect of the early rain and then heat was to give us a much earlier and longer bloom season for the early spring bloomers, as compared to 2001. My bet is that we'll track the 2001 curves now, with blooming times back to normal; i.e., we haven't "borrowed" any blooms from the rest of this year.

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Copyright © 2003 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 2 May 2003.