Plants of Southern California: Analysis Pages: Our Master List The following plots give a quick look at how our master list has grown with time.
This plot shows that we continue to add new trails at about the same rate with time, despite also repeating a number of trails to sample their flora at different times (also see below).
This plot shows the that the total number of taxa seen on all trails grows only very slowly with the number of trails, and at a declining rate as the number of trails increases. The first fact is quite surprising to many, and results from the fact that rare plants are common; common plants are rare. I.e., there are only a very small number of taxa that are found on many trails, and most taxa are restricted to a very small number of trails.
The declining rate of growth is a simple consequence of the fact that the number of taxa in Southern California is a fixed number. Eventually, the curve will hit the total number of taxa, and then stop increasing at all.
This is the same plot as the previous one, but now for the lists (digitized floras), and shows the same features.
This shows numerically how common rare plants are: 39% of all taxa in our digitized floras, and 39% of all taxa in our trails, are found in only a single flora or trail, respectively. Thus to see 39% of all the taxa in our trail guides, you would have to hike essentially every single one of our trail guides.
The number was higher initially, due simply to the fact that in the first trail or list, 100% of the plants were found on only one list. It took a while to stabilize on the true value.
The jump in the floras in April 2003 was due to the addition of floras from San Diego County, which had not been well-represented before. As more of those floras were added, the percentage quickly came down to the same percentage as found before the addition of that new area.
The jump in the trail guides in June 2003 was due to the same reason, the addition of trails in the Laguna and Palomar Mountains.
This plot shows that 23 of our 65 trails, 35%, have been visited just once, with 10 trails having 5 or more visits so far. The two most sampled trails are both from the Santa Rosa Plateau: the Granite Loop Trail (15 visits for the plant trail guide) and the Vernal Pool Trail (26 visits).
This plot shows that our trail guides began on 5/31/01, which was for the Big Horn Mine Trail, San Gabriel Mountains, and that we got serious about trail lists in mid-December 2001, just in time for the severe drought of that year. Interestingly, it shows no marked season where we were not able to work on a trail for its plant list. Of course, the heaviest workload is in the Spring and Summer, when there are more species blooming and hence more work needs to be done then to identify the species.
This plot shows that since 12/15/01, we have usually updated a trail guide every 1 to 4 days. The longest interval between updates, 24 days, was 4-28 November 2002. The second-longest interval was when we took a 20 day vacation from trail lists in 3-23 July 2003.
Number of taxa vs. time:
Date # on all trails # only on one trail % only on one trail # in all plant lists (doesn't include our trails) # only on one list % # in all plant lists plus our trails total number db entries % 1/25/2002 147 2/12/2002 234 3/7/2002 368 220 0.60 4/8/2002 453 243 0.54 5/2/2002 507 265 0.52 7/28/2002 625 8/11/2002 659 309 0.47 1405 783 0.56 1555 4706 0.33 8/11/2002 659 309 0.47 1404 789 0.56 1555 4706 0.33 8/25/2002 684 323 0.47 9/1/2002 696 321 0.46 1404 789 0.56 1555 9/7/2002 697 318 0.46 1496 781 0.52 1651 4743 0.35 9/11/2002 697 318 0.46 1588 873 0.55 1722 4746 0.36 9/15/2002 705 325 0.46 1636 832 0.51 1767 4754 0.37 9/19/2002 706 324 0.46 1717 855 0.50 1833 4755 0.39 9/22/2002 706 324 0.46 1739 838 0.48 1855 4759 0.39 9/30/2002 731 339 0.46 1757 818 0.47 1875 4760 0.39 10/4/2002 742 350 0.47 1757 818 0.47 1879 4760 0.39 10/8/2002 750 354 0.47 1757 818 0.47 1880 4761 0.39 10/18/2002 767 358 0.47 1782 809 0.45 1907 4767 0.40 10/21/2002 771 360 0.47 1782 809 0.45 1907 4767 0.40 10/25/2002 779 361 0.46 1782 809 0.45 1908 4768 0.40 10/29/2002 785 361 0.46 1790 812 0.45 1911 4769 0.40 11/2/2002 788 358 0.45 1790 810 0.45 1914 4772 0.40 11/5/2002 790 360 0.46 1842 779 0.42 1958 4774 0.41 11/6/2002 790 360 0.46 1856 780 0.42 1971 4775 0.41 11/7/2002 790 360 0.46 1863 781 0.42 1977 4781 0.41 11/20/2002 790 360 0.46 1867 776 0.42 1980 4783 0.41 The following plots shows, for each trail separately, a histogram of the number of trails in our database which contained each species found on that trail. Thus, for example, on the Dawson Saddle Trail, 39% of the species found on that trail were found only on that trail out of the 21 trails in our database at the time the histogram was made. Only 2.5% of those species were found on 12 trails (11 trails other than the Dawson Saddle Trail).
This plot should be interpreted with considerable caution, since the number of unique species on a given trail depends strongly on how many nearby trails are in our database. For example, if we did not have two neighboring trails of the Baden-Powell Trail, its percentage of unique species would be much higher. Thus any tentative conclusions drawn from this plot need to be supported with detailed follow-up analysis.
Go to Native and Introduced Plants of Southern California
Copyright © 2002 by Tom Chester and Jane Strong
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
http://tchester.org/plants/analysis/list/index.html
Comments and feedback: Tom Chester | Jane Strong
Last update: 31 August 2003