Jepson Manual Analysis: Number of Species by Geographic Region Resolved Into The Number Of Taxa From Successively Larger Areas

The Jepson Manual breaks California into a four-level tier of geographic subdivisions (Provinces, Regions, Subregions and Districts). This page gives a breakdown of the number of taxa in the areas of interest for Southern California, in a different way than is usually done. Normally, the total number of taxa in each area is tallied. Here, I separately break down that total number of taxa in each area into the number of taxa that come from successively larger areas and the number of taxa found in the area of interest that are not found in a larger area. So, for example, I present the number of taxa in the Tranverse Ranges ("TR") area as:

• those which are found in each and every subarea of all of California ("CA");
• those found in each and every subarea of all of the California Floristic Province ("CA-FP");
• those found in each and every subarea of all of the Southwest Region ("SW"); and finally
• those that are found in the Transverse Ranges Subregion but not in every subarea of any larger area.

This allows one to see at a glance the number of taxa in each area that are found over larger areas, and the number of taxa that are more localized in their distribution.

For a map showing all the geographic subdivisions, see, for example, Jepson Manual Treatment for Bromus Tectorum. All area abbreviations are given in a table at the end of this page.

The basis of this analysis are the plant lists by area obtained from the Jepson Flora Project's Jepson Online Interchange downloaded on 19-20 July 2003. These plant lists from the Interchange give all the plants found in a given area according to the Jepson Manual, which includes plants found in only a part of each area. Thus, for example, the list for the Transverse Ranges includes taxa identified as being in "CA", "CA-FP", "SW", "TR", as well as those from districts of the TR: "WTR", "SnGb" and "SnBr". Thus there seems to be no way to retrieve lists of just those plants with "TR" in their distributions.

However, one can easily use such lists to recreate lists of taxa with each geographic subdivision in their Jepson Manual distribution. In order to obtain those taxa with the higher-level area in their distributions, I downloaded the following areas outside of Southern California in addition to the Southern California areas:

JM Abbreviation	Full Name
CaRH	High Cascade Range (extreme north-middle California)
KR	Klamath Range (extreme nw California)
NCo	North coast
nSNF	north Sierra Nevada Foothills
SnFrB	San Francisco Bay area
cSNH	central High Sierra Nevada
Wrn	Warner Mountains (extreme ne California)

I used these other areas in my analysis, in addition to the Southern California lists, in order to establish which taxa were found in California as a whole, and which were in the California Floristic Province.

The lists were merged, keeping track of which taxa were in which area, and then analyzed to produce the Jepson Manual distribution information. Thus, for example, all species found in each and every one of the districts of the "TR" were identified as having the "TR" Jepson Manual distribution. In similar fashion, I assigned the 140 taxa found in each and every one of my downloaded areas to "CA". The remaining taxa found in each and every one of the downloaded "CA-FP" subareas, 382 taxa, were assigned to that area. The remaining taxa found in each and every one of the "SW" subareas, 426 taxa, were assigned to "SW". Finally, the remaining taxa found in each and every one of the "TR" subareas, 313 taxa, were assigned to "TR", and those found in both the "PR - SnJt" and "SnJt" subareans, 463 taxa, were assigned to "PR". The tables below present the final numbers.

Note that the resulting number of taxa in an area that are not found in a larger area containing that area are not necessarily taxa unique to that area. In fact, this is rarely the case. Most of those taxa are also found in other subareas. Thus, for example, most of the 217 taxa found in "SnGb" are also found in neighboring districts of "WTR" and "SnBr". But none of those 217 taxa are found in both of the neighboring districts; if they were, they would have been counted in the "TR" category.

In order to check my numbers, the only reference I could find for any of these numbers from the Jepson Manual itself is given in each of the downloaded areal plant lists, where it says that "the recorded distribution of some 230 plants in The Manual is the California Floristic Province (CA-FP) only". I assigned 382 taxa to the "CA-FP" area; of those 93 taxa are found in "D" as well, leaving 289 taxa that are found in "CA-FP" and not in "D". This seems like a reasonable number, since some of my 289 taxa will be found in other areas that I did not download or for which I did not do that comparison.

The first table presents the numbers down to the "region" level; the second two tables break down the "TR" and "PR" regions into their subregions.

Resolution of Number of Taxa To The Subregion Level

Area	Number of Taxa
	"CA"	"CA-FP"	"SW"	Other In Area	Grand Total
Provinces
CA-FP	140			6145	6285
D	140			1635	1775
CA-FP Region
SW	140	382		2478	3000
SW Subregions
TR	140	382	426	1097	2045
PR	140	382	426	795	1743
SCo	140	382	426	780	1728

Resolution of Number of Taxa For The Transverse Range Districts

District	"CA"	"CA-FP"	"SW"	"TR"	Other In Subregion	Grand Total
WTR	140	382	426	313	326	1587
SnGb	140	382	426	313	217	1478
SnBr	140	382	426	313	446	1707

Resolution of Number of Taxa For The Peninsular Range Districts

District	"CA"	"CA-FP"	"SW"	"PR"	Other In Subregion	Grand Total
PR-SnJt	140	382	426	463	178	1589
SnJt	140	382	426	463	153	1564

The "PR-SnJt" district contain those taxa given the designation "PR" in the Jepson Manual, and do not include those only given the designation "SnJt". As the table shows, there are 463 sources found in both "PR-SnJt" and "SnJt"; 178 taxa that are found in the PR outside of SnJt, and 153 taxa found in SnJt that are not found in the rest of the PR.

Abbreviations For The Geographic Areas Used On This Page

JM Abbreviation	Full Name
CA	the entire state of California
CaRH	High Cascade Range (extreme north-middle California)
CA-FP	the California Floristic Region (excludes the Great Basin and Desert portions of the state)
D	Desert Province
KR	Klamath Range (extreme nw California)
NCo	North coast
PR	Peninsular Ranges
SCo	South Coast
nSNF	north Sierra Nevada Foothills
cSNH	central High Sierra Nevada
SnBr	San Bernardino Mountains
SnFrB	San Francisco Bay area
SnGb	San Gabriel Mountains
SnJt	San Jacinto Mountains
TR	Transverse Ranges
Wrn	Warner Mountains (extreme ne California)
WTR	Western Transverse Ranges

Go to:

• Native and Introduced Plants of Southern California