Diversity of Plants

 

Desert Data

Click here for pictures and descriptions of plants at the following USDA web site. Then adjust the size of the USDA overlay screen so that you can view both the table and the USDA side by side. We suggest that you size the USDA screen so that you can read the both scientific and common name of the plant. The best way is to arrow down to 'scientific name'. Then type in the scientific name. You can also enter the common name and navigate the USDA web site until you find the information that you are seeking.

Plant Data from Desert(mesa top) Community

 

Species NameCommon Name OriginAbundance
Atriplex confertifoliashadscale native73
Hilaria jamesiigalleta grass native213
Bromus tectrumcheatgrass exotic257
Leucelene ericoidesbabywhite aster native170
Descurainia pinnatatansy mustard native55
Stipa hymenoidesIndian ricegrass native36
Gaillardia pinnatifidablanket flower native45
Salsola ibericaRussian thistle native75
Sporobolus airoidesalkali sacaton native22
Atriplex gardneriiGardner's saltbush native10
Eremopyrum triticeumannual wheatgrass native59
Distichlis spicatasaltgrass native27
Cymopterus sp.wild carrot native25
Gilia pumilapurple gilia native34
Gilia inconspicuashy gilia native31
Vulpia octoflorasixweeks fescue native22
Phacelia corrugatascorpion weed native9
Lepidium densiglorumspectacle pods native9
Guiterrezia sarotharaesnakeweed native5
Streptanthella longirostrislongbeak native3

 

Application

 

Now we apply the mathematical equation to the data above. To facilitate our work, download and fill in the table provided below.

  1. Construct a worksheet that looks like the one (20 x 5) below also click here and press "Print Screen".

     

    Species NamePi - a fraction Pi - a decimalLog of Pi Pi(log Pi)
    Distichlis spicata73/1177 0.0617214-2.780265 -.1724378
    Chrysothamnus linifolius68/1177 0.0577740-2.851216 -.1647262
    *** ***     
    etc.      

     

  2. Fill in the first column “Species Name” from the data sheet.

     

  3. Write Pi in the second column as a fraction. This represents the abundance of each species divided by the total abundance.

     

  4. Convert Pi in the second column to a decimal and fill in the third column.

     

  5. Find the logarithmic value of each Pi and fill in the fourth column.

     

  6. Calculate Pi (log Pi) - the product of the third column and the fourth column. See the table above for sample calculations for "saltgrass" and "rabbitbrush" in red font.

     

  7. Do you recall the equation?

    H’ = - Pi (log Pi)

    signifies "to sum". It means add all the Pi (log Pi) entries for all twenty species in the fifth column. Do not forget the negative sign before the . 

    - Multiply the sum of all twenty Pi (log Pi)'s by negative one.

     

  8. This gives us the diversity index H’.

     

  9. Repeat steps 1 - 7 for the Plant Data from the Desert (mesa top) community

     

  10. You now have two values, H’1 for the riparian and H’2 for the desert communities. Examine the results.

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