Mount St. Helens –

Permanent Plots and Grids

1980 to present

This site is maintained by

Dr. Roger del Moral

University of Washington

Department of Biology

Box 355325

Seattle, WA 98195-5325

e-mail: moral@u.washington.edu

 

The material found in this web site is based upon work supported by the National Science Foundation under LTREB Grants No. 0089704, 9406957, 8906544 and earlier grants.

 

Data are in Adobe Acrobat (download Acrobat Reader) format for viewing and printing.  Should you wish to use the data from this web site for any reason, please contact Dr. Roger del Moral.  Data are available in spreadsheet format.  Please acknowledge the use of any data or images from this site. 

Related sites:  Roger del Moral’s homepage

http://faculty.washington.edu/moral/

This site contains descriptions of how data have been used and provides links to many papers based on these data.

Mount St. Helens Photo collection:

http://content.lib.washington.edu/mtsthelensweb/index.html

permPlotscontain data from 250 m2 permanently marked circular plots.

Grid Plots contain the results of cover index scores obtained from contiguous 10 by 10 m plots.

The nomenclature follows that of Titus, J. H., S. Moore, M. Arnot, & P. J. Titus.  1998. Inventory of the vascular flora of the blast zone, Mount St. Helens, Washington.  Madroño 45:146-161.  Current names, common names and older names are provided in this link.

The bibliography lists papers produced by R. del Moral and his associates, 1981 to the present.

Permanent Plots

The plot locations, elevations, slope and aspect are summarized for each permanent plot.

Plots are permanently marked in the field as follows: there is a center stake and stakes at each of four radii 8 m from the central stake.

Six quadrats are aligned precisely along each radius at 1 m intervals.  From 1980 to 1986, 1/10th-m2 rectangles were used.  From 1986 on, 1/4-m2 quadrats have been used.  In addition, species found within the plot, but not sampled by quadrat, were listed and given a cover of 0.1%.  The mean cover and frequency of each species was determined.

For each plot in each year, the following plot summary data are provided:

Total number of species (richness)

Total plot cover percent (sum of all species)

H prime (Hp) based on the natural log of cover proportions (Shannon function)

Evenness (equitability) based on cover = Hp / ln (richness)

Mean Frequency of the species.

A zero indicates that a species was not encountered in a given year.

Data from these plots have been used in several papers.  See:

del Moral, R. 1983.  Initial recovery of subalpine vegetation on Mount St. Helens.  American Midland Naturalist 109: 72-80.  http://faculty.washington.edu/moral/publications/AMN_RDM_83.pdf  

del Moral, R. 2000a.  Succession and species turnover on Mount St. Helens, Washington.  Acta Phytogeographica Suecica  85: 53-62.  http://faculty.washington.edu/moral/publications/Acta2000.pdf

del Moral R., D. M. Wood & J. H. Titus.  2005. Proximity, microsites, & biotic interactions dur­ing early primary succession.  In:  V. H. Dale, F. Swanson & C. Crisafulli (eds.) Mount St. Helens 20 years after recovery.  Springer-Verlag, New York. http://faculty.washington.edu/moral/publications/delMoralEtAl2005.pdf

Data Summary for Permanent Plots

Tephra: — sites that received only coarse air-fall deposits and which recovered with a few years.  These plots are located near Butte Camp.

Scours: sites that received different degrees of erosion from rapidly melting glaciers.  Three degrees of scour are recognized:

  Light Scour: — plots on the lower portion of Pine Creek Ridge.

  Moderate Scour: — plots higher on Pine Creek Ridge.

  Heavy Scour: — plots located above Butte Camp.

Blast zone: sites that were affected by the hot directed blast.

  Secondary Blast: — plots on Toutle Ridge in which there was substantial survival of the understory vegetation.