Welcome to our interactive
Hubbard Brook Phytosociology program!

This program calculates some basic standard summaries about the forest composition at Hubbard Brook, online and on the fly!! The calculations are for the regrowing forest on Watershed 5, for which we have forest data starting in 1990 and then in 1994 and 1999. These are years 7, 11 and 16 after the whole-tree harvest in the winter of 1983-1984. Tabular output includes basal area, stem density and species frequency.

Please do not use any of these numbers in any official way without first checking with the Hubbard Brook research team.

If you are losing the page when reloading images in the calculators, please go back to the W6 front page and reenter by clicking "click here if your browser does not support frames".

This program is optimized for Internet Explorer 6.

Watershed 5

Please choose a year:
Please choose a health code (vigor):

You may select a diameter range over which you would like to make the summaries. The smallest diameter included in the data is 1.5 cm and there are no trees over 40 cm dbh. If no diameter range is specified, the program will run for all trees >2 cm dbh. (Note that the >2 cm diameter class includes trees >1.5 cm. See explanation.) To generate an accurate diameter distribution graph, we recommend using either integers or a midpoint range (i.e. X.5 to X.4), unless you have read all the notes and understand exactly what the program returns.
Enter lower diameter (in cm): 
Enter upper diameter (in cm): 

Please indicate by number which of the following plot summary options you are going to use:

1. Please choose one of our standard vegetation/elevation zones. Note that in 1990 there were no plots in the spruce-fir or high hardwood zones because these trees were not yet large enough for study by this plot method: 

2. OR, choose individual plots. Note that for 1990, plot numbers do not correspond to the numbered grid units on W5 (see notes). (Hold down the shift key to select large blocks of plots or hold down the Ctrl key to select several individual plots):

3. OR, enter a lower and upper elevation limit (in meters). The elevation range for Watershed 5 is 509 to 755m. This option will not run for 1990. (Please left justify and leave one space between the numbers, e.g. 600 700):

You may select a particular species for which you would like to see a diameter distribution by 1 cm diameter classes. If a species is not chosen, the program will make the summary graph for all species combined.
Please choose a species:


Would you like to see a watershed map and plot by plot data for this species? A map will not be generated for 1990 data. (this may take some extra time)

Please choose the units you would like to map: 
Only those trees within the size and vigor classes and plots selected above will be considered in the calculations. 

Would you like to identify those plots on which a particular species is dominant? (this may take some extra time)
Dominance is measured as the percentage of all trees on the plot this particular species composes. This may be based on either basal area or on stem density as chosen above, and you may choose the degree of dominance you are interested in. Only those trees within the size and vigor classes and plots selected above will be considered in the calculations. This option will not run for "all species combined" and a map will not be generated for 1990 data.

Please enter the minimum percent this species must occupy.
For example, if you are interested in plots that are composed of at least 30% of the selected species, then use 30:

Would you like to see the stem count for each species in each plot for the size class and vigor options chosen above?



Click here for the general overview and details of how all these calculations are being made.

Click here for Tom's very specific miscellaneous notes regarding this calculator.

Click here to access the data used in these calculations.

        Please note that this page may undergo changes in the future as we develop new ideas for calculating phytosociology. In the meantime, we welcome any suggestions that you may have for this page at thomas.siccama@yale.edu.

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Web page created March 2004
by Thomas Siccama and Ellen Denny