Niwot Ridge ITEX data.

The workbook Niwot_Itex2001.xls contains two sheets: species (species
list and codes) and ptquad (community data).

For years 1993 (warming treatments started this growing season, snow
treatments started the following winter), 1995, and 1996.  In 1995,
control plots (warmed and unwarmed) were added outside of the influence
of the snowfence.  These are designated by a negative value. I have no
record of the month and day most of these were sampled, so just
designated the year. Data has been collected in 1997 and 2000, although
it is not ready to be analyzed.

These data are coded for warming treatments (paired plots, indicated by
adjacent plot numbers), snow augmentation (in the influence of a
snowfence; these controls added in 1995), and location (distance from
the snowfence).  The location treatments includes variation in snow
accumulation (plots closer to the snowfence get more snow) and natural
variation (plots closer to the snowfence were more characteristic of
moist meadow tundra and plots further away from the snow fence
characteristic of dry meadow prior to experimentation).

These is one plot name (37176) for which I do not know its treatment
combination.  Marilyn may know but it is an unusual number and may need
to be deleted.  There were also some duplicate records in the data
files; these were deleted.

The woody variable was not taken in 1993 and so these cells are blank.

The last four columns are not necessary for this analysis.  Layer
indicates whether it was a top or bottom hit, species code is the
number assigned to it in the Niwot data set; height is the raw data;
and point refers the Niwot numbering of the x-y coordinates.  I kept
these columns in the data set for ease of my reference.

I can be reached at suding@colorado.edu or 303-735-1239. Lee Turner
collected most of this data and can be reached at
plturner@colorado.edu.