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GEOSTATS: The Spatial Forest

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  • Paul
    Dear Statistician, This letter informs you of the forestery reference in Rev Ciencia Forestal en México 19 (76) 1994: 141-152 by Bertil Matérn of the Dept of
    Message 1 of 1 , Oct 16, 2000
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      Dear Statistician,

      This letter informs you of the forestery reference in Rev Ciencia
      Forestal
      en México 19 (76) 1994: 141-152 by Bertil Matérn of the Dept of Forest
      Biometry, University of Agricultural Sciences, Umea, Sweden. The Poisson

      forest (Keuls et al., 1963), the angle count method (Bitterlich, 1984)
      and
      the central satellite model (Warren, 1991) are emphasized. Basal area at

      breast height going to square meters per hectare is the main target.

      Using Goodland’s (1971, J Ecol) work on the Brazilian Cerrado quite
      apart
      from Matérn’s brilliant review, the writer calculated these relations
      for
      4 niches—1) grassland, 2) matorral (short open woods), 3) light forest &

      4) forest. The relation of the 4 sites (X) to basal area (Y) is
      logistic,
      site by number of tree species fits: Species = a + b(Site)3 + c
      exp-Site,
      and Site by tree height fits: Height = a + b(Site) + c(Site)2. The
      coefficients of determination are at unity, and these relations are
      ideal.
      As the X and Y axes have only 4 points, perfect curves must result.
      These
      relations may help in the statistical management of new data from
      different niches.

      When the foliar morphometric averages in 4 mezquitales (mesquite woods)
      are so compared, logistic equations explain site by leaflet length and
      site by rachis length, because the curve that runs through any 4 points
      is
      likely to be logistic, sine, exponential, extreme value, rational, etc.
      Also, using (or overusing!) averages is just not the same as running a
      fit
      through the many original data points. Bias must arrive, because the
      experiential judgement of the researcher is called upon for expression
      of
      reasonable caution in the use of such models since many work as well as
      another. When several thousand raw data points are run, the results
      could
      be DF Adj r2 = 0.25 or less, leaving one to wonder what happened.

      More, of course. See Means, JE et al, “Software for computing plant
      biomass—BIOPAK user’s guide,” USDA, Forest Serv, Gen Tech Rep
      PNW-GTR-340,
      which refers to a DOS program on Internet that has a library of
      equations.
      Go to http://www.fsl.orst.edu/lter/data/software/biopak.htm

      Best Regards, Paul R. Earl

      PS See Software at http://www.fs.fed.us/links/software.shtml

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