From: hefa@ERE.UMontreal.CA (He Fangliang)
Subject: 50-ha Pasoh forest, a response
Organization: Universite de Montreal
Date: Tue, 12 Jan 1993 20:20:40 GMT

      To response some questions of Una's recent post in this
newsgroup, I would like to make clearer about the topics on the Spatial
Pattern of Diversity in the Pasoh Forest.
    
Diversity in this discusion refers to richness, abundance and
Shannon diversity index.
    
The Pasoh forest contains 334077 individuals of 825 tree species
(bigger than 1 cm in dbh) in a 50-ha plot (50*1000 m). The
environmental factor I have in hand is the topological data. All
the data are sampled by 20*20 m quadrat, total 1250 quadrats.

  The purpose of the study is to investigate how the community is
organized with respect to diversity patterns and what conclusion
about equilibrium and nonequilibrium hypothesis could be obtained
by the spatial pattern analysis of diversity.
   
  The following 3 groups of questions will be addressed in the
topics:
  
  1. How do the richness, abundance, diversity index change with
     plot size? Will the sampling location in that tropical rain forest
     affects the relationship of species-area, abundance-area and
     diversity index-area? What is the implication of species-area to
     equilibrium and non- equilibrium hypothesis?
The answers to these questions are:  The species-area relation
     follows the exponential form (species/logarea) rather than the
     power function model (logspecies/logarea). The sampling locations
     affect the species-, abundance- and diversity index-area in a very
     significant ways based on statistic test of linear models (H0:
     There is no difference between two lines derived from different
     locations). The non-equilibrium theory is supported by the species-
     area relation since the exponential function is superior to the
     power function which is derived from the assumption that species
     exchanges are in dynamic equilibrium (see Connor, E. F.  and
     McCoy, E. D.1979. The statistics and biology of the species-area
     relationship. Amer. Natural. 113:791-833).

  2. How are richness, abudance and diversity index distributed in the
     study area? What is their distributional features? Are they
     istropically or anistropically distributed?
The answers to these questions are: Richness, abundance and diversity
     index are all heterogeneiously distributed over the plot, based on
     some spatial statistics analyses (variograms and correlograms and
     mapping techniques). The distributional feature for richness,
     abundance and diversity index is the high heterogeneity within the
     local area. This conclusion is apart from the taking-in-grant
     statement of Una 'I would not expect any spatial pattern to emerge
     from an anlysis of the full dat base.' Surprising?! And more, the
     distribution of rhiness in the Pasoh forest clearly shows in
     anisotropic.

  3. What are the underlying processes to govern the spatial
     distribution of richness, abundance anb diversity index? To what 
     extent do environmental factors and 'space' effect contribute to
     the seeing spatial patterns? Again, what is the implication of 
     this study to the equilibrium and non- equilibrium?
The answers to the questions are: (The methodology to answer these
     questions can be found in Borcard, D., Legendre, P. and P.
     Drapeau. 1992. Partialling out the spatial component of ecological
     variation. Ecology 73:1045-1055.) Topological data (relative 
     elevation and slope, no aspect) and space (geometrical location)
     are taken to be the two explaining data sets (independent 
     varaibles) while richness, abundance and diversity index are the 
     explained data (dependent variables). I did not find any evidence 
     that both topological data and space make great contributions to
     the spatial distributions of richness, abundance and diversity 
     index. The total variance in ecological data which are explained
     by the independent variables are less than 20%. This result again
     supports the non-equilibrium hypothesis. The equilibrium theory
     assumes that historical effects, chance factors and occasional 
     environmental perturbation play a small role. Because the system
     heads toward equilibrium, the effect of history disappears, 
     environment has no lasting effect... .  (see Diamond, J. and T.
     J. Case (eds) 1986. Community Ecology, Harper and Row, New York).
     Although one may question that only topological data are not 
     adequate to make any conclusion, in reality who can say that his
     data set is a complete list of environmental factors. We just 
     use best what we have.

  I would not like to argue whether this kind of study is only a
  kind of statistic exploration. But I believe it is worth to do.

  Whether this study is interesting or not, for me, YES, in the
  evolutionary point of view, they may not. Unfortunately, I am not
  studying evolution, maybe one day, hopefully. But just remember,
  someone's meal may be another's poisson!

  I am studying tropical rain forest, unfortunately, I do not have
  much field experience with tropics. My original purpose to post a
  request to communicate with tropical biologists is to try to
  estabiblish some academic relations, on which I will benefit from
  ideas exchanges. I do benefit from communications since the last
  post. Anyway, if a list of tropical biologists could be prepared it
  will be a great thing. Applaud for that!

  Thanks a lot.


  Fangliang He