Take-Home Problem:

Tropical rain forests have up to 300 species of trees per hectare, which
leads to difficulties when studying processes which occur at the
community level.  To gain insight into species responses, a sample of
seeds were selected from a suite of eight species selected to represent
the range of regeneration types which occur in this community. This
representative community was then placed in experimental plots
manipulated to mimic the natural variation in light conditions found in
rain forests.  Mammals were excluded from one half of each plot in order
to assess their effects on the regeneration of rain forest trees.  Six
seeds of each type were planted and an indicator of whether they
germinated and survived was recorded. The two questions of specific
interest are:   

<NL>
<li>  Are species different in their probabilities of survival  across the
environmental mosaic of the forest?  <P>

<li> Are there interactions that influence survival probabilities? <P> 
</NL>

Variables:
<UL>
<LI> SURV:  Survival -- {No = 0, Yes = 1} of seedling.  Indicator of 
whether there was a seedling present at the end of the observation 
period. 

<LI> GAP:  {0, 1}  Indicator for understory versus clearing

<LI> CAGE  {0, 1} (0 = Absent, 1 = Present}  
      Enclosure to prevent mammals from eating the seeds

<LI> LITTER:  (different levels = 0,1,2,i)
<LI> SPECIES: 8 species names below, with additional information:

<PRE>
Name       Size Cotyledon type
Ardisia       3 H     
C. biflora    7 H     
Gouania       1 E
Hirtella      8 H
Inga          4 H 
Maclura       2 E
C. racemosa   6 H
Strychnos     5 E
</PRE>
Size is ordered from 1 =  smallest to 8 =  largest, the cotyledon type means,   E =
Epigeal - cotyledons, H=Hypogeal - food reserves in seed.  Epigeal
species rely on the cotyledons for photosynthesis and production of
energy to become estabished. Seed size tends to be small, with little
reserves in the seeds.  Hypogeal species tend to have larger seeds,
and can rely on reserves in the seed to produce energy, thus if 
initial leaves are lost to predators, there may still be additional
reserves that can be used to produce additional leaves.  Larger seeds,
however, may be easier to spot by predators.
<LI> LIGHT  measure of light levels at the forest floor
</UL>

The data set includes columns in the following order: 
<PRE>
plot number
subplot number within the plot
species
indiv (seeding number within plot/subplot)
surv 
germ (indicator for germination)
estab (intermediate measure of survival | germination)
light 
litter 
cage 
gap
</PRE>