﻿22 
  Gleason: 
  Some 
  applications 
  of 
  the 
  quadrat 
  method 
  

  

  typical 
  of 
  the 
  association 
  as 
  a 
  whole. 
  In 
  the 
  latter 
  case, 
  and 
  in 
  all 
  

   cases 
  of 
  verbal 
  description, 
  the 
  result 
  unconsciously 
  and 
  unavoid- 
  

   ably 
  embodies 
  the 
  author's 
  idea 
  of 
  the 
  conditions, 
  rather 
  th^n 
  the 
  

   actual 
  and 
  impersonal 
  facts, 
  in 
  that 
  conspicuous 
  species 
  may 
  be 
  

   emphasized 
  although 
  possibly 
  relatively 
  unimportant, 
  while 
  

   important 
  but 
  comparatively 
  inconspicuous 
  species 
  may 
  be 
  

   neglected. 
  While 
  the 
  quadrat 
  method 
  is 
  by 
  no 
  means 
  a 
  panacea 
  

   for 
  all 
  these 
  difficulties, 
  its 
  proper 
  combination 
  with 
  verbal 
  

   description 
  and 
  photography 
  does 
  much 
  to 
  aid 
  the 
  observer 
  in 
  

   securing 
  a 
  thorough 
  knowledge 
  of 
  the 
  association 
  and 
  in 
  more 
  

   satisfactorily 
  expressing 
  its 
  structure 
  in 
  terms 
  intelligible 
  to 
  his 
  

   readers. 
  The 
  merit 
  of 
  the 
  method 
  lies 
  not 
  merely 
  in 
  the 
  actual 
  

   results 
  which 
  it 
  affords 
  but 
  also 
  in 
  the 
  deductions 
  from 
  and 
  

   application 
  of 
  these 
  results. 
  

  

  While 
  quadrats 
  may 
  be 
  of 
  any 
  chosen 
  size, 
  a 
  single 
  square 
  

   meter 
  is 
  probably 
  most 
  frequently 
  used. 
  In 
  the 
  list 
  quadrat, 
  a 
  

   simple 
  list 
  is 
  prepared 
  of 
  the 
  species 
  included 
  within 
  it. 
  In 
  the 
  

   count 
  quadrat, 
  the 
  number 
  of 
  individuals 
  of 
  each 
  species 
  is 
  also 
  

   determined. 
  Both 
  of 
  these 
  are 
  of 
  value 
  as 
  a 
  method, 
  but 
  are 
  of 
  

   little 
  use 
  In 
  expressing 
  results. 
  For 
  the 
  latter 
  purpose, 
  the 
  map 
  

   quadrat 
  is 
  by 
  far 
  the 
  most 
  useful. 
  A 
  chart 
  is 
  prepared 
  on 
  a 
  

   suitable 
  scale, 
  usually 
  i 
  to 
  lo, 
  and 
  the 
  location 
  of 
  each 
  individual 
  

   plant 
  noted 
  upon 
  it. 
  Other 
  sorts 
  of 
  quadrats 
  may 
  be 
  made 
  for 
  

  

  ma 
  

  

  various 
  works 
  by 
  Clements 
  (1904, 
  1905). 
  

  

  The 
  structure 
  of 
  a 
  vegetational 
  unit 
  depends 
  upon 
  the 
  species 
  

   represented, 
  determining 
  the 
  flora; 
  on 
  the 
  relative 
  number 
  of 
  

   individuals 
  of 
  each, 
  determining 
  by 
  their 
  form, 
  size, 
  and 
  habit 
  the 
  

   appearance 
  of 
  the 
  vegetation; 
  and 
  on 
  the 
  total 
  number 
  of 
  indi- 
  

   viduals, 
  determining 
  the 
  density 
  of 
  the 
  vegetation. 
  

  

  The 
  use 
  of 
  a 
  chosen 
  quadrat 
  in 
  representing 
  this 
  structure 
  

   depends 
  absolutely 
  on 
  the 
  theory 
  of 
  the 
  homogeneity 
  of 
  the 
  asso- 
  

   ciation, 
  which 
  in 
  turn 
  depends 
  on 
  a 
  number 
  of 
  factors 
  (Gleason, 
  

   1917, 
  p. 
  471). 
  Given 
  a 
  uniform 
  physical 
  environment, 
  the 
  mere 
  

   migration 
  of 
  some 
  species 
  over 
  the 
  whole 
  area 
  requires 
  consider- 
  

   able 
  time 
  and 
  interferes 
  mth 
  the 
  uniformity 
  until 
  it 
  is 
  accom- 
  

   plished, 
  so 
  that 
  young 
  associations 
  are 
  always 
  less 
  uniform 
  than 
  

   old 
  ones, 
  while 
  in 
  open 
  associations 
  migration 
  may 
  continue 
  for 
  a 
  

  

  