50
M. E. D. POORE
species. I agree with the analysis of Dahl when he writes: “Goodall
(1952, 195413) is sceptical of giving any more fundamental definition of
the minimal area (than that of Evans and Cain). However, on inspection
of many of the species-area curves published, the flattening out of the
curve is very impressive and the situation may be easier in practice
than in theory ... . The minimal area, in spite of the theoretical difficulties involved, is a very important concept for the sociologist. The
minimal area gives some idea of the size of area t o be arialysed t o give a
fairly representative picture of a stand. The trained sociologist rapidly
gains an impression of the size of area t o choose t o give representative
pictures of the vegetation types in question, whether a certain sample
will yield all major constituents and whether a larger sample would
yield little but a few accidental species ... . It is important t o select
areas so large that the error involved by selecting areas of unequal size
is small in relation to the variance met with when different patches of
the same vegetation types are compared and when different communities are compared.”
By using techniques t o determine the “minimal area” the plant
sociologist is attempting t o set himself two standards.
(i) A criterion to judge whether his sample area falls in one community or in an ecotone or area of continuous variation. The difference
between the curves obtained in these two instances is so striking that
there is little doubt that the method is justified.
(ii) A method of obtaining the maximum information about the
stand in the most economical way.
In doing this he is not deluded into thinking that his results are
absolutely valid. Frequently after recording the “minimal area” he
adds t o the list all these species which occixr outside the sample plot
but within the stand as subjectively determined. There are always the
dangers that the minimal area will not include certain rare species, or
that the stand, as subjectively determined, will contain accidental
species; or that its limits may have been accidentally transgressed.
Anomalies of this sort generally appear during the later comparison of
lists and should, if possible, be subsequently rechecked in the field.
The validity of the delimitation of the stand can then be checked at
two points, during the determination of the minimal area and during
the subsequent comparison of descriptions.
B. DESCRIPTIVE METHODS
Once the borders of the stand have been determined, the ecologist
must choose a method of description ; and the range of possible choice is
wide -from a species list with a subjective estimate of cover, to increasingly more exact, and exacting, quantitative techniques. ‘The most
M. E. D. POORE
species. I agree with the analysis of Dahl when he writes: “Goodall
(1952, 195413) is sceptical of giving any more fundamental definition of
the minimal area (than that of Evans and Cain). However, on inspection
of many of the species-area curves published, the flattening out of the
curve is very impressive and the situation may be easier in practice
than in theory ... . The minimal area, in spite of the theoretical difficulties involved, is a very important concept for the sociologist. The
minimal area gives some idea of the size of area t o be arialysed t o give a
fairly representative picture of a stand. The trained sociologist rapidly
gains an impression of the size of area t o choose t o give representative
pictures of the vegetation types in question, whether a certain sample
will yield all major constituents and whether a larger sample would
yield little but a few accidental species ... . It is important t o select
areas so large that the error involved by selecting areas of unequal size
is small in relation to the variance met with when different patches of
the same vegetation types are compared and when different communities are compared.”
By using techniques t o determine the “minimal area” the plant
sociologist is attempting t o set himself two standards.
(i) A criterion to judge whether his sample area falls in one community or in an ecotone or area of continuous variation. The difference
between the curves obtained in these two instances is so striking that
there is little doubt that the method is justified.
(ii) A method of obtaining the maximum information about the
stand in the most economical way.
In doing this he is not deluded into thinking that his results are
absolutely valid. Frequently after recording the “minimal area” he
adds t o the list all these species which occixr outside the sample plot
but within the stand as subjectively determined. There are always the
dangers that the minimal area will not include certain rare species, or
that the stand, as subjectively determined, will contain accidental
species; or that its limits may have been accidentally transgressed.
Anomalies of this sort generally appear during the later comparison of
lists and should, if possible, be subsequently rechecked in the field.
The validity of the delimitation of the stand can then be checked at
two points, during the determination of the minimal area and during
the subsequent comparison of descriptions.
B. DESCRIPTIVE METHODS
Once the borders of the stand have been determined, the ecologist
must choose a method of description ; and the range of possible choice is
wide -from a species list with a subjective estimate of cover, to increasingly more exact, and exacting, quantitative techniques. ‘The most