4,8 and 2 using the seasonal botanical variations 
or the seasonal spectral variations. 
4 DISCUSSION AND CONCLUSION 
The classification of grasslands using seasonal bota 
nical and spectral data must be developped according 
to the following organigram given in Figiire 4. 
Phytosociological releves 
PltLftoAoCsLoloqZcaZ tizlzvzA 
anatyAiA modoJL 
Agro-ecoloqical units 
definition 
Spectral behaviour in 
red and near infra-red. 
SzaAonaZ Apzztn.aZ bzka- 
vZqua modzZ. 
I 
Spectral and botanical classification 
of grasslands. 
Figure 4 .Orqanigram of botanical and spectral 
classification of grasslands. 
It is necessary to describe phytosociological rele 
vés and classify them according to sigmatist method. 
Once this step acheived, the more abundant species 
are selected. They enable to define and describe 
the agro-ecological units. 
Phytosociological units my be converted in agro- 
ecological units, but reverse is impossible as there 
has been a loss of informtion meanwhile. 
The agro-ecologiacl units are characterized by spec 
tral behaviour, particularly in red and near infra 
red wavelengths. Once their spectral behaviour deter 
mined, it is possible to cluster any new relevé or 
spectral set of data to one or another agro-ecologi 
cal unit. 
On the contrary it is not possible to define first 
a spectral behaviour and then try to create agro 
nomical units as the worse agronomical value.units, 
on very dry or on muddy soils show spectral beha 
viour similarity and are difficult to separate. 
It is the first time that a combined botanical and 
spectral classification is tempted. It has been ela 
borated in order to use reflectance values measured 
in the field for green biomss evaluation, and sate 
llite data for grassland classification and survey 
over large areas. 
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