|It is important that the vegetation surrounding each trap is
recorded in a manner which allows distance weighted abundance to
be calculated for each plant taxon. It is recommended that this
is done in two stages, one, in the field and the second using
digitised maps, air photos or forest |Pollen deposited in the
traps has its origin in sources which may be at a whole range of
distances. However, modelling has demonstrated that the pollen
source area can be divided into two, the relevant source area
(within which different mosaics of vegetation communities are
separately reflected in the pollen assemblage) and the area
beyond this, from which the pollen signal is homogenous
(whatever the mosaic of vegetation communities). This latter can
be classed as background pollen (Sugita 1994, Davis 2000). For
this reason it is necessary to map vegetation out to several
hundred metres (even kilometres) from the trap but the degree of
detail of the mapping needs to be highest closest to the trap.
|We suggest three scale