East Perthshire - Botanical Society of the British Isles

Local Rarity
Status
Criteria
Locally Rare Recorded from between 1 and 3 sites in East Perth
Locally Scarce Recorded from between 4 and 15 sites in East Perth
Sites are ‘Wells’ sites, which can be defined as areas not exceeding that which can
be enclosed by a notional 1 km square. In some cases, where it is clear that sites
less than 1 km apart are in different management units, they are treated as separate
sites.
When the IUCN-based Red Data List was published in 2005 many species appeared
in it that had not been thought to be of particular interest before and were therefore
not recorded more precisely than to quadrant level. These included, for example,
many agricultural weeds that had been adversely affected by the intensification of
farming methods. Conversely many montane species that had previously received
the highest designation by virtue of their rarity were now judged to be at low risk and
were downgraded, sometimes even to being plants of Least Concern.
The present Register is a hybrid of the earlier and the later designation systems, as
both are thought to be important ways of defining the status and well-being of our
plants. This results in a variety of ways in which grid references are presented in the
tables. Where possible a 6-figure grid reference is shown. Very often this is not
possible but accuracy can be shown to 1 km, 2 km or 5km level. Kobresia
simpliciuscula (False Sedge), for example, is a Nationally Rare species that has
always been recorded in some detail, mainly through monitoring of its populations by
SNH. Of its 19 sites listed, 17 are 6-figure grid references and the remaining 2 are 1
km squares. Viola tricolor (Wild Pansy), on the other hand, is mainly an arable weed
that has only recently come to botanists’ notice as a plant to record accurately. It is a
Near-threatened species in the Red List, which has a similar number of sites in the
vice-county as Kobresia: 21. Of these, however, 6 are to 5km level only and only
12 are 6-figure grid references – the rest being something in between.
Certain more vulnerable species are shown at tetrad or 1 km level only.
The poor resolution of records in some species is also a product of the present
attempt to show local rarity and scarcity. A plant that is very common and not
designated in any way may yet have few sites in the vice-county. These may not
have attracted much notice in the past and were simply recorded at 5 km level along
with all the locally commoner species. Veronica agrestis (Green Field-speedwell), for
example, has 7 sites in the Register, of which 6 are to 5 km level only.
Many older records that do have 6-figure grid-references have had them allocated
later. This is especially true in the case of SNH records digitised by contract staff in
order to supply them to the Biological Records Centre and to the BSBI. Many of
these grid references are generic in nature, identifying the area of recording but not
the precise site. It is not always possible to know to which of the records this
treatment applies. The data presented are still a good indication of a plant’s status
and distribution, however, and will be refined over time.
6 SPECIES SELECTION
The register contains 288 species, including one stonewort (Charophyte). Although
more closely allied with the algae than with vascular plants stoneworts appear
superficially similar to vascular plants and are treated as ‘honorary’ ones by the BSBI
for recording purposes.
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