Scotland's Wildlife – an assessment of biodiversity in 20

Fluctuating
1. Marine fishing places pressure on marine diversity in a number of ways – by
reducing the abundance and average size of target stocks; in-turn affecting
species that depend on them for food; and physical impacts on seabed
communities. Conservation of commercial fish stocks in the sea is important both
to the economy and to the biodiversity of the seas around Scotland. Eleven key
commercial fish stocks are assessed annually, of which six were reported to be
at full reproductive capacity, i.e. not in danger of collapse, in 2007.
2. Moth abundance among 185 of the commoner species fluctuated between 1975
and 2004. Emerging evidence from the Rothamstead Insect Survey indicates
long-term declines among common moth species in Britain.
Divergent trends
1. Among marine plankton: cool water Calanus finmarchicus had declined to just
8% of its 1958 abundance by 2007; C. helgolandicus, a warmer water species,
increased to 281%; total Calanus abundance declined to 56%; decapod larvae
increased to 117%; phytoplankton abundance increased to 152%.
2. Butterfly trends were stable between 1979 and 2007. Prior to the mid-1980s,
butterfly species that are restricted to specific and often isolated habitats
decreased to 48% of their 1979 abundance, but have been stable since.
Decreased / negative trends
1. Scotland holds internationally important numbers of breeding seabirds. Against a
marked increase since 1970 in the UK, the numbers of breeding seabirds and the
numbers of chicks produced each year had been in decline since 1992, although
appeared to stabilise between 2007 and 2009.
2. The majority (84%) of 867 non-native species for which comparative records of
geographical distribution were available in 2004, showed no change. However,
14% had increased compared with 2% that decreased.
3. According to the Countryside Survey, vascular plant diversity fell by nearly 10%
between 1998 and 2007. Competitive plant species increased, as did plant
species associated with wet and with shady conditions. Species tolerant of harsh
environments (such as low nutrient soils) and those associated with open,
disturbed conditions (ruderals) decreased. Species associated with more fertile
conditions also decreased.
People and biodiversity
Among the five indicators that reflect people’s engagement with biodiversity:
- The composition of greenspace in built-up areas showed little overall change
(2007-2009);
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