Natural Heritage Trends: Scotland 2001
Distinctive Natural Heritage Settings
Chapter 9 considers trends in green space in and around settlements, places where most people live and interact frequently with the natural heritage.
Commonly accounting for as much as 20% of the urban area in Scotland, green space is integral to sustaining local biodiversity and to the quality of life in towns and cities. The extent of built-up land and transport corridor had expanded by over a third from the late-1940s to the late-1980s, but in the 1990s the rate of development appeared to have slowed. Although the number of households continued to increase during the 1990s, there was no clear evidence of that from the Countryside Survey. Between 1989 and 2000 the number of Local Nature Reserves increased from six to 34. During 1990/2000, seven out of 28 bird species in Scottish suburban gardens were reported more frequently, and ten species less frequently, than they had been in 1995/96. The extent of vacant and derelict land, around 50% of which had remained so for more than 14 years, decreased by 22% between 1993 and 1999. Over 450 school grounds natural heritage projects were supported between 1995/96 and 2000. Around 80 community-based woodland initiatives were in place by 2000. The Scottish Golf Course Wildlife Initiative had visited and provided environmental reports to around 200 (39%) golf courses between 1996 and 2000.
Chapter 10 summarises farmland trends, including increased participation in agri-environment schemes from 802 to 4491 (including the Organic Aid Scheme) between 1992/93 and 2000/01. Reductions in arable weeds between 1930-1960 and 1987-1988 indicate reduced biodiversity within arable fields. Declines between 1990 and 1998 were not statistically significant and so provide no clear evidence of change. The area of farm woodland doubled between 1991 and 2000, to represent 3.6% of the total agricultural area in 2000. Of 20 farmland bird species, 12 declined in range by more than 10% between 1968-72 and 1988-90 whilst only one increased by more than 10%. Of 13 species for which adequate abundance data are available, three showed a statistical significant decline between 1994 and 1999; the remainder showed no significant trend.
Chapter 11 considers forest and woodland trends. Following expansion of the conifer forest over recent decades, forest and woodland extended to around 17% of Scotland’s land area by 2000. Historically, neglect, overgrazing and replacement planting with exotic conifers contributed to a decline in the area and quality of Scotland’s semi-natural woodland. In a reversal of that trend, native woodland increased in area by 34% between 1984 and 1999. Natural regeneration of native woodland increased by 3,132 ha between 1995 and 2000. Changes in the range and abundance of widespread woodland bird species have generally been more favourable than for farmland birds. Between around 1970 and 1990, ten woodland species contracted in range by more than 10% and 11 expanded. In the more recent 1994-1999 survey, five out of 14 widespread woodland species showed a statistically significant increase in abundance, while one species declined.
Chapter 12 reports on trends in the uplands, where moorland, peatland and rough grassland form a mosaic of semi-natural habitats covering more than 50% of Scotland’s land area. Between 1982 and 1998 grazing pressure appears to have increased by at least 10% within about a third of the marginal and true uplands, but it also decreased equally markedly within a similar area. Between the 1970s and 1990s, the geographic range of the red grouse, the number of keepered moors in Scotland and the number of red grouse shot all fell substantially. During that time-frame also, the breeding range of nine upland bird species expanded, seven declined, and 15 showed little or no change. The number of breeding pairs of dotterel declined by 23% between 1987-88 and 1999.
Chapter 13 summarises trends in Scotland’s fresh waters of lochs and rivers. Beyond changes in fresh water extent arising from hydro-scheme development from the 1950s to the 1970s, the main changes have been in terms of water quality and in wildlife. Between 1996 and 1999, about 90% of Scotland’s rivers were of excellent or good quality. This included a small decrease (3%) in the length of rivers classified as excellent, and a corresponding increase (2%) in the length of rivers classified as good quality. Benefiting from improved water quality in Central Scotland, between 1977/79 and 1991/94 otters recolonised much of their former range.
Trends in other wildlife associated with fresh water are less favourable. The non-native American mink also increased in range and population density, and is thought at least partly responsible for reduced numbers of water vole, which declined from around 2.5 million to just over 354,000 between 1989/90 and 1996/98. Between 1986/72 and 1988/91 there was a contraction of at least 10% in the breeding range of nine bird species dependant on fresh waters, little or no change in 15, and an increase in the range of five. By 2000, 12 of the 26 native fish of Scotland had declined, the vendace had become extinct (although recently re-introduced), nine species were considered stable and four had increased. By 1998, rod-caught salmon had decreased by 6.3% and net-caught salmon by 94% compared to the 1950s. Of the six amphibians native to Scotland, the great crested newt had declined throughout its range, according to a re-survey in 1995/96 of sites with historical records. Surveys of freshwater pearl mussel sites with historical records from the 1900s showed that by 1996/99, 65% had functionally extinct populations and only about 7% were considered to be near-natural.