Key Scottish Environment Statistics 2014

Biodiversity

Broad Habitat Change: 1990-2007^[1]

Extent of broad habitat (thousand hectares)

In order to allow for accurate reporting for the UK Biodiversity Action Plan, the UK's natural habitats are classified into a range of 'broad habitat' types. Maintaining and restoring the biodiversity of the UK is ultimately dependant on the area and quality of these areas^[2]. The habitats range from developed land, such as built-up areas and gardens, to semi-natural land, such as grasslands, bog and bracken. The Countryside Survey 2007^[3] reported the status of 19 of the 27 broad habitats occurring in Scotland. Changes in the extents of the 11 most widespread broad habitats are presented above.

Within Scotland the most important habitat by area is bog land, which accounts for nearly a quarter of Scotland's total land area. Although frequently disregarded as wasteland in the past, Scotland's bogs are now seen as a vital area of biodiversity as well a large carbon sink.

Between 1998 and 2007 the area of broadleaved woodland, improved grassland and acid grassland increased significantly.^[4] Coniferous woodland and arable and horticultural land decreased significantly over the same time period. The area of all other broad habitats showed no significant change.

The largest change over the period 1998 to 2007 was in arable and horticultural land, which decreased by nearly 84,000 hectares (13.6%). The largest increase in area of broad habitat was for acid grassland, which increased by 72,000 hectares (7.9%) between 1998 and 2007, with most of this change being concentrated in the Scottish Uplands.

Source: Countryside Survey 2007 / Metadata

Changes in Plant Species Richness: 1990-2007

Mean number of vascular^[5] plant species per 1km square^[6]

Vascular plant species diversity is one measure that can provide an indication of changes in habitat quality. Vascular plants (also referred to as the 'higher plants') often form the base of the ecosystem and a decline in the average number of species can signal a decline in habitat quality. Changes are often associated with land management and atmospheric pollution, although the effects of climate change may become evident in the future.

In the case of bog land much of the habitat contains non-vascular plant (such as mosses) and so this measure may underestimate the habitat quality.

The Countryside Survey 2007^[3] reported changes between surveys in 1998 and 2007 of 195 1km sample squares. Plant diversity, in terms of the number of vascular plant species recorded, was estimated from plots placed within each square.^[7]

Vascular plant diversity declined between 1998 and 2007 across the majority of habitats, with significant changes^[4] to plant species richness in seven broad habitats. There was a 23% decrease in plant species richness in fen, marsh and swamp, and an 18% decrease in species richness in broadleaved, mixed and yew woodland. The habitats that did not show significant changes in species richness were bracken, dwarf shrub heath and arable and horticultural.

Source: Countryside Survey 2007 / Metadata

Status of UK Biodiversity Action Plan (BAP) Habitats in Scotland: 2008

Status of UK BAP Habitats^[8]
(based on 39 UK BAP priority habitats in Scotland)

Biodiversity refers to the variety of life. The conservation and enhancement of our rich and varied natural heritage of plants and animals, habitats and ecosystems, is essential to the quality of our lives and for a sustainable future.

In 1992, the UN Convention on Biological Diversity recognised the need to protect biodiversity. The UK was one of the 150 countries to sign up to the convention, and in 1994 the UK Biodiversity Action Plan (UK BAP)^[9] was launched. The plan aims to conserve and enhance the populations of species and habitats which are considered threatened within the UK.

Between 1995 and 1999, action plans were developed for 45 habitats in the UK^[10], of which 39 occur in Scotland. As at 2008, of these 39, 15% of the habitats were increasing, 28% were considered stable and 33% were in decline.^[11] For the remainder, 23% had an unknown trend and for 1 habitat the trend was unclear.

Source: Biodiversity Action Reporting System (BARS) / Metadata

Status of UK Biodiversity Action Plan (BAP) Species in Scotland: 2008

Status of UK BAP Species^[8]
(based on 197 UK BAP priority species)

In 1994 the UK Biodiversity Action Plan (BAP)^[9] was launched. The action plan aims to conserve and enhance the populations of species and habitats that are considered threatened in the UK.

Between 1995 and 1999, action plans were developed for 391 species in the UK^[10] that had been identified as priorities. 197 of these occur in Scotland. In the 2008 assessment for Scotland, 38% of the species were increasing or stable and 21% were in decline.^[11] For the remainder of the species considered, 7% showed no clear trend, 32% had an unknown trend, 1 species^[12] (Wryneck) had been lost since the commencement of BAP in 1994, 2 had been lost pre BAP and 1 (scurvy grass) was no longer considered a true species.

The Scottish Biodiversity Strategy, first published in 2004, sets out how Scotland plans to protect biodiversity in Scotland. Following the agreement of new targets under the UN's Convention on Biological Diversity in 2010^[13] and the publication of a European Biodiversity Strategy^[14], the Scottish Biodiversity Strategy was refreshed in 2013^[15] Following the publication of the refreshed strategy a revised Scottish Biodiversity List was produced ^[16]. A formal assessment of the status of these species has not yet been undertaken.

Source: Biodiversity Action Reporting System (BARS) / Metadata

Status of Wild Bird Populations^R,[17]: 1975-2012

Index (1994 = 100)

Bird populations are relatively well studied and can provide an indication of the state of biodiversity in Scotland's habitats.

The number of wintering waterbirds rose between the mid-1980s and mid-1990s, reaching a peak in 1997. Since then there has been a steady decline, with the abundance falling 26% between 1997 and 2011. Seabird abundance has declined by 54% between 1991 and 2012. The abundance of terrestrial breeding birds has shown a long term increase of 15.5% between 1994 and 2012; however, between 2008 and 2012 the abundance of terrestrial breeding birds decreased by 10%.

Naturally occurring birds and their habitats are protected under the Wildlife and Countryside Act 1981, the Nature Conservation (Scotland) Act 2004 and the EC Birds Directive (79/409/EEC and amendments). Actions to protect and enhance bird populations and habitats are coordinated under the Scottish Biodiversity Strategy.

The Scottish Government has established a National Indicator^[18] to increase the index of abundance of terrestrial breeding birds in Scotland against a 1994 base year. This is used as a proxy measure of biodiversity, as biodiversity cannot be measured by a single indicator and birds are diverse, easy to monitor and can be quite sensitive to environmental changes.

Source: British Trust for Ornithology / Joint Nature Conservation Committee / Wildfowl and Wetlands Trust / Metadata

Catches of Wild Salmon^[19]: 1952-2013^P

Number caught (thousands)^{[20],[21],[22]}

The salmon fishing industry is a significant economic and leisure resource in rural Scotland. To protect this resource, sustainable management practices are essential. Climate change, water pollution, predation and disease may affect populations. Yearly variations in weather, timing of runs and fishing effort can also affect catch sizes. Consequently, a difference in catch does not necessarily indicate a difference in the abundance of the stock that provides the catch.

Catch sizes for the fixed engine and net & coble fisheries have fallen by over 90% since 1952. Catches rose during the 1950s and 1960s but have declined rapidly since the early 1970s. The provisional data published for 2013 indicate that 16,732 wild salmon were reported caught and retained in the fixed engine fishery; an increase from the 12,584 caught in 2012. The net and coble fishery saw an increase in the number of salmon caught and retained in 2013 to a provisional figure of 7,579, from 3,646 caught in 2012.^[23]

Since 1994, salmon that have been caught and released by anglers have been reported separately from those caught and retained. There has been a long-term reduction in the number of salmon caught and retained by the rod & line fishery, from a peak of 96,488 in 1988 to 13,629 in 2013. The number of salmon caught and released increased from 6,595 in 1994 to 53,118 in 2013. The proportion of the rod catch accounted for by catch and release has generally increased since 1994. In 2013, 80% of the annual rod catch was released compared to less than 8% in 1994. Total reported rod catch (retained and released) for 2013 is 66,387 salmon. It is the lowest reported catch since 2003, and is 74% of the previous 5-year average.^[24],[25]

Source: Marine Scotland Science / Metadata