Decline in atmospheric sulphur deposition and changes in climate are the major drivers of long-term change in grassland plant communities in Scotland.

The predicted long lag time between a decrease in atmospheric deposition and a measured response in vegetation has generally excluded the investigation of vegetation recovery from the impacts of atmospheric deposition. However, policy-makers require such evidence to assess whether policy decisions to reduce emissions will have a positive impact on habitats. Here we have shown that 40 years after the peak of SOx emissions, decreases in SOx are related to significant changes in species richness and cover in Scottish Calcareous, Mestrophic, Nardus and Wet grasslands. Using a survey of vegetation plots across Scotland, first carried out between 1958 and 1987 and resurveyed between 2012 and 2014, we test whether temporal changes in species richness and cover of bryophytes, Cyperaceae, forbs, Poaceae, and Juncaceae can be explained by changes in sulphur and nitrogen deposition, climate and/or grazing intensity, and whether these patterns differ between six grassland habitats: Acid, Calcareous, Lolium, Nardus, Mesotrophic and Wet grasslands. The results indicate that Calcareous, Mesotrophic, Nardus and Wet grasslands in Scotland are starting to recover from the UK peak of SOx deposition in the 1970's. A decline in the cover of grasses, an increase in cover of bryophytes and forbs and the development of a more diverse sward (a reversal of the impacts of increased SOx) was related to decreased SOx deposition. However there was no evidence of a recovery from SOx deposition in the Acid or Lolium grasslands. Despite a decline in NOx deposition between the two surveys we found no evidence of a reversal of the impacts of increased N deposition. The climate also changed significantly between the two surveys, becoming warmer and wetter. This change in climate was related to significant changes in both the cover and species richness of bryophytes, Cyperaceae, forbs, Poaceae and Juncaceae but the changes differed between habitats.

Impact of Management on Avian Communities in the Scottish Highlands.

The protection of biodiversity is a key national and international policy objective. While protected areas provide one approach, a major challenge lies in understanding how the conservation of biodiversity can be achieved in the context of multiple land management objectives in the wider countryside. Here we analyse metrics of bird diversity in the Scottish uplands in relation to land management types and explore how bird species composition varies in relation to land managed for grazing, hunting and conservation. Birds were surveyed on the heather moorland areas of 26 different landholdings in Scotland. The results indicate that, in relation to dominant management type, the composition of bird species varies but measures of diversity and species richness do not. Intensive management for grouse shooting affects the occurrence, absolute and relative abundance of bird species. While less intensive forms of land management appear to only affect the relative abundance of species, though extensive sheep grazing appears to have little effect on avian community composition. Therefore enhanced biodiversity at the landscape level is likely to be achieved by maintaining heterogeneity in land management among land management units. This result should be taken into account when developing policies that consider how to achieve enhanced biodiversity outside protected areas, in the context of other legitimate land-uses.

Long-term impacts of nitrogen deposition on coastal plant communities.

Nitrogen deposition has been shown to have significant impacts on a range of vegetation types resulting in eutrophication and species compositional change. Data from a re-survey of 89 coastal sites in Scotland, UK, c. 34 years after the initial survey were examined to assess the degree of change in species composition that could be accounted for by nitrogen deposition. There was an overall increase in the Ellenberg Indicator Value for nitrogen (EIV-N) of 0.15 between the surveys, with a clear shift to species characteristic of more eutrophic situations. This was most evident for Acid grassland, Fixed dune, Heath, Slack and Tall grass mire communities and despite falls in EIV-N for Improved grass, Strand and Wet grassland. The increase in EIV-N was highly correlated to the cumulative deposition between the surveys, and for sites in south-east Scotland, eutrophication impacts appear severe. Unlike other studies, there appears to have been no decline in species richness associated with nitrogen deposition, though losses of species were observed on sites with the very highest levels of SOx deposition. It appears that dune vegetation (specifically Fixed dune) shows evidence of eutrophication above 4.1 kg N ha(-1) yr(-1), or 5.92 kg N ha(-1) yr(-1) if the lower 95% confidence interval is used. Coastal vegetation appears highly sensitive to nitrogen deposition, and it is suggested that major changes could have occurred prior to the first survey in 1976.

Species composition of coastal dune vegetation in Scotland has proved resistant to climate change over a third of a century.

Climate change is expected to have an impact on plant communities as increased temperatures are expected to drive individual species' distributions polewards. The results of a revisitation study after c. 34 years of 89 coastal sites in Scotland, UK, were examined to assess the degree of shifts in species composition that could be accounted for by climate change. There was little evidence for either species retreat northwards or for plots to become more dominated by species with a more southern distribution. At a few sites where significant change occurred, the changes were accounted for by the invasion, or in one instance the removal, of woody species. Also, the vegetation types that showed the most sensitivity to change were all early successional types and changes were primarily the result of succession rather than climate-driven changes. Dune vegetation appears resistant to climate change impacts on the vegetation, either as the vegetation is inherently resistant to change, management prevents increased dominance of more southerly species or because of dispersal limitation to geographically isolated sites.

Carcass provisioning to support scavengers: evaluating a controversial nature conservation practice.

A number of scavenger species have suffered population declines across Europe. In attempts to reverse their decline, some land and wildlife managers have adopted the practice of leaving or placing out carcasses of wild or domestic herbivores to provide a source of carrion. However, this can be a controversial practice, with as yet unclear outcomes for many target species and the ecosystems they are part of. Here we bring out the key aspects of this increasingly common conservation practice illustrated using three contrasting cases studies. We show that the provision of carcasses is often motivated by a desire to benefit charismatic species or to facilitate nutrient cycling throughout an ecosystem. Evidence for the effectiveness of this practice in achieving these objectives, however, is mostly lacking, with ecologists studying "easier" species groups such as beetles and therefore not providing relevant insights. Moreover, conflicts between environmental policies that carcass provisioning is aimed at and other social and economic objectives do occur but these projects are often designed without taking into account this broader context. We conclude that expecting carcasses to simply be "good for biodiversity" may be too naïve a view. A greater knowledge of the impact of carcass provisioning and placement on ecosystems and society at large is required before it can become a more effective conservation tool at a wider scale.