Ruth J. Mitchell

James Hutton Institute · Ecological Sciences Research

Ecological restoration, which encompasses habitat restoration and creation is essential to “bend the curve of biodiversity loss.” However, well‐intentioned actions could alter plant pest/pathogen distributions resulting in unanticipated detrimental impacts on both host plants and associated biodiversity. Awareness among practitioners of this risk i...

Obtaining accurate estimates of species presence or numbers helps inform their conservation. It allows us to assign conservation priorities and detect trends, such as how the distribution of their presence/absence or numbers respond to changes in pressures and habitat management. However, accurate estimates are challenging to obtain because, even f...

Trees outside woodlands facilitate dispersal of woodland invertebrates and may buffer against fragmentation impacts. European ash (Fraxinus excelsior) is common outside woodlands but is threatened by the fungal disease ash dieback (Hymenoscyphus fraxineus). Loss of ash trees to disease or pre-emptive felling could represent a substantial loss in co...

Non‐native plant pests and pathogens are increasing exponentially, causing extirpation of foundation species. The impact of large‐scale declines in a single host on associated biodiversity is widely documented. However, the impact of multiple host loss on biodiversity and whether these impacts are multiplicative has not been assessed. Ecological th...

Great Britain's native oaks (pedunculate oak, Quercus robur and sessile oak, Quercus petraea) are currently vulnerable to decline from a number of pests and pathogens, particularly in their southern British range. Stress created by extreme climatic events is likely to increase their susceptibility and this will vary in impact across Great Britain....

Questions Can bark characteristics be used to determine the suitability of trees to host epiphytic bryophytes and lichens or are other tree and site characteristics more important? Identification of substitute hosts is required in the face of epidemic tree deaths due to diseases that are a threat to affiliated epiphytic communities. We assess the s...

Key message Tree species differ in their functioning at the scale of an individual tree which will result in differences in ecosystem service provision. Replacement trees for diseased trees should take account of functional differences. Abstract Globally tree species composition is changing due to species loss from pests and pathogens. The impact...

Tree planting is increasingly being proposed as a strategy to combat climate change through carbon (C) sequestration in tree biomass. However, total ecosystem C storage that includes soil organic C (SOC) must be considered to determine whether planting trees for climate change mitigation results in increased C storage. We show that planting two nat...

Empirical critical loads are widely used to quantify and manage the ecological impacts of reactive nitrogen (N) deposition. Critical load values aim to identify a level of N deposition below which significant harmful effects do not occur according to present knowledge. Critical loads have been primarily based on experiments, but these are few in nu...

Soil carbon (C) pools and plant community composition are regulated by nitrogen (N) and phosphorus (P) availability. Atmospheric N deposition impacts ecosystem C storage, but the direction of response varies between systems. Phosphorus limitation may constrain C storage response to N, hence P application to increase plant productivity and thus C se...

As there is no agreed national list of species of socio-economic and/or cultural value for Scotland, a set of criteria for selecting species has been developed. These include: • Species prioritised for conservation value • Species identified as being culturally important • Species providing important ecosystem services • Game species • Species coll...

Globally there is increasing concern about the decline in the health of oak Quercus trees. The impact of a decline in oak trees on associated biodiversity, species that utilize oak trees, is unknown. Here we collate a database of all known birds, bryophytes, fungi, invertebrates, lichens and mammals that use oak (Quercus petraea and Q. robur) in th...

Oak (Quercus spp.) is declining globally due to a variety of pests, pathogens and climate change. Assessments of the impact of losing keystone species such as oak, should include the impact on associated biodiversity and ecosystem functioning, and consider mitigation options. Here, we assess the potential ecological implications of a decline in Que...

Here we summarise the main findings from recent work investigating site recovery following the removal of invasive rhododendron from Atlantic oak woodland sites across the west coast of Scotland. Published in Conservation Land Management, sister publication to British Wildlife, and not listed on ResearchGate. Good series for British conservationis...

Nitrogen (N) deposition poses a severe risk to global terrestrial ecosystems, and managing this threat is an important focus for air pollution science and policy. To understand and manage the impacts of N deposition, we need metrics which accurately reflect N deposition pressure on the environment, and are responsive to changes in both N deposition...

The potential impact of new invasive tree pests and diseases is usually quantified in economic terms. The ecological and social impacts are less often assessed. Using a comprehensive literature review we assess the potential ecological and social impact of two non-native invasive species (the box tree moth, Cydalima perspectalis and the fungus Calo...

Globally, peatlands provide an important sink of carbon in their near natural state but potentially act as a source of gaseous and dissolved carbon emission if not in good condition. There is a pressing need to remotely identify peatland sites requiring improvement and to monitor progress following restoration. A medium resolution model was develop...

Common ash (Fraxinus excelsior L.) is an important timber species that is widespread in broadleaved woodlands across Europe, where it is currently declining due to the fungal pathogen (Hymenoscyphus fraxineus (T. Kowal) Baral et al., 2014) causing ash dieback. Using the UK as our case study, we assess: (1) likely woodland composition following ash...

The boundary between productive land and hill land in Scotland has moved over time, in response to climate and also to market demand. Scotland's climate is changing, and this will mean changes for those areas of Scotland that sit on the margins of productive agriculture. [...] The potential impact of climate change on marginal land was identified b...

In alpine ecosystems, nitrogen (N) deposition has been linked to plant community composition change, including loss of bryophytes and increase of graminoids. Since bryophyte growth is stimulated by increased N availability, it has been hypothesized that loss of bryophyte cover is driven by enhanced decomposition. As bryophyte mats are a significant...

The soil seed bank plays an important role in determining what plant species emerge following the removal of monodominant invasive species. A depleted seed bank may provide a substantial barrier to site restoration, however, little is known about what changes occur in the seed bank during invasion and following clearance. This study used greenhouse...

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...

Following removal of the invasive species Rhododendron ponticum, the native understorey plant community typically fails to reestablish itself. Potential explanations for this failure include (1) lack of an appropriate native seed source; (2) inability of seed to penetrate a dense bryophyte layer; and (3) persistence of chemical “legacy effects” in...

Trees along linear features are important landscape features, and their loss threatens ecological connectivity. Until recently, trees outside of woodlands (TOWs) were largely unmapped however; the development of innovation mapping techniques provides opportunities to understand the distribution of such trees and to apply spatially explicit models t...

Background . The Procrustean residual vector (or PAM, an acronym for the alternative equivalent term Procrustean association metric) derived from Procrustes analysis can be seen as the univariate form of relationship between two or more data tables, which provides an interesting way for ecologists to place multivariate relationships as the central...

Background . The Procrustean residual vector (or PAM, an acronym for the alternative equivalent term Procrustean association metric) derived from Procrustes analysis can be seen as the univariate form of relationship between two or more data tables, which provides an interesting way for ecologists to place multivariate relationships as the central...

Analysis of changes in functional traits and functional diversity offers a means of identifying the main environmental drivers of change, the impacts of that change on community assembly and the consequence of change on ecosystem function and service delivery. Changes in key traits and functional diversity in Scottish grasslands were analysed for a...

Increased awareness of the negative impacts of invasive non-native species has led to a rapid increase in clearance programs around the world. One of the main goals of clearance is the restoration of native communities that were present pre-invasion. Little monitoring is typically carried out, however, to verify that native communities return witho...

Assessing effectiveness of international biodiversity targets requires long-term monitoring of species to identify changes in their abundance. Grasslands cover large areas of many countries, provide high levels of provisioning ecosystem services and are an important habitat for many species. While grasslands are often anthropogenic in nature, human...

A growing awareness of the destructive effects of non‐native invasive species has led to a massive increase in removal programmes around the world. However, little is generally known about what happens to sites following the removal of the invasives and the implicit assumption that the native community will return, unaided, to pre‐invasion conditio...

Ash is a widespread species which makes a substantial contribution to many landscapes. Ash trees are affected by ash dieback, a disease caused by a fungus. It is clear from the European experience of the disease that a significant number of ash trees could be lost from woodlands in the UK over the course of perhaps the next 20–30 years. The ecologi...

Wetlands are key components of upland landscapes and support a diverse and specialised biota. These habitats are subject to multiple drivers of change including pollutant deposition, climate change and grazing, which have varied over the last four decades. We used a resurvey approach to investigate vegetation change in Carex swamps and spring commu...

Forests worldwide are currently threatened by a number of non-native tree diseases. Widespread death of a tree species will have ecological impacts on species that in some way depend on that tree species to complete their life-cycle. One measure to mitigate these impacts is to establish alternative tree species to replace the threatened tree specie...

Nitrogen (N) deposition and climate are acknowledged drivers of change in biodiversity and ecosystem function at large scales. However, at a local scale, their impact on functions and community structure of organisms is filtered by drivers like habitat quality and food quality/availability. This study assesses the relative impact of large-scale fac...

Above-ground vegetation has long been acknowledged as an important driver of below-ground decomposer communities. Here we compare the relationship between the plant community and four microarthropod groups (oribatid, mesostigmatic and prostigmatic mites and Collembola) in alpine moss-sedge heath. We assess the relative importance of plant growth fo...

Atmospheric pollution by reactive nitrogen (N) can have profound effects on ecosystem functioning and biodiversity. Numerous mechanisms are involved, and response times vary among habitats and species. This complex picture can make it difficult to convey the benefits of controlling N pollution to policy developers and the public. In this study we e...

The non-native fungus Hymenoscyphus fraxineus which causes ash dieback is now established across much of Europe including the UK. The disease may potentially kill large numbers of Fraxinus excelsior (ash) trees in infected areas. Ash woods tend to be relatively rich in vascular plants and the composition of the flora might be expected to change if F...

The suitability of alternative tree species to replace species that are either threatened by pests/disease or at risk from climate change is commonly assessed by their ability to grow in a predicted future climate, their resistance to disease and their production potential. The ecological implications of a change in tree species are seldom consider...

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...

Summary The UK’s semi-natural habitats exceed their atmospheric nitrogen (N) deposition critical load ranges across much of their area, and survey data suggests there are adverse impacts of this excess N deposition. However, information from Common Standards Monitoring (CSM) of protected sites does not appear to identify N deposition as a potentia...

We developed a conceptual framework for evaluating the process of ecological restoration and applied it to 10 examples of restoration projects in the northern hemisphere. We identified three major phases, planning, implementation, and monitoring, in the restoration process. We found that evaluation occurred both within and between the three phases,...

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 re-visitation 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 from by...

Background The west coast habitats of the Uists hold concentrations of breeding waders that are exceptional in Scottish, British and wider European contexts. Observed declines in wader populations on South Uist and Benbecula since the 1980s were argued to be largely due to predation of clutches by hedgehogs, which were first introduced to the islan...

The correlation of multivariate data is a common task in investigations of soil biology and in ecology in general. Procrustes analysis and the Mantel test are two approaches that often meet this objective and are considered analogous in many situations especially when used as a statistical test to assess the statistical significance between multiva...

The criteria set out by the International Union for Conservation of Nature to identify threatened species requires information on population trends which, for priority lichen species within Scotland, is lacking. Collecting such data is problematic as there is a lack of empirical information on the performance of different sampling designs and surve...

www.snh.org.uk/pdfs/publications/commissioned_reports/562.pdf

Instructions on how to use the excel spreadsheet AshEcol

A database of ash associated biodiversity and a list of alternative trees that the associated biodiversity will use

The objectives of the research project were: • to collate information about the ecology of ash and species which use ash and how they do so; • to assess how British woodlands might change as a result of the loss of ash; • to define a range of management scenarios which might be applied as a result of ash dieback, and to assess how these might affec...

Animals can modify their environment by consumptive and physical activities such as herbivory and soil disturbance. Engineering species may create structures that long outlive them and have lasting impacts on local communities of plants and animals. Water voles, Arvicola amphibious, are rodents that visibly impact riparian plant communities by graz...

Upland heathland is an internationally important habitat but a large area in the UK has been degraded to acid grassland by intensive livestock grazing. Re-establishment of dwarf shrubs, particularly Calluna vulgaris (L.) Hull, is a key objective for restoring heathland on these sites. A replicated plot-scale experiment was set up to examine effects...

Background Understanding trends in species populations, range and habitat quality is a principle requirement for conservation evaluations. Such evaluations are vital if we are to direct conservation resources to protect species that are in most urgent need of action and for which Scotland has greatest international responsibility. Detecting species...

Aim To assess whether vegetation composition and soil chemistry explain the same or different parts of the variation in the soil microbial community (SMC). Method The above and below-ground communities and soil chemical properties were studied along a successional gradient from moorland to deciduous woodland. The SMC was assessed using PLFAs and M-...

Aim To test if there is an interactive effect between tree and understory species on the soil microbial community (SMC), community level physiological profiles (CLPP) and soil micro-fauna. Method A replicate pot experiment with five sapling tree species (Betula pendula, Betula pubescens, Sorbus aucuparia, Quercus petraea and Pinus sylvestris) and...

With the species composition and/or functioning of many ecosystems currently changing due to anthropogenic drivers it is important to understand and, ideally, predict how changes in one part of the ecosystem will affect another. Here we assess if vegetation composition or soil chemistry best predicts the soil microbial community. The above and belo...

1. Ecosystem engineering by a single species can have a cascading effect on many ecosystem processes. While the impact of above-ground ecological engineers on soil chemical properties has been studied, few studies have assessed their impact on the soil microbial community, which is largely responsible for many ecosystem functions. 2. Utilizing a l...

Questions: What is the impact on non‐target species of restoration methods to establish Calluna vulgaris on grass‐dominated moorlands? Location: A Nardus stricta ‐dominated moorland in Wales and a Molinia caerulea ‐dominated moorland in Northern England, UK. Methods: Two replicated experiments were established on grass‐dominated moorlands. The trea...

Background: The occurrence of fire is natural in many ecosystems but recently the number and frequency of fires has increased. Aim: To provide an assessment of the resilience of four habitats in the Serra de Monchique to fire and to assess the implications of changes in community composition for conservation. Methods: Plots were established in heat...

Calluna vulgaris-dominated heaths and moorlands are habitats of international conservation importance. Degradation has occurred throughout their range with Calluna typically being replaced by grass species. The cessation of grazing is often impractical and rarely results in the recovery of Calluna abundance when it is initially present at low cover...

The spatial relationship between the concentration and deposition of the major ions in precipitation and stemflow and their influence on the tissue nitrogen concentration of three epiphytic bryophytes on Quercus petraea (Matt) Liebl. and Q. robur L. was investigated at seven UK Atlantic oak woodland sites with a range of total N deposition of 55-25...

Habitat heterogeneity contributes to the maintenance of diversity, but the extent that landscape-scale rather than local-scale heterogeneity influences the diversity of soil invertebrates-species with small range sizes-is less clear. Using a Scottish habitat heterogeneity gradient we correlated Collembola and lumbricid worm species richness and abu...