Rob W Brooker

James Hutton Institute · Ecological Sciences Research

Introduction Crop mixtures can be an important part of the toolkit for maintaining crop production while addressing the climate and nature crises. However, uncertainties around some issues may prevent their uptake. Research question This study addressed several uncertainties, specifically the response of mixture yields to climate and management, a...

Plant interactions in extreme environments are often inferred from spatial associations and quantified by means of paired sampling. Yet, this method might be confounded by habitat-sharing effects. Here, we address whether paired and random sampling methods provide similar results at varying levels of environmental het-erogeneity. We quantified spat...

Modern “intensive” agriculture drives the biodiversity-climate crisis but is also central to global food security. Future farming needs management approaches that maintain (or even enhance) food production while reducing negative climate and biodiversity impacts. Intercrops could provide part of the solution, increasing biodiversity and boosting pr...

Plant interactions in extreme environments are often inferred from spatial associations and quantified by means of paired sampling. Yet, this method might be confounded by habitat-sharing effects. Here, we address whether paired and random sampling methods provide similar results at varying levels of environmental heterogeneity. We quantified spati...

Ecological Intensification (EI) is the enhancement of ecosystem services to complement or substitute for the role of anthropogenic inputs in maintaining or increasing yields. EI has potential to increase farming’s environmental sustainability, for example reducing environmentally harmful management activities while sustaining yields. EI is based up...

Interactions among plant species in extreme ecological systems are often inferred from spatial associations and quantified by means of paired sampling. Yet, this method might be confounded by habitat-sharing effects, in particular when microenvironmental heterogeneity and stress are high. Here, we address whether paired and random sampling methods...

The concept of Planetary Boundaries has sparked debate around tipping points and the limits of the Earth System for over a decade. One of the most investigated aspects is how to downscale this global concept to a country level, in order to make it operative at the scales at which decisions are taken, and policies applied. It remains unclear, howeve...

The attribution of biodiversity trends to the action of individual drivers is a first step in developing strategies to conserve, enhance and restore that diversity. One approach to that identification is to link information on species trends with information on ecological preferences that relate to the drivers. Long-term and short-term occupancy tr...

Better understanding of the mechanistic basis of plant plasticity will enhance efforts to breed crops resilient to predicted climate change. However, complexity in plasticity’s conceptualisation and measurement may hinder fruitful crossover of concepts between disciplines that would enable such advances. We argue active adaptive plasticity is parti...

Introduction Intercropping systems can be more productive than their respective monocultures and this positive net biodiversity effect is caused by complementarity and selection effects. While the complementarity effect is caused through resource partitioning or facilitation, the selection effect operates via the greater probability that a more div...

Increasing levels of dissolved organic carbon (DOC) have been detected in the last decades in water bodies of the Northern hemisphere, and climate change might fuel this rise. For drinking water reservoirs located in peatland catchments, already subjected to elevated amounts of DOC that needs to be removed, this might pose a further problem. Scotla...

Increasing biodiversity generally enhances productivity through selection and complementarity effects not only in natural, but also in agricultural, systems. However, the quest to explain why diverse cropping systems are more productive than monocultures remains a central goal in agricultural science. In a mesocosm experiment, we constructed monocu...

Plasticity is a widely used concept in plant sciences, but there is inconsistency over its interpretation and measurement. One aspect of plasticity – adaptive plasticity – may be particularly important in shaping plant fitness and reproductive success and represents the first line of a plants defence to environmental change. Here, we define adaptiv...

Species distribution models (SDMs) have been widely used to predict species ranges and their future distribution under climate change scenarios. In this study we applied Maxent, one of the most used SDMs, to project the distribution of some rare bryophyte species in Scotland in the 2050s. Most of these species are strongly linked to the blanket bog...

Intercropping, i.e., the simultaneous cultivation of different crops on the same field, has demonstrated yield advantages compared to monoculture cropping. These yield advantages have often been attributed to complementary resource use, but few studies quantified the temporal complementarity of nutrient acquisition and biomass production. Our under...

Background As agriculture has intensified, many once-common wildflowers have declined in arable landscapes, which has wide-spread implications for associated ecosystem services. Incorporation of sustainable practices, for example, growing living mulches (in-field, non-crop plant ground cover, maintained during the target crop growing season), can b...

Enhancing diversity within crop systems can have benefits including increased resource use efficiency and productivity, and increased control of weeds, pests and diseases. Some benefits are expected to operate through biodiversity-driven insurance effects, whereby enhanced diversity increases the chance that a system component can compensate for th...

- Intercropping, i.e. the simultaneous cultivation of different crops on the same field, has demonstrated yield advantages compared to monoculture cropping. These yield advantages have often been attributed to complementary resource use, but few studies quantified the temporal complementarity of nutrient acquisition and biomass production. Our unde...

We review the need for increasing agricultural sustainability, how this can in part be delivered by positive biodiversity–ecosystem function (BEF) effects, the role within these of plant–plant facilitation, and how a better understanding of this role may help to deliver sustainable crop (particularly arable) production systems. Major challenges fac...

Significance Biodiversity is driven by complex associations among species, but ecologists often look only at competitive or facilitative interactions either independently or only for few species at a time. Using a large dataset of mountain ecosystems encompassing more than 2,000 species across the globe, we analyze the prevalence and importance of...

Biological diversity depends on multiple, cooccurring ecological interactions. However, most studies focus on one interaction type at a time, leaving community ecologists unsure of how positive and negative associations among species combine to influence biodiversity patterns. Using surveys of plant populations in alpine communities worldwide, we e...

When plants compete what influences that interaction? To answer this we measured belowground competition directly, as the simultaneous capture of soil ammonium and nitrate by co‐existing herbaceous perennials, Dactylis glomerata and Plantago lanceolata, under the influence of: species identity; N uptake and biomass of focal and neighbour plants; lo...

Increasing biodiversity generally enhances productivity through selection and complementarity effects not only in natural but also in agricultural systems. However, explaining why diversity enhances productivity remains a central goal in agricultural science. In a field experiment, we constructed monocultures, 2- and 4-species mixtures from eight c...

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...

Aichi Target 13 (T13) focuses on the conservation of genetic diversity. • Major challenges in implementing T13 are that the type of genetic diversity to conserve is not clearly defined, and that key issues in genetic conservation vary across different sectors (e.g., forestry vs agriculture vs other species of socio-economic importance). • In Scotla...

There is a drive to improve the sustainability of agricultural systems including the biodiversity component. Cultivar mixtures offer yield benefits from the same land area, but the mechanisms behind this overyielding have not been completely worked out. One potential mechanism is improved competition with weeds. We use an experimental approach of v...

Few studies have explored how – within the same system – clonality and positive plant–plant interactions might interact to regulate plant community composition. Canopy‐dwelling epiphytes in species‐rich forests provide an ideal system for studying this because many epiphytic vascular plants undertake clonal growth and because vascular epiphytes col...

The Scottish Government is committed to reduce carbon emissions by 80% by 2050 (compared to a 1990–1995 baseline). Peatlands have been recognised as a key environment for the carbon balance as they sequester and store great quantities of carbon, but they also have the potential to release it. In Scotland, peatlands cover more than 20% of the surfac...

Root-derived compounds can change rates of soil organic matter decomposition (rhizosphere priming effects) through microbial production of extracellular enzymes. Such soil priming can be affected by plant identity and soil nutrient status. However, the effect of plant-plant competition on the temporal dynamics of soil organic matter turnover proces...

Understanding the contributions from the environment to society is seen as increasingly important globally. In Scotland this is currently a high priority, as policymakers begin to shift attention away from traditional wellbeing indicators such as GDP. Although alternative natural capital accounting techniques exist, and are useful for creating comm...

Background and aims Nutrient spatial heterogeneity occurs ubiquitously in soil, but its impact on plant growth and competition throughout the whole growth cycle remains unclear. We assessed the effects of different nutrient supply patterns and planting density on maize (Zea mays L.) growth rate, root competitive intensity and grain yield. Methods...

Environmental policy decisions should be based on robust indicators of changes in the environment. In Scotland these have been formalised as Ecosystem Health Indicators. Indicators work best where there is a direct link between what is measured and environmental change; changes in indices of species diversity or abundance provide alerts to environm...

Current niche models cannot explain multi-species plant coexistence in complex ecosystems. One overlooked explanatory factor is within-growing season temporal dynamism of resource capture by plants. However, the timing and rate of resource capture are themselves likely to be mediated by plant-plant competition. This study used Barley (Hordeum sp.)...

Mathematical tools for quantifying plant‐plant interactions are continuously improving, for example by attaining desirable statistical properties such as symmetry around zero (positive and negative effects have the same distribution). Standardisation is another such important property, making indices comparable between independent experiments, and...

Invasive plant impacts vary widely across introduced ranges. We tested the hypothesis that differences in the eco‐evolutionary experience of native communities with the invader correspond with the impacts of invasive species on native vegetation, with impacts increasing with ecological novelty. We compared plant species richness and composition ben...

Diverse experimental plant communities are more productive than monocultures. The increase of this biodiversity effect over time has been attributed to evolutionary selection for complementarity in mixtures. Here we show that evolutionary selection for enhanced net facilitative plant interactions occurred only in mixtures, while evolutionary select...

Please go to this address: http://arcg.is/q08iX The Natural Assets Theme of the Scottish Government's Strategic Research Programme 2016-21 is concerned with identification, quantification and valuation of Scotland’s environmental assets, biodiversity and ecosystem services. Modelling and mapping of key indicators of ecosystem services is an esse...

Background: Intensive farming affects farmland biodiversity, and some arable plants in particular. Increasing crop genetic diversity can increase crop productivity or resilience and could also benefit rare arable plants. Aims: We examined whether barley presence, sowing density and genetic diversity impacted the rare plant Valerianella rimosa and e...

Temporal dynamism of plant resource capture, and its impacts on plant-plant interactions, can have important regulatory roles in multispecies communities. For example, by modifying resource acquisition timing, plants might reduce competition and promote their coexistence. However, despite the potential wide ecological relevance of this topic, short...

Assisted colonisation, one form of species translocation, has been proposed as a tool for helping species to track suitable conditions in a changing climate. There are considerable practical challenges associated with it, including predicting where to place translocated individuals. This problem may be particularly big for small and immobile specie...

Evaluation of 'greening' measures in reform of EU Common Agricultural Policy

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...

Background Climate change is predicted to have very substantial impacts on biodiversity, in some cases driving species to extinction when they are unable to track suitable climatic conditions. This is a particular threat for alpine species, given both the strong control on them exerted by climatic conditions and the increasing isolation of alpine...

Over the last twenty years there has been increasing interest in facilitative plant-plant interactions. Research has examined the relationships between the role of plant interactions and gradients of environmental severity, the consequences of facilitation for biodiversity at a range of scales and the integration of facilitation into mainstream eco...

Climate change, land-use change, pollution and exploitation are among the main drivers of species’ population trends; however, their relative importance is much debated. We used a unique collection of over 1,000 local population time series in 22 communities across terrestrial, freshwater and marine realms within central Europe to compare the impac...

Understanding species coexistence and regulation of biodiversity are major research challenges, yet there is no consensus on the effects of diversity on diversity, including their mediation through plant–plant interactions. We examined how the diversity of recipient communities impacted on the establishment of colonising species. We ran a greenhous...

During the past 100 years, studies spanning thousands of taxa across almost all biomes have demonstrated that competition has powerful negative effects on the performance of individuals and can affect the composition of plant communities, the evolution of traits, and the functioning of whole ecosystems. In this review, we highlight new and importan...

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...

Understanding the mechanisms of community assembly may provide evidence to improve crop management, and in particular how weeds impact on crop yields. Focussing on plant functional traits and their diversity, we analysed a crop–weed interaction study with different levels of weed species and barley cultivar diversity to assess how weed species and...

Foundation species can change plant community structure by modulating important ecological processes such as community assembly , yet this topic is poorly understood. In alpine systems , cushion plants commonly act as foundation species by ameliorating local conditions. Here , we analyze diversity patterns of species ' assembly within cushions and...

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...

Food security is currently considered a major global problem. However, increasing intensity of food production in agricultural systems has driven reductions in farmland biodiversity. A major challenge is to enable biodiversity conservation whilst addressing the problem of food security. Here we describe how facilitative plant–plant interactions in...

Biodiversity regulates ecosystem functions such as productivity, and experimental studies of species mixtures have revealed selection and complementarity effects driving these responses. However, the impacts of intraspecific genotypic diversity in these studies are unknown, despite it forming a substantial part of the biodiversity. In a glasshouse...

Direct and indirect interactions among plants contribute to shape community composition through above- and belowground processes. However, we have not disentangled yet the direct and indirect soil and canopy effects of dominants on understorey species. We addressed this issue in a semi-arid system from southeast Spain dominated by the legume shrub...

Reviewed: Plant Life of the Dolomites. By Erika Pignatti and Sandro Pignatti. Heidelberg, Germany: Springer, 2014. xxxvii + 769 pp. US$ 209.00, £ 135.00, J 149.95. Also available as an e-book. ISBN 978-3-642-31042-3.

1. Key Points • This report describes an analytical procedure aimed at ranking Notifiable Features in Scotland according to the risk posed to them by climate change. • As well as discussing the results of this ranking process, it looks at potential adaptive management approaches for the most highly ranked features within that list. • Different anal...

Intercropping is a farming practice involving two or more crop species, or genotypes, growing together and coexisting for a time. On the fringes of modern intensive agriculture, intercropping is important in many subsistence or low-input/resource-limited agricultural systems. By allowing genuine yield gains without increased inputs, or greater stab...

Facilitative effects of some species on others are a major driver of biodiversity. These positive effects of a benefactor on its beneficiary can result in negative feedback effects of the beneficiary on the benefactor and reduced fitness of the benefactor. However, in contrast to the wealth of studies on facilitative effects in different environmen...

The evolutionary potential of populations is mainly determined by population size and available genetic variance. However, the adaptability of spatially structured populations may also be affected by dispersal: positively by spreading beneficial mutations across sub-populations, but negatively by moving locally adapted alleles between demes. We dev...

Facilitative interactions are defined as positive effects of one species on another, but bidirectional feedbacks may be positive, neutral, or negative. Understanding the bidirectional nature of these interactions is a fundamental prerequisite for the assessment of the potential evolutionary consequences of facilitation. In a global study combining...

Interactions among species determine local-scale diversity, but local interactions are thought to have minor effects at larger scales. However, quantitative comparisons of the importance of biotic interactions relative to other drivers are rarely made at larger scales. Using a data set spanning 78 sites and five continents, we assessed the relative...

1. Altitudinal gradients provide a useful space-for-time substitution to examine the capacity for plant competition and facilitation to mediate responses to climate change. Decomposing net interactions into their facilitative and competitive components, and quantifying the performance of plants with and without neighbours along altitudinal gradient...

In 2011 Scotland became, “The first country in the world to publish a detailed attempt to measure annual changes in its natural capital, based on an evaluation of ecosystem service potential” . The Natural Capital Asset Index (NCAI) was developed as a measure of relative change in the extent and condition of each of seven ecosystems (Broad Habitats...

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...

The Arctic region is one of the world’s last great wilderness areas where human impacts on terrestrial ecosystems are relatively light. Although species diversity is generally lower than at more southerly latitudes, the diversity of animals and plants, communities, and landforms is surprisingly rich. Patterns of biodiversity are strongly coupled wi...