Nicola P. Randall

A methodology for systematic mapping in environmental sciences

Systematic mapping was developed in social sciences in response to a lack of empirical data when answering questions using systematic review methods, and a need for a method to describe the literature across a broad subject of interest. Systematic mapping does not attempt to answer a specific question as do systematic reviews, but instead collates, describes and catalogues available evidence (e.g. primary, secondary, theoretical, economic) relating to a topic or question of interest. The included studies can be used to identify evidence for policy-relevant questions, knowledge gaps (to help direct future primary research) and knowledge clusters (sub-sets of evidence that may be suitable for secondary research, for example systematic review). Evidence synthesis in environmental sciences faces similar challenges to those found in social sciences. Here we describe the translation of systematic mapping methodology from social sciences for use in environmental sciences. We provide the first process-based methodology for systematic maps, describing the stages involved: establishing the review team and engaging stakeholders; setting the scope and question; setting inclusion criteria for studies; scoping stage; protocol development and publication; searching for evidence; screening evidence; coding; production of a systematic map database; critical appraisal (optional); describing and visualising the findings; report production and supporting information. We discuss the similarities and differences in methodology between systematic review and systematic mapping and provide guidance for those choosing which type of synthesis is most suitable for their requirements. Furthermore, we discuss the merits and uses of systematic mapping and make recommendations for improving this evolving methodology in environmental sciences.

The effectiveness of integrated farm management, organic farming and agri-environment schemes for conserving biodiversity in temperate Europe - A systematic map

BackgroundAgriculture is the dominant land use throughout much of Europe. Changes to farming practices have led to concerns about negative impacts on biodiversity, and current agricultural policy has an emphasis towards conservation. The objective of this study was to investigate and describe the nature and coverage of research pertaining to the effectiveness of integrated farm management, organic farming and agri-environment schemes as interventions for conserving biodiversity in temperate Europe.Systematic mapping methodology was adapted from social sciences, and used to create a searchable database of relevant research.MethodsSearches were made of 10 electronic databases containing peer reviewed journals, PhD theses, conference proceedings and organisational reports. Web searches for relevant research were also made. The title and abstracts of results were examined for relevance. Studies were included when published in English, when an intervention was applied to increase biodiversity or species diversity on farmland, and where there was a measured effect on study organism(s). Correlative and manipulative studies from temperate Europe were included. The research was incorporated into a searchable database (systematic map) and key wording used to describe, categorise and code studies.ResultsThe searches identified 83,590 records. Following removal of duplicates and the application of inclusion criteria, 743 references were coded for the final systematic map database. Most of the studies reported were from Western Europe, particularly from the UK. Invertebrates were the most commonly studied organism followed by plants and birds, and field margins were the most commonly studied biotope.ConclusionsThe systematic map describes the scope of research on the topic. It can be used to inform future primary research, or research synthesis and evaluation methods such as systematic review. Areas for which there appear to be evidence gaps, and so may have potential for further primary research, are highlighted. They include the effectiveness of agri-environment options under different farming systems and in providing for amphibians and reptiles. Implications for the development of future systematic maps are discussed, including the question of how to incorporate study quality appraisal. The development of a Collaboration for Environmental Evidence systematic mapping methods group will address some of these issues.

The size and nature of the evidence-base for smallholder farming in Africa: a systematic map

Relevant systematic reviews and impact evaluations were systematically sought and described in order to assess the size and nature of the evidence-base about the effectiveness of interventions for smallholder farmers in Africa. A total of 21 relevant systematic reviews and 415 reports of impact evaluations were identified. This paper describes this African evidence-base in terms of the interventions and outcomes assessed, and the geographical spread of the primary research across the continent. Gaps in the evidence-base are identified and recommendations made for future research.

How effective are on -farm mitigation measures for delivering an improved water environment? A systematic map

BackgroundAgricultural activities are estimated to contribute 70% of nitrates, 28% of phosphates and 76% of sediments measured in UK rivers. Catchments dominated by agriculture also have elevated levels of pesticides and bacterial pathogens. European member states have a policy commitment to tackle this pollution through the water framework directive. Here we report on the results of a systematic map to investigate and describe the nature and coverage of research pertaining to the effectiveness of 6 on-farm mitigation measures, slurry storage, cover/catch crops, woodland creation; controlled trafficking, subsoiling and vegetated buffer strips for delivering an improved water environment in terms of a reduction in nitrogen (N), phosphorus (P), sediment, pesticides and faecal indicator organisms (FIOs) or pathogens from faecal material.MethodsResearch evidence for the effectiveness of the 6 on-farm mitigation measures for delivering an improved water environment (as detailed above) was collated using English language search terms for temperate farming systems in Europe, Canada, New Zealand and northern states of the United States of America. Searches for literature were made from online publication databases, search engines, specialist websites and bibliographies of topic specific reviews. Recognised experts, authors and practitioners were also contacted to identify unpublished literature. Articles were screened for relevance at title, abstract and full text using predefined inclusion criteria set out in an a priori published protocol. All relevant articles were mapped in a searchable database using pre-defined coding and critically appraised for relevance and reliability. Articles reporting the same study were removed. All full text studies without confounding factors were identified and coded for in a separate searchable database.ResultsA total of 718 articles were included in the database. Buffer strips were the most commonly studied intervention followed by cover crops and slurry storage. Little evidence was found for woodland creation and sub-soiling. No studies were found for controlled trafficking on grassland. Nitrogen was most frequently measured, followed by P, sediment, pesticides and FIOs or pathogens from faecal material.ConclusionsThe majority of the evidence collated in this map investigated the effectiveness of buffer strips and cover crops for improving water quality. This evidence was predominantly focussed on reducing N pollution. An evidence gap exists for the impact of cover/catch crops in reducing leaching of pesticides, FIOs and pathogens, and for organic forms of N and P. There was limited research investigating the effectiveness of buffer strips for reducing leaching of organic forms of N or P, or for pesticides that are currently authorised for use/commonly used in UK agriculture. Further, long term studies across different seasons with controls, pre and post water quality measurements and multiple sampling points from both field and rivers would improve the evidence base. Evidence gaps exist for woodland creation, subsoiling and controlled trafficking on grassland.

The multifunctional roles of vegetated strips around and within agricultural fields. A systematic map protocol

BackgroundAgriculture and agricultural intensification can have significant negative impacts on the environment, including nutrient and pesticide leaching, spreading of pathogens, soil erosion and reduction of ecosystem services provided by terrestrial and aquatic biodiversity. The establishment and management of vegetated strips adjacent to farmed fields (including various field margins, buffer strips and hedgerows) are key mitigation measures for these negative environmental impacts and environmental managers and other stakeholders must often make decisions about how best to design and implement vegetated strips for a variety of different outcomes. However, it may be difficult to obtain relevant, accurate and summarised information on the effects of implementation and management of vegetated strips, even though a vast body of evidence exists on multipurpose vegetated strip interventions within and around fields. To improve the situation, we describe a method for assembling a database of relevant research relating to vegetated strips undertaken in boreo-temperate farming systems (arable, pasture, horticulture, orchards and viticulture), according to the primary question: What evidence exists regarding the effects of field margins on nutrients, pollutants, socioeconomics, biodiversity, and soil retention?MethodsWe will search 13 bibliographic databases, one search engine and 37 websites for stakeholder organisations using a predefined and tested search string that focuses on a comprehensive list of vegetated strip synonyms. Non-English language searches in Danish, Finnish, German, Spanish, and Swedish will also be undertaken using a web-based search engine. We will screen search results at title, abstract and full text levels, recording the number of studies deemed non-relevant (with reasons at full text). A systematic map database that displays the meta-data (i.e. descriptive summary information about settings and methods) of relevant studies will be produced following full text assessment. The systematic map database will be displayed as a web-based geographical information system (GIS). The nature and extent of the evidence base will be discussed.

How effective are slurry storage, cover or catch crops, woodland creation, controlled trafficking or break-up of compacted layers, and buffer strips as on-farm mitigation measures for delivering an improved water environment?

BackgroundAgriculture has intensified over the last 50 years resulting in increased usage of fertilizers and agrochemicals, changes in cropping practices, land drainage and increased stocking rates. In Europe, this has resulted in declines in the quality of soils and waters due to increased run off and water pollution. Fifty percent of nitrates in European rivers are derived from agricultural sources in the UK this value is as high as 70%, where agriculture also contributes to approximately 28% of phosphates and 76% of sediments recorded in rivers. Catchments dominated by agricultural land use have increased levels of pesticides and bacterial pathogens.European member states have a policy commitment to tackle water pollution through the Water Framework Directive. An analysis of the effectiveness of water pollution mitigation measures should enable decision makers and delivery agencies to better facilitate catchment planning.The aim of this systematic review is to assess the effectiveness of slurry storage, cover/catch crops, woodland creation, controlled trafficking/break-up of compacted layers and buffer strips, as on farm mitigation measures, for delivering an improved water environment.MethodsThe systematic review will consist of a searchable systematic map database for all the named interventions. Where possible, quantitative analysis will be used to assess the effectiveness of interventions.Electronic databases, the internet, and organisational websites will be searched, and stakeholders will be contacted for studies that investigate the impact of the on-farm mitigation measures on water quality. All studies found will be assessed for suitability for inclusion in the next stage. Inclusion criteria will be based on subject, intervention, comparator and outcome. The details of included studies will be incorporated into the systematic map database, and studies scored for effectiveness of intervention and study design. Where there is suitable data available, meta-analysis will be carried out to test the effectiveness of individual mitigation measures. A report will summarise the evidence, highlight any gaps in the available research, and provide recommendations for future research.

Making the Most of What We Already Know: A Three-Stage Approach to Systematic Reviewing

Background: Conducting a systematic review in social policy is a resource-intensive process in terms of time and funds. It is thus important to understand the scope of the evidence base of a topic area prior to conducting a synthesis of primary research in order to maximize these resources. One approach to conserving resources is to map out the available evidence prior to undertaking a traditional synthesis. A few examples of this approach exist in the form of gap maps, overviews of reviews, and systematic maps supported by social policy and systematic review agencies alike. Despite this growing call for alternative approaches to systematic reviews, it is still common for systematic review teams to embark on a traditional in-depth review only. Objectives: This article describes a three-stage approach to systematic reviewing that was applied to a systematic review focusing in interventions for smallholder farmers in Africa. We argue that this approach proved useful in helping us to understand the evidence base. Results: By applying preliminary steps as part of a three-stage approach, we were able to maximize the resources needed to conduct a traditional systematic review on a more focused research question. This enabled us to identify and fill real knowledge gaps, build on work that had already been done, and avoid wasting resources on areas of work that would have no useful outcome. It also facilitated meaningful engagement between the review team and our key policy stakeholders.

Intercropping flowering plants in maize systems increases pollinator diversity

Maize is a poorly competitive crop. Accordingly, soil preparation and high application rates of herbicides are required to reduce early competition with weeds. This leaves a large amount of bare ground with few flowering weeds, providing a poor farmland habitat for pollinators. The present study evaluates the effect of four different maize management regimes on pollinator diversity and community composition. Flowering plants intercropped with maize attracted pollinators, helping to support pollinator communities. Similar intercropping techniques using a grass ground cover did not increase pollinator density, demonstrating that pollinator richness, density and diversity is intrinsically linked to the presence of flowering plants. A maize system with a diverse intercrop may make it possible for pollinators to thrive; however, these systems may only be sufficiently attractive to bring pollinators in temporarily from the surrounding areas. These results show that there can be significant improvements to pollinator diversity, density and community composition as a result of modifying maize cultivation practices; however, these benefits must be balanced with yield penalties of approximately 60% to farmers.

What is the evidence on smallholder agriculture interventions in Africa

A majority of people living in poverty in rural Africa are smallholder farmers. Though the Green Revolution has improved livelihoods in Asia and Latin America, innovative farming practices have not been implemented as widely in Africa. Supporting smallholder agriculture through training, innovation and new technology has the potential to improve households’ incomes and food security, and boost rural economies.