- Systematic Review Protocol
- Open Access
Environmental impacts of farm land abandonment in high altitude/mountain regions: a systematic map of the evidence
Environmental Evidencevolume 2, Article number: 18 (2013)
Environmental impacts of farm land abandonment can be viewed as either an opportunity for ecological restoration to a state prior to agricultural establishment, or as the loss of an on-going process of land management and an associated threat to biodiversity. Whether land abandonment poses an ecological opportunity or threat depends upon the agricultural history and the presence of ecological systems that depend upon regular management for their existence. In Europe, many ecosystems have developed in the presence of agriculture and the loss of continued management resulting from land abandonment can have significant negative ecological impacts. Around 56 percent of the utilised agricultural area (UAA) of the EU is classified as ‘less-favourable areas’ and much of this is mountainous. The small-scale and extensively managed farmlands that are common in mountain areas are particularly vulnerable to marginalisation and abandonment. The work herein will form the first systematic synthesis of the evidence of impacts of farm land abandonment in mountain areas across the globe.
This review will take the form of two interrelated systematic maps, cataloguing the existing evidence across a wide range of variables such as setting, methodology, scale, measured outcomes etc. Mapping will be undertaken both at abstract-level at a coarse scale and at full text-level at a finer scale. Literature databases, organisational web sites, and search engines will be used to collate all of the available literature regarding the impacts of agricultural land abandonment. All studies investigating farmland abandonment in mountainous regions with an appropriate comparator and measuring an appropriate outcome will be included. Outcomes will be coded in a partly iterative process but will include; natural hazards (fire-/flood risk, land/mud slides), soil (fertility, erosion), water (chemistry, eutrophication, sediment load, hydrology), ecosystem functioning (biodiversity, abundance, invasive species presence), socio-economics (e.g. health, wellbeing, employment). The systematic map outputs will be in the form of searchable databases of relevant and obtainable (full text only) literature, coded by subject, methodology and study design, and internal validity.
Farm land abandonment can be simply defined as the cessation of agricultural activities on a given surface of land, yet there is no common precise definition of agricultural farmland abandonment in the literature . Farm land abandonment occurs when income or resource generation cease to be economically viable or sustainable and the possibilities of adapting via changes in farming practices have been expended . According to a study by Ramankutty and Foley , global abandonment of croplands has occurred over an estimated 1.47 million km2 between 1700 and 1992. Meanwhile, Pointereau et al.  estimate that 9.09 Mha of agricultural land have been abandoned across 20 European countries between 1990 and 2000. Data cited for France for the period 1992 and 2003 show that grassland represented 57% of abandoned agricultural land; cropland 30% and vinyards and hedges/groves each 6%. However, the lack of a standardised definition of abandoned agricultural land, and the difficulty of matching this to available datasets, means that accurate estimates of abandoned area are lacking.
Land abandonment has a number of well-studied drivers, including environmental (e.g. reductions in soil fertility), economic (e.g. market globalisation) and socio-political (e.g. rural depopulation) causes .The environmental impacts of farm land abandonment can be viewed as either an opportunity for ecological restoration to a state prior to agricultural establishment, or as the loss of an ongoing process of land management and an associated threat to biodiversity. Whether land abandonment poses an ecological opportunity or threat depends upon the agricultural history and the presence of systems that depend upon regular management for their existence. In Europe, many ecosystems have developed in the presence of agriculture and the loss of continued management resulting from land abandonment can have significant negative ecological impacts . Pointereau et al.  suggest that abandonment of intensive agriculture often results in ecological benefits for the affected parcel of land, whilst abandonment of low intensity agricultural is more likely to result in a negative ecological impact owing to the role of such agriculture in maintaining systems classified as “high nature value” (HNV). From a soci-economic perspective, the abandonment of agricultural land is usually regarded as detrimental owing to implied loss of employment and income in rural areas.
Around 56 percent of the utilised agricultural area (UAA) of the EU is classified as ‘less-favourable areas’ by the Common Agricultural Policy (CAP). According to MacDonald et al. , much of this is mountainous, and a report in 2004 identified mountainous regions as constituting 39.9 percent of the area of the 15 Member States at the time . Mountain areas, however, are difficult to define. For the purposes of examining farm land abandonment, mountainous areas are defined by their unfavourable topography, remoteness and extreme climate. Mountainous areas are typically described by elevation and/or slope, but this can vary significantly between countries. For example, Austria defines mountain areas as being above 700 m or above 500 m if slope is greater than 20 percent, whilst Spain more strictly defines them as being above 1000 m, over 20 percent slope and a 400 m elevation gain relative to surrounding land. Some definitions include low altitude areas where temperature contrasts reflect those in the high altitude Alps, such as Sweden and Finland. Other definitions use ruggedness assessed from satellite imagery e.g. .
The small-scale and extensively managed farmlands that are common in mountain areas are particularly vulnerable to marginalisation and abandonment . A report from the Cross-Compliance Network identified mountainous areas as key areas at threat from farmland abandonment . The causes of farmland abandonment in mountainous areas are expanded upon in more detail in Pointereau et al.  to include; steep slope, distance from the farm to the field, low accessibility, poor soils, land used as alpine pastures, small farms, high cultivation costs and small field size.
Resilience and adaptability in farming systems in mountain regions is limited for a number of reasons, including remoteness, climate and physical constraints, and the aversion to risk-taking, traditional cultural values and limited skill sets often held by the local population . Limitations to the adaptability of mountain regions have been compounded by the historical paucity of agricultural research in these areas and a bias towards lowland regions e.g. .
A limited review of CAB Abstracts focusing on land abandonment was published in 2007 . A systematic review is currently underway on the subject of land abandonment in the Mediterranean . A conceptual review of several case studies of land abandonment and EU policies responding to the problem for mountain areas was published in 2000 . The work herein will form the first systematic synthesis of the evidence of impacts of farm land abandonment in mountain areas across the globe. This systematic map of the literature will identify and catalogue all available evidence from a wide variety of sources, including the grey literature. Here we set out our methodology.
Objective of the review
The primary question of this systematic review will be;
What are the environmental impacts of farm land abandonment in high altitude/mountain regions?
This review will take the form of a systematic map, cataloguing the existing evidence across a wide range of variables such as setting, methodology, scale, measured outcomes etc. Mapping will be undertaken at two levels. Coarse-scale mapping will be undertaken on all identified abstracts, whilst fine-scale mapping will be undertaken on all available full texts.
The map databases that we will produce will catalogue the focus and location of relevant articles on the subject of agricultural land abandonment in high altitude/mountain regions. We anticipate that these maps will form a vital resource for researchers to identify subsets of this literature for further systematic review, and to identify knowledge gaps in the primary research.
The question has the following components:
Population: All mountainous* agricultural lands (global scope).
Comparator: Before-after land abandonment (temporal comparator), or un-abandoned nearby surrogate (spatial comparator).
Outcome: All outcomes relating to environmental and socio-economic impacts, including but not restricted to; natural hazards (fire-/flood risk, land/mud slides), soil (fertility, erosion), water (chemistry, eutrophication, sediment load, hydrology), ecosystem functioning (biodiversity, abundance, invasive species presence), socio-economics (household income, gender equity, health, wellbeing, employment).
*Due to the difficulties in defining a mountainous region and the differences in definition between institutions, we will include any studies that make reference to a study site that is mountainous (including synonyms, e.g. uplands) or that has limited accessibility (e.g. of farming machinery) due to topography (i.e. altitude or slope).
By mapping the literature at abstract AND full text levels we hope to identify significant details about the availability of certain groups of studies. Scoping has suggested that a potentially large body of research has been carried out in the Loess Hilly Plateau in China on soil erosion. Preliminary scoping suggests that many of these articles may be published in Chinese language journals with restricted access; a potentially systematic limitation to the synthesis of the entire body of available evidence. Comparisons between the two levels of maps will highlight these potential deficiencies in the full text map and will allow users of the full text map to avoid outcomes that may be particularly susceptible to such restrictions.
No language restrictions will be employed in this systematic map. However, searches will be undertaken only using English search terms, since inclusion of all languages in such a global study would be impractical. In order to identify whether evidence exists that may have been missed by this limitation, during coding we will extract author email addresses. Following full-text coding we will then invite authors to participate in a simple online survey asking several questions: (1) if they are aware of non-English language research and research that may have gone un-catalogued by databases searched herein that has been published in this topic within their country/language/research area; (2) requesting that they give examples of such studies against which the search can be tested. The results of this survey will be compared with the two maps to identify where potentially missed studies may lie. To our knowledge, such involvement of primary researchers has not previously been undertaken in CEE systematic reviews and will strengthen any conclusions made concerning knowledge gaps in the evidence base.
Scoping was undertaken in order to identify suitable relevant key terms to be included in the finalised search string. These terms include aspects of the exposure (farm land abandonment) and the population (high altitude/mountain regions) and are displayed in Table 1. Outcome terms were not included in the search string because of the size of returns based only on exposure and population terms, which was deemed to be manageable. Furthermore, the aim of the map is to document the available literature, including the forms of outcomes measured in the evidence base. Outcome documentation will therefore be an iterative process, and all relevant outcomes will be coded. No language restrictions will be put in place: automated language translation software will be used to complement the review teams’ abilities.
The search aims to include the following online databases which cover the breadth and depth of available literature on the topic:
ISI Web of Knowledge (inc. ISI Web of Science and ISI Proceedings)
Directory of Open Access Journals
Where databases cannot accept the full search strings detailed in Table 1, search strings will be modified according to the database help files. All database searches and outcomes will be recorded in a Search Record Appendix.
The following internet search engines will be used to identify relevant grey literature. The first 150 hits from each engine will be screened (based on sorting by relevance of results where possible).
Google Scholar http://scholar.google.co.uk/.
Where search engines cannot accept the full search strings detailed in Table 1, search strings will be modified according to the search engine help files. All search engine searches and outcomes will be recorded in a Search Record Appendix.
The following specialist organisations will be searched for relevant grey literature using manual searches of their websites and automatic search facilities using key terms (such as abandon*).
Centre for Ecology and Hydrology http://www.ceh.ac.uk/.
National Farmers Union http://www.nfuonline.com/home/.
Global Environment Centre http://www.gec.org.my/.
Joint Nature Conservation Committee http://jncc.defra.gov.uk/.
Macaulay Land Use Research Institute http://www.macaulay.ac.uk/.
National Soil Resources Institute http://www.cranfield.ac.uk/sas/nsri/.
Natural England http://www.naturalengland.org.uk/.
Royal Society for the Protection of Birds http://www.rspb.org.uk/.
Society for Ecological Restoration http://www.ser.org/.
Environment Agency http://www.environment-agency.gov.uk/.
PBL Netherlands http://www.pbl.nl/en/.
German Federal Ministry of Ag http://www.bmelv.de/EN/Homepage/homepage_node.html.
Thunen Institute http://www.ti.bund.de/en/.
ETH Zurich http://www.ethz.ch/index_EN.
European Environment Agency http://www.eea.europa.eu/.
EC Ag and Rural Dev site http://ec.europa.eu/agriculture/.
JRC Institute for Env Sustainability http://ies.jrc.ec.europa.eu/.
JRC Institute for Prospective Tech Studies http://ipts.jrc.ec.europa.eu/.
United Nations Environment Programme http://www.unep.org/.
Food and Agriculture Organisation http://www.fao.org/index_en.htm.
Convention on Biological Diversity http://www.cbd.int/convention/.
World Wildlife Fund http://www.wwf.org.uk.
Associations des Populations des Montagnes du Monde http://www.mountainpeople.org.
Mountain Partnership http://www.mountainpartnership.org.
The International Centre for Integrated Mountain Development http://www.icimod.org.
Where organisational website search facilities cannot accept the full search strings detailed in Table 1, search strings will be modified according to the search help files (where provided), or a small subset of key terms will be searched individually. All organisational website searches and outcomes will be recorded in a Search Record Appendix.
Search comprehensiveness assessment
The comprehensiveness of the above search strategies will be assessed in a number of ways. Firstly, key bibliographies from relevant reviews e.g.  will be compared to the search results to check that all relevant articles have been identified through searches. Secondly, search results will be compared with a list of includable studies, identified by subject experts prior to the review (see Table 2). We will post questions on social media (http://www.academia.edu, http://www.researchgate.net and http://www.linkedin.com) to alert the research community to this systematic map and to request that subject experts submit studies that they feel may not be readily accessible or catalogued by the most common academic databases. In addition, authors of unobtainable articles will be contacted by email to request the submission of other pertinent articles in addition to the unobtainable literature. These studies will be used in addition to the articles highlighted in Table 2 to test the comprehensiveness of our search strategy.
Study inclusion criteria
Study selection according to the predefined inclusion criteria detailed below will proceed according to a three stage, hierarchical process: titles, abstracts and finally full texts will be assessed against the inclusion criteria. If there is any doubt over the presence of a relevant inclusion criterion (or if information is absent) the articles will be retained for assessment at a later stage. Title- and abstract- level assessment will not assess the presence of a comparator, which is typically not explicit. Since titles and abstracts in grey literature do not conform to scientific standards, assessment will proceed immediately to full text assessment. Consistency checks will be undertaken using a subset of 100 abstracts by two reviewers independently of one another. Screening decisions will then be compared using a Kappa test of agreement . A score of greater than 0.6 indicates substantial agreement. Any disagreements will be discussed and any terms that need redefining or expansion will be adapted accordingly.
The following aspects of the systematic review question will form inclusion criteria when assessing potentially relevant literature:
Relevant population(s): Any high altitude or mountainous region, any region with restricted access due to ruggedness, any region with agricultural difficulties or limits on agricultural advancement or adaptability due to slope, altitude or ruggedness [global scope]
Types of exposure/intervention: Abandonment of agricultural land or reinstating of agricultural activity in agricultural land following abandonment
Types of comparator: Before land abandonment and/or an un-abandoned control site
Types of outcome: All outcomes, including but not restricted to; soil chemistry (including carbon and GHG flux), soil erosion, water chemistry, hydrology, natural hazards, biological diversity and abundance, presence of invasive species, socio-economics (including health, wellbeing, employment)
Types of study: Both observational and experimental field studies. Experimental field studies (i.e. simulated abandonment) must investigate continued abandonment over a period in excess of one year.
Mapping will be undertaken in two stages to produce two interrelated databases. One database will map studies using abstracts at a coarse scale (i.e. study location, population descriptor, measured outcome, study design, and comparator type).
A second database will expand on this information by extracting summary details for each study where a full text is available, producing a fine-scale. Coding of full texts will be undertaken using key words describing various aspects of study design and setting. Key variables of interest were identified through scoping activities and discussion with subject experts. Coding options within these key variables were then compiled in a partly iterative process, expanding the range of options as they were encountered during scoping. The finalised coding tool for the full text map is displayed in Table 3.
Studies may be coded with multiple keywords within each coding variable where appropriate, for example one study in multiple countries. The coding will be undertaken by one reviewer, with a subset of 10% of the coding carried out independently by a second reviewer and cross checked. Discrepancies will be discussed and coding moderated accordingly to reflect any clarification.
Critical appraisal of study internal validity
Coding will be used to describe the internal validity (IV) of each included study. This will be assessed using the following coding variables; study length, study timescale, comparator appropriateness, comparator type, replication, sources of potential bias and methodological detail. A judgment based on this critical appraisal will be made by placing each study into one of three categories; low, high, or unclear IV. For each study a short descriptive explanation for this judgement will be given for transparency.
Systematic map database
The systematic map outputs will be in the form of two databases of studies (at abstract and full text levels) that will describe the nature and location of evidence on the review topic. These databases will be easily searchable and freely accessible. The maps may form the basis for further primary research by identifying key knowledge gaps, and may also form the basis for further secondary research as a starting point for the synthesis of information in focused systematic reviews.
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The authors thank the European Commission for funding this research. We also thank Nicola Randall for advice on systematic mapping practicalities.
Source of support
This research is undertaken as part of a project funded by the European Commission’s Joint Research Centre through Service Contract Number 153172–2012 A08 GB. All statements/comments within this document belong to the authors and do not necessarily represent the views of the European Commission.
The authors declare that they have no competing interest.
NH, DS and AP conceived the review question. NH undertook pilot research. NH drafted the protocol text with support from DS and AP. All authors read and approved the final manuscript.