This website has a searchable database of documented evidence for the effectiveness of actions to conserve a given species group or habitat, or to tackle a particular conservation issue. Each synopsis is also available as a downloadable pdf.

We gather documented evidence by systematically collecting studies from key scientific journals. We also search reports, unpublished literature and include documented evidence provided by advisory boards. We summarise the results of each study that are relevant to each action.

Only studies that have quantitatively monitored the effect of an action are included in a synopsis. Predictive modelling studies and studies looking at species distributions in areas with long-standing management histories (correlative studies) are excluded. See below for further details.

For each action, simple key messages provide a descriptive index to studies we have found that test that action.

We derive a list of actions by consulting an advisory board of 10-20 experts in the subject. They help us identify all the potential actions conservationists might take for a particular species group, habitat, or conservation issue. Actions are included regardless of whether current documented evidence suggests they are effective/ineffective or whether documented evidence is currently available. We aim to make comprehensive lists of actions, so we welcome suggestions if you find something missing.

Synopses for species groups and habitats focus on actions to benefit biodiversity. The soils synopsis focuses on actions to improve soil conditions and enhance soil biodiversity. The natural pest control synopsis examines actions to enhance ecosystem services that control crop pests and weeds. The aquaculture synopsis focuses on actions to improve the sustainability of Atlantic salmon and warm water prawn farming. The Mediterranean farmland synopsis includes evidence for the effects of interventions on six targets ecosystem services (crop production, soil, water, pest regulation, pollination and biodiversity conservation).

Lists of actions for species group or habitat are organized into categories based on the International Union for the Conservation of Nature (IUCN) classifications of direct threats and conservation actions.

The control of freshwater invasive species, Mediterranean farmland, pest control and management of captive animals synopses are pilot versions, with evidence summarised for a selected set of actions rather than the full list. We are currently summarising evidence for the control of additional invasive species and are actively seeking funding to cover additional actions for the management of captive animals.

We systematically search relevant scientific journals, usually from volume one through to a recent volume. We have now searched over 330 English language journals. We have also searched over 300 non-English language journals. 

We also systematically search report series and other 'grey literature', and include relevant documented evidence provided by our advisory boards.

The aquaculture, natural pest control and soil synopses include studies found by systematically trawling through NERC’s Open Research Archive (containing 16,410 references in August 2012). Two of our synopses used systematic mapping exercises undertaken by, or in partnership with, other institutions. Systematic mapping uses a rigorous search protocol (involving an array of specified search terms) to retrieve studies from several scientific databases.

The full list of sources used for each synopsis can be found here.

Evidence from all around the world is included in synopses.  Exceptions are farmland conservation, which only covers northern Europe (all European countries west of Russia, but not those south of France, Switzerland, Austria, Hungary and Romania), and Mediterranean farmland, which only includes studies from California and other Mediterranean ecosystems.  Any apparent bias towards evidence from some regions reflects the current biases in published research papers available to Conservation Evidence.

Study inclusion

There are two fundamental criteria for inclusion of studies on the website:

- There must have been an intervention that conservationists would do.

- Its effects must have been monitored quantitatively and documented.

More specifically our inclusion criteria are:

  1. Does the study measure the effect of an action that is or was under the control of humans, on wild taxa (including captives), habitats, or invasive/problem taxa? If yes, go to 2. If no, go to 3. 
  2. Could the action be put in place by a conservationist/decision maker to protect, manage or restore wild taxa or habitats, to reduce impacts of threats to wild taxa or habitats, or to control or mitigate the impact of the invasive/problem taxon on wild taxa or habitats? If yes, include. If no, exclude. 
  3. Does the study measure the effect of an action that is or was under the control of humans, on human behaviour that is relevant to conserving biodiversity? If yes, go to a. If no, exclude.

a) Does this study measure the effect of an action that is or was under human control on human behaviour (actual or intentional) which is likely to protect, manage or restore wild taxa or habitats, or reduce threats to wild taxa or habitats? If yes, go to b. If no, exclude.

b) Could the action be put in place by a conservationist, manager or decision maker to change human behaviour? If yes, include. If no, exclude.

We DO NOT include:

Theoretical modelling studies, as no action has been taken on the ground.

Correlative studies, i.e. studies that examine associations between biodiversity and habitat features without a clear link to a management action. Where correlative studies have strong conservation implications, they may be mentioned in the background sections for actions.

Studies solely reporting monitoring methods, species ecology, biodiversity surveys, or threats to biodiversity.

Studies with no quantitative monitoring of effects of actions including some review studies, descriptions of experiments with no results presented, or results presented qualitatively (as “success” or photographs).

Papers/reports with no additional scientific evidence including opinion pieces or papers that review literature but do not introduce any new data we have not covered already.

This website describes existing documented evidence and shows you where to find details. It will not tell you what action to take. To help you interpret and assess the quality of the evidence presented, we describe the size and design of each study in our summary paragraphs. We use particular words to describe study design, which we explain here. The strongest evidence comes from randomised, replicated, controlled trials with paired sites and before and after monitoring. 

Panels of experts have also assessed the collated evidence for each action to determine its effectiveness, the certainty of the evidence and, in most cases, whether there are negative side-effects on the group of species or habitat of concern (harms), for more information see What Works in Conservation.

The systematic map for the farmland conservation synopsis was developed by collaborators at Harper Adams University College, UK. The systematic map for the pest control synopsis was developed in partnership with collaborators at Fondation pour la Recherche sur la Biodiversité, Paris, France. 

What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

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