CALIBRE (Co-delivery of food and climate regulation from temperate agroforestry) is an 18 month project funded by NERC Greenhouse Gas Removal Programme.

Project Team is led by the University of Reading.

The Challenge

Agroforestry is a type of agriculture which combines trees with either arable or pastoral systems. This practice allows for simultaneous growth of trees in rows 15-40m apart to allow for conventional food production in the same field. Thus, agroforestry offers the potential to deliver carbon sequestration in tree biomass and in soils, food production and multiple other benefits such as biodiversity conservation, water and nutrient cycling and microclimate regulation.

‘Tree technology’ needed for agroforestry is already available to use on a mass scale, unlike other negative emission technologies (NET) that require further research and development. Given the urgent need for NET to be implemented before 2020 to avoid 2oC warming (Rogelij et al. 2013), agroforestry is very well-placed to play an immediate transitionary role in the transformative innovation needed to move towards a low-carbon future with multifunctional land use beyond food production in isolation.  There are significant policy and socio-economic issues that need to be addressed to unlock the potential of agroforestry within current regulatory and market environment.

Key questions

  • What is the potential for GHG removal by UK AF over the next 30-100 years? (e.g. information needed for policy makers over the period relevant for meeting existing UK climate change mitigation commitments to justify action)
  • What policy and socio-economic barriers need to be overcome to enable land owners/farmers to adopt AF systems across the UK?

Specific objectives

  1. Quantify the potential for temperate AF systems in the UK to remove GHGs from the atmosphere by 2050-2100, using a global vegetation model SGDVM though a range of scenarios involving different land use combinations (crop/pasture vs trees) and time of planting against the backdrop of changing climate. The emphasis will be on estimates of relative change in C storage within trees and soil.
  2. Evaluate both policy and farmer attitudes toward AF and identify legal and fiscal mechanisms needed to adopt this practice across (i) grassland and (ii) arable farming systems within the UK.
  3. In discussion with farmers, create detailed examples of direct and indirect GHG savings of AF systems per hectare within four different agro-climatic regions of the UK (south west/south east/north west/north east) and for different soil types.
  4. Using the AF scenarios, create business case/value chains (e.g. bioenergy feedstock) for (i) grassland and (ii) arable farming systems across the four UK agro-climatic regions. The goal is to enable policy to offer the right incentives to help farmers to make decisions at a field scale.
  5. Engage with wider academic and research user community workshops, data sharing through the Agrimetrics platform, the project web site and social media.



In absence of human habitation, nearly all land in the temperate biome would be covered by forests holding large quantities of carbon within the trees and the soils. Historically, much of these forests have been cleared to make way for agriculture, releasing most of the carbon into the atmosphere. Converting agricultural land back to forestry therefore offers significant potential for greenhouse gas removal, however in most instances would come at the cost of reduced food production. Existing land capability studies indicate that the best locations for afforestation are in some of the most productive agricultural areas, highlighting the conflict between forestry and agriculture.

Agroforestry (AF) is a well-understood land use system which purposefully integrates trees with either arable or pastoral food production. AF is not novel, its many benefits include crop diversification, improved water and nutrient cycling in agricultural landscapes, provision of habitats for biodiversity or improved productivity at landscape scale. A well-planned AF system allows for continued food production, while a small percentage of the land is dedicated to tree planting – usually in single line formations. However, the combination of modern farming methods, existing regulatory regime and the historical distinction between agriculture and forestry do not allow for wider application of this system.

This project will estimate GGR potential of AF in the UK under a combination of time (rollout of AF across the landscape) and intensity (the proportion of land dedicated to the tree component) by using the SDGVM model to investigate the competition between the agricultural and forest plant functional types. We will develop a new functional type to describe and model AF systems and to predict the change in carbon stocks in trees and in the soil when compared to current agriculture. The model will allow us to predict the amount of harvestable biomass and thus indicate the amount of bioenergy feedstock that UK landscape can generate without harming food production.

Concurrent with the modelling exercise, we will carry out a series of targeted workshops and stakeholder surveys to identify current barriers limiting adoption of AF on a wider scale. It is clear that educational, cultural and regulatory barriers stand in the way of AF in the UK, the project will identify, evaluate and put forward strategies to addressing the barriers at farm and national scales. We will develop value propositions designed to incentivise farmers and landowners to commit to AF in both arable and pasture settings.