Agroforestry has numerous potential environmental benefits: It can improve soil structure and root differentiation, it can regulate nutrients and water in the soil, and supports grazing animals whilst enhancing their welfare by providing for example, protection from sun and wind. Additionally, agroforestry also provides benefits towards carbon sequestration, biodiversity, grazing resilience, renewable fuel, and decreased agricultural pollution.

The Loughgall site is one of six experiments in the silvopastoral UK National Network that was conceived by the Agroforestry Research Co-ordinating Group in 1985. In 1986, the Agroforestry Research UK Discussion Form (now the UK Farm Woodland Forum) began, and details of the experiments were finalised up with regional partners, including AFBI (formerly the Science Service of the Department for Agriculture for N. Ireland and Queen’s University Belfast). In 1989, Loughgall was officially established, and it became part of a number of EU funded research programmes (AGFORWARD, AGROMIX and UNDERTREES).

The experimental site at Loughgall now has a larger focus on climate change and the investigation of genetic and silvicultural pathways to preserve ash trees in different land use ecosystems.

Prior to the experiment, the land was used as pasture and the grassland was dominantly ryegrass.

 9 plots were set up; with 3 plots receiving 3 different treatments (see Site map):

 • 3 plots of silvopastoral treatment with ash trees Fraxinus excelsior (L.) set up with a density of 400 stems ha-1 and grazing sheep (12 ewes ha-1) [as indicated by red in the Site map]

• 3 woodland plots with ash set up with a density of 2500 stems ha-1 [as indicated by blue in the Site map]

• 3 permanent grassland plots with Lolium perenne/ ryegrass with grazing sheep (12 ewes ha-1) [as indicated by yellow in the Site map]

Up until 2025, fertiliser has been applied to the silvopastoral and grassland plots at 160 kg N ha-1 yr-1.

In 2004, the overall density of the silvopastoral plot was reduced to 265 stems ha-1. And in 2009 and 2023,  it was reduced again to 170 and 128 stems ha-1 respectively. The tree density in the woodland plots was reduced to 1100 and 708 stems ha-1  in 2009 and 2021 respectively.

Silvopastoral systems enriches biodiversity

As silvopasture systems mature they enhance environmental heterogeneity via changes in the ground vegetation. But how this affects associated fauna is unknown. Mcadam et al. (2007) examined invertebrate and bird species at Loughgall and the other sites in the national network experiment to see how they were affected by the developing silvopasture.  

They found that open grassland invertebrate species usually associated with high density woodland – ground beetles- were attracted to the silvopastoral systems. Spiders responded more quickly than any of the other invertebrates and had high abundance. In turn, the invertebrates attracted birds both associated with both woodland and grassland, which increased bird species diversity.

Overall, the environmental heterogeneity that silvopastoral systems create increase biodiversity.

Planting trees alongside livestock production could potentially promote soil carbon sequestration but only if left long enough

Carbon sequestration benefits soils in that the soil organic carbon (SOC) helps food production and ecosystem services: SOC stabilises the soil, regulates water infiltration, can improve nutrient supply, and makes soil less prone to erosion. However, it is unknown how silvopastoral systems can promote soil carbon sequestration.

Fornara et al. (2018) compared the quantity of SOC and the carbon stock in different soil aggregate fractions sizes (macro- and micro- aggregates) across the three land uses. They found that while the permanent grassland soils had higher SOC pools in the macro-aggregate organic fraction, in the woodland and silvopastoral soils, the SOC pools were higher in the micro- aggregate organic fraction. Additionally, they found that soil carbon stock was lower in the silvopastoral soils compared to the other treatments.

Therefore, creating silvopastoral systems by planting trees may not increase the carbon in the soil relative to grassland and woodland. But in the long-term (30 years+), it might increase the distribution of carbon within the soil to the micro-aggregate organic fractions offering potentially more stability of that carbon.

Encouraging farmers to transition towards silvopastoral systems

Despite the potential carbon sequestration benefits that silvopastoral systems provides, there are scientific, economic, legislative and social challenges that prevent farmers from adopting silvopasture (Olave et al., 2025). For example, although farmers may see silvopasture as land use option they are trying to balance their resources and the risk associated with adopting a new technique may be perceived to be too great to change practices.

Burbi and Olave (2018) offer a solution to overcome these issues by designing a decision-supporting tool that provides practical advice for farmers. This tool incorporates agro-ecological principles and best practices that increase carbon sequestration. It would provide farmers with more confidence in the evidence base, it would enable farmers to see advice tailored to the land that they manage, and it provides all the information in a user-friendly format.

The goal of creating the tool was that it should provide suitable advice that would then encourage the farming community to adopt silvopastoral systems in a way that is beneficial for them, and enables them to be supported.

Dr Rodrigo Olave

Tel: +44(0)28 9268 2484

Email: rodrigo.olave@afbini.gov.uk