Sonja Kay

Agroforestry systems (AFS), which integrate trees into agricultural landscapes, offer a promising strategy for climate change mitigation and biodiversity restoration. The trees can access additional resources, improving soil functions and contributing to soil regeneration through increased organic matter inputs. However, evidence is scattered and thus hindering unified global quantification of impacts. Here, we present the first bias‐adjusted global quantitative synthesis of agroforestry effects on distinct soil and water attributes, drawing on 1590 primary studies summarized in 26 meta‐analyses. We evaluated each meta‐analysis against 16 standardized quality criteria. Less than half of the meta‐analyses met > 75% of these criteria, while most did not weigh effect‐sizes or assess heterogeneity and publication bias. We quantified primary studies overlap, finding an overall redundancy of 18% across all soil parameters, most of which arise from studies reporting on soil carbon. Accounting for meta‐analysis quality and bias, AFS tend to increase soil organic carbon by 20%, improve chemical soil quality by 59%, physical soil quality by 22%, and enhance water regulation by 71%. Biological soil quality (86%), nutrient leaching reduction (67%), and erosion control (6%) also benefit from AFS, though with higher heterogeneity. Evidence is extensive for soil organic carbon and chemical properties (73% of studies), whereas it remains limited for AFS effects on biological (< 12%), physical (< 19%), and water‐regulation traits (< 27%). 58% of meta‐analyses report no details at all on system characteristics, such as stand age, species diversity, or tree density, limiting the identification of AFS management practices that maximize soil health attributes and highlight the need for standardized definitions of agroforestry and consistent sampling protocols. By systematically evaluating meta‐analysis quality and study overlap, this synthesis provides a robust framework to distinguish reliable from uncertain outcomes and demonstrates the capacity of agroforestry to deliver multifunctional benefits, particularly regarding soil health.

The world’s growing population raises concerns about future food security. At the same time, environmental challenges such as climate change, biodiversity loss, and the depletion of natural resources must be addressed, calling for a transformation of agriculture. This need is exacerbated by the limited availability of land suitable for arable farming. In this study, we examined the potential of agricultural land for arable farming and grassland use in Switzerland, under the premise that agricultural land use should align with the biophysical and environmental capacity of each location. In an iterative co-design process with scientists and public authorities, we elaborated three scenarios for agricultural transformation, which progressively incorporated (i) biophysical constraints (soil, climate, and topography) and (ii) environmental constraints (soil loss and eutrophication due to risk of erosion), as well as (iii) greenhouse gas emissions from drained organic soils. Our results show that the allocation of 40% arable land and 60% grassland in the most restrictive scenario closely resembles the current distribution (46% and 54%), respectively. However, the scenarios also revealed significant spatial shifts between arable land and grassland at the local level: only two-thirds of today’s arable land areas match their natural site conditions. Evidence from this study underscores the critical importance of site-adapted transitions of agricultural land use and the need for site-adapted management alternatives for farmland presently assigned to inadequate land use. Overall, this research provides a novel contribution by allowing the identification of hotspot areas for agricultural transformation at the local scale. We show that these site-specific land use analyses are essential for guiding effective land use planning and policy advice that strengthen the integrity of environmental performance and agricultural productivity, and support the development of targeted and sustainable land use strategies.

Biodiversity, particularly insects, faces considerable threats in intensively managed agricultural landscapes. Agroforestry systems (AFS), which integrate woody elements into agricultural land, can enhance biodiversity. This study aims to identify management factors influencing orthopteran richness and abundance in AFS. Additionally, it evaluates the utility of passive acoustic monitoring (PAM) for orthopteran detection by comparing it to field monitoring. Orthopteran monitoring was conducted at 20 silvoarable AFS in western Switzerland. Orthopteran richness was recorded using transects and PAM, while abundance was obtained only from transects. Both methods yielded similar species numbers. Daytime PAM detected cryptic or low-abundance species missed by daytime transects but failed to record one non-stridulating and some nocturnal species. Consequently, data from both methods were combined to provide a more comprehensive analysis of factors influencing orthopteran richness. The analysis revealed that increasing plant species diversity within the understory vegetation strips (UVS) had a positive, though not statistically significant, effect on orthopteran species richness. Furthermore, a non-significant reduction trend in orthopteran abundance was observed in conventionally managed agroforestry systems compared to organically managed ones. Implications for insect conservation: Our study shows that PAM can effectively monitor orthopteran richness in AFS. By increasing plant diversity in UVS and through organic management, farmers can enhance orthopteran richness and abundance in AFS and support biodiversity conservation.

Agroforestry can help to conserve biodiversity and enhance multiple ecosystem services such as carbon sequestration, microclimate regulation and nutrient cycling. However, in land planning and biodiversity certification schemes it remains difficult to quantify the effect of agroforestry on biodiversity across time and space. Here we combine insights from a second‐order meta‐analysis, a stakeholder questionnaire, and a review of biodiversity assessment tools to establish a route towards more accurate estimates of agroforestry effects on biodiversity. Via a synthesis of cross‐taxa meta‐analyses, we evaluated the impact of agroforestry and landscape structure on biodiversity. Complementing the literature evidence, we performed a stakeholder questionnaire to determine the perceptions and preferences of stakeholders with regards to biodiversity. The meta‐analyses synthesis indicates predominantly positive or no effects of agroforestry practices on biodiversity, albeit with contextual nuances such as landscape structure and system design. The questionnaire revealed stakeholders' recognition of biodiversity's pivotal role in agroecosystems and a willingness to support methods to assess the effects of agroforestry on biodiversity. There was a preference for user‐friendly, web‐based tools that integrated mapping features and checklists tailored to diverse agroforestry types. Finally, we evaluated 73 existing biodiversity tools in terms of their capability of incorporating agroforestry components. The tools' review revealed limitations in terms of their specificity, accessibility or capacity to encompass multifaceted agroforestry designs. Practical implication. Our three‐faceted approach provided comprehensive insights about the building blocks required to develop an evidence‐based and user‐friendly tool for predicting the effects of agroforestry on biodiversity. Specifically, our interdisciplinary synthesis underscores the potential of agroforestry in promoting biodiversity while emphasizing the need for an evidence‐based, user‐centric tool to effectively assess biodiversity within agroforestry systems, accounting for landscape context and system design. Such a tool should be constructed with input data for different agroforestry types, across taxa and updateable when knowledge gaps are filled.

Selecting the right tree species is a crucial step in designing sustainable and effective agroforestry systems. To support this process, several decision support systems (DSS) have been developed in various countries to help farmers and advisors choose appropriate species. However, these tools are often limited in reach—typically used only within the country where they were created—and tend to focus on different aspects of adaptation to local conditions or achieving specific farming objectives. In this context, we introduce a new framework for agroforestry tree species selection. Its goals are twofold: (i) to compile and organize the knowledge embedded in existing tree selection tools, and (ii) to offer an intuitive, user-friendly graphical interface—AgroforesTreeAdvice. This tool allows users to input local parameters such as soil type, climate, biotic factors, and farm-level or socio-economic constraints, alongside production goals (e.g., timber, fruits) and ecosystem service objectives (e.g., soil conservation, carbon storage). The unified system successfully integrates eight existing agroforestry DSS, improving their (i) findability by centralizing them in one location, (ii) accessibility through a standardized and user-friendly interface, (iii) interoperability by enabling API-based queries across all tools, and (iv) reusability for future DSS development. Finally, we present early user feedback from pilot deployments in three countries, highlighting the tool’s benefits and outlining next steps toward further harmonization of agroforestry databases.

Despite its potential for fostering farm sustainability, the adoption of agroforestry faces context-dependent challenges, among which the (perceived) shortage of decision-supporting tools and barriers hindering the assessment of economic, environmental, and social benefits. The process of digitalization offers significant opportunities to enhance sustainability, but it remains crucial to foster a human-centric, fair, and sustainable approach. In the context of the DigitAF Horizon Europe project, we present the results of a multi-stakeholder questionnaire aimed at understanding the perceptions of stakeholders regarding agroforestry and digitalization, as well as the needs of these stakeholders for a successful implementation of this agricultural practice. In the questionnaire, there was a specific focus on the need for and the conditions for the use of digital tools and models, such as generalized digital tools, applications and mapping, climate and weather forecasting and recording, farm management and decision support, and agroforestry and environmental tools. The purpose of this survey was to provide insights to inform agroforestry actors and to foster collaborative initiatives that enhance the potential of digital tools to support the design, implementation, and maintenance of effective and sustainable agroforestry in the European context. Our questionnaire was completed by stakeholders from seven European countries, including farmers, academics, policy actors, farm advisors, and actors in the value chain with an interest in agroforestry. Stakeholders from six living labs, representing Czechia, Finland, Germany, Italy, the Netherlands, and the UK, were involved in the appraisal, along with a multi-stakeholder group from Belgium. Respondents used data and digital tools for various purposes in farming systems and were interested in their potential to improve agroforestry including animal, tree, and crop performance, management guidance, system design, and tree species selection. Our survey revealed that the perceived usefulness of digital tools for agroforestry was substantially higher than stakeholders' awareness of existing tools, indicating a need for better promotion and development of user-friendly, accessible solutions. Additionally, significant obstacles to agroforestry adoption, such as large up-front investments, administrative burdens, and fear of reduced CAP support, were identified, emphasizing the necessity for targeted support and policy improvements. Moving forward, efforts should focus on developing targeted solutions to promote agroforestry according to stakeholder perception, and user-friendly digital tools tailored to the needs and preferences expressed by stakeholders, while also increasing knowledge sharing and capacity building among practitioners and researchers.