Current and future climate change interactions with Land Degradation in the EU: Land Degradation and climate change are interconnected processes. However, there is still limited understanding of the exact interactions and feedback mechanisms between Land Degradation and climate change (European Commission 2015, IPCC (Inter-Governmental Panel on Climate Change) 2001, Intergovernmental Panel on Climate Change 2019, Odebiri et al. 2023). An example of some related knowledge gaps can be found in the following questions (Reed and Stringer 2016): Which variables play a crucial role in monitoring the interactions and feedback loops between climate change and land degradation? What role do climatic factors play in either mitigating or accelerating land degradation, and how can emerging opportunities be harnessed to achieve Land Degradation Neutrality (LDN) within the framework of a changing climate? What is the impact of Land Degradation on Climate? Furthermore, there is a strong focus on climate change on climate change impacts almost solely on agricultural crops and food production, overlooking livestock, forest farming and pests, as well as disregarding components of the food system and security (Farooq et al. 2022). As such, research is needed to assess the impacts of climate change on LD, as well as the potential of degraded land to contribute to climate change.

Historical, current and future social-economical interactions with Land Degradation within the EU: The interactions between land degradation and socio-economic aspects represent a complex and multifaceted field of study. While there has been significant research in this area, several knowledge gaps still exist, such as understanding the long-term socio-economic consequences of land degradation, the factors that enable or hinder communities in coping with land recovering from land degradation, understanding the potential socio-economic benefits of suitable land management practices and integrating and validating indigenous and local knowledge (The Economics of Land Degradation 2015, Economics of Land Degradation 2016). Addressing these knowledge gaps will contribute to a more comprehensive understanding of the intricate relationship between land degradation and socio-economic pathways, ultimately enabling more effective policies and interventions to mitigate and adapt to the impacts of land degradation.

Current and future biodiversity loss interactions with Land Degrdation in the EU: Land Degradation and biodiversity loss are interlinked processes. Despite this fact, there are several limitations in understanding the causal relationships and feedback loops between biodiversity loss and land degradation. Examples of relevant knowledge gaps can be found in the effects of climate adaptation options on soil's role as a habotat and genetic reservoir. More precisely, according to the study of Hamidov et. al., 2018 (Hamidov et al. 2018), among the 20 EU case studies that they examined regarding the impacts of climate change adaption options on soil functions, solely a few consider the impacts on soil biodiversity. The evident neglect of soil biodiversity issues in the majority of case studies contradicts the growing recognition of the crucial functional role of soil organisms in soil processes (Cluzeau et al. 2012). This represents a significant knowledge gap that requires attention in future research endeavors (Hamidov et al. 2018). Additionaly, there is a need for standarized, comprehensive approaches for measuring the compaction, diversity, and function of soil biota (Thiele et al. 2020, Saljnikov et al. 2022).

Lack of Land Degradation-related data at different scales: Without comprehensive Land Degradation data at different scales, our understanding of the causes and extent of land/soil degradation remains incomplete, making it difficult to develop targeted solutions and implement effective initiatives (Saljnikov et al. 2022, European Commission 2019a, European Commission 2020a, United Nations to Combat Desertification 2016, Lunik 2022). One relevant example that was mentioned in the study of Panagos et. al., 2020 (Panagos et al. 2020), is the uncertainty in the soil erosion by water estimates, that arises from the absence of georeferenced data that provide information on the crop type and the soil managment practices implemented in the field in an annual basis. Monitoring and assessing land and soil health, advocating for evidence-based policies, securing funding, and fostering collaboration all rely on the availability of accurate data. It is essential to prioritise data collection, digital transformation and research efforts to support R&I initiatives aimed at addressing and mitigating Land Degradation.

Limited Land Degradation mitigation strategies: There is a need for further research to optimise soil management practices, strategies and techniques that can help mitigate and prevent Land Degradation (Vanino et al. 2023). More emphasis should be placed on developing innovative and sustainable soil management practices that are suitable for different regions, scales and cases (European Commission 2020a, FAO 2015). In particular, according to Haregeweyn et. al., 2023 (Haregeweyn et al. 2023), there is a pressing demand for the establishment of systematic and validated methodologies that will enhance our comprehension and facilitate the advancement and adoption of appropriate Sustainable Land Management (SLM) practices to diverse conditions (Giger et al. 2018, Gonzalez-Roglich et al. 2019, Liniger et al. 2019). In this regard, Linger et. al., 2019 (Liniger et al. 2019), highlighted the "insufficient attention to monitoring" at the field level and identified the "involvement of land user" in SLM and monitoring tasks as ongoing challenges. Demonstrating both on- and off-site impacts, as well as assessing both monetary and non-monetary "costs and benefits of SLM" are essential to provide evidence for informed decision-making (Schwilch et al. 2014, Giger et al. 2018).

Absence of well-established and interlinked policies and legislations concerning Land Degradation and its components: Lack of well-established and/or Land Degradation-related policy frameworks lead to unclear guidelines for soil management, resulting in a lack of standardisation in R&I methodologies (European Environment Agency 2019, Guerra et al. 2016). While this can be mainly seen as a bottleneck, it can also be characterised as lack of knowledge when interlinkages between drivers affects the process of establishing clear policies. A relevant example refer to the study of Paleari, 2017 (Paleari 2017), where it was noted that despite the existence of several policies to address and regulate some soil threats, otheres, such as salinization, receive only limited consideration and lack a comprehensive framework for soil protection.

Knowledge gaps on the quantification of off-site Land Degradation effects and costs: The contemporary understanding of land degradation is marked by a significant gap in knowledge, particularly concerning the quantification of off-site effects and costs associated with Land Degradation (Saljnikov et al. 2022, Boardman et al. 2019). This refers to the impacts that extend beyond the immediate area of degradation and affect surrounding regions or ecosystems. The existing knowledge deficit in this specific aspect underscores the need for up-to-date research efforts to address and quantify these off-site effects and costs comprehensively.

Insufficient knowledge for accessing funds related to Land Degradation and soil projects and initiatives: Insufficient knowledge to navigate the administrative procedures for accessing funds related to Land Degradation and soils (European Commission 2021c, EU Soil Observatory 2019). Are Land Degradation related funds and efforts sufficient to stop it?

Land Degradation models’ limitations, uncertainties and capabilities: Despite the existence of several models and methodologies to assess the Land Degradation status or components, there is a limitation in understanding their capabilities and uncertainties due to the lack of validation data and long-term measurements (Hessel et al. 2014, Saljnikov et al. 2022, European Commission 2020a, Aouragh et al. 2023, Li et al. 2021, Prăvălie et al. 2021, Xu et al. 2023).

Land/soil health and Ecosystem Services interactions: The concepts of land/soil health and the ecosystem services provided by land/soil need to be supported by empirical evidence obtained through field and landscape indicators and measurements (Petrosillo et al. 2023). It is worth mentioning that these measurements should be region or case specific. Furthermore, ES include also cultural and aesthetic values, and thence it is important to investigate the connection between human well-being and all the variables that contribute to it. Moreover, collaborative methods are indispensable for resolving conflicts among stakeholders and gaining a comprehensive understanding of land and soil functioning and its sustainable use over time. This necessitates the development of an advanced field diagnostic system that relies on dependable on-site measurement technology, complemented by expert-driven knowledge and assessment methodologies. Enhancing the field of soil science is crucial for making strides in the effort to mitigate and reverse land degradation. Additionally, the economic valorization of ES, which is currently lacking, is a key point for their effective delivery (Kieslich and Salles 2021, Mirici 2022).

Lack of sufficient understanding of urban soils in relation to Land Degradation : As indicated in the Soil Mission Implementation Plan (European Commission 2019a), the scope of land/soil degradation knowledge predominantly revolves around agricultural soils, with limited attention given to other land uses. It is necessary to bridge this gap and enhance our capabilities for supporting and rejuvenating land and soil health, both in urban and rural areas.

Difficulties in understanding the drivers of individual and collective decisions associated with Land Degradation : Understanding the drivers behind individual and collective decisions is crucial for addressing land degradation effectively. Individual or collective decisions made by land users, such as farmers or landowners, play a significant role in shaping land management practices (Boardman and Evans 2019, European Commission 2019a, EU Soil Observatory 2019). Despite advancements in research, there are still difficulties in understanding individuals' decisions as decision-making is dynamic (it evolves over time in response to changing conditions), is represented by an inherent diversity (decision-making heterogeneity) and there is lack of data to capture the behavioural factors (EJP Soil 2018).

Lack of understanding of subsurface processes related to Land Degradation : The insufficient comprehension of subsurface processes associated with land//soil degradation underscores a notable gap in current research and data acquisition efforts. In comparison to topsoil, subsurface processes have not received a proportionate level of scrutiny. This incompatibility is further exacerbated by the fact that a predominant portion of existing Land Degradation and soil datasets (e.g. Soil Organic Carbon), as well as research projects and initiatives, predominantly concentrates on the topsoil layer (European Commission 2019a).

How to ensure land restoration is an integral part of social structures and actions at all scales? Engaging local communities and tapping into their traditional knowledge and innovations plays a vital role for achieving effective conservation endeavors (Economics of Land Degradation 2016). This princliple alligns with the Aichi Biodiversity target 8, which underscores the importance of respecting and leveraging traditional knowledge, innovations, and practices of indigeneous people while involving local communities in conservation efforts (Convention of Biological Diversity (CBD) 2014). Their active participation not only ensures that they benefit from and are rewarded for their conservation efforts but also contributes to addressing land degradation. However, the limited capacity of local communities to address technical aspects of natural resource management poses a significant constraint that undermine SLM (Economics of Land Degradation 2016). More specifically, a challenge arises when attempting to integrate land restoration into social structures that drive social actions, particularly in the context of indigenous knowledge (Santini and Miquelajauregui 2022). In this light, despite the existence of studies exploring the benefits of indigenous knowledge in enhancing land restoration, involving local communities in restoration activities does not consistently result in successful ecosystem restoration or benefits for those communities (Tellez et al. 2019). Moreover, the social aspects related to land restoration are not thoroughly explored and there is not sufficient participation from local rural communities (Wehi and Lord 2017, Reyes-García et al. 2018, Van Noordwijk et al. 2020). There is still much work to be done in identifying the factors that contribute to successful restoration efforts that also bring advantages to local communities.

How to build commons-based land governance systems? Contemplating land-based commons allows us to delve into the intricate dynamics of how individuals, communities, and humanity navigate interconnected natural and social environments (Giraud et al. 2016). From there, we can assess which organizational levels hold the greatest significance in understanding the interaction among customary, informal, and formal rules and practices. By incorporating these insights, we can craft adaptive approaches to natural resources management and delve into how territorial development strategies and organizational structures might impact the future of highly coveted land,such as arable and irrigable areas, as well as vulnerable territories like grazing and wildlife zones, forests, mountain tops, sacred sites, lakes and rivers - areas often targeted for land grabbing (International Land Coalition 2016). However, there are still existing challenges in establishing transparent and effective land governance systems (Giraud et al. 2016).

How do we shift from the current trend of intensification of agricultural production and overexploitation to land conservation? More precisely, during the last decades, the EU's rapidly expanding population has placed increasing demands on essential resources like food and fiber, necessitating a substantial boost in agricultural production. Modern agricultural technologies, such as machinery, fertilizers, and advanced irrigation, are crucial to meet this demand. However, large-scale construction and environmetal challenges like climate change also stress European resources, particularly agricultural land (F.A.O. 2015). Soil, a non-renewable resource formed over millennia, is central to food, energy, and water security, as it supports over 95% of global food production (Saljnikov et al. 2022). Yet, the pursuit of higher agricultural output through technology can accelerate soil degradation to a critical point where further advancements can't compensate for soil limitations (Saljnikov et al. 2022).

How can we support a land workers-led research on Land Degradation and how can we integrate the outputs of such endeavors? Citizen science is an untapped resource for European soil and land research. In this light, the recent years the EU has been investing in a cornucopia of actions and projects to engage citizens in soil science and support them to preserve soil health (Panagos et al. 2024). Such actions and projects refer to but are not limited to the Soil funDamentals project, the UKSO Soil Observatory, the Grow observatoy, the ECHO project, the Soil Plastics monitoring application, and the Heavy Metal City Zen project. Despite the significance and the achievements of these efforts, there is a need to better communicate soil science to the plausible citizen scientists and a need to integrate the outputs of these projects (Wadoux and McBratney 2023).

How can we overcome the challenges in land regulatory framework introduced by land ownerships? As land is not a common good.

Lack of understanding Nature Based Solutions: Not well studied yet (Dunlop et al. 2024).

Is it possible to identify sets of adaptation options that complement each other, mitigating trade-offs and fostering mutually beneficial outcomes for both climate change and land degradation (Reed and Stringer 2016)?

At what spatial scale do Land Degradation vulnerability maps offer the most valuable insights to decision-makers while maintaining a rich level of information and detail (Reed and Stringer 2016)?

What resources are required for studying Land Degradation , and how do the monitoring (action) costs compare with the costs of not monitoring (inaction) across short, medium, and long time frames (Reed and Stringer 2016)?

How do we pinpoint the thresholds, both in terms of time and space, at which Land Degradation adaptive practices and technologies may turn counterproductive, warranting discouragement of their widespread adoption (Reed and Stringer 2016)?

What is the optimal resolution and frequency of monitoring to provide decision-makers with crucial information on key variables associated with climate change and land degradation (Reed and Stringer 2016)?

How can we harmonize findings from monitoring both slow and fast Land Degradation -related variables (Reed and Stringer 2016)?

Is the concept of Land Degradation Neutrality enough to ensure healthy land and soils in the future (Mikhailova et al. 2024)?

There is insufficient awareness and recognition of the risk of arable land loss. How can we effectively convey knowledge about this risk?

How do we educate and inform the population about the value of natural resources, including soil?

How can we enhance regional planning in regards to Land Degradation ?

What are the green investments for Land Degradation? Green investments for Land Degradation will facilitate EU actions concerning climate change and will result in much quicker reactions. However, there are gaps in terms of resource allocation (how can government budget and private sector investements tackle Land Degradation?) and the strengthening of political will to face the issue.

How do we support the farmers to make the turning point towards sustainable land and soil management practices? Sometimes farmers might use management practices (e.g. ploughing) assuming that this will lead to an increase in their production. However, this is contradicting the reality as it actually decreases their production. While there is willingness to change as they can realize the current and plausible future production issues, there is a lack of knowledge on how to start changing and how to make the turning point.

How can farmers manage their animals more effectively in regards to Land Degradation ?

How can we alter the thinking-behaviour of farmers, consumers, markets and society towards Land Degradation Neutrality?

What are the solutions, awarding-motivation schemes, and policies to revive farmers’ hope?

What are the means to further educate policy makers so they can support better practices towards sustainability and Land Degradation Neutrality?

How can we tackle the existing issues in policy implementation and how can we better align all the Land Degradation related policies with each other?

How can we enhance knowledge transfer?

How do we deal with the markets? There is a need to create a balance between Land Degradation and markets/ecological economics (European Commission 2020a).

How can we sufficiently control water resources to avoid provoking issues in soils? How could the water directive be adjusted?

What is considered a sustainable treatment for land and soil?

What are the risks associated with Land Degradation and ice caps? What will happen and why?

What are the most efficient and cost-effective Land Degradation prevention and restoration measures, incorporating an assessment of trade-offs between different land uses and pedo-climatic zones?

What are the most reliable thresholds, monitoring systems and indicators to estimate soil and land degradation in the EU?