Unpacking the concept of land degradation neutrality and addressing its operation through the Rio Conventions

Land degradation neutrality: Testing the indicator in a temperate agricultural landscape

Land degradation directly affects around 25% of land globally, undermining progress on most of the UN Sustainable Development Goals (SDG), particularly target 15.3. To assess land degradation, SDG indicator 15.3.1 combines sub-indicators of productivity, soil carbon and land cover. Over 100 countries have set Land Degradation Neutrality (LDN) targets. Here, we demonstrate application of the indicator for a well-established agricultural landscape using the case study of Great Britain. We explore detection of degradation in such landscapes by: 1) transparently evaluating land cover transitions; 2) comparing assessments using global and national data; 3) identifying misleading trends; and 4) including extra sub-indicators for additional forms of degradation. Our results demonstrate significant impacts on the indicator both from the land cover transition evaluation and choice or availability of data. Critically, we identify a misleading improvement trend due to a trade-off between improvement detected by the productivity sub-indicator, and 30-year soil carbon loss trends in croplands (11% from 1978 to 2007). This carbon loss trend would not be identified without additional data from Countryside Survey (CS). Thus, without incorporating field survey data we risk overlooking the degradation of regulating and supporting ecosystem services (linked to soil carbon), in favour of signals from improving provisioning services (productivity sub-indicator). Relative importance of these services will vary between socioeconomic contexts. Including extra sub-indicators for erosion or critical load exceedance, as additional forms of degradation, produced a switch from net area improving (9%) to net area degraded (58%). CS data also identified additional degradation for soil health, including 44% arable soils exceeding bulk density thresholds and 35% of CS squares exceeding contamination thresholds for metals.

Land degradation neutrality (LDN) in Rajasthan, Western India: a combined approach of pressure-state-response model and MODIS data products

Land degradation has become a key concern worldwide due to changes in meteorological variables and human-caused activities. This study primarily focuses on the rate, impact, and pattern of land degradation in western India. In this instance, we evaluated the effectiveness of land degradation neutrality (LDN) between 2000 and 2020 using an integrative approach based on a PSR (pressure-state-response) model developed by the OECD-UNEP under the UNCCD framework. Here, we mainly used MODIS products (e.g., NDVI, PET, LULC, and NPP). Also, soil organic carbon (SOC) and climatic variables (e.g. precipitation, aridity index and soil moisture) were taken into account. These indicators were analysed using the Google Earth Engine (GEE) code editor platform, and post-processing was done through Q-GIS software. The analysed parameters indicate that the NDVI and NPP values are + 0.20 to + 0.3 and 4.27 × 109 to 7.74 × 109 kg Cm-2, respectively. However, overall precipitation and soil moisture depicted a positive trend, and the aridity index adeptly followed a negative trend. Hence, the land degradation rate has increased in the north-western region besides the Aravalli range and neutrality work in the southwest part of the study area. The overall land degradation trend is negative over the last two decades. Therefore, this study anticipates the policymakers and government bodies to understand about land degradation of western India.

Do adaptive policy adjustments deliver ecosystem-agriculture-economy co-benefits in land degradation neutrality efforts? Evidence from southeast coast of China

Ecosystem restoration projects (ERPs) facilitate land degradation neutrality (LDN). However, the response dynamics and interactions of sectors within ecosystem-agriculture-economy nexus (EAEN) have not been sufficiently explored, which constrains the coordinated efficacy of LDN efforts. To bridge the knowledge gaps, the present study selected a land restoration hotspot in southeastern China as a case to investigate the simultaneous responses of the EAEN sectors to ERPs from a novel social-ecological system (SES)-based LDN perspective. Various biophysical models and Manne-Kendall trend test as well as multi-source spatially explicit data and socioeconomic statistics were applied to quantify the co-evolution of natural and socioeconomic indicators. ERPs converting cropland to woodland and grassland promoted vegetation restoration, reduced soil erosion, and enhanced carbon sequestration. However, cropland loss initially resulted in a decline in grain productivity. Policy adjustments and improvements in ecosystem restoration efforts and agricultural production conditions improved food security and increased agricultural production capacity. Effective policymaking and favorable resident engagement accelerated the transformation from a grain-production-based agriculture to diversified industries and, by extension, economic output, income, and population. The success of socioeconomic development under the SES framework for LDN demonstrated that this strategy could achieve the desired environmental, agricultural, and economic targets. EAEN under the SES conceptual framework provides an inclusive, comprehensive LDN perspective and improves ERP efficacy. The findings of the present work might be applicable to other land restoration areas challenged by the complex interactions among multidimensional factors. Comparably successful implementation of these ERPs could be realized if individual environmental and socioeconomic conditions are thoroughly considered during the formulation of coordinated development policies.

Application of spatial environmental indicators in the assessment of degradation potential of water resources in water basins

Changes in land use have been occurring in a continuous and disorderly way in recent decades due to rapid population growth and the growing demand for food. These constant changes result in a series of harmful effects to the environment, especially to water resources, significantly changing their availability and quality. This study aims to evaluate the degradation potential of watersheds through an evaluation of some environmental indicators using arithmetic means to construct an index called in this research "index of potential environmental degradation" (IPED). To form the IPED, the hydrographic sub-basins of the Sorocabuçu River, located in the central west of the State of São Paulo, Brazil, comprised the study area. The results showed that most hydrographic sub-basins, that is, eight units, present degradation values ranging from moderate to very high, resulting mainly from low conservation values of forests plus a use destined to the planting of temporary cultures depending on good physical conditions. On the other hand, only one sub-basin showed a low degradation value. The methodology used for the development of the IPED is easy to apply and an effective tool for environmental analyses. It may contribute to studies and forms of planning and land use management aiming the conservation of water resources and protected areas and reduction of degradation.

Unfolding the Success of Positive Human Interventions in Combating Land Degradation

A global challenge to sustainable development is land degradation, and to achieve land degradation neutrality, monitoring, mapping, and impact assessment of ongoing ecological restoration efforts is necessary. Here, we analyze the desertification process and role of restoration projects at a spatial and temporal scale in Mu Us Desert from 2001 to 2018. We used 17 years of data to (1) assess the vegetation trend including its significance and map land degradation based on Sustainable Development Goal Indicator 15.3.1 (2) address how vegetation activity has changed under the influence of restoration programs and climate change (3) estimate how successful are the positive human interventions to achieve Land degradation neutrality. Results showed an overall increasing vegetation trend (85.69% significant increasing) and a partial decreasing vegetation trend (1.33% significant decreasing) in Mu Us desert. Ecological restoration activities are found to be one of the key driving forces of vegetation restoration in the desert, however, limited impact of climatic factors on vegetation cover change was observed. Results revealed that 41.42% of total significant restoration is attributed to ecological restoration programs out of which 40.42% area has shown improvement in all three sub-indicators of land degradation.

Assessing the Impact of Science in the Implementation of the United Nations Convention to Combat Desertification

In 2013, the United Nations Convention to Combat Desertification (UNCCD) established a science–policy interface (SPI) to address Parties’ need for demand-driven, timely, interdisciplinary science and technical knowledge to tackle problems of desertification, land degradation and drought. Since then, a comprehensive assessment of the SPI’s impacts on policy decision-making has been lacking, despite perceptions that the SPI is vital to the Convention’s success. Addressing this gap, this paper evaluates whether the SPI and its processes and outputs have provided the necessary scientific and technological knowledge and advice to Parties to support timely, evidence-informed decision-making. It applies an analytical framework to assess performance metrics, considering associated documents and evidence of societal relevance and social quality. The findings indicate that SPI outputs have improved implementation of the UNCCD since 2015, particularly in the context of Sustainable Development Goal Target 15.3. SPI outputs have supported scientific cooperation between the Convention and its strategic partners while enhancing its science and technology profile in line with Article 16 and Article 17. The findings indicate that further formalization of the SPI’s status within the UNCCD is vital to improve its functions, undertake its work, and enable the UNCCD to maintain its global lead in providing knowledge and advice on combating desertification, land degradation and drought.

Land Degradation Neutrality: State and Trend of Degradation at the Subnational Level in Mexico

Identifying degraded lands and degradation trends is essential to determine measures that contribute to avoiding, reducing, and reversing the rate of deterioration of natural resources. In this study, we assessed the state and trend of degradation in Ixtacamaxtitlan, Puebla, Mexico, by determining the spatial and temporal changes of three indicators, Land Cover (LC), Land Productivity Dynamics (LPD), and Soil Organic Carbon (SOC), during the period 2000–2015, using global data proposed by the Convention to Combat Desertification for the implementation of Land Degradation Neutrality (LDN). The results showed increases in croplands (6.89%) and a reduction in grasslands (9.09%), with this being the transition that presents the most significant extension in the territory. The LPD is the indicator where the most deterioration was observed, and due to negative changes in LC, SOC losses were estimated at more than 7000 tons in the study period. The proportion of degraded land was 19% of approximately 567.68 km2 of Ixtacamaxtitlan’s surface. Although the municipality presents incipient degradation and only a tiny part showed improvement, identifying areas with degradation processes in this work will favor degradation monitoring and the adequate planning and application of restoration measures in the local context to promote the path towards LDN.

‘Old’ Territorial Disparities and ‘New’ Spatial Patterns: Unraveling the Latent Nexus between Sustainable Development and Desertification Risk in Italy

Although sustainable development and desertification risk are hegemonic concepts in environmental economics, their intimate relationship was occasionally studied and made spatially explicit. The present study contributes to fill this knowledge gap by delineating a statistical procedure that investigates, at the municipal scale in Italy, the association between two composite indexes of sustainable development (SDI) and desertification risk (ESAI). Based on a refined knowledge of the local context, results of a geographically weighted regression delineate two distinctive territorial models reflecting the mutual interplay of sustainable development and desertification risk in Italy. The level of sustainable development was negatively associated with desertification risk in Southern Italy, a region classified as ‘affected’ based on the Italian National Action Plan (NAP) to combat desertification. These findings document a traditional ‘downward spiral’ between local development and early desertification processes, suggesting that a high desertification risk is associated with local contexts having structural conditions that lead to unsustainable development, e.g., population growth, industrial development, tourism pressure, crop intensification, agricultural mechanization, and land abandonment. In non-affected regions such as Northern and Central Italy, the level of sustainable development was positively associated with desertification risk, indicating that sustainability conditions can be unable, at least in some local contexts, to assure a significant containment of environmental degradation. Policy strategies reconnecting local development with more specific environmental conservation targets in development countries are increasingly required to adapt to (and differentiate on the base of) heterogeneous local contexts.

Ultimately, What is Forest Landscape Restoration in Practice? Embodiments in Sub-Saharan Africa and Implications for Future Design

Forest landscape restoration (FLR) is gaining ground as a novel, holistic approach to sustainable environmental management across developing countries. In sub-Saharan Africa, 30 countries have joined the African Forest Landscape Restoration Initiative to advance FLR goals. Although conceptually compelling, and despite efforts articulating initial implementation guidelines, divergent discourses and interpretations confound FLR translation into practice. We propose a characterization of FLR in practice using insights from political ecology; principles of ecological restoration and landscape sustainability science; and the philosophy, principles, and objectives of the FLR paradigm. Our qualitative analysis further draws on secondary data and insights from participant observation during FLR-related workshops. We build and organize the FLR characterization around answers to ten questions: why restoration; what purpose; for what desired outcomes; where (location and land uses); what spatial extent and scale(s); who; which techniques; how (approach/strategy); when and how long; and how much to achieve. We then assess early FLR strategic priorities for interventions across nine African countries and analyze five selected actual projects to illustrate use of the proposed FLR characterization framework. The illustrative characterization of both planned interventions and actual projects does not reflect all the proposed characteristics of FLR in practice. Missing features include the initial biophysical condition, the desired target ecosystem state, and evaluation dimensions, and ill-articulated aspects include cross-sectoral integrations. We contend that any significant differences between FLR conceptualization, including its principles, and the practical manifestations can undermine coherence, the value that the FLR approach adds, and its wider adoption. The proposed characterization of FLR in practice contributes to scholarly attempts to realign FLR conceptual philosophy, principles, and rhetoric to its practical manifestations in different contexts, and can inform future design of FLR undertakings for more inclusive landscape governance.

Situating China in the Global Effort to Combat Desertification

International efforts to tackle desertification led by the United Nations Convention to Combat Desertification (UNCCD) support participatory approaches. The emphasis has been on dialogue between different perspectives, which are often grounded in individualism rather than prioritizing society as a whole, and as a result progress in implementation has been slow. China has made substantial progress in tackling desertification, but its approaches have been controversial, and the sustainability of its achievements has been questioned. While China has been active in UNCCD processes, its approach to addressing desertification has differed from those of other countries. China can thus offer important insights into the international campaign, while acknowledging that China can also learn from the efforts of others. We compare the UNCCD’s “bottom-up” approach and China’s “top-down” approach to better understand the challenges of tackling desertification. We examine the evolution in how desertification has been addressed and shed light on the context behind the changes, focusing on the role of science, policies, and public participation. We find a convergence between top-down and bottom-up approaches and that similar challenges have been experienced. Constant communications with outsiders have enabled adjustments and changes in both China and the international community, even though their approaches remain distinct. We conclude that both approaches are moving toward solutions that start from proactive investments of governments in financial, legal, institutional, and organizational aspects, draw on scientific insights, and which are grounded in the motivated and voluntary participation of non-state actors. Improved sharing of lessons across these approaches would help to create a better enabling form of environmental governance that contributes to tackling desertification.

Exploring soil erosion trajectories and their divergent responses to driving factors: a model-based contrasting study in highly eroded mountain areas

Soil erosion threatens environmental sustainability worldwide. Exploring the trajectories of soil erosion and associated drivers is of great significance for combating land degradation. This study selected the highly eroded Loess Plateau (LP) and Karst Plateau (KP) as contrasting regions to monitor soil erosion dynamics. Monitoring was performed by applying the Revised Universal Soil Loss Equation based on a GIS platform and multi-source input data to investigate associated drivers. The results established that soil erosion in both regions was substantially reduced by ecological restoration projects and significant land use/cover conversions. Landscape and geomorphological variables were found to be the dominant factors controlling soil erosion in the LP and KP, as they influenced land use patches and geomorphological patterns, respectively. The correlations between fragmentation metric indices and soil erosion indicated that the appropriately intensive fragmentation in the LP could mitigate or prevent soil erosion by disturbing its formation and transportation and ultimately positively influenced soil erosion control. Geomorphological patterns were also determinative factors, particularly for the KP, where almost all geomorphological variables were significantly correlated with the erosion modulus. Owing to the peculiar landform and landscape conditions in karst areas and loess hilly-gully areas, geomorphological and landscape variables should be considered when determining the main factors affecting soil erosion processes and integrated into the forecasting model to improve the accuracy of the simulation. The findings of this study are expected to (i) improve the efficacy of soil erosion control and (ii) promote the sustainable planning and management of land and soil resources.

Uncovering the Role of Biophysical Factors and Socioeconomic Forces Shaping Soil Sensitivity to Degradation: Insights from Italy

Following an operational framework derived from earlier research, our study research estimates the specific contribution of biophysical and socioeconomic factors to soil sensitivity to degradation at two-time points (Early-1990s and Early-2010s) in Italy, a Mediterranean hotspot for desertification risk. A total of 34 variables associated (directly or, at least, indirectly) with different processes of soil degradation (erosion, salinization, sealing, contamination, and compaction) and climate change were considered here, delineating the predominant (underlying) cause (i.e., biophysical or socioeconomic). This set of variables represented the largest (quantitative) information available from national and international data sources including official statistics at both national and European scale. Contribution of biophysical and socioeconomic dimensions to soil sensitivity to degradation was heterogeneous in Italy, with the level of soil sensitivity to biophysical factors being the highest in less accessible, natural areas mostly located in hilly and mountainous districts. The highest level of soil sensitivity to socioeconomic drivers was instead observed in more accessible locations around large cities and flat rural districts with crop intensification and low (but increasing) population density. All these factors delineated an enlarged divide in environmental quality between (i) flat and upland districts, and between (ii) Northern and Southern Italian regions. These findings suggest the appropriateness of policy strategies protecting soils with a strong place-specific knowledge, i.e., based on permanent monitoring of local (biophysical and socioeconomic) conditions.

Unfolding the effectiveness of ecological restoration programs in combating land degradation: Achievements, causes, and implications

Land degradation is one of the most serious environmental problems worldwide. To combat land degradation, China has implemented a series of ecological restoration programs (ERPs). This study selected the northern dryland of China as a case study to examine the efficiency of ERPs, and the response of soil loss to afforestation efforts and climatic conditions was discussed using the principles from the ecological theory of non-linear ecosystem dynamics. Owing to the combined impacts of declining wind speed and rapid vegetation restoration, the soil erosion for the entire region was substantially reduced from 1990 to 2015. However, the rainfall fluctuated considerably, particularly for the period from the late 1990s to early 2000s. Several drought events to some extent inhibited vegetation growth and further offset afforestation efforts, resulting in degradations in vegetation structure and soil retention function, which have been aggravating soil erosion since 2005. In certain representative sandstorm areas, limited increase in rainfall was not enough to promote vegetation growth, and therefore the vegetation cover did not present increasing trends and, in some cases, even declined significantly. The responses in terms of land degradation to climatic conditions and afforestation efforts behaved in a non-linear dynamic manner, providing essential insights into appropriate timings, climate-induced windows of opportunity, and risk in recovering and sustaining ecosystems, and eventually moving towards the land degradation neutrality (LDN) target. The climate-induced windows of opportunity and risk are critical in identifying the time for starting human interventions to mitigate and halt land degradation. Meanwhile, effective investment actions should be taken according to existing environmental conditions and critical thresholds, to achieve LDN at minimum risk and cost.

Forest landscape restoration: state of play

Tree planting has been widely touted as an inexpensive way to meet multiple international environmental goals for mitigating climate change, reversing landscape degradation and restoring biodiversity restoration. The Bonn Challenge and New York Declaration on Forests, motivated by widespread deforestation and forest degradation, call for restoring 350 million ha by 2030 by relying on forest landscape restoration (FLR) processes. Because the 173 million ha commitments made by 63 nations, regions and companies are not legally binding, expectations of what FLR means lacks consensus. The frequent disconnect between top-level aspirations and on-the-ground implementation results in limited data on FLR activities. Additionally, some countries have made landscape-scale restoration outside of the Bonn Challenge. We compared and contrasted the theory and practice of FLR and compiled information from databases of projects and initiatives and case studies. We present the main FLR initiatives happening across regional groups; in many regions, the potential need/opportunity for forest restoration exceeds the FLR activities underway. Multiple objectives can be met by manipulating vegetation (increasing structural complexity, changing species composition and restoring natural disturbances). Livelihood interventions are context-specific but include collecting or raising non-timber forest products, employment and community forests; other interventions address tenure and governance.

Delivering an enabling environment and multiple benefits for land degradation neutrality: Stakeholder perceptions and progress

Achieving land degradation neutrality (LDN) was adopted by countries in 2015 as one of the targets of the global Sustainable Development Goals (SDGs). As LDN is a relatively new concept there is an increasing need for evidence on the potential socio-economic and environmental benefits of LDN as well as how an enabling environment for implementing LDN measures can be developed. This paper summarises the results from a global survey of LDN stakeholders, and a review of national progress in target setting that was commissioned by the United Nations Convention to Combat Desertification (UNCCD) in 2018. The study presents the perceptions of relevant stakeholders on the key components of an enabling environment for achieving and maintaining LDN (institutional, financial, policy/regulatory, and science-policy) as well as expectations of multiple benefits from its implementation. We also highlight key challenges and gaps in progress to date that are emerging from ongoing national target setting programs to implement LDN. The study finds that progress in implementing LDN has been widespread across countries. However there remains a lack of awareness of LDN and its key concepts along with high-level political buy-in. This may be impeding the integration of LDN into national development planning and budgeting processes where progress was assessed as limited. National capacities for securing land tenure and governance arrangements and integrated land use planning were perceived as comparatively low, further hampering the implementation of LDN. Despite these gaps, most stakeholders (>90 %) who participated in the global survey expected LDN to deliver a broad range of multiple benefits for human wellbeing, livelihoods and the natural environment. We argue that greater efforts are needed to raise awareness of LDN, educate core stakeholders in its concepts, enablers and benefits, raise its political profile, and provide evidence on national measures that will support implementation of LDN.

Revisiting the Environmental Kuznets Curve: The Spatial Interaction between Economy and Territory

A complex interplay of socio-ecological drivers of change exists at the different spatiotemporal scales affecting environmental degradation. This is a key issue worldwide and needs to be understood to develop efficient management solutions. One of the most applied theories in the regional analysis is the U-shaped relationship between environmental degradation and the level of income in a given economic system or Environmental Kuznets Curve (EKC). Specifically, the EKC hypothesis underlines the (potentially positive) role of formal responses to environmental degradation grounded on government policies that are usually more ambitious in wealthier economic systems. However, there is a lack of knowledge on the role of space in EKC, arguing that spatial variability in the environment–income relationship may indicate additional targets for integrated socio–environmental policies. We hypothesize that a spatially differentiated response to environmental degradation could better adapt to differentiated local contexts. Therefore, to achieve this goal, we present a multi-scale investigation of degradation processes at the local level, providing a refined knowledge of the environment–economy linkages considering more traditional, cross-country and cross-region exercises. Our results demonstrated that—together with temporal, sectoral, and institutional aspects—space and, consequently, the related analysis’ spatial scales, are significant dimensions in ecological economics, whose investigation requires improvements in data collection and dedicated statistical approaches.

Practicing land degradation neutrality (LDN) approach in the Shazand Watershed, Iran

Neutralizing land degradation due to overexploitation of natural resources is an acceptable strategy under developing conditions. However, this important approach has not been adequately introduced and adopted in the world. The present study therefore aimed to calculate Land Degradation Neutrality (LDN) for the Shazand Watershed with an area about 1740 km² located in central arid and semi-arid region of Iran. The LDN status was basically assessed using three indicators, viz. land use and land cover, soil organic carbon and land productivity using Land Cover/Use Changes (LUC), Soil Organic Carbon (SOC) and Net Primary Productivity (NPP) metrics for two sub-periods during 2000 to 2016. Towards this, 140 soil samples were then taken from the top 30-cm of the soil from homogeneous units representing an area ≥ 1-km² for four different main land uses including irrigated farms, rain fed farms, range lands, and orchards. Consequently, SOC and various soil properties such as sand, silt, clay, gravel, bulk density (BD), pH, electrical connectivity (EC), calcium carbonate (CaCO₃) and nitrogen (N) were analyzed. NPP metric was also obtained using MODIS satellite images for three periods of 2000-2008, 2008-2016, and 2000-2016. The results of combination of study metrics indicated that net loss occurred in irrigated lands, rain fed lands, and range lands in the first eight-year period (2000-2008) and in contrary a balanced and stable situation in the second eight-year period (2008-2016). Overall, the LDN status in the Shazand Watershed was in a net loss situation during the period from 2000 to 2016 in irrigated lands, rain fed lands, and range lands covered areas of 12,290, 44,170 and 66,630 ha, respectively.

Opportunities and Limitations for Achieving Land Degradation-Neutrality through the Current Land-Use Policy Framework in Kenya

The United Nations Convention to Combat Desertification (UNCCD) land degradation neutrality (LDN) scientific conceptual framework underscores that LDN planning and implementation should be integrated into existing planning processes and supported by an enabling policy environment. Land-use planning, which requires the integration of different policy goals across various sectors concerned with land-use, can be an effective mechanism through which decisions with respect to LDN can be coordinated. Using Kenya as a case study, we examined current policy instruments that directly or indirectly impact on the use of land in a rural context, to assess their potential to implement LDN objectives. The qualitative content analysis of these instruments indicated that they are rich with specific legal provisions and measures to address LDN, and that there are a number of relevant institutions and structures across governance levels. However, the main shortcoming is the disjointed approach that is scattered across policy areas. Key policy improvements needed to support effective implementation of LDN include: a national soil policy on the management and protection of soil and land; a systematic and coordinated data collection strategy on soils; mobilisation of adequate and sustained financial resources; streamlined responsibilities, and governance structures across national, regional and county levels.

Soil Organic Carbon Baselines for Land Degradation Neutrality: Map Accuracy and Cost Tradeoffs with Respect to Complexity in Otjozondjupa, Namibia

Recent estimates show that one third of the world’s land and water resources are highly or moderately degraded. Global economic losses from land degradation (LD) are as high as USD $10.6 trillion annually. These trends catalyzed a call for avoiding future LD, reducing ongoing LD, and reversing past LD, which has culminated in the adoption of Sustainable Development Goal (SDG) Target 15.3 which aims to achieve global land degradation neutrality (LDN) by 2030. The political momentum and increased body of scientific literature have led to calls for a ‘new science of LDN’ and highlighted the practical challenges of implementing LDN. The aim of the present study was to derive LDN soil organic carbon (SOC) stock baseline maps by comparing different digital soil mapping (DSM) methods and sampling densities in a case study (Otjozondjupa, Namibia) and evaluate each approach with respect to complexity, cost, and map accuracy. The mean absolute error (MAE) leveled off after 100 samples were included in the DSM models resulting in a cost tradeoff for additional soil sample collection. If capacity is sufficient, the random forest DSM method out-performed other methods, but the improvement from using this more complex method compared to interpolating the soil sample data by ordinary kriging was minimal. The lessons learned while developing the Otjozondjupa LDN SOC baseline provide valuable insights for others who are responsible for developing LDN baselines elsewhere.

Can Strategic Spatial Planning Contribute to Land Degradation Reduction in Urban Regions? State of the Art and Future Research

Land degradation is becoming a serious environmental issue threatening fertile agricultural soils and other natural resources. There are many driving forces behind land degradation. The expansion of artificial surfaces due to various economic activities, such as housing, industry, and transport infrastructure, known as soil sealing, constitutes one of the most intensive forms of land degradation in urban regions. Measures to halt and reverse land degradation require both strong land-use management policies, as well as effective spatial planning mechanisms. In this regard, strategic spatial planning has been increasingly practised in many urban regions worldwide, as a means to achieve sustainable land-use patterns and to guide the location of development and physical infrastructures. It is reasonable, therefore, to expect that strategic spatial planning can counteract the outlined undesired land degradation effects, specifically those resulting from soil sealing. In this paper, we review strategic spatial planning literature published between 1992 and 2017. The focus is on the phenomena causing land degradation that are addressed by strategic spatial planning literature, as well as on the mechanisms describing the role of strategic spatial planning in land degradation reduction. Results show that sustainable development and environmental concerns have become core objectives of strategic planning in recent years, yet references to the drivers of land degradation are rare. The mechanisms that exist are mainly intended to address environmental issues in general, and are not aimed at reducing particular forms of land degradation. The paper concludes by sketching future research directions, intended to support strategic spatial planning and land-use policymaking related to coping with the global phenomenon of land degradation.