Restoring degraded land is essential for regaining ecosystem services (ES) and attaining the UN-Sustainable Development Goals by 2030. Unfortunately, 24% of the global land is degraded, significantly affecting the lives of 3.2 billion people worldwide. Therefore, innovative restoration practices are vital during ‘UN-Decade on Ecosystem Restoration.’ A meta-analysis of 2093 documents on land degradation and restoration was conducted in this context, and 117 empirical studies were analyzed in detail. These studies were based on the different drivers of land degradation as per the criteria of IPBES and IPCC, respectively. Results suggested that woodland encroachment (18.25%), cropland expansion (18.11%), species loss/compositional shifts (16.06%), climatic factors (14.96%), infrastructure development/urbanization (14.17%), water erosion (13.87%), wind erosion (9.49%) and other demographic pressures (8.66%) were the significant drivers of land degradation. Interestingly, there was a continent-wide change in the critical drivers of land degradation and depleting ES. The infrastructure development/urbanization, demography, and economic attributes were the essential drivers in the Asia–Pacific and African regions. In contrast, the fire-regime shift and invasiveness were the significant drivers in Europe, and the climatic attribute was the crucial driver in the Americas. Out of the 117 studies selected worldwide, some ongoing restoration efforts had little emphasis on research-driven on-site restoration for improving different ES. Furthermore, some restoration projects lack proper stakeholder involvement thereby, fail to attract large-scale public acceptance. Moreover, only 12.8% of the studies focused on improving the ES in highly degraded lands. Therefore, this meta-analysis suggests that site-specific, research-driven, and on-site restoration strategies coupled with proper stakeholder engagement are imperative for regaining the ES and functions of the degraded landscape to attain UN-SDG.

Guiding principles for the restoration measures and conservation strategies on the degraded lands from the reviewed empirical studies

Analysing the sustainability of cultivating biomass and biofuel plant species on marginal and degraded lands is essential for assessing the socio-economic and environmental perspectives. Various approaches have been suggested for the sustainability analyses, such as life cycle assessment, footprint analysis, multi-criteria decision analysis, and emergy analysis. Among these approaches, the emergy analysis is one of the most direct methods to assess the system's sustainability. The present article was aimed to perform the emergy analysis to quantify the ecological impacts, bioenergy potential, socio-economic efficiency, and the sustainability of the bioenergy production systems. The emergy-based sustainability analysis was conducted for the Soyabean-, Pongamia-, Jatropha-based biodiesel and Tectona-based biomass production systems from the Indian marginal and degraded lands. Results depicted that under a set of system boundaries for each plant species, total emergy output (U) of 1000 kg biodiesel (biomass in case of Tectona) was calculated to be 0.99E+16 for Soyabean-; 1.01E+16 for Pongamia-; 1.33E+16 for Jatropha- and 0.72E+16 sej for Tectona-based bioenergy production options. Emergy of fuels dominated the economic inflows (F) (32.53%) under the Soyabean-based option making it the second system to represent a greater environmental load ratio (ELR) of 17.98. Furthermore, the emergy of water resources was dominated under F in other studied bioenergy options, i.e., 38.08% of F in Pongamia-, 44.54% in Jatropha-, and 66.52% in Tectona-based systems. The emergy sustainability indices (ESI) of 0.06, 1.04, 0.34, and 0.02 were found for Soyabean-, Pongamia-, Jatropha-, Tectona-based bioenergy production systems, respectively. Sensitivity analysis further suggested that a decrease of 3.5% in F resulted in a 10.02% increase of ESI for the Pongamia-based option. Pongamia-based options depicted an ESI > 1, which could be considered to have a sustainable contribution to the economy for medium periods. The estimated ESIs were fundamentally low because the systems were dependent mainly on the F.

Multicriteria representations of selected bioenergy production systems. 

Land degradation is one of the major global environmental issues that need serious attention. The land itself is a complex system regulating myriads of processes and perturbation in anyone; these would undoubtedly lead to the stimulation of land degradation. Among these, fly ash (FA) dumping is one of the standard practices, which has been adopted to overcome land-use disruption and other health hazards. However, this practice has become a driving factor for FA-induced land degradation. Therefore, in purview to tackle this issue, the present article is aimed to identify and suggest sustainable practices to restore and manage FA contaminated sites. It preliminarily deals with the systematic exploration and identification of FA-based and associated contaminated lands via geospatial technology with a brief focus on assessing its different contaminant profiles in the FA and soil systems. Moreover, the article emphasizes identifying the potential local plant species in the FA-contaminated regions to meet the local people’s demands. Following this, it would suggest the appropriate sustainable approaches to expedite the restoration of FA contaminated lands and the critical highlights of their bottlenecks while the ground implementation. Nevertheless, the article aimed to unravel the recommended prospects to address those bottlenecks to develop an efficient restoration enterprise during the Decade on Ecosystem Restoration (2021-2030).

Predicted land areas (mha) in countries/regions prone to FA contamination

Variable estimates of global marginal and degraded lands

A conceptual framework for accelerating the LR efforts via synchronizing various disciplines under TD research and attaining the multiple benefits

PCA-based indicator development

Restoration of degraded land is imperative for addressing climate change, deriving additional benefits such as biomass and biofuel for supporting a biobased economy and also for meeting various targets of the Bonn Challenge and the UN Sustainable Development Goals (UN‐SDGs). In this context, this research aimed to evaluate the performance of mixed biomass plantations on the saline land of western India over a period of 4 years. The impact of plantations on soil quality over the study period (2015–2018) was analyzed by the Saline Soil Reclamation Index (SSRI), developed through principal component analysis. The study found a strong correlation between plant growth attributes and soil quality (p < .01). Among the various test plants, six species (Albizia lebbeck, Casuarina equisetifolia, Cordia dichotoma, Pithecellobium dulce, Pongamia pinnata, Terminalia arjuna) were found with high SSRI; while the rest displayed moderate SSRI, except for Azadirachta indica, which shown low SSRI. The trees having high SSRI are most suitable for the reclamation of saline soil and therefore, SSRI can be used as a tool for assessing the progress of saline land restoration.

Effect of P. juliflora invasion on livestock. (a,b) species invasion in the nearby grazing land reducing fodder availability (c) than the control site

Restoration of marginal and degraded lands is essential for regaining biodiversity and ecosystems services, and thereby attaining UN-Sustainable Development Goals. During the last few decades, many fast growing and hardy trees have been introduced worldwide to restore the marginal and degraded lands for ecosystem stability. Unfortunately, most of these introduced species have become invasive and invaded the nearby productive systems, leading to significant biodiversity loss and land degradation. Present study performed the sustainability analysis by assessing the socio-ecological impacts of a widely used species, i.e., Prosopis juliflora (Sw.) DC based restoration of degraded land North India. Ecological and social indicators have been studied through direct field sampling and questionnaire-based surveys. While there was a positive difference (p < 0.01) in the key physico-chemical properties of the P. juliflora-invaded soil than the non-invaded site. Additionally, the invasion of P. juliflora had significantly reduced the biodiversity by displacing the local flora. Although the local people utilised P. juliflora as fuelwood mostly during summer and winter seasons, the invasion resulted in a fodder deficit leading to resource scarcity in the invaded area. Eco-distribution mapping clearly showed that P. juliflora is already found in most of the tropical and subtropical countries (~103) including in India and has become invasive in many countries. Therefore, we recommend that P. juliflora must be wisely used for the land restoration programs targeted during the United Nations Decade of Ecosystem Restoration (2021–2030) as this species has invasive traits and thereby reduces the ecosystem sustainability of the invaded areas.