Managing the global land resource

Spatial-Temporal Pattern and Convergence Characteristics of Provincial Urban Land Use Efficiency under Environmental Constraints in China

Revealing the spatial-temporal pattern and convergence characteristics of urban land use efficiency has important guiding significance for adjusting and optimizing the regional urban land use structure. Taking the provincial units in China as the research object, the urban land use efficiency evaluation system considering the unexpected output was constructed, and the slack-based measure (SBA) model was used to quantitatively measure the provincial urban land use efficiency from 2000 to 2020. The exploratory spatial data analysis (ESDA) model and spatial convergence index were combined to reveal the spatial-temporal pattern and convergence characteristics of provincial urban land use efficiency. The results showed that the provincial urban land use efficiency has been continuously improving, with regional differences as shown in eastern region > northeast region > central region > western region. Moran's I of provincial urban land use efficiency was greater than 0, there was a positive spatial correlation, and the clustering feature became increasingly significant. The spatial form of LISA was characterized by "small agglomeration and large dispersion"; the H(High)-H(High) type was clustered in the Yangtze River Delta and Beijing-Tianjin-Hebei, while the L(Low)-L(Low) type was clustered in Xizang, Xinjiang and Qinghai. There was a σ convergence in provincial urban land use efficiency, and there was significant absolute β convergence and conditional β convergence of provincial urban land use efficiency. The results showed that the differences in provincial urban land use efficiency were shrinking, showing a "catch-up effect", and converging to their respective stable states over time. Based on the analysis of the spatial-temporal pattern and convergence characteristics of provincial urban land use efficiency in China, we could provide a direction for the optimization of the urban land use structure and efficiency improvement in China, in order to narrow the differences in urban land use efficiency in China's four major regions.

Desertification of Iran in the early twenty-first century: assessment using climate and vegetation indices

Remote sensing of specific climatic and biogeographical parameters is an effective means of evaluating the large-scale desertification status of drylands affected by negative human impacts. Here, we identify and analyze desertification trends in Iran for the period 2001-2015 via a combination of three indices for vegetation (NPP-net primary production, NDVI-normalized difference vegetation index, LAI-leaf area index) and two climate indices (LST-land surface temperature, P-precipitation). We combine these indices to identify and map areas of Iran that are susceptible to land degradation. We then apply a simple linear regression method, the Mann-Kendall non-parametric test, and the Theil-Sen estimator to identify long-term temporal and spatial trends within the data. Based on desertification map, we find that 68% of Iran shows a high to very high susceptibility to desertification, representing an area of 1.1 million km2 (excluding 0.42 million km2 classified as unvegetated). Our results highlight the importance of scale in assessments of desertification, and the value of high-resolution data, in particular. Annually, no significant change is evident within any of the five indices, but significant changes (some positive, some negative) become apparent on a seasonal basis. Some observations follow expectations; for instance, NDVI is strongly associated with cooler, wet spring and summer seasons, and milder winters. Others require more explanation; for instance, vegetation appears decoupled from climatic forcing during autumn. Spatially, too, there is much local and regional variation, which is lost when the data are considered only at the largest nationwide scale. We identify a northwest-southeast belt spanning central Iran, which has experienced significant vegetation decline (2001-2015). We tentatively link this belt of land degradation with intensified agriculture in the hinterlands of Iran's major cities. The spatial and temporal trends identified with the three vegetation and two climate indices afford a cost-effective framework for the prediction and management of future environmental trends in developing regions at risk of desertification.

Earth as construction material in the circular economy context: practitioner perspectives on barriers to overcome

The need for a vast quantity of new buildings to address the increase in population and living standards is opposed to the need for tackling global warming and the decline in biodiversity. To overcome this twofold challenge, there is a need to move towards a more circular economy by widely using a combination of alternative low-carbon construction materials, alternative technologies and practices. Soils or earth were widely used by builders before World War II, as a primary resource to manufacture materials and structures of vernacular architecture. Centuries of empirical practices have led to a variety of techniques to implement earth, known as rammed earth, cob and adobe masonry among others. Earth refers to local soil with a variable composition but at least containing a small percentage of clay that would simply solidify by drying without any baking. This paper discusses why and how earth naturally embeds high-tech properties for sustainable construction. Then the potential of earth to contribute to addressing the global challenge of modern architecture and the need to re-think building practices is also explored. The current obstacles against the development of earthen architecture are examined through a survey of current earth building practitioners in Western Europe. A literature review revealed that, surprisingly, only technical barriers are being addressed by the scientific community; two-thirds of the actual barriers identified by the interviewees are not within the technical field and are almost entirely neglected in the scientific literature, which may explain why earthen architecture is still a niche market despite embodying all the attributes of the best construction material to tackle the current climate and economic crisis. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.

The Process-Mode-Driving Force of Cropland Expansion in Arid Regions of China Based on the Land Use Remote Sensing Monitoring Data

The center of gravity of China’s new cropland has shifted from Northeast China to the Xinjiang oasis areas where the ecological environment is relatively fragile. However, we currently face a lack of a comprehensive review of the cropland expansion in oasis areas of Xinjiang, which is importantly associated with the sustainable use of cropland, social stability and oasis ecological security. In this study, the land use remote sensing monitoring data in 1990, 2000, 2010 and 2018 were used to comprehensively analyze the process characteristics, different modes and driving mechanisms of the cropland expansion in Xinjiang, as well as its spatial heterogeneity at the oasis area level. The results revealed that cropland in Xinjiang continued to expand from 5803 thousand hectares in 1990 to 8939 thousand hectares in 2018 and experienced three stages of expansion: steady expansion, rapid expansion, and slow expansion. The center of gravity of cropland showed the characteristic of shifting to the South. Edge expansion and encroachment on grassland were the dominant spatial pattern mode and land use conversion mode of Xinjiang’s cropland expansion, respectively. The expansion of cropland in Xinjiang was affected by multiple factors. Irrigation conditions played a dominant role. Topography indirectly affected cropland expansion by affecting the suitability of agricultural production and development. Population growth and farmers’ income were important driving forces. There was significant spatial heterogeneity in the intensity, mode and driving force of cropland expansion among different oasis areas in Xinjiang. The spatial shift of China’s new cropland has occupied a large amount of water resources and ecological land in Xinjiang and exacerbated the vulnerability of the ecosystem in arid regions. The key to sustainable management of cropland in Xinjiang in the future lies in maintaining an appropriate scale of cropland and promoting the coordinated development of cropland, population, water resources and industry.

Effect of Tenebrio molitor larvae meal on the antioxidant status and stress response pathways in tissues of growing pigs

Insect meal (IM) produced from edible insects, such as Tenebrio molitor, has been recognised as a potentially suitable protein component in feeding rations for monogastric livestock. While several studies with broilers have shown that animal´s health is not negatively affected by IM, less is known with regard to the influence of IM on metabolism of pigs. The present study investigates whether IM from Tenebrio molitor larvae causes oxidative stress and activates oxidative stress-sensitive signalling pathways in key metabolic tissues of pigs. To address this question, male 5-week-old crossbred pigs were randomly assigned to three groups of 10 pigs each and fed nutrient-adequate, isonitrogenous diets either without (CON) or with 5% IM or 10% IM from Tenebrio molitor larvae for 4 weeks. Concentrations of thiobarbituric acid reactive substances, tocopherols and glutathione in liver, gastrocnemius muscle and/or plasma did not differ between groups. Activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD) in the liver and of GPX and SOD in gastrocnemius muscle were not different between groups, whereas the activity of CAT in skeletal muscle was increased in the two IM-fed groups compared to group CON (p < 0.05). The mRNA levels of most of the target genes of oxidative stress-sensitive signalling pathways, such as nuclear factor-κB, nuclear factor erythroid 2-related factor 2 and endoplasmic reticulum stress-induced unfolded protein response, in liver and gastrocnemius muscle did not differ between the three groups. The present study shows that feeding a diet containing adequate levels of antioxidants, such as vitamin E and selenium, and Tenebrio molitor larvae meal as a protein component neither causes oxidative stress nor activates oxidative stress-sensitive signalling pathways in key metabolic tissues of growing pigs. Based on these observations, IM from Tenebrio molitor larvae can be regarded as a safe source of protein in growing pigs.

Is domestic agricultural production sufficient to meet national food nutrient needs in Brazil?

Reducing the impacts of agriculture on the environment is one of the greatest challenges of this century. In Brazil, it is often argued that more land use change is needed to achieve food security. However, analyses seeking to understand the dynamics between agricultural production for exports and food intended for the Brazilian population have not approached the question if national agriculture is sufficient to provide Brazilians with the necessary nutrients, according to nutritional recommendations. In this sense, we sought to combine supply and dietary requirements for food (calories and nutrients) to assess trends in nutrient production and how future population projections and possible changes in diets would affect land necessity for nutritional security. We use sub-national data on agricultural production, population, Food Balance Sheets from FAO, and a compilation of nutritional information on the Brazilian agricultural production. Our results show that, in the last three decades, Brazil produced enough food calories to feed on average 115% of its population. We found that the agricultural land in 2017, without any expansion, is sufficient to feed, at least, 105% of projected population in 2060, considering the same productivity and dietary patterns. In a vegan diet scenario, less than 10% of the land dedicated to agricultural production in the past 30 years would be required. Despite limitations on supplying certain micro-nutrients, a vegan diet would require even less land in the future. We conclude that Brazilian agriculture could deliver enough food to meet Brazilians’ nutritional needs without further land expansion. Food production is compatible with environmental conservation in Brazil, especially if meat consumption is reduced.

Direct evidence using a controlled greenhouse study for threshold effects of soil organic matter on crop growth

Soil organic matter (SOM) is a key indicator of soil fertility, and building SOM is assumed to decrease reliance on external inputs and ensure stable crop production. Recent syntheses of field data support this assumption with positive SOM-productivity relationships that asymptote at ~4% SOM. Teasing out the directionality of this relationship-the extent to which SOM increases crop growth vs. greater growth leading to higher SOM concentrations-requires controlled experimentation. To disentangle this causative pathway, we conducted a greenhouse experiment whereby we manipulated SOM concentrations from 1% to 9% and evaluated whether the SOM-productivity relationship differed for spring wheat (Triticum aestivum, L.) under nitrogen fertilization crossed with irrigation due to the expectation that SOM buffers the effects of reduced fertilization and/or irrigation. We found that higher concentrations of SOM led to greater productivity (measured as aboveground biomass) up to a threshold of 5% SOM, after which productivity declined across all treatments. These declines occurred despite the fact that indicators of soil health (water-holding capacity, microbial biomass, and bulk density) improved linearly with increasing SOM concentrations. That is, improvements in soil properties did not translate to gains in productivity at the highest SOM levels. Nitrogen fertilization led to greater productivity across all treatments, but to a greater relative extent at lower SOM levels, where we found that productivity on unfertilized soils with 4% SOM matched that of fertilized soils with 2% SOM. Differences in productivity on unfertilized soils due to irrigation emerged at higher SOM levels (>5%), highlighting SOM's role in water retention. Our results demonstrate that building SOM leads to improved growth of a globally important crop; however, our results also indicated a pronounced SOM threshold, after which crop growth declined. This underscores the need to develop optimal SOM targets for desired agricultural and environmental outcomes.

The overlooked spatial dimension of climate-smart agriculture

Climate-smart agriculture (CSA) and sustainable intensification (SI) are widely claimed to be high-potential solutions to address the interlinked challenges of food security and climate change. Operationalization of these promising concepts is still lacking and potential trade-offs are often not considered in the current continental- to global-scale assessments. Here we discuss the effect of spatial variability in the context of the implementation of climate-smart practices on two central indicators, namely yield development and carbon sequestration, considering biophysical limitations of suggested benefits, socioeconomic and institutional barriers to adoption, and feedback mechanisms across scales. We substantiate our arguments by an illustrative analysis using the example of a hypothetical large-scale adoption of conservation agriculture (CA) in sub-Saharan Africa. We argue that, up to now, large-scale assessments widely neglect the spatially variable effects of climate-smart practices, leading to inflated statements about co-benefits of agricultural production and climate change mitigation potentials. There is an urgent need to account for spatial variability in assessments of climate-smart practices and target those locations where synergies in land functions can be maximized in order to meet the global targets. Therefore, we call for more attention toward spatial planning and landscape optimization approaches in the operationalization of CSA and SI to navigate potential trade-offs.

Use It Sustainably or Lose It! The Land Stakes in SDGs for Sub-Saharan Africa

Sub-Saharan Africa (SSA) failed to meet most Millennium Development Goals (MDGs). The Sustainable Development Goals (SDGs) require knowledge-intensive actions that weigh development goals against sustainability options with several possibilities in various contexts. Land resources are the mainstay for most African communities and the basis of achievement of most SDGs. The “transformation imperative” in Africa will only take place in a differentiated set of resource management and use. The baselines in African countries are rather low in terms of internal policy and economic functions. The objective of this paper is to instate ideas on ways to achieve the SDGs through a new transformative design based on a collective capacity of diverse actors to access a range of land-based practices. We should selectively adapt, adopt, or consolidate various land innovations by targeting place and time where various practices have worked or can work in a range of ecologies; what seems to work over the short-term but reduces risks for the long-term; and what the implications are for wealth, food production, livelihoods, climate change, resilience, and development. This requires a greater capacity to apply what is known about transformative action but also set a collaborative learning system to influence policy-makers and action-takers to support sustainable transformation.

Climate and land-use change homogenise terrestrial biodiversity, with consequences for ecosystem functioning and human well-being

Biodiversity continues to decline under the effect of multiple human pressures. We give a brief overview of the main pressures on biodiversity, before focusing on the two that have a predominant effect: land-use and climate change. We discuss how interactions between land-use and climate change in terrestrial systems are likely to have greater impacts than expected when only considering these pressures in isolation. Understanding biodiversity changes is complicated by the fact that such changes are likely to be uneven among different geographic regions and species. We review the evidence for variation in terrestrial biodiversity changes, relating differences among species to key ecological characteristics, and explaining how disproportionate impacts on certain species are leading to a spatial homogenisation of ecological communities. Finally, we explain how the overall losses and homogenisation of biodiversity, and the larger impacts upon certain types of species, are likely to lead to strong negative consequences for the functioning of ecosystems, and consequently for human well-being.