Cropland Intensification Research Articles

The multiscale response of global cropland cropping intensity to urban expansion

CONTEXTUrban expansion(UE) and multiple cropping(MC) are key factors in anthropogenic impacts on global environmental change. However, the multi-scale response patterns of UE and MC have not yet been revealed, and how urbanization affects cropland intensification is still not deeply explored. OBJECTIVEThis study examines the spatial and temporal trends in global UE and MC and analyses the multi-scale response patterns of both. METHODSThe GEE (Google Earth Engine) platform was used to count global cropland cropping intensity (CCI) and impervious surface rasters on an image-by-image basis, while GIS was employed for spatial analyses, and the generalized additive model (GAM) was applied to inscribe variable response trajectories. RESULTS AND CONCLUSIONThe global multiple cropping index(MCI) increased significantly (by 4.1 %) over the period 2001–2019, with growth in double- and triple-cropped cropland dominating this change. Double cropping, as a widespread global farming strategy, has led to a shift towards the intensification of agriculture, with countries in the northern hemisphere contributing more. Global UE significantly expands to twice the baseline level at an average annual growth rate of 2. 42 × 104 km2 over the period 2001–2019, with the expansion of world-class urban agglomerations in China, the United States and Europe dominates this trend. The spatial clustering of MC and UE has continued to intensify, with high-intensity cropping strategies progressively clustering towards areas of significant UE, and this tendency has a clear decreasing urban-rural gradient effect. The global CCI grows significantly and non-linearly with UE, but an important inflection point in the growth trajectory has occurred under the influence of threshold effects. Developed countries tend to be more flexible in their cropping intensity strategies as they move forward with urbanization. There is a clear increasing effect of the urban-rural gradient in the degree of non-linearity in the response of urbanization and cropping intensity. SIGNIFICANCEThe results of the study contribute to the understanding of the complex spatial and temporal coupling mechanisms between UE and MC, and provide useful insights for the development of trade-offs between urbanization and maturity strategies.

Coupling Coordination Analysis of Cropland Intensification and Agroecosystem Services: Evidence from Loess Plateau in Shaanxi Province, China

Coupling Coordination Analysis of Cropland Intensification and Agroecosystem Services: Evidence from Loess Plateau in Shaanxi Province, China

The socio-ecological implications of shifting patterns of cropland use in northeast China

Globally, mid-latitude Mollisol regions are vital breadbasket areas, but their ecosystems are being exhausted by overproduction. Understanding the evolution of agricultural practices and the associated consequences across different socio-ecological contexts is crucial for planning future crop production. Most studies to date have focused mainly on tropical regions, and have concentrated on fixed effects while overlooking spatiotemporal heterogeneity. We present an important case study from northeast China, using shifting patterns of cropland expansion, intensification and specialization from 2000 to 2019 to demonstrate how agricultural practices have evolved and encroached on natural resources. The locational Gini coefficient, revised universal soil loss equation, modified InVEST models, and geographically and temporally weighted regression model were applied to estimate the underlying socio-ecological implications. The results indicated that, cropland expansion (+44.22 %) and specialization were prominent, with grain cultivation increasing to almost 87 % while crop diversity was drastically reduced. Cropland intensification revealed a homogenizing transition, with an increase in machinery power (+97.25 %) and fertilizer (+28.80 %) applications. In the northern Songnen Plain and Sanjiang Plain, alongside expansion, cropland distributions have changed, with the majority of intensification and specialization indicators being pushed to higher latitudes. For example, maize production has driven soybean production to the Lesser Khingan Mountains, and rice has been transferred from the Liaohe Plain to Sanjiang Plain. During 2000–2019, some social indicators, including rural household income, grain production and inequality of agricultural development, improved, but not necessarily in relation to the changes in cropland use. Cropland expansion was beneficial to grain production, but detrimental to spatial equality. Water stress and pollution were identified as major ecological threats as a result of cropland expansion. Carbon sequestration also experienced an expansion-driven increase, but at the expense of crucial local ecosystems with higher carbon densities. Although the overall quality of natural habitats had improved, these habitats were threatened by most of the changes witnessed on the plains. Soil loss was sensitive to expansion in hilly reclaimed areas, but in Songnen Plain and Liaohe Plain, where conservation tillage has been promoted, intensification and specialization pressures were mitigated. A northwards shift of cropland distribution is currently a primary driver of the intensifying socio-ecological implications, representing the ongoing adaption of farming in marginal areas. The intensification and specialization of agricultural practices in Mollisol regions should be the focus for addressing the necessary future reconciliation of agriculture and nature.

Can the transition of multiple cropping systems affect the cropland change?

CONTEXTIntensification of cropland can achieve food security by increasing agricultural production pre-unit yield, thereby slowing down cropland expansion. However, it is also possible to accelerate the cropland expansion due to the increasing net benefits of cropland. The transition of multiple cropping system (MCS) caused by climate change is an important strategy for cropland intensification, its impact on cropland changes needs further in-depth discussion. OBJECTIVEThis research aims to address the following two questions: (1) The transition patterns of the MCS in China against the background of climate change; (2) The impact of the MCS's transition on the change rate of cropland and grain production capacity. METHODSBased on meteorological observation data, the Global Agro-Ecological Zones (GAEZ) model is utilized to map the China's MCS to analyze the temporal and spatial variation patterns of MCS under the comprehensive influence of various meteorological factors. On this basis, we investigate the change of cropland area and grain production capacity under the transition of MCS. RESULTS AND CONCLUSIONSThe results indicate that in the past 20 years, the increase of cropping intensity in China has led to 0.42Mha expansion in the multiple cropping area. Temporally, the probability of maintaining the original cropping system (2000) in 2020 was greater than the probability of transiting (83% > 17%). These transitions occurred more frequently between cropping systems with small gradation differences, and the probability of cross-gradation changes decreased with increasing cropping intensity. Spatially, the MCS exhibited a decreasing trend with increasing distance from the coastline. Although regardless of whether the MCS transiting or maintaining, the cropland area would reduce, the increase in cropping intensity would reduce the cropland area more than the decrease (6.48% > 2.66%). Moreover, we found that the decreased cropping intensity was beneficial to slow down the cropland reduction (4.35%; 2.93%; 5.95% > 2.66%), while increased cropping intensity accelerated the cropland reduction (1.56%; 4.35%; 2.93%; 5.95% < 6.48%). This result was further validated by grid-based statistical regression results (p < 0.05). In regions where the MCS transited, 96% of the cropland decrease was occupied by construction land, and 76% of the cropland expansion was due to the conversion of grassland. Among them, when the cropping intensity increased, although the cropland area reduced even more, the grain production capacity would actually increase by 40.29%, and when the planting intensity decreased, the grain production capacity would decrease by 10.55%. SIGNIFICANCEIncreasing the cropping intensity of cropland through multiple cropping can increase the comprehensive grain yield under the condition of limited cropland resources. This strategy holds significant promise for bolstering China's food security and fostering sustainable agricultural development.

Impact of suburban cropland intensification and afforestation on microbial biodiversity and C sequestration in paddy soils

AbstractRapid urbanization drives changes in suburban cropland and afforestation, but the impact on soil microbes and carbon (C) dynamics remains unclear. Using genetic sequencing (16S rRNA sequence and functional prediction), we assessed the effects of cropland intensification and afforestation on the soil microbial communities and C sequestration potential in a suburban agricultural area. Traditional rotation (rice–wheat) homogenized microbial diversity along soil depth (0–100 cm). Cropland intensification (rice–wheat to rice–vegetables) and afforestation (rice–wheat to forest) decreased fungal diversity below 20 cm, while bacterial diversity and dominant taxa were less affected, due to the advantages of bacterial diversity and dominant taxa distribution. Cropland intensification increased profile C accumulation, mainly due to excessive fertilization (obviously decreased aerobic_chemoheterotrophy below 20 cm in bacterial function), but not C stability (significantly increased permanganate oxidizable C (POXC), and microbial‐dependent C sources tend to from crop litter to soil sources). Afforestation offset C accumulation through no fertilization and inundation, but increased saprophytic function for C sequestration. In addition, pH and C had opposing effects on dominant microbial taxa, mitigating extreme differentiation. Subsoil was more sensitive to changes than topsoil. Altogether, soil C stability decoupled from C accumulation in the suburban agricultural area. Cropland intensification increased C accumulation yet decreased bacterial C sequestration potential and C stability; cropland afforestation facilitated fungi‐derived C accumulation and its C sequestration. Deep soil C sequestration was more vulnerable to suburban agriculture practices, emphasizing the need to consider subsoil C‐cycling in agricultural practices amid urbanization.

Progress in the Study of the Drivers of the Transformation of Arable Land Use

The sustainable use of arable land is a necessity to ensure future global food security. Arable land provides most of the food and necessities of life for human beings, and is the key to achieving the "poverty-free" (Sustainable Development Goals 1, hereinafter referred to as SDG1), "zero hunger" (SDG2), "sustainable cities and communities" (hereinafter referred to as SDG2) and "sustainable cities and communities" (hereinafter referred to as SDG2) objectives of the United Nations Sustainable Development Programme. SDG1 (hereinafter referred to as "SDG1"), "Zero Hunger" (SDG2), "Sustainable Cities and Communities" (SDG11), and "Climate Action" (SDG13) of the United Nations Sustainable Development Programme (SDP), "terrestrial organisms" (SDG15), and other key resource-environmental elements of the Sustainable Development Goals (SDGs). Cropland expansion and cropland intensification have been important strategies for increasing food production, but with the global depletion of cropland reserves, increasing food production by expanding the area of cropland is no longer viable, and the pressure for food security has shifted to the existing cropland, which accounts for 38 per cent of the global terrestrial area. In the last 20 years, global food production has almost doubled, but the area of arable land has increased by only 9%. Demand for food is accelerating in tandem with rapid global economic and social development, population expansion and improved diets. The global demand for food is expected to increase by about 70 to 100 per cent by 2050, which not only puts enormous pressure on existing arable land but also poses a great challenge to the future food security of the world. The sustainable use of existing arable land is the only way to meet the growing demand for food and avoid a global food crisis.

Significant increase in gray water footprint enhanced the degradation risk of cropland system in China since 1990

Cropland intensification is one of the main ways to achieve food growth; however, it also leads to the degradation of the water quality. The gray water footprint (GWF) is an important index for evaluating the degradation of the water quality caused by the overuse of cropland. Therefore, evaluating the GWF and analyzing the degradation risk caused by the rapid growth of crops are important ways to measure the sustainable intensification of cropland use. In this study, by using agricultural production panel data at the national level from the China National Agricultural Production database and nitrogen, and phosphorus cycle parameter data from previous studies, we adopted the gray water model and gray water stress to evaluate the GWF and related degradation risk of cropland systems in China from 1990 to 2018. We found that the GWF in China increased fourfold from 1990 to 2018. The GWF increase in southern China was generally lower than that in the northern provinces. GWFs of rice, wheat, and maize increased rapidly by 200%, 258%, and 741%, respectively, whereas for soybean, potato, and other cereals, the increases in the GWF were relatively small. GWF intensities of rice, wheat, and maize were higher than those of other crops, ranging from 1.71 × 104 to 5.5 × 104 m3/hm2. Chemical fertilizers were the main source of GWF from 1990 to 2018. Moreover, the degradation risk caused by the GWF significantly increased. Thirty-five percent increased to seventy percent of the provinces had serious gray water stress and were at a severe risk of degradation from 1990 to 2018. To reduce the GWF and related degradation risk in cropland systems, the intensity of cropland use should be reduced, and the spatial distribution of cropland should be improved and optimized.

Mapping Cropland Intensification in Ecuador through Spectral Analysis of MODIS NDVI Time Series

Multiple cropping systems constitute an essential agricultural practice that will ensure food security within the increasing demand of basic cereals as a consequence of global population growth and climate change effects. In this regard, there is a need to develop new methodologies to adequately monitor cropland intensification. The main objective of this research was to assess cropland intensification by means of spectral analysis of MODIS NDVI time series in a high cloudiness tropical area such as Ecuador. A surface of 89,225 ha of the main staple crops in this country, which are rice and maize crops, was monitored to assess the evolution of the number of crop cycles. The 20-year period of NDVI time series was used to calculate the periodograms across four subperiods (2001–2005, 2006–2010, 2011–2015, 2016–2020). The maximum ordinate value of each periodogram was used as an indicator of the number of growing crop cycles per year identifying single-, double-, and triple-cropping systems in each subperiod. Cropland intensification was assessed by comparing the cropping system between the subperiods. Results reveal that more than half of the studied croplands experienced changes in the cropping systems, and 40% showed positive trends in terms of the number of growing crop cycles, being principally located near the main rivers where irrigation facilitates crop development during the dry season. Therefore, the area under single cropping decreased from over 60,000 ha in the first subperiod to less than 50,000 ha in the last two subperiods. The cropland surface subjected to multi-cropping practices increased during the second decade of the study period, with a double-cropping system being more widely used than growing three crops per year, reaching surfaces of 24,400 ha and 10,450 ha in the last subperiod, respectively. The robust results obtained in this research show the great potential of the periodogram approach for the discrimination of cropping systems and for mapping intensification areas in tropical regions where dealing with noisy remote sensing time series as a consequence of high cloudiness is a great challenge.

Markedly declining reproductive functional diversity of food plants in the world’s largest tropical country despite rapid cropland expansion

Cropland intensification in tropical regions is usually associated with agricultural commodity expansion that penalizes the species diversity and environmental services of natural ecosystems. However, the extent to which cropland expansion affects the reproductive functional diversity of crop arrangements remains poorly investigated. Here we examine the agricultural development of a leading agricultural producer and megadiverse country (Brazil) over the last six decades to understand the effects of agricultural expansion on the reproductive functional diversity of crops, particularly those bearing specialized traits. We used the FAO database, which provides annualized information on crop production from 1961 to 2018. Cultivated species were classified according to their reproductive traits and levels of dependence on biotic pollination, used as indicators of functional diversity. Our results show that cropland areas in Brazil expanded by 201.3% from 1961 to 2018. In particular, pollinator‐dependent crops expanded over this period by 305.2% compared to 125.3% in non-dependent crops. Expansion of monoculture farmland was remarkable, comprising 88% of the entire agricultural cropland acreage in 2018, 45% of which was represented by soybean. Additionally, cropland expansion was related to a reduction in functionally diverse crop species, which was most intense for those with specialized reproductive traits. These results indicate a threat to a diversified food production system and its resilience, given the impacts of cropland expansion on native biodiversity and the reduction in pollination services for many crops. We argue that agroecosystems in Brazil require sustainable, pollinator-friendly agricultural practices to maintain or enhance a nutritionally diversified food production system. Integrated practices that sustain agricultural cropland mosaics characterized by high reproductive functional diversity of the cultivated species can be a nature-based solution to protect natural pollinators and pollination services within a diversified food system.

Quantifying recent trends in multifaceted cropland intensification in China: Cropping intensity, land productivity, and their effects on farmer livelihoods

AbstractAssessing changes in the extent and intensity of cropland use is essential to understanding the processes underlying agricultural development. However, our knowledge of the spatiotemporal dynamics of cropland intensification, and how they connect to the livelihoods of rural households, is currently limited. This paper aims to quantify key components of cropland intensification in China through trend analysis of cropping intensity and land productivity over time. This information is then used to model the effects of cropland intensification on farmers’ livelihoods. We found that most croplands were under intensive use characterized by steady cropping frequency or multi‐cropping from 2001 to 2018, while the variation in cropping frequency exhibited a significant north–south spatial disparity. High cropping intensity increased land productivity. However, over 25% of the total cropland area experienced productivity improvements that were characterized as inconsistent. Our work suggests that the economic output of farming is greatly driven by land management intensity and that fertilizer use is the predominant driver of this. We also found that cropping intensity at the landscape scale showed no correlation with agricultural income, but land productivity correlated significantly with both land management intensity and rural livelihood metrics. The findings presented here highlight the importance of integrating the long‐term consistency of land productivity and rural livelihoods into the research framework of land use intensification. Doing so advances the current understanding of diverse cropland use change in China.

Cropland intensification mediates the radiative balance of greenhouse gas emissions and soil carbon sequestration in maize systems of sub-Saharan Africa.

Sub-Saharan Africa (SSA) must undertake proper cropland intensification for higher crop yields while minimizing climate impacts. Unfortunately, no studies have simultaneously quantified greenhouse gas (GHG; CO2 , CH4 , and N2 O) emissions and soil organic carbon (SOC) change in SSA croplands, leaving it a blind spot in the accounting of global warming potential (GWP). Here, based on 2-year field monitoring of soil emissions of CO2 , CH4 , and N2 O, as well as SOC changes in two contrasting soil types (sandy vs. clayey), we provided the first, full accounting of GWP for maize systems in response to cropland intensifications (increasing nitrogen rates and in combination with crop residue return) in SSA. To corroborate our field observations on SOC change (i.e., 2-year, a short duration), we implemented a process-oriented model parameterized with field data to simulate SOC dynamic over time. We further tested the generality of our findings by including a literature synthesis of SOC change across maize-based systems in SSA. We found that nitrogen application reduced SOC loss, likely through increased biomass yield and consequently belowground carbon allocation. Residue return switched the direction of SOC change from loss to gain; such a benefit (SOC sequestration) was not compromised by CH4 emissions (negligible) nor outweighed by the amplified N2 O emissions, and contributed to negative net GWP. Overall, we show encouraging results that, combining residue and fertilizer-nitrogen input allowed for sequestering 82-284 kg of CO2 -eq per Mg of maize grain produced across two soils. All analyses pointed to an advantage of sandy over clayey soils in achieving higher SOC sequestration targets, and thus call for a re-evaluation on the potential of sandy soils in SOC sequestration across SSA croplands. Our findings carry important implications for developing viable intensification practices for SSA croplands in mitigating climate change while securing food production.

Response of landscape dynamics to socio-economic development and biophysical setting across the farming-pastoral ecotone of northern China and its implications for regional sustainable land management

The farming-pastoral ecotone, one of the most sensitive eco-climatic zones worldwide, is suffering from the impacts of rapid socio-economic development and climate change. However, there is still only limited knowledge of how the land system responded to these large changes. Therefore, this study selected the farming-pastoral ecotone of northern China (FPEN) as a typical study area, and tried to use long-term (1980 s-2015) land use data, socio-economic data and climatic data to investigate the landscape dynamics in response to socio-economic development and biophysical setting. Results showed that the entire FPEN experienced three divergent stages, i.e., strong land development/reclamation (before 2000), then land restoration (2000–2010), and finally land use optimization management (after 2010) in the past four decades. In the stage of land reclamation, the croplands of FPEN went through a rapid expansion and reached the maximum area in 2000 with 2.41 × 105 km2. Meanwhile, the entire study area's cropland gravity center had the highest spatial shift rate by ∼3.0 km/a, compared to the averaged ratio for the entire period (1.38 km/a) and those in the other two periods. The most fragmentized landscape patterns were also observed in this stage. In the second stage, large areas of sloped croplands were converted into ecological land (i.e., forests and grasslands). Its landscape complexity and spatial aggregation peaked the whole research period at 84.07 km and 3.82 km. Land consolidation and cropland intensification based on land engineering are the main characteristics in the current third stage of land use optimization management. The analyses based on geographical detector software (a tool for measuring of spatial stratified heterogeneity and attributing of spatial patterns) indicated that per capita GDP and elevation-dependent factor were the top two indictors in determining landscape dynamics at present. Besides, the findings of this study suggest that more efforts could focus on balancing the ecology and livelihoods in future sustainable land-use management.

From woodfuel to industrial wood: A socio-metabolic reading of the forest transition in Spain (1860–2010)

After centuries of deforestation, many, mostly industrialized countries have recently been experiencing net increases in forest area and biomass stocks, a phenomenon described as ‘Forest Transition’. In this article, we analyse the Spanish forest transition over the last 150 years from a socio-metabolic perspective. We provide the first estimation on forest surface, wood production and biomass stocks and we relate these changes to the socio-metabolic transformations of Spain's economy. Between 1860 and 1950, within a context of organic metabolism and growing population pressure, the stock of forest biomass decreased by 25.3%, falling to its lowest level in c. 1950. By conducting a decomposition analysis, we show that deforestation (i.e., declining forest area) explains 33.7% of the decrease in stock, while the reduction of biomass density accounts for 66.3%. Since 1950, and coinciding with the industrial socio-metabolic transition, forest biomass stocks multiplied by a factor of 2.5. Cropland intensification, the outsourcing of land use to third countries and agricultural policy encouraged the expansion of forest areas. Nevertheless, the substitution of firewood with fossil fuels was the main explanatory factor of the stock increase, since it enabled a dramatic decline in wood appropriation and the consequent increase in biomass density.

CHANGES IN GLOBAL LAND USE AND CO2 EMISSIONS FROM US BIOETHANOL PRODUCTION: WHAT DRIVES DIFFERENCES IN ESTIMATES BETWEEN CORN AND CELLULOSIC ETHANOL?

Land use change (LUC) CO2 emissions associated with bioenergy production depend on the amount of land required to produce bioenergy crops, the carbon stored in such crops (including in the leaves, stalk, roots and soil), and the carbon emitted when another land cover is directly or indirectly displaced as a result. In this study, we use a global integrated assessment model [the Global Change Analysis Model (GCAM)] to explore the differences in estimates of LUC CO2 emissions for two crops (corn and switchgrass) used to produce ethanol in the United States under alternative assumptions about natural lands protection. Varying the latter assumptions for corn ethanol results in net LUC CO2 emissions between 7 and 41 gCO2 per MJ of ethanol, whereas varying the same assumptions for switchgrass ethanol results in net emissions between [Formula: see text]26 and 14 gCO2 per MJ of ethanol. The low-end estimate for each occurs when natural lands are assumed to be fully protected everywhere, which leads to significant cropland intensification. The high-end estimate for each occurs when natural lands are assumed to be unprotected everywhere, leading to greater cropland expansion and associated conversion of unmanaged forest and pasture. Results from this study could be used to inform scenarios of future energy system change or life cycle assessment of biofuels for which LUC emissions would be an input.

Assessing benefits of land use intensification on extensive grain cropping systems of the Pampas

A holistic approach in the design of cropping systems is essential to boost productivity in a sustainable manner. One of the most important decisions in the cropping system is the way that crops are organized in sequences, which is commonly oriented to obtain high yields and associated economic return while minimizing variability and risk. Increased cropping intensity based on sequenced winter/summer crops has proven to raise annual land productivity due to a larger utilization of environmental resources. In this study, we aim to compare a soybean monoculture sequence with more diverse and intensified crop rotations in terms of resource use, overall productivity, and economic return in four sites, along six years, exploring a relatively wide range of environmental conditions in the central area of the Argentine Pampas. Results showed that more intensified and diverse cropping sequences yielded 41–51% more, in average, than soybean monoculture, given that this latter crop makes use of available environmental resources only during summer. In addition, despite higher production cost when growing more diverse and intensified rotations, annual gross margin was 10–13% higher, in average, than soybean monoculture. According to our results, cropland intensification resulted in larger productive, economic, and environmental benefits. At this point, new alternative winter crops and intensified cropping systems may expand. However, to effectively promote such process in the Pampas, it appears that policy decision makers should target the development of new markets and create opportunities to use or sell the extra production.

The effects ofAgriculture Productivity, Land Intensification, on Sustainable Economic Growth: A panel analysis from Bangladesh, India, and Pakistan Economies.

Population in South Asia is increasing ever than a faster rate, subsequently; food security, climate change, and capital intensive agro farming techniques are the prevailing challenges in this region. This is a tri-country penal analysis, Pakistan, India, and Bangladesh, and the study covers the data throughout (1973-2020). This study has used modern farm input data besides demographic variables in the study. In this study, we use panel data set, ARDL (PMG) approach, autoregressive distributed lag model pooled mean group, which is an extensively dynamic modeling technique for heterogeneous data. The results of the study explore that transition in the demographic pattern in Pakistan, India, and Bangladesh is the real cause of low crop productivity and land intensification. Technology innovation is the only ray of hope to fulfill the food demand of the future ahead and climate agriculture practices can hamper the further deterioration of the small farmlands.

Enhanced surface urban heat islands due to divergent urban-rural greening trends

Satellite observations show that the surface urban heat island intensity (SUHII) has been increasing over the last two decades. This is often accompanied by an increased urban-rural contrast of vegetation greenness. However, the contribution of uneven vegetation trends in urban and rural areas to the trend of SUHII is unclear, due to the confounding effects of climate change and changes in man-made infrastructures and anthropogenic heat sources. Here we use a data-model fusion approach to quantify such contributions during the peak growing season. We show that the LAIdif (the urban-rural difference of leaf area index) is increasing (P< 0.05) in 189 of the selected 228 global megacities. The increasing trend of LAIdif from 2000 to 2019 accounts for about one quarter of the trend in satellite-derived SUHII, and the impact is particularly evident in places with rapid urbanization and rural cropland intensification. The marginal sensitivity of SUHII to LAIdif is the strongest in hot-humid megacities surrounded by croplands and in hot-dry megacities surrounded by mixed woody and herbaceous vegetation. Our study highlights the role of long-term vegetation trends in modulating the trends of urban-rural temperature differences.

Integrating inductive and deductive analysis to identify and characterize archetypical social-ecological systems and their changes

Archetype analysis is a key tool in landscape and sustainability research to organize social-ecological complexity and to identify social-ecological systems (SESs). While inductive archetype analysis can characterize the diversity of SESs within a region, deductively derived archetypes have greater interpretative power to compare across regions. Here, we developed a novel archetype approach that combines the strengths of both perspectives. We applied inductive clustering to an integrative dataset to map 15 typical SESs for 2016 and 12 social-ecological changes (1999–2016) in Andalusia region (Spain). We linked these types to deductive types of human-nature connectedness, resulting in a nested archetype classification. Our analyses revealed combinations of typical SESs and social-ecological changes that shape them, such as agricultural intensification and peri-urbanization in agricultural SESs, declining agriculture in natural SESs or population de-concentration (counter-urbanization) in urban SESs. Likewise, we identified a gradient of human-nature connectedness across SESs and typical social-ecological changes fostering this gradient. This allowed us to map areas that face specific sustainability challenges linked to ongoing regime shifts (e.g., from rural to urbanized systems) and trajectories towards social-ecological traps (e.g., cropland intensification in drylands) associated with decreasing human-nature connectedness. This provides spatial templates for targeting policy responses related to the sustainable intensification of agricultural systems, the disappearance of traditional cropping systems and abandonment of rural lands, or the reconnection of urban population with the local environment, among others. Generally, our approach allows for different levels of abstraction, keeping regional context-specificity while linking to globally recognisable archetypes, and thus to generalization and theory-building efforts.

Impact of cropland development intensity and expansion on natural vegetation in different African countries

The world's rapid population growth is also fueling the high demand for food. Cropland intensification and expansion as the primary source of increasing food production thrives everywhere, yet hinders natural vegetation. This study aims to examine the extent to which the development of Cropland intensity affects natural vegetation and scrutinizes its relationship with Gross Domestic Product (GDP) on the African continent from 1992 to 2015. The ratio of total Crop area harvested and Cropland extent (CE) datasets used to compute the cropping intensity CI (yr−1) for each year over 24 years. The correlation coefficient and comparison method were applied for cropland intensity and natural vegetation to reveal the rate at which cropland intensity affects natural vegetation. The same method was applied between CI, CE and GDP percentage from Agriculture to know their relationship. The results revealed that Cropland extended at a rate of about 9130.17 km2 yr−1, leading to a rise of 219,123.99 km2 of increase. Shrubland was the most devastated natural vegetation at a rate of −9461.96 km2 and cleared about 227,087.1 km2. The CI and GDP percentage from agriculture showed a strong negative correlation in most of the countries, especially in developing countries. The CI is low and the CE is high, which means the degradation of existing natural vegetation and the eradication of potential environment health. Ethiopia and Tanzania have been the only two countries which experienced cropland decrease among the top 10 African countries with a large cropland area, while Nigeria and Sudan have increased the most. Further Malawi witnessed the highest percentage growth for cropland. South Sudan has identified strong trends in GDP percent from agriculture, while Libya has seen substantial decline. On the other hand, Liberia, Sierra Leone, Guinea-Bissau, Ethiopia, and Chad identified to have the biggest % of agriculture to GDP during the study period.

The complexity of measuring cropland use intensity: An empirical study

CONTEXTCropland intensification promises additional food supply without further expanding croplands into natural ecosystems. Cropland use intensity measures the degree of intensification by various indicators, both from input and output perspectives; all of these indicators are however not always coherent—which may cause confusion and send contradicting signals to policymakers. Few empirical studies have been conducted to relate and compare various intensity indicators. OBJECTIVEIn this study, we start with a hypothesis that cropland use intensity measured by different indicators may differ. We then test such a hypothesis based on empirical evidence in a typical multi-cropped region (i.e., Jinxian County) in Jiangxi Province—a major breadbasket in Southern China. METHODSWe focus on two widely used indicators, i.e., multi-cropping frequency (MCF) and crop growth duration (GDa), measured by a hybrid time-series remote sensing dataset which fuses MODIS and Gaofen-1 images for the year 2015. We map these two indicators independently at a 16 m spatial resolution. For each pixel, MCF takes value from 1 to 3 corresponding to single-, double- and triple- cropping; while GDa is quantified by the accumulative crop growth days within the study year. We relate the values of two indicators, summarize the descriptive statistics of GDa grouped by MCF categories, and compare MCF and GDa values by using a box-whisker chart, a bivariate map, and a set of statistical tests. RESULTS AND CONCLUSIONSWe find that a significant overlap of GDa exists between single cropping and double cropping both visually and statistically. In other words, the different cropland intensity levels measured by MCF appear to be the same if measured by GDa. The box-whisker chart shows that the GDa of single cropping in the upper quarter is substantially longer than the GDa of double cropping in the lower quarter. The non-parametric tests show that the overlapped GDa between single cropping and double cropping exists substantially, which may cause confusion. Moreover, the bivariate map shows that single cropping with shorter growth duration (i.e., consistent low intensity) and double cropping with longer growth duration (i.e., consistent high intensity) account for 44% and 28%, respectively, while the rest manifested as inconsistent which accounts for another 28% of the total cropland area. SIGNIFICANCEThese results confirm our hypothesis—the inconsistency among intensification indicators. Different measurements may convey contradicting messages for policymakers in pursuing the sustainable intensification goals, which suggests more efforts are required to understand the multidimensionality of the process of cropland intensification for distinct policy measurements.