Land Margin Research Articles

Contribution of Aerobic Cellulolytic Gut Bacteria to Cellulose Digestion in Fifteen Coastal Grapsoid Crabs Underpins Potential for Mineralization of Mangrove Production

Grapsoid crabs (Decapoda: Grapsoidea) inhabiting along the land-sea transition provided various amounts and quality of vascular plant carbon (e.g., fresh mangrove leaf, leaf litter, and mangrove-derived organic carbon) and perform differing levels of herbivory. Other than endogenous cellulase, symbiotic cellulolytic bacteria could also contribute to the crabs’ vascular plant carbon assimilation and mineralization. In this study, we isolated culturable cellulolytic bacteria from three gut regions (i.e., stomach, midgut, and hindgut) of 15 species of grapsoid crabs that inhabit in various coastal habitats (i.e., land margin, mangrove forest, tidal flat, and subtidal area). Bacillus, which was isolated from 11 out of the 15 grapsoid crabs, was the most common genus of culturable prominently cellulolytic bacteria among the target species. Seventy to ninety nine percent of culturable cellulolytic bacteria were removed, and the endoglucanase activity of five species was significantly reduced by 14.4–27.7% after antibiotic treatment. These results suggest that cellulolytic bacteria play a role in assisting mangrove carbon utilization in coastal grapsoid crabs, especially those inhabiting mangrove, mudflat, and subtidal areas. The significantly higher abundance of cellulolytic bacteria and the generally higher hydrolytic capacity of the bacteria in mangrove crab species suggest that they receive more contribution from symbionts for mangrove carbon utilization, while semi-terrestrial crabs seem to depend little on symbiotic cellulase due to the lower abundances.

Analysis of The Implementation of Sustainable Food Agricultural Land Protection Policy in Bandung District: A Case Study of Rice Field Conversion in Cikancung District

The policy of sustainable protection of agricultural land becomes crucial in addressing land degradation and land use conversion, especially from agriculture to non-agriculture, alongside the increasing demand for land due to population growth and economic development, which can lead to negative impacts such as a decrease in food security, marginalization of agricultural land, and an increase in flood risks. This research aims to analyze the implementation of the Sustainable Protection of Food Agricultural Land Policy, understand the rate of paddy field conversion, and identify trends in land conversion after the policy's enforcement. This study employs a qualitative approach, with data obtained through interviews, observations, and documentary studies. The research is conducted in Bandung Regency, with samples taken from Cikancung Sub-district, Bandung Regency, West Java Province. Informants involved in this research are selected through judgment sampling and are individuals related to the sustainable protection of agricultural land policy and relevant stakeholders. Data analysis is conducted using qualitative and spatial analysis. The research findings indicate that the implementation of sustainable agricultural land protection policy in Bandung Regency is still in the socialization and planning stages. Based on spatial analysis, the implementation of the policy in Cikancung Sub-district has led to the conversion of paddy fields, particularly in non-technical irrigation paddy fields, predominantly converted into industrial land. This conversion covers a total area of 20.3 hectares, with the most significant change occurring in non-technical irrigation paddy fields converted into industries, covering an area of 13.7 hectares. Based on internal, external, and policy analysis, it can be concluded that the policy implementation in Cikancung Sub-district has not been optimal in addressing the conversion of paddy fields.

Neodymium isotope composition and rare earth element distribution of East Antarctic continental shelf and deep waters

Circumpolar Deep Water (CDW) and Antarctic Bottom Water (AABW) play key roles in the Earth's climate system. Both water masses form critical components of the Antarctic Circumpolar Current and Meridional Overturning Circulation and therefore directly influence the large-scale redistribution of heat, nutrients and carbon. Reconstruction of past CDW transport and AABW production and export has been a key target in palaeoceanography. One promising proxy to achieve this has been the neodymium (Nd) isotope composition of seawater. The biogeochemical processes controlling Nd in the ocean, however, remain underconstrained, and modern observations of Nd isotopes in the Southern Ocean are still geographically limited.To overcome this limitation, 61 seawater samples were collected for Nd isotope and rare earth element (REE) analysis at nine stations along the Wilkes Land continental margin and in the Australian-Antarctic Basin (65°S 125°E) near East Antarctica. The results show that the different water masses have the following Nd isotope characteristics: Antarctic Surface Water (AASW), εNd = −9.0 ± 1.0 (2SD; n = 22); Modified CDW (MCDW), εNd = −8.8 ± 0.8 (2SD; n = 22); AABW, εNd = −8.3 ± 0.5 (2SD; n = 17).There is no evidence of continental REE inputs to surface waters on the Wilkes Land margin. Observed zonal variability of Nd isotope composition in AASW can be attributed to seasonal competition between the poleward flow of warm AASW from the AAG and the westward export of cold surface shelf waters by the Antarctic Slope Current.In terms of deep and bottom waters, mixing of upwelled CDW with AASW and AABW exclusively controls the Nd isotope composition of MCDW, with no indication of boundary processes modifying the Nd isotope composition of MCDW as it encroaches the shelf or slope. The regional Nd isotope signature for AABW is intermediate between published data for the Atlantic sector AABW (εNd = −9.1 ± 0.7) and Pacific sector AABW (εNd = −7.4 ± 0.9). In the absence of active convection, this Nd isotope signature can be explained by a mixture of advected AABW from the Adélie Land coast with a more dominant component of local MCDW and CDW.The data presented in this study constitute the first Nd isotope data set in this part of the Southern Ocean and suggest conservative behaviour of Nd in proximity to the old East Antarctic continent.

Coastal bathymetry in central Dronning Maud Land controls ice shelf stability

Knowledge of the bathymetry of Antarctica’s margins is crucial for models and interpretations of ice-ocean interactions and their influence on ongoing and future sea level change, but remains patchy where ice shelves and multi-year sea ice block measurements. Here, we present a bathymetric model for the central Dronning Maud Land margin, based on a constrained inversion of airborne gravity data. It shows the cavities beneath the region’s two ice shelves to be much deeper than in existing bathymetric compilations, but to be shielded from Warm Deep Water ingress and basal melting by the presence of shallow bathymetric sills along the continental shelf. Over areas of multi-year sea ice, the model returns bathymetric estimates of similar accuracy to gravity interpolation-based methods over open water. Airborne gravity thus presents an opportunity to bathymetrically map hundreds of thousands of square kilometres of the most inaccessible margins of Antarctica at resolutions adequate for regional and global oceanographic and glaciological modelling and interpretation.

Understanding the impact of cultivated land-use changes on China's grain production potential and policy implications: A perspective of non-agriculturalization, non-grainization, and marginalization

Cultivated land plays a pivotal role in ensuring national food security. The challenges of non-agriculture, non-grain production and the marginalization of cultivated land have become increasingly pronounced in the context of urbanization and industrialization in China, posing potential threats to long-term food security. This study employs a combination of remote sensing and statistical data to reveal the effects of non-agriculturalization, non-grainization, and the marginalization of cultivated land on grain production potential (GPP) at the grid scale. From 1992 to 2020, the total farmland area initially exhibited an ascending trend followed by a subsequent decline, resulting in a net decrease of approximately 0.84% in China. the northward shift in the center of gravity of cultivated land has accentuated the spatial disparity between grain production and consumption. Non-agriculturalization, non-grainization, and marginalization of cultivated land contributed 35.22%, 22.58%, and 42.20% to the GPP loss, respectively. GPP loss exhibited significant differences across the agroclimatic zones, with the combined loss in the Middle-lower Yangtze Plain and Huang-Huai-Hai Plain exceeding 60% of the national total. Cultivated land marginalization has emerged as the most impactful land-use change affecting GPP, leading to a substantial loss of approximately 11471.30 × 104 t. The affected area is predominantly concentrated in the southern region. The marginalization of cultivated land has not been effectively alleviated, and the expansion trend continues. Conservation endeavors targeting cultivated land should prioritize enhancing farmers' willingness to cultivate, curbing the extensive utilization of farmland, and mitigating the escalating trend of farmland marginalization.

Soil extracellular enzyme activity and microbial resource limitation exhibited close relationships with groundwater table decline in desert wetlands

In groundwater-fed desert wetlands, groundwater table (GWT) decline leads to the loss of carbon and nutrients, followed by the expansion of desertification. How the GWT decline affects soil nutrient cycling and microbial resource limitation is still unclear. Here, we sampled soils along a steep GWT decline gradient in desert wetlands and surroundings traversing marshland (ML), sandy grassland (SG) and bare sandy land (SL) in the southern margin of Mu Us Sandy Land, China, then determined the extracellular enzyme activity (EEA, including carbon (C)-, nitrogen (N)- and phosphorus (P)-acquiring enzymes) and related soil environmental variables, and quantified the relative value of microbial metabolic limitation by vector analysis. Results showed that GWT decline eventually inhibited the activities of soil C-, N- and P-acquiring enzymes, which might be unfavourable for nutrient cycling. The relationship between soil microbial C limitation and GWT showed a downwards unimodal trend, despite the largest SOC value observed in ML. However, microbial P limitation was relieved by a slight GWT decline, and the continuous decline in GWT eventually shifted microorganisms from P to N limitation. We further provide evidence that DOC and C:P were the key factors explaining the variations in microbial C and nutrient limitations along the decline in GWT, respectively. Altogether, these findings suggest that soil EEA and microbial resource limitation exhibit close relationships with GWT decline in desert wetlands. Moreover, they highlight that alleviating microbial N limitation may be the primary solution for vegetation restoration and carbon sequestration in sandy land around wetlands.

Agriculture Distress and Farmers' Suicide in Kerala in the Globalization Era

Liberalization, privatization, and globalization are to blame for Kerala's rural poverty and farmer suicides. Ineffective state and federal government policies, a lack of coordinated public investment, ongoing flooding, trade manipulation, false seeds and pesticides, a fluctuating price for agricultural products, growing cultivation expenses, an increase in droughts, as well as a loss of biodiversity are all factors that negatively affect agriculture. Though it receives criticism, the opposition to the current administration is strong in states with high rates of farmer suicide. A.R. Vasavi's Triple Crisis of Agriculture (1999), the widespread use of hybrid seeds, chemical fertilizers, and pesticides, as well as the inadvertent escalation of farmer debt, are the five primary debates that need to be addressed in order to investigate farmer suicides. As of now, a significant amount of government funding—1,69,6718 crores in 2017–18 and 97,3729 crores in the 12th five-year plan—was allocated to the agriculture sector. However, the state of farming and agrarian hardship has not much improved. H+owever, the rate of agriculturalists' concern dramatically increased. The price of the cash crop products grown in Kerala—pepper, coffee, and rubber—is significantly impacted by free trade agreements with ASEAN. Farmer's suicide has a significant relationship with these factors as well as extreme climate change along with, the heavy burden of debt, marginalization of land, etc.

Predicting Biomass Yields of Advanced Switchgrass Cultivars for Bioenergy and Ecosystem Services Using Machine Learning

The production of advanced perennial bioenergy crops within marginal areas of the agricultural landscape is gaining interest due to its potential to sustainably produce feedstocks for biofuels and bioproducts while also improving the sustainability and resilience of commodity crop production. However, predicting the biomass yields of this production system is challenging because marginal areas are often relatively small and spread around agricultural fields and are typically associated with various abiotic conditions that limit crop production. Machine learning (ML) offers a viable solution as a biomass yield prediction tool because it is suited to predicting relationships with complex functional associations. The objectives of this study were to (1) evaluate the accuracy of commonly applied ML algorithms in agricultural applications for predicting the biomass yields of advanced switchgrass cultivars for bioenergy and ecosystem services and (2) determine the most important biomass yield predictors. Datasets on biomass yield, weather, land marginality, soil properties, and agronomic management were generated from three field study sites in two U.S. Midwest states (Illinois and Iowa) over three growing seasons. The ML algorithms evaluated in the study included random forests (RFs), gradient boosting machines (GBMs), artificial neural networks (ANNs), K-neighbors regressor (KNR), AdaBoost regressor (ABR), and partial least squares regression (PLSR). Coefficient of determination (R2) and mean absolute error (MAE) were used to evaluate the predictive accuracy of the tested algorithms. Results showed that the ensemble methods, RF (R2 = 0.86, MAE = 0.62 Mg/ha), GBM (R2 = 0.88, MAE = 0.57 Mg/ha), and GBM (R2 = 0.78, MAE = 0.66 Mg/ha), were the most accurate in predicting biomass yields of the Independence, Liberty, and Shawnee switchgrass cultivars, respectively. This is in agreement with similar studies that apply ML to multi-feature problems where traditional statistical methods are less applicable and datasets used were considered to be relatively small for ANNs. Consistent with previous studies on switchgrass, the most important predictors of biomass yield included average annual temperature, average growing season temperature, sum of the growing season precipitation, field slope, and elevation. This study helps pave the way for applying ML as a management tool for alternative bioenergy landscapes where understanding agronomic and environmental performance of a multifunctional cropping system seasonally and interannually at the sub-field scale is critical.

Estimate provincial-level effectiveness of the arable land requisition-compensation balance policy in mainland China in the last 20 years

The “requisition-compensation balance policy” is a basic arable land protection policy promulgated by the Chinese government to maintain the dynamic balance of the total arable land. Since the implementation of the “requisition-compensation balance policy”, its important role in the conservation of arable land has been widely noted. Multiple studies indicate the effectiveness of the policy by estimating the quantity and quality change of arable land. In addition, the defects and negative externalities of the policy are disputed. The overall goal of this study is to estimate the provincial-level effectiveness of the “requisition-compensation balance policy” in mainland China in two periods (i.e., 2000—2010; 2010—2020) from four perspectives: arable land quantity dynamic balance; arable land productivity balance; farming distance; and sustainability of arable land use. The results showed that, first, the arable land quantity balance was achieved during 2000–2020 from a national perspective. There are still 19–23% of provinces have failed to reach the quantity balance. Second, the decrease in China’s total arable land productivity was exacerbated from 9612.1 thousand tons. to 31254.6 thousand ton. The average potential yield balance index was less than 1 for nearly all provinces during 2000–2010 and became even worse in the next decade because of occupying superior arable land while compensating for inferior arable land. The conservation of arable land productivity has become more important than the conservation of quantity. Third, due to the lack of constraints on the farming distance changes in the “requisition-compensation balance policy”, most provinces convert arable land around urban and rural areas to built-up land while replenishing land far from residential areas without providing adequate agricultural infrastructure, which leads to an increase in the cost of farming and consequently to an increase in the marginalization of arable land. During 2010–2020, the average farming distance of compensated arable land at the provincial level reached 2–7 times that of occupied arable land. However, the average farming distance of the whole arable land at the provincial level decreased by 3.82–63.88% during the same period. This contradiction is mainly due to increasing marginalization and opportunity costs resulting in arable land with high farming distance (including arable land that was compensated in the past) to be used with low intensity or even abandoned and thus identified as other land use types by remote sensing classification models. This factor outweighed that of “occupy nearby arable land while compensating farther one”, resulting in a reduction in the provincial average farming distance. Fourth, the percentage of sustainable compensated arable land in most provinces was lower than 70%. This indicated that the utilization and protection of arable land in these provinces was insufficiently implemented and monitored. Challenges along optimization of the “requisition-compensation balance policy” were discussed from two respects: data, theory and methodology and policy design and implementation. The authors argue that a more comprehensive “requisition-compensation balance policy” should be designed considering not only the quantity and productivity of arable land but also the farming distance, sustainability and ecological protection. A differentiated regulation mechanism of arable land requisition compensation in trans-provincial areas should be formulated. This study can provide guidance for optimizing the implementation of regional arable land protection and can also provide a reference for other countries to protect arable land.

Multiple episodes of ice loss from the Wilkes Subglacial Basin during the Last Interglacial

The Last Interglacial (LIG: 130,000–115,000 years ago) was a period of warmer global mean temperatures and higher and more variable sea levels than the Holocene (11,700–0 years ago). Therefore, a better understanding of Antarctic ice-sheet dynamics during this interval would provide valuable insights for projecting sea-level change in future warming scenarios. Here we present a high-resolution record constraining ice-sheet changes in the Wilkes Subglacial Basin (WSB) of East Antarctica during the LIG, based on analysis of sediment provenance and an ice melt proxy in a marine sediment core retrieved from the Wilkes Land margin. Our sedimentary records, together with existing ice-core records, reveal dynamic fluctuations of the ice sheet in the WSB, with thinning, melting, and potentially retreat leading to ice loss during both early and late stages of the LIG. We suggest that such changes along the East Antarctic Ice Sheet margin may have contributed to fluctuating global sea levels during the LIG.

Potential productivity of Arundo donax in two contrasting environments from medium-term experiments

ABSTRACT Marginal land exploitation devoted to versatile crops, such as giant reed, is related to the degree of land marginality. Two experiments were conducted in two sites of Sardinia (Italy) to investigate the effects of management on dry matter yield and water productivity (WP). Experiment 1 compared four crop evapotranspiration restoring treatments (100%, 75%, 50%, 25%, and a rainfed control) over 5 years. Experiment 2 lasted 7 years and investigated zero-input supply on crop response. Experiment 1, notwithstanding well-watered conditions (Irr100), showed a higher value of biomass production during the last year monitored, but yielding only 13.5 Mg DM ha−1 and with no significant difference from Irr75. Moreover, being equal the average dry matter yield, in the Irr100, we would save 3630 m3 of irrigation water by achieving the same WP recorded in the Irr25 (25% ETc restoring). Experiment 2, being equal rainfall amount, raised WP values that picked 8.2 kg m−3 during 2018. Results indicate that in less favourable soils as the Experiment 1, well-watered conditions do not ensure better crop growth and productivity, whereas in deep soils (Experiment 2) promising productive results, as well as ecosystem services, could be obtained without any input supply.

Widespread occurrence of endogenous cellulase production and glycosyl hydrolase in grapsoid crabs along the land-sea transition indicates high potential for mineralisation of mangrove production

Previous studies on mangrove carbon utilisation and mineralisation were focused on mangrove sesarmid crabs (Grapsoidea: Sesarmidae) because they are initial processors of mangrove organic carbon. Grapsoid crabs from other families and habitats were generally ignored although they also perform various levels of herbivory. It remains unclear how the herbivorous crabs utilise the production from mangrove or vascular plants because of the high C/N ratio and high structural carbon content of these materials. In this study, production of cellulase and expression of hepatopancreatic glycosyl hydrolase of grapsoid crabs were investigated in a more extensive way in terms of their taxa (15 species) and habitats (i.e., land margin, mangrove, mudflat, and subtidal area). Generally, low gastric endoglucanase (1.46-2.98 μmol min−1 ml−1) and β-glucosidase (0.06-0.61 μmol min−1 ml−1) activity was detected in 15 grapsoid crabs distributed along the land-sea transition. The activity of both enzymes was significantly affected by the taxonomic affiliation and habitat of the crabs: endoglucanase in sesarmids > varunids > grapsids; and land margin, mangrove and limnic habitats > mudflat and subtidal area. For β-glucosidase: sesarmids > varunids and grapsids; and land and limnic > mangrove and subtidal > mudflat. Our detection of gastric cellulases in mudflat and subtidal grapsoid crabs has rarely been reported. These results show that there is a need to re-evaluate the role of crabs from these habitats in mangrove/vascular plant carbon mineralisation. Further, low cellulase activity could be a common trait among crabs along the land-sea transition and the importance of cellulase in vascular plant carbon utilisation could have been previously over-rated. Glycosyl hydrolase family 9 (GH9) genes were identified in the hepatopancreatic transcriptome of all 15 species, indicating endogenous production of cellulase. In addition, the presence of other digestive carbohydrate-active enzymes (CAZymes), including GH5_10, GH13, GH13_24, and GH16, suggests that a capacity for the utilisation of carbon sources other than cellulose by the grapsoid crabs, which may enable sufficient assimilation of vascular plant carbon despite the low cellulase activity.

Deep water sedimentary processes in the Enderby Basin (East Antarctic margin) during the Cenozoic

AbstractThe thick sequence of mid‐late Cenozoic sediments preserved within the Enderby Basin of the East Antarctica margin contains key information regarding glacial history and palaeo‐oceanographic conditions during the last 34 My. The interplay between glacial processes and ocean circulation can be reconstructed from seismic stratigraphic studies. Here, interpretation of seismic sequences and geomorphology from an extensive 2D seismic dataset (∼75,000 km) are correlated with lithological data of the ODP site 1165 drilled on the continental rise, and used to assess the age and origin of the sediment, and the possible influence of oceanic currents on its distribution. Mapping of seismic units and facies reveals that, in addition to glacial sediments derived from the Antarctic mainland, the upper Cenozoic succession includes drift units with prograding sequences building out from the Mac. Robertson Land margin, west of the Prydz Bay. Three contourite drifts grew on the western side of submarine channels and large sediment wave fields suggest a mixed system of turbidity currents influenced by west‐flowing bottom currents. The drifts are composed of four seismic units representing stages of onset (Lower Oligocene), main growth (Early‐Middle Miocene), maintenance (Middle‐Late Miocene) and burial (Pliocene). The internal geometry and reflection patterns of the drifts imply an intensified current activity from the Early to Middle Miocene. The results plausibly reflect that the formation of proto Antarctic Bottom Water (AABW) started around the Eocene–Oligocene boundary and intensified episodically from the early to middle Miocene.

Risk Assessment and Regulation Strategy of Farmland Marginalization: A Case Study of Mengjin County, Henan Province

The marginalization of farmland is the progression of farmland utilization from high to low net profit, and the abandonment of farmland is its extreme form, and cultivated land marginalization is an important problem that needs to be properly controlled in the process of economic and social development. In this paper, cultivated land was extracted from the land database and evaluated from the aspects of natural suitability, farming convenience and farming opportunity cost, etc. By setting the combined weight of the three evaluation results and stacking them with the forest land extracted from remote sensing images, the potential risk range of cultivated land marginalization was identified, and an empirical study was carried out in Mengjin County, Henan Province. Results showed that: 1) the natural factors of cultivated land were stable and not easy to change, and the natural suitability was the basic condition that affected the marginalization of cultivated land. There was a spatial correlation between the natural suitability of cultivated land and the cultivation convenience, and the risk of marginalization of cultivated land with poor natural suitability and inconvenient cultivation conditions was higher. 2) The high-opportunity cost areas are mainly distributed in the inner suburbs of cities, and the cultivated land in this area is highly likely to be adjusted to high-benefit agriculture such as flowers, vegetables and sightseeing agriculture. Therefore, the risk of abandonment of cultivated land is less. 3) Adjusting cultivated land with poor natural suitability and inconvenient tillage conditions to forest land is conducive to the restoration of regional fragile ecology. Comprehensive improvement of cultivated land with high natural suitability but inconvenient tillage is an important way to delay the marginalization of cultivated land. This study provides a new idea for the formulation of farmland marginalization prevention and control policies at county level.

Application of Atmospheric Solids Analysis Probe Mass Spectrometry for the Taxonomic Analysis of Pollen

Globally, both managed and wild pollination services are unable to meet current rates of crop production and pollination demand. Wild pollination services could be improved through the reforestation of agricultural land margins, however plant–pollinator networks remain poorly understood and the collection of key floral traits a complex process. Herein, we consider the merits of pollen as a floral trait and the application of a rapid pollen comparison method in assessing whether pollen traits are conserved at a taxonomic level. Reporting the previously unstudied, pollen fingerprints of 18 Australian plant species, these are compared against the seed crop Daucus carota L. and two naturalised Brassica hybrids. Applying atmospheric solids analysis probe mass spectrometry (ASAP-MS) for rapid pollen fingerprinting, pollens are compared through non-metric multidimensional scaling (NMDS), Jaccard index correlation and hierarchical clustering. Demonstrating the merits of this analytical method for the grouping of potential revegetation flora, we identify key pollen similarities and differences that could correlate with wild pollinator preferences.

Mapping Abandoned Cropland Changes in the Hilly and Gully Region of the Loess Plateau in China

As a form of land marginalization, abandoned cropland has an important impact on food security and the effective supply of agricultural products. With rapid urbanization across the world, large areas of cropland are abandoned in some regions, especially in mountainous and hilly areas with poor terrain. Due to the fine fragmentation and scattered distribution of abandoned cropland, and considering differences in the abandoned and fallow time of cropland, it is difficult to extract information using remote sensing technology. Therefore, this paper proposes a change in the detection method for extracting abandoned cropland information based on identifying the annual land use trajectory. Based on Landsat satellite data, annual land use was mapped from 2011 to 2020 in Gaolan County, which is located in the hilly and gully region of the Loess Plateau of China, using the random forest classification method. Subsequently, abandoned cropland information in Gaolan County was extracted, based on the land use change trajectory and analysis of the influencing factors of abandoned land. The results showed that: (1) The overall accuracy of land use interpretation in Gaolan County ranged from 86.44% to 95.45%, from 2011 to 2020, with a kappa coefficient of up to 0.93, and the classification results were ideal. (2) The recall of extracted abandoned cropland was 81%, the extraction accuracy of which was relatively high. (3) From 2013 to 2020, the cropland abandonment rate in Gaolan County ranged from 8.41% to 19.65%, with an average of 14.55%, which increased and then decreased. The abandonment rate was highest in 2015 but it then decreased year by year. The average period of abandoned cropland was 4.2 years. (4) The influence factors of the plot scale explain the difference in the spatial distribution of cultivated land abandonment. The higher the slope condition, the lower the soil nutrient content and the greater the possibility of abandonment.

Correlation assessment of NDVI and land use dynamics with water resources for the southern margin of Mu Us Sandy Land, China.

To prevent desertification, countries worldwide have made diversified efforts, and vegetation restoration has been demonstrated to be an effective approach. However, in regard to sandy land with limited water resources, measures such as revegetation may lead to an increased drought risk. Despite confirmed sand utilization achievements, many controversies remain regarding the advantages of desert greening, especially considering water scarcity. Therefore, the long-run and causal relationships between sandy land, water consumption, and vegetation coverage are necessarily explored. Choosing the southern margin of the Mu Us Sandy Land as the study area, this study explored the interactions between sandy land, water consumption, and normalized difference vegetation index (NDVI) of 2000-2018 with the vector autoregression (VAR) model approach. In the study area, various revegetation projects have been implemented, resulting in a notable reduction in the sandy land area. In addition, the NDVI increased from 0.196 in 2000 to 0.371 in 2018, an increase of 89.3%. The results indicated that there exist long-term stable equilibrium and causal relationships existed between water consumption and sandy land and NDVI. NDVI enhancement is relatively the direct factor that causes the increase of water consumption. It could be inferred that the implemented revegetation measures may rely on a large water consumption amount, which may further aggravate water shortages and ecological damage issues. More scientific and stronger effective water resource management measures should be locally implemented to achieve a balance between water resources and revegetation.

Supply potential of lignocellulosic energy crops grown on marginal land and greenhouse gas footprint of advanced biofuels—A spatially explicit assessment under the sustainability criteria of the Renewable Energy Directive Recast

AbstractAdvanced biofuels produced from lignocellulosic crops grown on marginal lands can become an important part of the European Union (EU) climate change mitigation strategy to reduce CO2 emissions and meet biofuel demand. This study quantifies spatially explicit the availability of marginal land in the EU, its production biomass potentials for eight different crops, and the greenhouse gas (GHG) performance of advanced biofuel supply chains. Available land is mapped based on land marginality and Renewable Energy Directive Recast (REDII) land‐related sustainability criteria. Biomass potentials are assessed with a water‐use‐to‐biomass‐production approach while considering the available land, location‐specific biophysical conditions and crop‐specific phenological characteristics. The GHG balance of advanced biofuels from energy crops produced on marginal lands is assessed considering both land‐related carbon stock changes and supply chain emissions with the carbon footprint approach from the REDII. Available marginal land that meets REDII criteria is projected at 20.5–21 Mha 2030 and 2050, respectively. Due to biophysical limitations, not all available land is suitable for energy crop production. The maximum biomass potential of lignocellulosic energy crops (optimal crop choice with maximum yield for each available location) varies between 1951 PJ year−1 in 2030 and 2265 PJ year−1 in 2050. The GHG emission performance (net emissions) of different advanced biofuel supply chains varies on average between −32 g CO2‐eq MJfuel−1 for poplar/willow diesel to 38 g CO2‐eq for reed canary grass renewable jet fuel. The large variability in GHG performance is strongly determined by the spatial heterogeneity, which dictates the type of feedstock produced under specific local biophysical conditions, the crop characteristics, and the best conversion pathway. Negative GHG emissions are related to increased carbon stocks for the biomass and soil organic carbon pools compared to the land prior to conversion. When for each location, the advanced biofuel supply chain with the highest GHG performance (lowest net GHG emissions) is selected, 618 PJ year−1 of advanced biofuels can be produced by 2030. Under REDII GHG emission criteria, slightly less (552 PJ year−1) is viable. Smart choices on location, crop type and supply chain design are paramount to achieve maximum benefits of bioenergy systems.

Temperate Oligocene surface ocean conditions offshore of Cape Adare, Ross Sea, Antarctica

Abstract. Antarctic continental ice masses fluctuated considerably during the Oligocene “coolhouse”, at elevated atmospheric CO2 concentrations of ∼600–800 ppm. To assess the role of the ocean in the Oligocene ice sheet variability, reconstruction of past ocean conditions in the proximity of the Antarctic margin is needed. While relatively warm ocean conditions have been reconstructed for the Oligocene offshore of Wilkes Land, the geographical extent of that warmth is unknown. In this study, we reconstruct past surface ocean conditions from glaciomarine sediments recovered from Deep Sea Drilling Project (DSDP) Site 274 offshore of the Ross Sea continental margin. This site, located offshore of Cape Adare is ideally situated to characterise Oligocene regional surface ocean conditions, as it is situated between the colder, higher-latitude Ross Sea continental shelf and the warm-temperate Wilkes Land margin in the Oligocene. We first improve the age model of DSDP Site 274 using integrated bio- and magnetostratigraphy. Subsequently, we analyse organic walled dinoflagellate cyst assemblages and lipid biomarkers (TEX86, TetraEther indeX of 86 carbon atoms) to reconstruct surface palaeoceanographic conditions during the Oligocene (33.7–24.4 Ma). Both TEX86-based sea surface temperature (SST) and microplankton results show temperate (10–17 ∘C ± 5.2 ∘C) surface ocean conditions at Site 274 throughout the Oligocene. Oceanographic conditions between the offshore Wilkes Land margin and Cape Adare became increasingly similar towards the late Oligocene (26.5–24.4 Ma); this is inferred to be the consequence of the widening of the Tasmanian Gateway, which resulted in more interconnected ocean basins and frontal systems. Maintaining marine terminations of terrestrial ice sheets in a proto-Ross Sea with offshore SSTs that are as warm as those suggested by our data requires a strong ice flux fed by intensive precipitation in the Antarctic hinterland during colder orbital states but with extensive surface melt of terrestrial ice during warmer orbital states.

Space Transformation Due to Conflict: Changes from Agricultural to Industrial Space in Manyar District, Gresik Regency

Changes in the spatial area showed the dynamics of political economy. There is a problem regarding power relations in reproducing space, which will trigger a conflict between interests. These land changes, especially those related to changes in the form of agricultural land use to non-agricultural, have resulted in the loss of income sources for farmers. This paper focuses on the transformation of agricultural land into a non-agricultural one caused by conflict between several elements, including the local government, private businessmen, and the community, especially fishpond farmers who experience marginalization of agricultural land due to industrial development in Gresik Regency. The research is conducted using a qualitative approach with a descriptive type to support more in-depth research in analyzing urban spatial planning issues in the perspective of seeking spatial politics in Gresik district. The current reality is that the government tends to be more aligned with capital owners, which implies that spatial planning is manifested by profit-oriented development, high economic growth, and accumulation. The government mostly ignores ecological and social dimensions, which it considers non-linear with economic investment.