Spatio-temporal detection of agricultural disaster vulnerability in the world and implications for developing climate-resilient agriculture.

Drought and floods seriously affect agriculture across the world. It is of great importance to lower down the agricultural vulnerability to disasters to build climate-resilient agriculture. The paper aims to investigate the spatio-temporal changes of agricultural vulnerability to drought and floods in the world in the period 2003-2019. Research results show that (1) the agricultural vulnerability to drought and floods is at a low level across the globe owning to the dual effects of decreasing exposure and increasing adaptability; (2) the northern parts of United States, northeastern parts of China, and the border between Russia and Kazakhstan are identified as most vulnerable areas to drought and floods; and (3) spatio-temporal mismatch of precipitation is the main factor to cause floods and drought while better adaption is beneficial to minimize the adverse effects of disasters. Based on analysis on the drivers and spatial patterns of drought and floods risk in all dimensions, tailored measures and policies are put forwards to make adaptive strategies of agriculture to climate change.

BMP4 up-regulated by 630 nm LED irradiation is associated with the amelioration of rheumatoid arthritis.

Rheumatoid arthritis (RA) is caused by inflammatory response of joints with cartilage and damage of synovium and bone erosion. In our previous studies, it has showed that irradiation of 630 nm LED reduce inflammation of synovial fibroblasts and cartilage and bone destruction in RA. However, the key genes and mechanism in ameliorating RA by irradiation of 630 nm LED remains unknown. In this study, human fibroblast-like synoviocytes (FLS) cell line MH7A and primary human RA-FLSs were treated with TNF-α and 630 nm LED irradiation with the different energy density. The mRNA sequencing was performed to screen the differentially expressed genes (DEGs). In all datasets, 10 DEGs were identified through screening. The protein interaction network analysis showed that 8 out of the 10 DEGs interacted with each other including IL-6, CXCL2, CXCL3, MAF, PGF, IL-1RL1, RRAD and BMP4. This study focused on BMP4, which is identified as important morphogens in regulating the development and homeostasis. CCK-8 assay results showed that 630 nm LED irradiation did not affect the cell viability. The qPCR and ELISA results showed that TNF-α stimulation inhibited BMP4 mRNA and protein level and irradiation of 630 nm LED increased the BMP4 mRNA and protein level in MH7A cells. In CIA and transgenic hTNF-α mice models, H&E staining showed that irradiation of 630 nm LED decreased the histological scores assessed from inflammation and bone erosion, while BMP4 expression level was up-regulated after 630 nm LED irradiation. Pearson correlation analysis shown that BMP4 protein expression was negatively correlated with the histological score of CIA mice and transgenic hTNF-α mice. These results indicated that BMP4 increased by irradiation of 630 nm LED was associated with the amelioration of RA, which suggested that BMP4 may be a potential targeting gene for photobiomodulation.

Glycosylation Contributes to Thermostability and Proteolytic Resistance of rFIP-nha (Nectria haematococca).

Glycosylation is an important post-translational modification of proteins, contributing to protein function, stability and subcellular localization. Fungal immunomodulatory proteins (FIPs) are a group of small proteins with notable immunomodulatory activity, some of which are glycoproteins. In this study, the impact of glycosylation on the bioactivity and biochemical characteristics of FIP-nha (from Nectria haematococca) is described. Three rFIP-nha glycan mutants (N5A, N39A, N5+39A) were constructed and expressed in Pichia pastoris to study the functionality of the specific N-glycosylation on amino acid N5 and N39. Their protein characteristics, structure, stability and activity were tested. WT and mutants all formed tetramers, with no obvious difference in crystal structures. Their melting temperatures were 82.2 °C (WT), 81.4 °C (N5A), 80.7 °C (N39A) and 80.1 °C (N5+39A), indicating that glycosylation improves thermostability of rFIP-nha. Digestion assays showed that glycosylation on either site improved pepsin resistance, while 39N-glycosylation was important for trypsin resistance. Based on the 3D structure and analysis of enzyme cleavage sites, we conclude that glycosylation might interfere with hydrolysis via increasing steric hindrance. WT and mutants exerted similar bioactivity on tumor cell metabolism and red blood cells hemagglutination. Taken together, these findings indicate that glycosylation of FIP-nha impacts its thermostability and digestion resistance.

Structural insights into the oligomeric effects on catalytic activity of a decameric feruloyl esterase and its application in ferulic acid production.

Oligomeric feruloyl esterase (FAE) has great application prospect in industry due to its potentially high stability and fine-tuned activity. However, the relationship between catalytic capability and oligomeric structure remains undetermined. Here we identified and characterized a novel, cold-adapted FAE (BtFae) derived from Bacteroides thetaiotaomicron. Structural studies unraveled that BtFae adopts a barrel-like decameric architecture unique in esterase families. By disrupting the interface, the monomeric variant exhibited significantly reduced catalytic activity and stability toward methyl ferulate, potentially due to its impact on the flexibility of the catalytic triad. Additionally, our results also showed that the monomerization of BtFae severely decreased the ferulic acid release from de-starched wheat bran and insoluble wheat arabinoxylan by 75 % and 80 %, respectively. Collectively, this study revealed novel connections between oligomerization and FAE catalytic function, which will benefit for further protein engineering of FAEs at the quaternary structure level for improved industrial applications.

Responses of Soil Collembolans to Land Degradation in a Black Soil Region in China.

Land degradation in black soil regions has a significant effect on belowground systems, and Collembolans can adequately indicate environmental changes in the soil. However, there is currently a knowledge gap in the literature regarding the responses of soil Collembolans to land degradation. In order to better understand this issue, in this study, a total of 180 soil Collembolan samples were collected from four habitats with varying degrees of land degradation in the Songnen Plain, namely a no land-degradation habitat (NLD), light land-degradation habitat (LLD), moderate land-degradation habitat (MLD) and severe land-degradation habitat (SLD). The results reveal that the different degrees of land degradation caused some differences in the taxonomic composition of the Collembolans; however, the majority of the Collembolan species are distributed relatively evenly. Proisotoma minima are always a dominant species during the study period. Seasonal variations are observed in the abundance, richness and diversity levels. In the severe land-degradation habitats (SLD), the abundance, richness, diversity and community complexity of the Collembolans are aways at the lowest levels. In addition, Proisotoma minima is negatively correlated with a majority of the species of Collembolans in the low levels of the land-degradation habitats, whereas they are positively correlated with most of the other species in the high levels. Epedaphic and euedaphic Collembolans responded to land degradation more obviously. The structural equation model (SEM) displays that soil Collembolan communities respond negatively to land degradation. Overall, our results provide implications that soil Collembolan communities are affected by land degradation, and that different taxa of soil Collembolans respond to degradation in numerous ways.

Coordinated regulation of Bacteroides thetaiotaomicron glutamate decarboxylase activity by multiple elements under different pH.

Glutamate decarboxylase catalyzes the conversion of glutamate to γ-aminobutyric acid, which plays a vital role in the gut-brain axis. Herein, a novel glutamate decarboxylase from Bacteroides thetaiotaomicron (BTGAD) was heterologously expressed. BTGAD possessed high catalytic efficiency at 60℃ and pH 3.6. As pH response, N-terminal sequence (NTS), C-terminal sequence (CTS), and ß-hairpin in BTGAD coordinately regulated its activity under different pH. NTS folded into a loop under acidic pH, and the truncation of NTS severely reduced its activity to 4.2%. While CTS occupied the active site under neutral pH and became disordered to release the inhibition effect under acidic conditions. The ß-hairpin, located near the active site, swung and formed open and closed conformations, which acted as an activity switch. This study provides the molecular basis for the coordinated regulation mechanism of BTGAD and lays a theoretical foundation for understanding the metabolism of dietary glutamate and its interaction relationships with the gut-brain axis.

Dynamic Variation of Ecosystem Services Value under Land Use/Cover Change in the Black Soil Region of Northeastern China.

A better understanding of the dynamic variation in the ecosystem service value (ESV) under land use/cover change (LUCC) is conductive to improving ecosystem services and environmental protection. The present study took Landsat TM/ETM remote sensing images and socio-economic statistic data as data sources and extracted land-use data using RS and GIS technology at 5-year intervals from 1990 to 2020. Then, we interpreted the spatio-temporal characteristics of LUCC and analyzed ESV changes using the value equivalence method in the black soil region of northeastern China (BSRNC). The main results showed that land use changed significantly during the study period. Cultivated land continued to expand, especially paddy areas, which increased by 1.72 × 106 ha, with a relative change of 60.9% over 30 years. However, grassland decreased by 2.47 × 106 ha, with a relative change of -60.6% over 30 years. The ESV showed a declining trend, which decreased by CNY 607.96 million during 1990-2020. The decline in forest and grassland caused a significant decline in the ESV. Furthermore, the ESV sensitivity coefficients were less than one for all of the different categories of ecosystem services. LUCC has a considerable impact on ESV in the BSRNC, resulting in ecosystem function degradation. As a result, future policies must emphasize the relationship between food security and environmental protection in situations of significant land-use change.

Linking the thermostability of FIP-nha (Nectria haematococca) to its structural properties.

Fungal immunomodulatory proteins (FIPs) have been investigated for their use as potential natural derived anti-tumor molecules. However, the stability of FIPs is critical for their preparation and storage. In this study, the correlation between thermal stability and protein structural features of rFIP-nha, with significant anti-tumor activity, has been evaluated. For comprehensive analysis, FIP-nha and its homologues FIP-gmi, FIP-fve, and LZ-8 were all recombinantly expressed in E. coli. In solution, rFIP-nha and rFIP-gmi formed tetramers; rFIP-fve and rLZ-8 appeared as dimers. Their melting temperatures were 85.1 °C, 77.8 °C, 66.5 °C, and 64.4 °C, respectively. Accordingly, their cytotoxicity was also temperature dependent. To investigate the underlying mechanism of their thermostability, we solved the crystal structure of FIP-nha. Detailed structure analysis, molecular dynamic simulation and mutagenesis studies indicated that a higher thermostability was correlated to higher oligomerization states, larger interface area, and more interactions. The structure property studies indicate that Y12, D61 and Y108 were critical for oligomerization and high thermostability of rFIP-nha, but the dimeric and tetrameric states of rFIP-nha exert similar cytotoxicity on A549 cells. Taken together, these findings reveal that thermostability of FIPs was dependent on their oligomerization state, and correlated with their cytotoxicity.

[Analysis of cropping pattern in black soil region of Northeast China based on geo-information Tupu.] / 基于地学信息图谱的东北黑土区种植模式分析.

Different cropping patterns have their own economic and ecological significance. Developing cropping patterns suitable for local conditions is needed to protect and make good use of black soils. At present, the cropping patterns and their spatial characteristics in the black soil region of Northeast China is poorly understood. Based on the crop classification data in 2017-2019, we used geo-information Tupu methods, distribution index model, and bivariate spatial autocorrelation to examine the cropping patterns. The results showed that: 1) The main cropping patterns in the black soil region of Northeast China were continuous maize cropping, continuous rice cropping, continuous soybean cropping, and maize-soybean rotation, accounting for 38.3%, 18.5%, 10.3% and 26.0%, respectively. The maize-soybean rotation included maize-soybean two-year rotation, maize-maize-soybean three-year rotation, and soybean-soybean-maize three-year rotation, accounting for 44.1%, 34.5% and 21.4% of the rotation area, respectively. 2) Various cropping patterns had obviously horizontal differentiation. For instance, continuous maize cropping had very obvious gradient differentiation characteristics in temperature and humidity, but soybean continuous cropping and maize-soybean rotation showed no gradient differentiation, while continuous rice cropping had gradient differentiation only in humidity. 3) Various cropping patterns had obviously spatial clustering characteristics. They had spatial transition characteristics from soybean continuous cropping, soybean-soybean-maize three-year rotation, maize-soybean two-year rotation, maize-maize-soybean three-year rotation, to continuous maize cropping. The cropping pattern in black soil region of Northeast China was dominated by continuous cropping. Understanding its distribution pattern can provide a basis for future spatial optimization of crop rotation.

Cropland redistribution to marginal lands undermines environmental sustainability.

Cropland redistribution to marginal land has been reported worldwide; however, the resulting impacts on environmental sustainability have not been investigated sufficiently. Here we investigated the environmental impacts of cropland redistribution in China. As a result of urbanization-induced loss of high-quality croplands in south China (∼8.5 t ha-1), croplands expanded to marginal lands in northeast (∼4.5 t ha-1) and northwest China (∼2.9 t ha-1) during 1990-2015 to pursue food security. However, the reclamation in these low-yield and ecologically vulnerable zones considerably undermined local environmental sustainability, for example increasing wind erosion (+3.47%), irrigation water consumption (+34.42%), fertilizer use (+20.02%) and decreasing natural habitats (-3.11%). Forecasts show that further reclamation in marginal lands per current policies would exacerbate environmental costs by 2050. The future cropland security risk will be remarkably intensified because of the conflict between food production and environmental sustainability. Our research suggests that globally emerging reclamation of marginal lands should be restricted and crop yield boost should be encouraged for both food security and environmental benefits.

A reverse catalytic triad Asp containing loop shaping a wide substrate binding pocket of a feruloyl esterase from Lactobacillus plantarum.

Feruloyl esterase is an indispensable biocatalyst in food processing, pesticide and pharmaceutical industries, catalyzing the cleavage of the ester bond cross-linked between the polysaccharide side chain of hemicellulose and ferulic acid in plant cell walls. LP_0796 from Lactobacillus plantarum was identified as a feruloyl esterase that may have potential applications in the food industry, but the lack of the substrate recognition and catalytic mechanisms limits its application. Here, LP_0796 showed the highest activity towards methyl caffeate at pH 6.6 and 40 °C. The crystal structure of LP_0796 was determined at 2.5 Å resolution and featured a catalytic triad Asp195-containing loop facing the opposite direction, thus forming a wider substrate binding pocket. Molecular docking simulation and site-directed mutagenesis studies further demonstrated that in addition to the catalytic triad (Ser94, Asp195, His225), Arg125 and Val128 played essential roles in the function of the active site. Our data also showed that Asp mutation of Ala23 and Ile198 increased the catalytic efficiency to 4- and 5-fold, respectively. Collectively, this work provided a better understanding of the substrate recognition and catalytic mechanisms of LP_0796 and may facilitate the future protein design of this important feruloyl esterase.

Polymorphisms of RIG-I-like receptor influence HBV clearance in Chinese Han population.

Retinoic acid-inducible gene I-like receptors (RLRs) play an essential role in human innate immune, which may influence the spontaneous clearance of hepatitis B virus (HBV) infection. We aimed to investigate whether the SNPs in RLR family were associated with HBV spontaneous clearance. The current study included 82 participants with spontaneous clearance, 601 asymptomatic hepatitis B surface antigen (HBsAg) carriers, and 168 participants with chronic hepatitis B (CHB). Six SNPs (DDX58 rs3824456, rs3205166, DHX58 rs2074160, rs2074158, IFIH1 rs2111485, rs3747517) were genotyped to explore their association with HBV spontaneous clearance. Patients carrying the mutant allele C at rs3824456 or A at rs2074160 were more likely to achieve spontaneous clearance compared with asymptomatic HBsAg carriers (additive model: odds ratio [OR] = 0.69, 95% confidence interval [CI] = 0.49-0.97; dominant model: OR = 0.54, 95% CI = 0.31-0.95, respectively). In addition, patients carrying the mutant allele G at rs2111485 were more likely to achieve spontaneous clearance compared with CHB (dominant model: OR = 0.47, 95% CI = 0.25-0.87). The mutations were protective factors for HBV spontaneous clearance. These results suggest the DDX58 rs3824456, DHX58 s2074160, IFIH1 rs2111485 were associated with spontaneous clearance of HBV, which may be predictive markers in the Chinese Han population of HBV.

The 10-m crop type maps in Northeast China during 2017-2019.

Northeast China is the leading grain production region in China where one-fifth of the national grain is produced; however, consistent and reliable crop maps are still unavailable, impeding crop management decisions for regional and national food security. Here, we produced annual 10-m crop maps of the major crops (maize, soybean, and rice) in Northeast China from 2017 to 2019, by using (1) a hierarchical mapping strategy (cropland mapping followed by crop classification), (2) agro-climate zone-specific random forest classifiers, (3) interpolated and smoothed 10-day Sentinel-2 time series data, and (4) optimized features from spectral, temporal, and texture characteristics of the land surface. The resultant maps have high overall accuracies (OA) spanning from 0.81 to 0.86 based on abundant ground truth data. The satellite estimates agreed well with the statistical data for most of the municipalities (R2 ≥ 0.83, p < 0.01). This is the first effort on regional annual crop mapping in China at the 10-m resolution, which permits assessing the performance of the soybean rejuvenation plan and crop rotation practice in China.

Berbamine ameliorates ethanol-induced liver injury by inhibition of hepatic inflammation in mice.

Alcoholic liver disease (ALD) has become one of the leading causes of death in the world. Berbamine (BM), a natural product mainly derived from Berberis vulgaris L, possesses multiple bioactivities as a traditional medicine. However, the protective effect of BM on ALD remains unknown. In this study, we investigated the effect of BM on ethanol-induced hepatic injury in mice and its underlying mechanism. It was shown that BM at 0.3125-40 µmol·L-1had no effect on macrophages and hepatocytes proliferation. BM at 5-20 µmol·L-1 significantly inhibited lipopolysaccharide (LPS) or acetate-induced IL-1ß and IL-6 mRNA expression in RAW264.7 cells. Moreover, BM treatment significantly inhibited LPS-induced p65 and STAT3 phosphorylation in RAW264.7 cells. Hepatic histopathology analysis showed that inflammatory cells infiltration and lipid accumulation were suppressed by 25 and 50 mg·kg-1 BM administration in ethanol-induced hepatic injury mouse model. Meanwhile, BM treatment significantly inhibited serum ALT and AST levels in ethanol-fed mice. Oil red O staining results showed that BM administration ameliorated hepatic lipid accumulation in ethanol-fed mice. Preventions of ethanol-induced hepatic injury by BM were reflected by markedly decreased serum and hepatic triglyceride (TG) and total cholesterol (TC) contents. Real-time PCR results showed that BM treatment significantly inhibited pro-inflammatory cytokines mRNA expression in ethanol-fed mouse liver. Remarkably, the mechanism of action of BM was related to the reduction of ethanol-induced NF-κB and STAT3 phosphorylation levels in liver. In addition, BM treatment significantly inhibited ERK phosphorylation but not JNK and p38 of MAPK pathway. Taken together, our results demonstrate a beneficial effect of BM on ethanol-induced liver injury via a mechanism associated with inactivation of NF-κB, STAT3 and ERK pathway, which gives insight into the further evaluation of the therapeutic potential of BM for ALD.

Large-scale rain-fed to paddy farmland conversion modified land-surface thermal properties in Cold China.

The recent acute evolution of cropland structure in Cold China could lead to rapid rice paddy expansion, potentially altering land-surface thermal processes and influencing climate. To address the issue, this study investigated the changes in cropland type, land-surface temperature (LST) and heat fluxes in the agricultural region of Cold China during 2000-2015 based on time-series of land-use data and MODIS LST product, using the split-window algorithms (SWA) model and the pixel component arranging and component algorithm (PCACA). The investigation revealed large-scale land transformation from rain-fed farmland to paddy field in Cold China during 2000-2015. Compared to the rain-fed farmland, lower LST was observed in paddy field throughout crop growing seasons, with the highest LST threshold found in June (7.17 ± 1.05 °C) and the lowest value found in August (1.04 ± 0.35 °C). The cooling effect of paddy-field ranged from 0.59 ± 0.06 °C, 0.77 ± 0.07 °C, and 1.08 ± 0.08 °C for the low-, medium-, and high-density paddies, respectively. Compared to other months, stronger cooling effect was found in May and June. Further analysis showed the conversion of a rain-fed farmland to paddy field reduced the sensible heat flux and soil heat flux by 52.94 W/m2 and 15.26 W/m2, respectively, while increased the latent heat flux and net radiation by 115.66 W/m2 and 47.34 W/m2, respectively. The findings from this study indicated the changes in cropland structure and management regime (e.g., irrigation) could profoundly modify land-surface thermal processes and local/regional climate, interfering the signals from global warming. Therefore, instrumental climate data that collected from areas experienced large-scale conversion between rain-fed and paddy farmland should be carefully screened and corrected to prevent land-use induced biases.

Large increases of paddy rice area, gross primary production, and grain production in Northeast China during 2000-2017.

China is the largest rice producer and consumer in the world. Accurate estimations of paddy rice planting area and rice grain production is important for feeding the increasing population in China. However, Southern China had substantial losses in paddy rice area over the last three decades in those regions where paddy rice has traditionally been produced. Several studies have shown increased paddy rice area in Northeast China. Here we document the annual dynamics of paddy rice area, gross primary production (GPP), and grain production in Northeast China (Heilongjiang, Jilin and Liaoning provinces) during 2000-2017 using agricultural statistical data, satellite images, and model simulations. Annual maps derived from satellite images show that paddy rice area in Northeast China has increased by 3.68 million ha from 2000 to 2017, which is more than the total combined paddy rice area of North Korea, South Korea, and Japan. Approximately 82% of paddy rice pixels had an increase in annual GPP during 2000-2017. The expansion of paddy rice area slowed down substantially since 2015. Annual GPP from those paddy rice fields cultivated continuously over the 18 years were moderately higher than that from other paddy rice fields, which suggested that improved management practices could increase grain production in the region. There was a strong linear relationship between annual GPP and annual rice grain production in Northeast China by province and year, which illustrates the potential of using satellite-based data-driven model to track and assess grain production of paddy rice in the region. Northeast China is clearly an emerging rice production base and plays an increasing role in crop production and food security in China. However, many challenges for the further expansion and sustainable cultivation of paddy rice in Northeast China remain.

Divergent changes in cropping patterns and their effects on grain production under different agro-ecosystems over high latitudes in China.

Drastic rice paddy expansion and rapid upland crop loss have occurred over high latitudes in China, which would affect national food security. Different agro-ecosystems (i.e., state farms guided by the central government for agriculture and private farms guided by individual farmers for agriculture) could lead to different agricultural land use patterns; but this topic has not been investigated, which has limited our understanding of the dynamics of cropping patterns (i.e., rice paddies and upland crops) under different agro-ecosystems and their effect on total grain production. Thus, this study examined these issues over high latitudes in China. The results showed that: the developed methodology for determining cropping patterns presented high accuracy (over 90%). Based on the cropping pattern data, first, a satellite evidence of substantial increase in rice paddies with the loss of upland crops was found, and the large-scale conversion from upland crops to rice paddies has become the principal land use changes during the period of 2000-2015. Second, the new phenomenon was observed with rice paddies in state farms expanding at faster rates (at proportions of 12.98%-70.11%) than those in private farms (4.86%-30.48%). Third, the conversion of upland crops into rice paddies contributed 10.69% of the net increase in grain, which played a significant role in ensuring food security. The study provided new evidence of different changes in cropping patterns under different agro-ecosystems, thereby affecting rice cropping pattern and total grain production. This information is important for understanding and guiding the response to food sustainability and environmental issues.

[Cultivated landscape pattern change due to the rice paddy expansion in Northeast China: A case study in Fujin].

On the background of global climate change, agriculture in North China has been experiencing substantial modifications to adapt to the ongoing regional warming. One of the most significant land use change is the conversation from upland cropland to paddy cropland, which is characterized by the dramatic changes of agricultural landscape pattern. In this study, we generated land use maps in Fujin City in 2000 and 2013 by using Landsat TM imagery, and analyzed the landscape pattern changes (cropland composite, special distribution, and patch characteristics, etc.) of croplands by using landscape indices and empirical approach. The results indicated a rapid cropland increase from 512400 hm2(reclamation ratio 60.4%) in 2000 to 699300 hm2(reclamation 82.4%) in 2013, especially, the paddy cropland proportion in the total cropland increased from 6.7% to more than half (54.1%) , that is, the agricultural land use mode had changed from the initial stage of paddy agriculture to the intermediate stage. The reclamation area and common agricultural area showed different paddy agriculture development characteristics: in 2000, the paddy field ratios in the common agricultural area and reclamation area were similar (5.5% and 8.3% respectively); however, in 2013, the paddy field ratio in the common agricultural area (33.6%) was significantly lower than that in reclamation area (83.4%). In 2000, the total number of cropland patches was 2311 in the study, including 1010 patches from the common agricultural area and 1301 patches from the reclamation area. The coefficient of variation (CV) , and shape index (SI) of cropland patches in upland cropland were always higher than in paddy cropland. Upland cropland had larger mean patch size with the plaque area index above 60% and higher connectivity. The patch density of upland cropland was lower than that of paddy cropland. In the conversions to the intermediate and later stages of paddy agriculture, the patch number of cropland increased rapidly with different rates in upland and paddy croplands. The CV of paddy cropland patches increased while fluctuated in upland cropland. The SI of paddy cropland increased first and then decreased, while that of upland cropland decreased continuously. The mean patch sizes of paddy and upland croplands increased and decreased respectively. The patch density increased in upland cropland while decreased in paddy cropland. The connectivity of upland cropland decreased while that of paddy cropland increased. The staggered degree of both cropland types was enhanced from 2000 to 2013. In general, the paddy agriculture was becoming the dominated agricultural land use mode in the study area while the convesions had different rates in two administrative regions (reclamation and common agricultural areas).

Urban flood risk warning under rapid urbanization.

In the past decades, China has observed rapid urbanization, the nation's urban population reached 50% in 2000, and is still in steady increase. Rapid urbanization in China has an adverse impact on urban hydrological processes, particularly in increasing the urban flood risks and causing serious urban flooding losses. Urban flooding also increases health risks such as causing epidemic disease break out, polluting drinking water and damaging the living environment. In the highly urbanized area, non-engineering measurement is the main way for managing urban flood risk, such as flood risk warning. There is no mature method and pilot study for urban flood risk warning, the purpose of this study is to propose the urban flood risk warning method for the rapidly urbanized Chinese cities. This paper first presented an urban flood forecasting model, which produces urban flood inundation index for urban flood risk warning. The model has 5 modules. The drainage system and grid dividing module divides the whole city terrain into drainage systems according to its first-order river system, and delineates the drainage system into grids based on the spatial structure with irregular gridding technique; the precipitation assimilation module assimilates precipitation for every grids which is used as the model input, which could either be the radar based precipitation estimation or interpolated one from rain gauges; runoff production module classifies the surface into pervious and impervious surface, and employs different methods to calculate the runoff respectively; surface runoff routing module routes the surface runoff and determines the inundation index. The routing on surface grid is calculated according to the two dimensional shallow water unsteady flow algorithm, the routing on land channel and special channel is calculated according to the one dimensional unsteady flow algorithm. This paper then proposed the urban flood risk warning method that is called DPSIR model based multiple index fuzzy evaluation warning method, and referred to as DMFEW method. DMFEW first selects 5 evaluation indexes based on the DPSIR model for flood risk warning evaluation, including driving force index, pressure index, state index, impact index and response index. Based on the values of all evaluation indexes, one evaluation index for the whole system evaluation result is determined by using the fuzzy comprehensive evaluation method. The flood risk level is divided into 4 levels, having Level 1 the most serious. Every evaluation index is also categorized as 4 levels, and a linear fuzzy subjection function is proposed to do the fuzzy comprehensive evaluation. Dongguan City is used as the study case to validate the proposed method. The urban flood forecasting model is set up with the topographic data, the city map, the underground pipelines and land cover types, and two flood events are simulated with observed precipitation, one is interpolated from the rain gauges data, and another is estimated by digital weather radar. The simulated results are compared with the investigated water depth, and the results show the model has very good performances. The results are further used for the flood risk warning simulation, and are very reasonable.