Effects of Climate Warming on Net Primary Productivity in China During 1961–2010

The response of ecosystems to different magnitudes of climate warming and corresponding precipitation changes during the last few decades may provide an important reference for predicting the magnitude and trajectory of net primary productivity (NPP) in the future. In this study, a process-based ecosystem model, Carbon Exchange between Vegetation, Soil and Atmosphere (CEVSA), was used to investigate the response of NPP to warming at both national and subregional scales during 1961–2010. The results suggest that a 1.3°C increase in temperature stimulated the positive changing trend in NPP at national scale during the past 50 years. Regardless of the magnitude of temperature increase, warming enhanced the increase in NPP; however, the positive trend of NPP decreased when warming exceeded 2°C. The largest increase in NPP was found in regions where temperature increased by 1–2°C, and this rate of increase also contributed the most to the total increase in NPP in China\u27s terrestrial ecosystems. Decreasing precipitation depressed the positive trend in NPP that was stimulated by warming. In northern China, warming depressed the increasing trend of NPP and warming that was accompanied by decreasing precipitation led to negative changing trends in NPP in large parts of northern China, especially when warming exceeded 2°C. However, warming stimulated the increase in NPP until warming was greater than 2°C, and decreased precipitation helped to increase the NPP in southern China

Field test on the biodegradation of poly(butylene adipate-co-terephthalate) based mulch films in soil

The use of plastic much films has been fundamental to promoting food production in many regions of the world. However, concern is growing about the progressive accumulation of plastic residues in soil after crop harvest and its subsequent impact on soil health and potential to enter the food chain. Although biodegradable films have been developed to prevent these problems, it is still unclear whether they are environmentally benign. Here we evaluated the physical and chemical breakdown of four commercial poly(butylene adipate-co-terephthalate) based biodegradable mulch films (BMF1, BMF2, BMF3 and BMF4) in an agricultural soil over a 26-month period. Based on visual examination, degradation followed the series BMF4 > BMF1, BMF2 > BMF3. Importantly, microplastic residues (fragments <5 mm) still remained in the soil of all 4 plastic types after 2 years, suggesting that they are likely to accumulate over time if used on an annual basis. Viscosimetry, Fourier transform infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA) were used to characterise the breakdown process. Our results indicated that the degradation of the mulch film after burial in agricultural soil may be linked to the nature of the polymer but also to its manufacturing formulation. Although the peak changes of polyester in the infrared spectrum were not distinct, the plastic films showed other signs of degradation including a reduction in intrinsic viscosity after burial in soil. The different degradation rates of BMF1 and BMF2 at the molecular level may be due to the different CaCO3 contents. In conclusion, under field conditions, we show that slight variations in the formulations of commercial biodegradable mulch films leads to very different persistence rates in soil. Further, we conclude that their slow rate of degradation will ultimately lead to their progressive accumulation in soil if used repeatedly

Effects of a ‘one film for 2 years’ system on the grain yield, water use efficiency and cost-benefit balance in dryland spring maize (Zea mays L.) on the Loess Plateau, China

‘One film for 2 years’ (PM2) has been proposed as a practice to control the residual film pollution; however, its effects on grain-yield, water-use-efficiency and cost-benefit balance in dryland spring maize production have still not been systematically explored. In this study, we compared the performance of PM2 with the annual film replacement treatment (PM1) and no mulch treatment (CK) on the Loess Plateau in 2015-2016. Our results indicated the following: (1) PM2 was effective at improving the topsoil moisture (0-20 cm) at sowing time and at seedling stage, but there was no significant influence on soil water storage, seasonal average soil moisture or evapotranspiration; (2) PM2 induced significantly higher cumulative soil temperatures compared to CK, and there was no significant difference between PM2 and PM1; (3) no significant differences were identified in grain-yield and water-use-efficiency between PM1 and PM2, and compared to CK, they improved by 16.3% and 15.5%, respectively; (4) because of lower cost of plastic film, tillage, film laying and remove in PM2, economic profits improved by 21% and 70% compared to PM1 and CK. This research suggested that PM2 was effective at alleviating the spring drought and was beneficial in reducing poverty traps in dryland

Spatiotemporal variation of drought characteristics in the Huang- Huai-Hai Plain, China under the climate change scenario

peer reviewedUnderstanding the potential drought characteristics under climate change is essential for reducing vulnerability and establishing adaptation strategies, especially in the Huang-Huai-Hai Plain (3H Plain) which is the grain production base in China. In this paper, the variation of drought characteristics including drought event frequency, duration, severity and intensity for the past 50 years (1961-2010) and future scenarios (2010-2099) based on observed meteorological data and RCP 8.5 projections were investigated, respectively. Firstly, the applicability of three climatic drought indices including the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index based on the Penman–Monteith equation (SPEI-PM) and the Thornthwaite equation (SPEI-TH) were compared in tracing recorded agricultural drought areas. Then, the drought characteristics including drought event, duration, severity and intensity using “run theory” was analyzed for both historical observations and future RCP 8.5 scenarios based on the proper index. Correlation analysis between drought indexes and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain. Based on the results of SPEI-PM, droughts over the past 50 years have experienced reduced drought with shorter durations, and weaker severity and intensity. However, for the future RCP 8.5 scenario, drought is predicted to rise in frequency, duration, severity and intensity from 2010-2099 although drought components during the 2010-2039 were milder compared to historical conditions. This study highlights that the estimations for atmospheric evaporative demand would bring in differences in long term drought trend of drought indexes and consequently the applicability in 3H Plain. The results of this paper can help inform researchers and local policy makers to establish drought risk management strategies

Study of weld characteristics for repair using sequential experimental design and artificial neural networks

For remanufacturing dies and moulds, it is of significance to obtain information about weld characteristics because it plays a critical role on the mechanical strength of welded area. In this paper, a novel design of experiment methodology to study the relationship between the process parameters and weld profiles utilizing sequential experiment design and artificial neural networks is proposed. For the sequential experiment design, Taguchi experimental arrays were used for the preliminary experiments to survey the main effects of process parameters on weld characteristics of laser surfacing and the overall optimal conditions were obtained for all the performances. By means of Uniform Design, a reduced number of experimental runs are employed for further regression modelling of the influence of the selected parameters on the weld characteristics. Mathematical models were established by approximating designed radial basis function neural networks (RBFNNs) which are capable of modelling any function. Validation runs were finally conducted for testing the generalisation of fitted radial basis function neural network models. The prediction errors of validation runs are less than 10 %, which indicates good generalisation of developed models

A review on remanufacture of dies and moulds

Dies and moulds, which are essential tools for manufacturing engineered products, usually fail or become obsolete after a certain period of use for a variety of reasons. Thus, they often need remanufacture. The objectives of this paper are to review the current state of the art in remanufacture of dies and moulds and to investigate the potential benefits and opportunities associated with remanufacturing. In this paper, the benefits of introducing remanufacture into the die and mould industry are firstly discussed. This is followed by a summary of the unique characteristics of remanufacturing of dies and moulds compared to those of other products. Industrial repair strategies of the main types of dies and moulds are examined. Key technologies needed for remanufacture are then reviewed in detail including welding repair technologies, remaining useful life evaluation methods, and reliability analysis. Finally, challenges and opportunities facing the industry and academia are discussed in order to draw several key conclusions

Effects of Biodegradable Plastic Film on Carbon Footprint of Crop Production

Polyethylene film mulch (PM) is a kind of widely used technology to improve crop yields worldwide; however, because of a problem related with plastic residual pollution, it has gradually been replaced by biodegradable plastic film mulch (BDP). Although BDP has helped to solve the plastic residual pollution, its consequences in terms of greenhouse gas (GHG) emissions have rarely been revealed. Related knowledge is important for forming low-carbon development strategies for the plastic industry and agriculture. The objective of this study is to evaluate the influence of BDP on GHG emissions at different stages of its life cycle, and determine whether replacing polyethylene (PE) film with BDP film is a helpful way to reduce national GHG emissions. The results of this study suggest that the application of BDP improved the GHG emissions associated with agricultural inputs, but induced lower GHG emissions at the growing stage and the waste disposal stage, and resulted in lower total area-scale GHG emissions. Compared to the no mulch (NM) cultivation system, the yield-scale carbon footprint was reduced in both the PM and BDP cultivation systems, which meant that both PM and BDP produced lower GHG emissions than NM for the production of the same amount of grain. It was concluded that BDP is not only a measure to control the problem of plastic residue pollution in agriculture, but it can also mitigate the GHG emissions

Potential effect of climate drought on the yield and water productivity of winter wheat over the Huang-Huai-Hai Plain

Climate change is widely accepted to be one of the most critical problems faced by the Huang－Huai－Hai Plain (3H Plain), which is a region in which there is an over-exploitation of groundwater region and where future warmer and drought conditions might intensify crop water demand. The Huang－Huai－Hai Plain is subject to the middle and lower of the Yellow River basin, the Huaihe River plain, and the Haihe River valley plain, extending over 32°00′–40°30′N and 113°00′E to the east coast. It is surrounded by the south foot of Yanshan Mountain to the north, north foot of Tongbai Mountainand Dabie Mountain and Jianghuai Watershed to the south, and eastern foot of Taihang Mountainand Qinling Range to the west, whereas the eastern boundary lies the Bohai Sea and Yellow Sea. The Huang－Huai－Hai Plain belongs to the extratropical monsoon climatic region.The annual mean precipitation is 500－600 mm (with more than 70% falls in July to September), while the atmospheric evaporative demand is about 800 mm/year. For the wheat－maize rotation system, rainfall can just meet 65% of total agricultural water demand, especially for winter wheat, during which only 25%－40% is satisfied by rainfall. Irrigation water is mainly pumped from groundwater. Drought is one of the most damage and widespread climate extreme facing the world, and has been the relatively restriction factor for agriculture and economy development in China. As world’s largest water consumption industries, irrigation farming system consumes around 70% (even more than 80% for some country) of total freshwater usages. However, the accessible freshwater for agriculture has been challenged and declined along with the booming of population and the increasing water usage in living, industry and environment protection. Additionally, the change of quantitative value and spatial-temporal distribution of solar radiation, heat resources, and precipitation further fluctuate agricultural production. It showed that the precipitation had decreased significantly at the amount of 30mm during past 50 years in North and Northeast China, inducing a rapidly expanding of drought areas. In the background of global warming, the irrigation water resource for agricultural production is expected to be more unstable due to the increasing complexity of the regional difference and the annual/interannual variability of precipitation. Thus, how to produce more food with less water will become a subject to solve urgently in next decades, which in virtually depends on crop water productivity. Thus, improving crop water productivity is of primary importance for alleviate water resources crisis, guarantee national food security, and ensure society sustainable development. Firstly, the main purpose of writing this book is introduced. 3H Plain belongs to semi-arid and semi-humid region. Heat resources can meet the demand of double cropping system. The main cropping pattern is winter wheat-summer maize rotation system. The annual mean precipitation is 500－900 mm with inhomogeneous seasonal distribution that 45%－65% falls in summer.In spring, autumn, and winter, precipitation is insufficient to cover water output. There are about 400 mm of water deficit every year, while almost 150－200 mm was from winter wheat growing season. The winter wheat is typically planted in October and harvested next year in June in 3H Plain. The precipitation of this period is 125－250 mm (25%－29% of the year sums) which can not satisfy the water requirements for winter wheat development, and subsequently induce the high frequency of agricultural drought. Thus, the original intention of publishing this book is to provide reference and technical support for agrometeorological department to enhance disaster prevention and mitigation capacity and ensure national food security through: (1) analyzing the changing characteristics of climatic resources in regional scale, and (2) investigating the potential effect of climate drought on the yield and water productivity of winter wheat over the Huang－Huai－Hai Plain. Secondly, the basic structure and content. This book introduces the basic situation, regional differentiation of agricultural climate resources, meteorological drought characteristics and the evaluation of winter wheat water productivity of 3H Plain. The book is divided into seven chapters. Chapter 1 introduces the basic situation of the studied region, including the geographical location, administrative division, natural environmental condition and agricultural production status. Chapter 2 analysis the characteristics of agroclimatic resources, including the changing characteristics of solar radiation, annual mean temperature, precipitation and potential evapotranspiration. Chapter 3 describes the phenological phase and climatic water deficit of winter wheat, mainly including the impact of climate change on winter wheat phenology and the characteristics of water budget during winter wheat growth period in 1970s and 2000－2015, respectively. Chapter 4 investigates the potential effect of climate drought on winter wheat yield, including the spatial-temporal distribution of arid / humid conditions during winter wheat growing period, characteristics of meteorological drought for different growth stage of typical sites and its potential effect on wheat production. Chapter 5 presents a study on the drought adaptive capacity of wheat with different soil types (cinnamon and moisture soil). Chapter 6 describes the approach to estimate actual evapotranspiration of winter wheat, including the extraction of winter wheat planting information and actual evapotranspirationestimation based on SEBAL model. Chapter 7 evaluates the water productivity of winter wheat, including the research progress, the basic characteristics of wheat production and its rasterization, and the spatial-temporal differentiation of winter wheat water productivity. This book’s composition and publication has taken years of hard work of many experts who conduct long-term research of climatic drought assessment and its potential effect, and gotten a lot of support from Institute of Environment and Sustainable Development in Agriculture (CAAS), Key Laboratory of Dryland Agriculture and Chinese Academy of Meteorological Sciences. We also thank the National Basic ResearchProgram of China (973 Program, 2012CB955904), the National Key Technologies R&D Programs (2012BAD29B01), and theNational Science Foundation for Young Scientists of China (41401510). As a newly introduce book about “Potential effect of climate drought on the yield and water productivity of winter wheat over the Huang－Huai－Hai Plain”, it takes out great effect, and it is inevitable to have made mistakes in this book, so we are expecting scholars and readers to give feedback

Impact of climate change on potential evapotranspiration under a historical and future climate scenario in the Huang-Huai-Hai Plain, China

peer reviewedClimate change is widely accepted to be one of the most critical problems faced by the Huang-Huai-Hai Plain (3H Plain), which is a region in which there is an over-exploitation of groundwater region and where future warmer and drought conditions might intensify crop water demand. In this study, the spatiotemporal patterns of ET0 and primary driving meteorological variables were investigated based on a historical and RCP 8.5 scenario daily data set from 40 weather stations over the 3H Plain using linear regression, spline interpolation method, a partial derivative analysis and multivariate regression. The results indicated a negative trend in all the analysis periods (except spring) of the past 54 years of which only summer and the entire year were statistically significant (p < 0.01) with slopes of -1.09 and -1.30 mm·a-1 respectively. In contrast, a positive trend was observed in all four seasons and the entire year under the RCP 8.5 scenario, with the biggest increment equal to 1.36 mm·a-1 in summer and an annual increment of 3.37 mm·a-1. The spatial patterns of the seasonal and annual ET0 exhibited the lowest values in southeastern regions and the highest values in northeastern parts of Shandong Province, probably because of the combined effects of various meteorological variables over the past 54 years. Relative humidity (RH) together with solar radiation (RS) were detected to be the main climatic factors controlling the reduction of ET0 in summer, autumn, and the entire year on the 3H Plain. ET0 in spring was mainly sensitive to changes in RS and RH, whereas ET0 in winter was most sensitive to changes in wind speed (WS) and decreased due to declining RH. Under the future RCP 8.5 scenario, the annual ET0 distribution displays a rich spatial structure with a clear northeast-west gradient and anarea with low values in the southern regions, which is similarly detected in spring and summer. The most sensitive and primary controlling variables with respect to the increment of future ET0 are in the first place RS and then mean temperature in spring, while turn to be mean temperature and then RS in summer. In autumn, future ET0 is most sensitive to RH changes. WS and RH are the controlling variables for ET0 in winter. Annual future ET0 is most sensitive to RH changes and accordingly RS is responsible for the predicted increment of the annual ET0. Better understanding of current and future spatiotemporal patterns of ET0 and of the regional response of ET0 to climate change can contribute to the establishment of a policy to realize a more efficient use of water resources and a sustainable agricultural production in the 3H Plain