• Energy Research
• natural sciences close
• 15. Life on land close
• 11. Sustainability close
• GB close

Abstract Bioenergy crops are one of the renewable energy options available to decarbonise the energy sector in Scotland and help to achieve the overall planned target of 80% reduction in greenhouse gas (GHG) emissions by 2050. A process-based model for poplar and willow developed for simulating the effect of different environmental and management options on growth and biomass yield was used to estimate the GHG abatement potential (GHG-AP) under different crop management options in Scotland. The model results of annual wood yield did not show a strong relation with any of the environmental factors except that of initial soil organic carbon (SOC) content. Increasing plant density and decreasing harvest frequency increased GHG-AP. Application of N-fertilizers at a rate of 50–100 kg N ha−1 resulted in the buildup of carbon in soils with less than 180 Mg C ha−1. However, in soils with greater SOC contents, annual emissions resulting from N fertilizer application were greater than the carbon saving through marginal increases in wood yield and SOC changes. The best management scenario in terms of economic and environmental objectives depends on identifying an optimum plant density based on the site specific conditions with a fertilizer application of 20–100 kg ha−1 y−1 and a five year harvest interval. Even under the best economic scenarios, SRC willow and poplar have a GHG-AP ranging from 9.9 to 11.6 and 8.8–10.0 Mg CO2 eq. ha−1 y−1, respectively. Under the best environmental scenarios this range increases to 10.5- 13.2 and 9–11.1 Mg CO2 eq. ha−1 y−1 for willow and poplar, respectively.

Featured paper: See Editorial p553

Summary1. Migrant bird populations are declining and have been linked to anthropogenic climate change. The phenology mismatch hypothesis predicts that migrant birds, which experience a greater rate of warming in their breeding grounds compared to their wintering grounds, are more likely to be in decline, because their migration will occur later and they may then miss the early stages of the breeding season. Population trends will also be negatively correlated with distance, because the chances of phenology mismatch increase with number of staging sites.2. Population trends from the Palaearctic (1990–2000) and Nearctic (1980–2006) were collated for 193 spatially separate migrant bird populations, along with temperature trends for the wintering and breeding areas. An index of phenology mismatch was calculated as the difference between wintering and breeding temperature trends.3. In the Nearctic, phenology mismatch was correlated with population declines as predicted, but in the Palaearctic, distance was more important. This suggests that differential global climate change may be responsible for contributing to some migrant species’ declines, but its effects may be more important in the Nearctic.4. Differences in geography and so average migration distance, migrant species composition and history of anthropogenic change in the two areas may account for the differences in the strength of the importance of phenology mismatch on migrant declines in the Nearctic and Palaearctic.

This study investigates potential changes in erosion rates in the Midwestern United States under climate change, including the adaptation of crop management to climate change. Previous studies of erosion under climate change have not taken into account farmer choices of crop rotations or planting dates, which will adjust to compensate for climate change. In this study, changes in management were assigned based on previous studies of crop yield, optimal planting date, and most profitable rotations under climate change in the Midwestern United States. Those studies predicted future shifts from maize and wheat to soybeans based on price and yield advantages to soybeans. In the results of our simulations, for 10 of 11 regions of the study area runoff increased from +10% to +310%, and soil loss increased from +33% to +274%, in 2040–2059 relative to 1990–1999. Soil loss changes were more variable compared to studies that did not take into account changes in management. Increased precipitation and decreasing cover from temperature-stressed maize were important factors in the results. The soil erosion model appeared to underestimate the impact of change in crop type, particularly to soybeans, meaning that erosion increases could be even higher than simulated. This research shows that future crop management changes due to climate and economics can affect the magnitude of erosional impacts beyond that which would be predicted from direct climate change

Seaweed assemblages represent the dominant autotrophic biomass in many coastal environments, playing a central structural and functional role in several ecosystems. In Europe, seaweed assemblages are highly diverse systems. The combined seaweed flora of different European regions hold around 1550 species (belonging to nearly 500 genera), with new species continuously uncovered, thanks to the emergence of molecular tools. In this manuscript we review the effects of global and local stressors on European seaweeds, their communities, and ecosystem functioning. Following a brief review on the present knowledge on European seaweed diversity and distribution, and the role of seaweed communities in biodiversity and ecosystem functioning, we discuss the effects of biotic homogenization (invasive species) and global climate change (shifts in bioclimatic zones and ocean acidification) on the distribution of individual species and their effect on the structure and functioning of seaweed communities. The arrival of new introduced species (that already account for 5–10% of the European seaweeds) and the regional extirpation of native species resulting from oceans' climate change are creating new diversity scenarios with undetermined functional consequences. Anthropogenic local stressors create additional disruption often altering dramatically assemblage's structure. Hence, we discuss ecosystem level effects of such stressors like harvesting, trampling, habitat modification, overgrazing and eutrophication that impact coastal communities at local scales. Last, we conclude by highlighting significant knowledge gaps that need to be addressed to anticipate the combined effects of global and local stressors on seaweed communities. With physical and biological changes occurring at unexpected pace, marine phycologists should now integrate and join their research efforts to be able to contribute efficiently for the conservation and management of coastal systems.

La sécheresse agricole est l'un des risques agricoles les plus dommageables dans le monde qui peut entraîner des pertes agricoles importantes et une pénurie d'eau. L'utilisation d'images satellites pour surveiller la sécheresse agricole a fait l'objet d'une attention croissante de la part des chercheurs et a également été appliquée à l'échelle régionale et mondiale. Dans cet article, la température de surface de la terre (LST) et les produits d'éclat du nouveau Sentinel-3A SLSTR (radiomètre de température de surface de la mer et de la terre) lancé par l'Agence spatiale européenne (ESA) sont utilisés pour la première fois pour estimer l'indice de condition de température de la végétation (VTCI), qui à son tour est utilisé pour surveiller la sécheresse agricole dans la plaine de Hetao en Mongolie intérieure, en Chine. Cet article analyse initialement la corrélation entre le LST et l'indice de végétation à différence normalisée (NDVI) en utilisant des séries temporelles MODIS LST et NDVI dans différentes conditions de croissance de la végétation. Les résultats révèlent que VTCI ne peut être utilisé que pendant les saisons chaudes (fin du printemps et période estivale) lorsque des corrélations négatives entre LST et NDVI sont observées. Par conséquent, les images VTCI sont capturées dans la zone d'étude entre juillet et août 2017 à l'aide de Sentinel-3A SLSTR LST et NDVI et sont utilisées pour l'enquête sur la sécheresse. Ces images révèlent que le VTCI moyen des pixels des terres cultivées dans la zone d'étude est passé de 0,4511 le 28 juillet à 0,5229 le 12 août avant de diminuer à 0,4710 le 18 août en raison des précipitations de la première période, indiquant ainsi que VTCI a une réponse opportune aux précipitations. Pendant ce temps, la comparaison croisée des valeurs VTCI de Sentinel-3A SLSTR montre une grande cohérence en termes de distribution spatiale avec celle estimée à partir des produits EOS MODIS. La différence entre ces indices variait de −0,1 à 0,1 pour la plupart des points, en particulier dans la couverture terrestre cultivée. Dans l'ensemble, les résultats appuient l'utilisation des produits LST et NDVI de Sentinel-3A SLSTR dans la surveillance de la sécheresse agricole. La sequía agrícola es uno de los peligros agrícolas más dañinos en todo el mundo que puede provocar importantes pérdidas agrícolas y escasez de agua. El uso de imágenes satelitales para monitorear la sequía agrícola ha recibido cada vez más atención de la investigación y también se ha aplicado a escala regional y mundial. En este documento, la temperatura de la superficie terrestre (LST) y los productos de radiancia del nuevo Sentinel-3A SLSTR (radiómetro de temperatura de la superficie del mar y la tierra) lanzado por la Agencia Espacial Europea (esa) se utilizan por primera vez para estimar el índice de condición de temperatura de la vegetación (VTCI), que a su vez se utiliza para monitorear la sequía agrícola en la llanura de Hetao de Mongolia Interior, China. Este documento analiza inicialmente la correlación entre LST y el índice de vegetación de diferencia normalizada (NDVI) mediante el uso de productos MODIS LST y NDVI de series de tiempo en diferentes condiciones de crecimiento de la vegetación. Los hallazgos revelan que el VTCI solo se puede usar en estaciones cálidas (finales de los períodos de primavera y verano) cuando se observan correlaciones negativas entre LST y NDVI. Por lo tanto, las imágenes de VTCI se capturan en el área de estudio entre julio y agosto de 2017 mediante el uso de Sentinel-3A SLSTR LST y NDVI y se utilizan para la investigación de la sequía. Estas imágenes revelan que el VTCI promedio de los píxeles de tierra cultivada en el área de estudio ha aumentado de 0.4511 el 28 de julio a 0.5229 el 12 de agosto antes de disminuir a 0.4710 el 18 de agosto debido a las precipitaciones en el primer período, lo que indica que el VTCI tiene una respuesta oportuna a las precipitaciones. Mientras tanto, la comparación cruzada de los valores de VTCI de Sentinel-3A SLSTR muestra una alta consistencia en términos de distribución espacial con la estimada de los productos EOS MODIS. La diferencia entre estos índices osciló entre -0,1 y 0,1 para la mayoría de los puntos, especialmente en la cubierta vegetal cultivada. En general, los hallazgos respaldan el uso de los productos LST y NDVI de Sentinel-3A SLSTR en el monitoreo de la sequía agrícola. Agricultural drought is one of most damaging agricultural hazards worldwide that can bring significant agricultural losses and water scarcity. The use of satellite images for monitoring agricultural drought has received increasing research attention and has also been applied at both the regional and global scales. In this paper, the land surface temperature (LST) and radiance products of the new Sentinel-3A SLSTR (sea and land surface temperature radiometer) launched by European Space Agency (ESA) are used for the first time for estimating the vegetation temperature condition index (VTCI), which in turn is used for monitoring agricultural drought in the Hetao Plain of Inner Mongolia, China. This paper initially analyzes the correlation between LST and normalized difference vegetation index (NDVI) by using time series time MODIS LST and NDVI products under different vegetation growth conditions. The findings reveal that VTCI can only be used in warm seasons (late spring and summer periods) when negative correlations between LST and NDVI are observed. Therefore, VTCI images are captured in the study area between July and August 2017 by using Sentinel-3A SLSTR LST and NDVI and are utilized for drought investigation. These images reveal that the average VTCI of the cultivated land pixels in the study area has increased from 0.4511 on July 28 to 0.5229 on August 12 before declining to 0.4710 on August 18 due to the rainfall in the first period, thereby indicating that VTCI has a timely response to rainfall. Meanwhile, cross-comparison of VTCI values from Sentinel-3A SLSTR shows high consistency in terms of spatial distribution with that estimated from EOS MODIS products. The difference between these indices ranged from −0.1 to 0.1 for most points, especially in the cultivated land cover. Overall, the findings support the use of the LST and NDVI products of Sentinel-3A SLSTR in monitoring agricultural drought. يعد الجفاف الزراعي أحد أكثر المخاطر الزراعية ضررًا في جميع أنحاء العالم والذي يمكن أن يؤدي إلى خسائر زراعية كبيرة وندرة المياه. حظي استخدام صور الأقمار الصناعية لرصد الجفاف الزراعي باهتمام بحثي متزايد وتم تطبيقه أيضًا على المستويين الإقليمي والعالمي. في هذه الورقة، يتم استخدام درجة حرارة سطح الأرض (LST) ومنتجات الإشعاع الخاصة بالمقياس الإشعاعي الجديد Sentinel -3A SLSTR (مقياس درجة حرارة سطح البحر والأرض) الذي أطلقته وكالة الفضاء الأوروبية (ESA) لأول مرة لتقدير مؤشر حالة درجة حرارة الغطاء النباتي (VTCI)، والذي يستخدم بدوره لرصد الجفاف الزراعي في سهل هيتاو في منغوليا الداخلية، الصين. تحلل هذه الورقة في البداية العلاقة بين LST ومؤشر الاختلاف الطبيعي للغطاء النباتي (NDVI) باستخدام السلاسل الزمنية لمنتجات MODIS LST و NDVI في ظل ظروف نمو مختلفة للغطاء النباتي. تكشف النتائج أنه لا يمكن استخدام VTCI إلا في المواسم الدافئة (أواخر فصلي الربيع والصيف) عند ملاحظة الارتباطات السلبية بين LST و NDVI. لذلك، يتم التقاط صور VTCI في منطقة الدراسة بين يوليو وأغسطس 2017 باستخدام Sentinel -3A SLSTR LST و NDVI وتستخدم للتحقيق في الجفاف. تكشف هذه الصور أن متوسط VTCI لبكسلات الأراضي المزروعة في منطقة الدراسة قد ارتفع من 0.4511 في 28 يوليو إلى 0.5229 في 12 أغسطس قبل أن ينخفض إلى 0.4710 في 18 أغسطس بسبب هطول الأمطار في الفترة الأولى، مما يشير إلى أن VTCI لديها استجابة في الوقت المناسب لهطول الأمطار. وفي الوقت نفسه، تُظهر المقارنة المتقاطعة لقيم VTCI من Sentinel -3A SLSTR اتساقًا عاليًا من حيث التوزيع المكاني مع تلك المقدرة من منتجات EOS MODIS. تراوح الفرق بين هذه المؤشرات من -0.1 إلى 0.1 لمعظم النقاط، خاصة في الغطاء الأرضي المزروع. بشكل عام، تدعم النتائج استخدام منتجات LST و NDVI من Sentinel -3A SLSTR في مراقبة الجفاف الزراعي.

For the purpose of efficiency improvement, a linear motor that performs a linear reciprocating motion can be employed to directly drive the piston in a reciprocating refrigeration compressor without crankshaft mechanism. This also facilitates the modulation of cooling capacity as the stroke and frequency can be readily varied in response to heat load. A novel design of moving magnet linear motor for linear compressor was analyzed in the paper. A finite element analysis (FEA) model was built to simulate the characteristics of the linear motor. Current and displacement signals were measured from a test rig and were defined in the transient FEA model. Transient motor force was simulated with the FEA model and good agreements are shown between the results from the FEA model and interpolated shaft force from static force measurements. Major Losses, such as copper loss and core loss were also computed. Motor efficiency decreased from 0.88 to 0.83 as stroke increased from 9 mm to 12 mm, while the pressure ratio remained unchanged. Comparisons were made between the present moving magnet linear motor and moving coil linear motors. Generally, the moving magnet linear motor demonstrates higher efficiency than moving coil motors, which have significantly higher copper loss. The present moving magnet design with simple structure could be further optimized to improve motor efficiency.