Conopy architecture of Larrea tridentata (DC.) Cov., a desert shrub: foliage orientation and direct beam radiation interception

Summary At sites in the United States, creosote bushes (Larrea tridentata (DC.) Cov.) orient foliage clusters predominantly toward the southeast. Foliage of bushes at the southernmost distribution extreme in Mexico shows no predominant orientation. Clusters at all sites are inclined between 33° and 71° from the horizontal. Inclinations are steeper in the drier and hotter Mojave Desert than in the Chihuahuan Desert. Individual leaflets, though not measured, appear more randomly oriented than foliage clusters. In several populations studied, branches were shorter in the southeastern sectors of the crown, reducing self-shading early in the morning. Measurements of direct beam radiation interception by detached branches, using digital image processing, indicated that foliage clusters oriented toward the southeast exhibited less self-shading during spring mornings than clusters oriented northeast. This effect was not apparent at the summer solstice. This type of canopy architecture may tend to minimize self-shading during the morning hours when conditions are more favorable for photosynthesis, resulting in an improved daily water use efficiency.     

Faster induction of photosynthesis increases biomass and grain yield in glasshouse-grown transgenic Sorghum bicolor overexpressing Rieske FeS

Sorghum is one of the most important crops providing food and feed in many of the world's harsher environments. Sorghum utilizes the C₄ pathway of photosynthesis in which a biochemical carbon-concentrating mechanism results in high CO₂ assimilation rates. Overexpressing the Rieske FeS subunit of the Cytochrome b₆f complex was previously shown to increase the rate of photosynthetic electron transport and stimulate CO₂ assimilation in the model C₄ plant Setaria viridis. To test whether productivity of C₄ crops could be improved by Rieske overexpression, we created transgenic Sorghum bicolor Tx430 plants with increased Rieske content. The transgenic plants showed no marked changes in abundances of other photosynthetic proteins or chlorophyll content. The steady-state rates of electron transport and CO₂ assimilation did not differ between the plants with increased Rieske abundance and control plants, suggesting that Cytochrome b₆f is not the only factor limiting electron transport in sorghum at high light and high CO₂. However, faster responses of non-photochemical quenching as well as an elevated quantum yield of Photosystem II and an increased CO₂ assimilation rate were observed from the plants overexpressing Rieske during the photosynthetic induction, a process of activation of photosynthesis upon the dark–light transition. As a consequence, sorghum with increased Rieske content produced more biomass and grain when grown in glasshouse conditions. Our results indicate that increasing Rieske content has potential to boost productivity of sorghum and other C₄ crops by improving the efficiency of light utilization and conversion to biomass through the faster induction of photosynthesis.     

Novel Miscanthus hybrids: Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception

New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020–2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020–2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7–89.7 Mt year⁻¹ biomass, with potential for 1.2–1.3 EJ year⁻¹ energy and 36.3–40.3 Mt year⁻¹ carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety.     

Feeding by the pine weevil Hylobius abietis in relation to sun exposure and distance to forest edges

Abstract 1 The intensity of feeding by adult pine weevils Hylobius abietis (L.) on the stem bark of Norway spruce Picea abies (L.) Karst. seedlings planted in rows with a north–south orientation across a clear‐cutting, was measured throughout a growth season. The feeding was then correlated to light interception, soil temperature and distance to the nearest forest edge. 2 Feeding was at least twice as intense on seedlings in the central part of the clear‐cutting compared to those at the edges. The decline began approximatety 15 m from the edge and was of similar proportions on both the sun‐exposed and shaded sides. 3 Measures of global radiation and soil temperature correlated well with consumption on the shaded side. However, on the sun‐exposed side, there were no apparent correlations with global radiation or soil temperature that could explain the decline in consumed bark area. 4 We conclude that the decline in feeding towards the forest edges was mainly due to factors other than the microclimate variables we monitored. We suggest that the presence of roots of living trees along the forest edge may reduce damage to seedlings, since they provide an alternative source of food for the weevils. This alternative‐food hypothesis may also explain why seedlings in shelterwoods usually suffer less damage from pine weevils than seedlings in clear‐cuttings.     

我国口岸小条实蝇属截获情况分析

[目的] 小条实蝇属害虫原产非洲,在我国无分布且具有一定的入侵风险。分析该虫在我国口岸的截获情况,能更好地利用已知实蝇截获数据防范实蝇人为传播。[方法] 经动植物检验检疫信息资源共享服务平台查询,统计小条实蝇属的有害生物类别、截获途径及截获地区等。[结果] 全国口岸共截获8种共计524批次的小条实蝇属害虫;地中海实蝇的截获批次数最多,为415批次,为小条实蝇属截获率的79.2%;截获的种类最多的国家来自尼日利亚,5种;截获批次最多的国家为南非,71批次;截获方式最多的为旅客携带物,占总批次的68.3%;在我国口岸中,广东口岸截获批次最多,占总数的57.4%。[结论] 从今后防控的重点种类、加大查验力度、推广新技术在鉴定上的应用、应急预案等几个方面,加强针对该类有害生物的检验检疫措施。     

Memory and prediction in natural gaze control

In addition to stimulus properties and task factors, memory is an important determinant of the allocation of attention and gaze in the natural world. One way that the role of memory is revealed is by predictive eye movements. Both smooth pursuit and saccadic eye movements demonstrate predictive effects based on previous experience. We have previously shown that unskilled subjects make highly accurate predictive saccades to the anticipated location of a ball prior to a bounce in a virtual racquetball setting. In this experiment, we examined this predictive behaviour. We asked whether the period after the bounce provides subjects with visual information about the ball trajectory that is used to programme the pursuit movement initiated when the ball passes through the fixation point. We occluded a 100 ms period of the ball''s trajectory immediately after the bounce, and found very little effect on the subsequent pursuit movement. Subjects did not appear to modify their strategy to prolong the fixation. Neither were we able to find an effect on interception performance. Thus, it is possible that the occluded trajectory information is not critical for subsequent pursuit, and subjects may use an estimate of the ball''s trajectory to programme pursuit. These results provide further support for the role of memory in eye movements.     

管网雨水补给河道用水的人工湿地水质净化流程研究

中国北方部分地区水资源短缺,河道干涸,但夏季雨水资源潜力丰富。虽径流受到一定污染,但较于生活污水和工业废水,其污染程度更低,成分更简单。雨水通过低运行成本的人工湿地净化系统,可以实现较好的净化效果,满足河道景观需求和生态补水。城市管网雨水承载能力过重的城市边缘区,建设更新过程中进行雨污分流制度,更适于采用人工水质净化的方式将城市雨水管网中的雨水进行就近消纳,减轻城市雨水管网压力,并利用表面负荷率（ALR）来确定并校核人工湿地面积。在综合现在人工水质净化主流程预处理单元、人工湿地单元和消毒存储单元3个环节的基础上,以低运营成本、低管理成本、最优净水量为指向,引入物联网技术智能管控系统,行程具有能控制各级出水水质监测、多级管控、净水生态功能与游览景观功能相结合等多重优点的人工水质净化全流程,达到符合河道水质标准的净化效果。该流程为缓解北方城镇河道缺水现状、解决城市雨洪问题提供新思路。     

Towards Productive Cities: Environmental Assessment of the Food‐Energy‐Water Nexus of the Urban Roof Mosaic

Cities are rapidly growing and need to look for ways to optimize resource consumption. Metropolises are especially vulnerable in three main systems, often referred to as the FEW (i.e., food, energy, and water) nexus. In this context, urban rooftops are underutilized areas that might be used for the production of these resources. We developed the Roof Mosaic approach, which combines life cycle assessment with two rooftop guidelines, to analyze the technical feasibility and environmental implications of producing food and energy, and harvesting rainwater on rooftops through different combinations at different scales. To illustrate, we apply the Roof Mosaic approach to a densely populated neighborhood in a Mediterranean city. The building‐scale results show that integrating rainwater harvesting and food production would avoid relatively insignificant emissions (13.9–18.6 kg CO₂ eq/inhabitant/year) in the use stage, but their construction would have low environmental impacts. In contrast, the application of energy systems (photovoltaic or solar thermal systems) combined with rainwater harvesting could potentially avoid higher CO₂ eq emissions (177–196 kg CO₂ eq/inhabitant/year) but generate higher environmental burdens in the construction phase. When applied at the neighborhood scale, the approach can be optimized to meet between 7% and 50% of FEW demands and avoid up to 157 tons CO₂ eq/year. This approach is a useful guide to optimize the FEW nexus providing a range of options for the exploitation of rooftops at the local scale, which can aid cities in becoming self‐sufficient, optimizing resources, and reducing CO₂ eq emissions.     

Prey stimuli trigger trophic interception across ecosystems

Specialised predators foraging in the boundaries of adjacent ecosystems can control or redirect the flow of subsidies through trophic interception. Ecologically diverse predators can capture terrestrial invertebrates that fall on the water surface and, consequently, influence the flow of energy to aquatic environments. In this study, we show that the movement of prey triggers ripples on the surface of the water, and these stimuli are detected by bulldog bats (Noctilio albiventris, Noctilionidae) during foraging. Thus, the bats located live crickets (Gryllus assimilis, Gryllidae) on average of 15 times faster when compared to the location of dead or artificial crickets (i.e. without movements or ripples on the water surface). The bats also inspected (i.e. touched with their feet) all floating objects on the water surface. During this behaviour, the characteristics of the object (i.e. texture) were critical for bats to distinguish between debris (e.g. leaves and sticks) and the resource (i.e. insect carcasses) that floated on the water surface. In addition, when we compare the efficiency of predators (i.e. bats and fishes) in capturing this resource, our findings suggest that bats are extremely effective (i.e. consumed 100% of the available prey), since the fishes consumed only 40% of the available crickets on the surface of the water over a 60‐s period. These results bring novel information about the influence of prey‐based stimuli on the behaviour of its predators and, consequently, on the flow of nutrients between terrestrial and aquatic ecosystems.     

Characteristics and simulation of snow interception by the canopy of primary spruce‐fir Korean pine forests in the Xiaoxing'an Mountains of China

Snow interception by the forest canopy is an important control on the forest hydrological cycle in the Xiaoxing'an Mountains within the northern temperate region of China. In this study, the effects of snowfall characteristics and stand structures on the snowfall redistribution of the canopies within primary spruce‐fir Korean pine forests are analyzed at the forest stand scale. Characteristics of snowfall, through‐canopy snowfall, and stand structure are continuously measured using positioning observations. A semiempirical theoretical model is used to conduct snow interception simulations in the Xiaoxing'an Mountain region. The results indicate that the snowfall, canopy density, slope gradient, and tree height have a significant effect on the through‐canopy snowfall. The interception efficiency gradually decreases with an increase in the amount of snowfall and is particularly sensitive to the snowfall and canopy density, although it shows no significant correlation with average diameter at breast height, tree height, basal area, canopy height, canopy width, leaf area, or slope gradient. Very similar results have been observed in Canada and Switzerland, suggesting the transferability of the results between North America, Western Europe, and China. However, although model results provide a satisfactory simulation of snow interception, further studies are required to optimize the model in this region.