Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei

Light levels determine regeneration in stands and a key concern is how to regulate the light environment of different stand types to the requirements of the understory.In this study,we selected three stands typical in south China(a Cryptomeria japonica plantation,a Quercus acutissima plantation,and a mixed stand of both)and three thinning intensities to determine the best understory light environ-ment for 3-year-old Phoebe bournei seedlings.The canopy structure,understory light environment,and photosynthe-sis and growth indicators were assessed following thin-ning.Thinning improved canopy structure and understory light availability of each stand;species composition was the reason for differences in the understory light environ-ment.Under the same thinning intensity,the mixed stand had the greatest light radiation and most balanced spectral composition.P.bournei photosynthesis and growth were closely related to the light environment;all three stands required heavy thinning to create an effective and sustained understory light environment.In a suitable understory light environment,the efficiency of light interception,absorption,and use by seedlings was enhanced,resulting in a higher carbon assimilation the main limiting factor was stomatal conductance.As a shade-avoidance signal,red/far-red radia-tion is a critical factor driving changes in photosynthesis and growth of P.bournei seedlings,and a reduction increased light absorption and use capacity and height:diameter ratios.The growth advantage transformed from diameter to height,enabling seedlings to access more light.Our findings suggest that the regeneration of shade-tolerant species such as P.bournei could be enhanced if a targeted approach to thinning based on stand type was adopted.

Heterogeneous population distribution enhances resistance to wheat lodging by optimizing the light environment

Lodging is still the key factor that limits continuous increases in wheat yields today,because the mechanical strength of culms is reduced due to low-light stress in populations under high-yield cultivation.The mechanical properties of the culm are mainly determined by lignin,which is affected by the light environment.However,little is known about whether the light environment can be sufficiently improved by changing the population distribution to inhibit culm lodging.Therefore,in this study,we used the wheat cultivar“Xinong 979”to establish a low-density homogeneous distribution treatment(LD),high-density homogeneous distribution treatment(HD),and high-density heterogeneous distribution treatment(HD-h)to study the regulatory effects and mechanism responsible for differences in the lodging resistance of wheat culms under different population distributions.Compared with LD,HD significantly reduced the light transmittance in the middle and basal layers of the canopy,the net photosynthetic rate in the middle and lower leaves of plants,the accumulation of lignin in the culm,and the breaking resistance of the culm,and thus the lodging index values increased significantly,with lodging rates of 67.5%in 2020–2021 and 59.3%in 2021–2022.Under HD-h,the light transmittance and other indicators in the middle and basal canopy layers were significantly higher than those under HD,and the lodging index decreased to the point that no lodging occurred.Compared with LD,the activities of phenylalanine ammonia-Lyase(PAL),4-coumarate:coenzyme A ligase(4CL),catechol-O-methyltransferase(COMT),and cinnamyl-alcohol dehydrogenase(CAD)in the lignin synthesis pathway were significantly reduced in the culms under HD during the critical period for culm formation,and the relative expression levels of TaPAL,Ta4CL,TaCOMT,and TaCAD were significantly downregulated.However,the activities of lignin synthesis-related enzymes and their gene expression levels were significantly increased under HD-h compared with HD.A partial least squares path modeling analysis found significant positive effects between the canopy light environment,the photosynthetic capacity of the middle and lower leaves of plants,lignin synthesis and accumulation,and lodging resistance in the culms.Thus,under conventional high-density planting,the risk of wheat lodging was significantly higher.Accordingly,the canopy light environment can be optimized by changing the heterogeneity of the population distribution to improve the photosynthetic capacity of the middle and lower leaves of plants,promote lignin accumulation in the culm,and enhance lodging resistance in wheat.These findings provide a basis for understanding the mechanism responsible for the lower mechanical strength of the culm under high-yield wheat cultivation,and a theoretical basis and for developing technical measures to enhance lodging resistance.

Tempo-Spatial Variations in Stomatal Conductance, Aperture and Density of Ligustrum sinense Acclimated to Different Light Environments

There was heterogeneous distribution in stomatal conductance (g-s) and stomatal aperture for both high- and low-light leaves of Ligustrum sinense Lour. in four designated positions within a leaf. Linear or exponential or polynomial relationships between g-s and stomatal aperture were found when regression of g-s and stomatal aperture was established. Statistical analysis revealed that the relationship between g-s and stomatal aperture for high-light leaves was more significant than that of low-light leaves. A linear relationship between g-s and stomatal aperture existed in both positions 1 and 3 for both high- and low-light leaves. The stomatal density of the low-light leaves was much lower than that of the high-light leaves. The sensitivity of stomata to changing environment for high-light leaves was higher than that for low-light leaves, which may also relate to the higher stomatal density for the high-light leaves.

Photosynthetic Gas Exchange and Leaflet Movement of Robinia pseudoacacia in Relation to Changing Light Environments

On the sunny days, there were little diurnal changes in both azimuth and directional angle for either sun_ or shade_leaflet. However, there existed a significant diurnal change in midrib angle that reflected movements regarding evasion of light stress around noon hours. On the cloudy day, a very little diurnal difference was found in azimuth, directional and midrib angle. It is suggested that changing light environment is the main factor for inducing leaflet movement of Robinia pseudoacacia , and the rhythmical movement does not attribute to the leaflet movement. Leaf orientation control test showed that the photosynthetic rate ( Pn ), stomatal conductance ( g s ) and transpiration ( Tr ) of the artificial fixed_leaflets were significantly lower than that of control_leaflets. And the leaf temperature ( Tl ) of the fixed leaflets significantly exceeded that of control_leaflets, which may attribute to the significant difference of light interception between the fixed and control_leaflets. The light_dependent leaflet movement is the morphological adjustment of maintaining optimal physiological status.

Systemic regulation of photosynthetic function in maize plants at graining stage under a vertically heterogeneous light environment

To cope with a highly heterogeneous light environment,photosynthesis in plants can be regulated systemically.Currently,the majority of studies are carried out with various plants during the vegetative growth period.As the reproductive sink improves photosynthesis,we wondered how photosynthesis is systemically regulated at the reproductive stage under a vertically heterogeneous light environment in the field.Therefore,changes of light intensity within canopy,chlorophyll content,gas exchange,and chlorophyll a fluorescence transient were carefully investigated at the graining stage of maize under various planting densities.In this study,a high planting density of maize drastically reduced the light intensities in the lower canopy,and increased the difference in vertical light distribution within the canopy.With the increase of vertical heterogeneity,chlorophyll content,light-saturated photosynthetic rate and the quantum yield of electron transport in the ear leaf(EL) and the fourth leaf below the ear(FLBE) were decreased gradually,and the ranges of declines in these parameters were larger at FLBE than those at EL.Leaves in the lower canopy were shaded artificially to further test these results.Partial shading(PS) resulted in a vertically heterogeneous light environment and enhanced the differences in photosynthetic characteristics between EL and FLBE.Removing the tassel and top leaves(RTL) not only improved the vertical light distribution within the canopy,but also reduced the differences in photosynthetic characteristics between the two leaves.Taken together,these results demonstrated that maize plants could enhance the vertical heterogeneity of their photosynthetic function to adapt to their light environment;slight changes of the photosynthetic function in EL at the graining stage under a vertically heterogeneous light environment indicated that the systemic regulation of photosynthesis is weak at the graining stage.

Research on color image matching method based on feature point compensation in dark light environment

Image matching refers to the process of matching two or more images obtained at different time,different sensors or different conditions through a large number of feature points in the image.At present,image matching is widely used in target recognition and tracking,indoor positioning and navigation.Local features missing,however,often occurs in color images taken in dark light,making the extracted feature points greatly reduced in number,so as to affect image matching and even fail the target recognition.An unsharp masking(USM)based denoising model is established and a local adaptive enhancement algorithm is proposed to achieve feature point compensation by strengthening local features of the dark image in order to increase amount of image information effectively.Fast library for approximate nearest neighbors(FLANN)and random sample consensus(RANSAC)are image matching algorithms.Experimental results show that the number of effective feature points obtained by the proposed algorithm from images in dark light environment is increased,and the accuracy of image matching can be improved obviously.

Prediction of Photosynthetic Carbon Assimilation Rate of Individual Rice Leaves under Changes in Light Environment Using BLSTM-Augmented LSTM

A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and productivity.Long short-term memory(LSTM),a neural network suitable for time-series data,enables prediction with high accuracy but requires mesophyll variables.In addition,for practical use,it is desirable to have a technique that can predict A from easily available information.In this study,we propose a BLSTM augmented LSTM(BALSTM)model,which utilizes bi-directional LSTM(BLSTM)to indirectly reproduce the mesophyll variables required for LSTM.The most significant feature of the proposed model is that its hybrid architecture uses only three relatively easy-to-collect external environmental variables—photosynthetic photon flux density(Q_(in)),ambient CO_(2) concentration(C_(a)),and temperature(T_(air))—to generate mesophyll CO_(2) concentration(C_(i))and stomatal conductance to water vapor(g_(sw))as intermediate outputs.Then,A is predicted by applying the obtained intermediate outputs to the learning model.Accordingly,in this study,1)BALSTM(Q_(in),C_(a),T_(air))had a significantly higher A prediction accuracy than LSTM(Q_(in),C_(a),T_(air))in case of using only Q_(in),C_(a),and T_(air);2)BALSTMC_(i),g_(sw),which had C_(i) and g_(sw) as intermediate products,had the highest A prediction accuracy compared with other candidates;and 3)for samples where LSTM(Q_(in),C_(a),T_(air))had poor prediction accuracy,BALSTMC_(i),g_(sw)(Q_(in),C_(a),T_(air))clearly improved the results.However,it was found that incorrect predictions may be formed when certain factors are not reflected in the data(e.g.,timing,cultivar,and growth stage)or when the training data distribution that accounts for these factors differs from the predicted data distribution.Therefore,a robust model should be constructed in the future to improve the prediction accuracy of A by conducting gasexchange measurements(including a wide range of external environmental values)and by increasing the number of training data samples.

Responses of fractal dimensions of Picea koraiensis seedlings to different light environments

The changes of fractal dimension ofPicea koraiensis seedlings under different light intensities in natural secondary forests was studied. The results showed that with the change of light environment, crown characters ofPicea koraiensis seedlings exhibited a greater plastic in lateral number, lateral increment, lateral dry weight, and specific leaf area. The range of calculated fractal dimensions of seedling crowns was confined between 2.5728 and 2.1036, but maximum of fractal dimension achieved in term moderate shading and in extreme low light conditions fractal dimension was least.

Approach to the Zoning and Management for the Function of Light Environment

Light pollution becomes more and more serious, but the study on this field is far from enough. In this paper, light environment is defined as light-free area, dark area, intermediate sight area, and bright area. In addition, it is marked with index value by index system, which includes average brightness, brightness evenness, glare index, and background brightness.

Seaberry (<i>Hippophae rhamnoides L.</i>) and Water Lily (<i>Nymphaeaceae</i>) Extracts Protect Human Skin against Blue Light, Environmental Pollutants and UV-A Irradiations in an <i>Ex Vivo</i>Model System

Background: The skin is the outer shell of the mammalian body and it is continuously exposed to a large spectrum of external stimuli including sun irradiation and atmospheric pollutants. These factors present deleterious effects on the cutaneous compartment by altering the skin barrier functions and accelerating the aging of the skin. Objectives: The goal of this study was to investigate the activity of Seaberry and Water Lily extracts, here called Dermina complex, against different external stresses. Methods: Human skin explants were exposed to different stimuli including delipidation by organic solvents, blue light, atmospheric pollutants and UV-A. The activity of the Seaberry and Water Lily extracts was assessed by immunohistochemistry and by biochemical assays. Results: We showed that Dermina complex prevents the delipidation-induced filaggrin decrease, suggesting that these plant extracts exhibited barrier function protecting properties. Also, we observed that Dermina complex showed an antioxidant and DNA protection activity by decreasing the activated form of Nrf2, the oxidized proteins and the formation of γ-H2AX induced upon stress conditions. The Dermina complex also decreased the pro-inflammatory cytokine IL-1 alpha released in the culture medium following atmospheric pollutants and UV-A exposure confirming its anti-inflammatory activity. Moreover, Dermina complex reduced the blue light-induced overexpression of opsin 3, indicating that its skin protection activities may be due, in part, to filter property against environmental stresses. Conclusions: Dermina complex shows a protective activity of the skin against different environmental stresses and these extracts may be able to slow down the aging process of the cutaneous compartment.

Biomass allocation and assimilation efficiency of natural Tilia amurensis samplings in response to different light regimes

Biomass allocation and assimilation efficiency of natural Amour linden (Tilia amurensis) samplings in different light regimes were analyzed in the paper. The results showed that shoot increment of samplings in gap was the highest and that of samplings under canopy was the least. Samplings in gap expressed apical dominance strongly but samplings in full sun and under canopy behaved intensive branching. Lateral competition or moderate shading was favored to bole construction. The patters of biomass allocation of samplings in different light environment were rather similar. The biomass translocated to stem was more than that to other organs, and about one half of photosynthate was used to support leaf turn over. On the contrary, photosynthates of samplings in full sun were mostly consumed in leaves bearing and energy balancing. The carbon assimilation for leaves of samplings in gap was the most efficient, and more carbons were fixed and translocated to non-photosynthetic organs, especially to stemwood.

Dye-Enhanced Self-Electrophoretic Propulsion of Light-Driven TiO_2–Au Janus Micromotors

Light-driven synthetic micro-/nanomotors have attracted considerable attention in recent years due to their unique performances and potential applications. We herein demonstrate the dye-enhanced self-electrophoretic propulsion of light-driven Ti O_2–Au Janus micromotors in aqueous dye solutions. Compared to the velocities of these micromotors in pure water, 1.7, 1.5, and 1.4 times accelerated motions were observed for them in aqueous solutions of methyl blue(10-5g L^(-1)), cresol red(10^(-4)g L^(-1)),and methyl orange(10^(-4)g L^(-1)), respectively. We determined that the micromotor speed changes depending on thetype of dyes, due to variations in their photodegradation rates. In addition, following the deposition of a paramagnetic Ni layer between the Au and Ti O_2 layers, the micromotor can be precisely navigated under an external magnetic field. Such magnetic micromotors not only facilitate the recycling of micromotors, but also allow reusability in the context of dye detection and degradation.In general, such photocatalytic micro-/nanomotors provide considerable potential for the rapid detection and ‘‘on-thefly'' degradation of dye pollutants in aqueous environments.

Relationship Between the Spatiotemporal Distribution of Dominant Small Pelagic Fishes and Environmental Factors in Mauritanian Waters

The relationship between the spatiotemporal distribution of three dominant small pelagic fishes,including chub mackerel(Scomber japonicus),horse mackerel(Trachurus trecae)and round sardinella(Sardinella aurita),and the environmental factors in Mauritanian waters were analyzed by using 4 years of logbook data of commercial purse seine fisheries to improve the efficiency of fishery and management of sustainable exploitation.A Tweedie-generalized additive model(GAM)of 8-day average catches and the monthly geostatistical analysis of daily catches were used in this study to analyze the influence of environmental factors on catch per unit of effort(CPUEs)and to map the spatial distribution of three mixed dominant small pelagic fishes,respectively.A 10'×10' grid was used,and environmental factors were processed from remote sensing,including 8-day average sea surface temperature(SST),the nearest distance between SST fronts and CPUE position(Df),chlorophyll-a(Chl-a)concentration,salinity,and eddy kinetic energy.Results showed that 1)the distribution of three dominant small pelagic fishes might be related to the intensity of upwelling in Mauritanian waters;2)oceanic fronts might play a key role in the ecology of chub mackerel,horse mackerel,and round sardinella;3)Chl-a concentration might be associated with the feeding grounds of chub mackerel;4)the target species distribution appeared sensitive to gradient changes in the amount of salinity;5)three zones(northern,central,and southern)with variable abundances were delineated;and 6)a high concentration of the center of gravity in the central zone might be related to the strong upwelling of nutrient-rich waters.This study can provide new insights to enhance the fishery efficiency and sustainable exploitation management of purse seiners in certain area off Mauritania.

UV-LED表面消毒辐射场的数学模拟体系的建立及试验验证

为了实现紫外发光二极管(Ultraviolet Light-Emitting Diodes,UV-LED)表面消毒器设计的优化、高效、智能化目的,研究建立了UV-LED表面消毒辐射场的数学模型,并进行了试验验证。根据该数学模型,编写了VBA(Visual Basic for Applications)程序,对辐射场进行了模拟和分析。结果显示,辐射模型的计算值与实测值接近,试验验证了辐射模型的可行性。试验进行了应用举例,当照射距离与灯间距的比值为0.4时,选择最大发光角90°的UV-LED可使辐射场最优化;当照射距离与灯间距的比值为0.8和1.6时,对应的最优选择分别是45°和30°的UV-LED。数学模型和相关计算方法为优化设计紫外线表面消毒设施提供了模拟、优化的有效工具。

植物工厂内LED光调控在果树栽培中应用的研究进展

相比露天栽培和大田生产,植物工厂具有不受气候条件影响、自动化程度高、空间单位面积利用率高、可周年不间断连续生产等突出优点。该文重点阐述和分析了植物工厂内发光二级管(LED)光调控在果树栽培中的应用,从光质、光周期、光照度三个角度出发,总结LED光调控对果树生长发育与生理生化的影响,并提出存在的问题,展望了未来的发展趋势。

照明光污染防治现状及对中国的建议

随着城市建设加快,照明技术快速发展,人造光源导致的光污染问题日益凸显,已经成为城市环境污染防治的新领域。光污染防治工作在国外已开展了几十年,具有丰富的管理经验和技术基础。在综述国外照明光污染研究进展的基础上,指出中国光污染防治管理现状及问题,并提出对策与建议,为国家综合施策、统筹推进光污染防治,建立国家光环境监督管理体系提供科学依据。

教学楼智能灯光控制设计研究

以某教学楼为例,探讨并设计了一套基于物联网技术的智能灯光控制系统,旨在提升照明效率、优化能源使用,并创造更加舒适的学习环境。系统融合了环境光感应、人体红外探测、时间调度以及远程控制功能,通过智能化调节实现按需照明,有效降低了能耗,提高了师生的满意度。

基于相似日和Optuna-LightGBM的智能控制柜内部环境预警评估方法

针对基于事件驱动的智能控制柜温湿度预测精度较低,无法及时对柜内温湿度异常进行预警的问题,提出了一种基于相似日和Optuna-LightGBM的温湿度预测方法。利用相似日算法选取合适的模型训练数据集,构建基于LightGBM的温湿度预测模型,用Optuna优化模型参数。最后,提出了一种基于曲线拐点检测的预警参数阈值计算方法,分析预测模型得到的温湿度曲线特性,实现温湿度预警。实验结果显示,所提方法的温度预测误差MAPE为0.35%,湿度预测误差MAPE为0.73%,可实现对柜内温湿度的精准预测并及时预警。

基于光照需求的老旧小区公共空间更新设计研究

文章旨在探讨营造老旧小区公共空间高品质的光照场景与环境风貌的更新设计思路与应用策略。通过以天津本溪楼小区为例,运用问卷调研、访谈观察、需求卡片、行为注记等方法,剖析其公共空间的光环境资源分布、居民活动类型、行为习惯特征以及光照需求程度间的动态联系,提出遵循光照优先性、空间整体性、边界共享性、尺度适用性的设计原则。针对区内复合型街道、灵活型边界、开放型活动空间类型分别采取了功能融合与光照适配、场地互借与需求过渡、场景聚焦与群体共享的应用策略,有效提升了区内公共空间的光照资源的利用率与空间、设施功能适配的精准度,可使居民在日常活动中获得良好的光环境体验。

绿色视角下轻化工产业绿色供应链环境成本管理研究

在当代社会,随着经济的蓬勃发展与人们环保意识的不断增强,绿色环保已然成为众多行业共同追求的目标。特别是在轻化工产业这一与日常生活紧密相连的领域。如何有效地进行环境成本管理,成为行业内外普遍关注的问题。基于此,探讨轻化工产业在追求绿色发展的过程中,绿色供应链管理的实践及其显著特点,并进一步剖析当前环境成本管理的现状与面临的挑战。通过深入分析,强调了采取绿色供应链管理对优化环境成本控制的重要性,不仅能显著提升企业的环保形象,还能促进企业经济效益的提高和可持续发展。针对现存的环境成本管理中的种种不足,如管理主动性不足、成本核算机制的不完善以及控制体系的薄弱等问题,提出了一系列切实可行的优化策略和保障措施。这些措施旨在为轻化工产业的绿色转型提供理论指导和实践支持,助力企业实现环境与经济效益的双赢。