Responses of vegetation cover to the Grain for Green Program and their driving forces in the He-Long region of the middle reaches of the Yellow River

The implementation of the Grain for Green Program is a great breakthrough in the history of China＇s ecological environment construction,which can control soil erosion effectively,increase land productivity and improve the ecological environment.To investigate the eco-environmental benefits brought by the Grain for Green Program,the spatiotemporal variations of vegetation cover in the growing season from 2000 to 2010 across the Hekou-Longmen （He-Long） region were analyzed by using remote sensing information,meteorological data and land use data.Moreover,the impacts of climate and human activities on vegetation change were evaluated objectively.Annual vegetation cover in the growing season increased very significantly.Increased vegetation cover occurred in 98.7％ of the region,of which the area for vegetation cover improved slightly constituted 79.8％ of the whole area.Vegetation moderately improved was mainly distributed in the south of the He-Long region,covering 9.6％ of the area,and the area for vegetation basically unchanged concentrated in the middle and upper reaches of the Wuding River.Precipitation was found to be an important natural factor influencing vegetation cover change.The area of vegetation cover showing a significantly positive correlation with precipitation occupied 22.14％ of the region.As driven by policies from the Grain for Green Program,forestland increased significantly and land use structure became more intensive.Human activities played a positive and effective role in the protection,restoration and improvement of vegetation in the places where vegetation cover was basically unchanged,even though precipitation declined greatly,and vegetation improved moderately with massive increases of forestland and grassland.

Effects of V-pits covering layer position on the optoelectronic performance of InGaN green LEDs

The impact of the V-pits covering layer(VCL) position on the optoelectronic performance of InGaN-based green light-emitting diodes(LEDs) was investigated. It is found that earlier covering of V-pits will hinder the hole injection via the sidewall of V-pits, and then result in less quantum wells(QWs) participating in radioluminescence. The current-voltage characteristics show that the LEDs with earlier covering of V-pits have higher operating voltage at room temperature, and a more dramatic voltage rise with the reduction of temperature. Meanwhile, more manifested emission peaks for sidewall QWs and deeper QWs near to ntype layer was observed in the sample with earlier coveing of V-pits at cryogenic temperatures, for the reason that the holes being injected via V-pits sidewall have higher kinetic energy and could transport to deeper QWs.

Explaining farmers'reluctance to adopt green manure cover crops planting for sustainable agriculture in Northwest China

Green manure cover crops(GMCCs)planting has a potential for mitigating greenhouse gas emissions(GHG)in agroecosystems and provides important ecosystem services,thereby achieving the Sustainable Development Goals(SDGs)stipulated by the United Nations.However,the advantages of cultivating GMCCs on arable land are not widely recognized.For example,in the whole of China,the GMCCs planting area is less than 3.5%of total arable land.The aim of this study is to explore reasons for the low adoption rate of GMCCs planting.Using best–worst scaling(BWS)approach,farmers ranked their preferred conservation practices including three types of GMCC cropping systems.Taking Gansu Province in Northwest China as a case study,a survey with 276 farmers was conducted.The findings indicated that three factors are related to the low adoption rate of GMCCs:1)farmers preferred improving farmland irrigation facilities and substituting chemical fertilizers with organic rather than planting GMCCs;2)lack of awareness and understanding of government policy on GMCCs and limited access to training courses;3)financial support and subsidies from the government are insufficient.This study provides insights and strategic implications for policymakers on how to further promote GMCCs in the future.

Effects of Snow Cover on Alfalfa Overw intering and Turning Green

In order to investigate the effect of snow cover on alfalfa overwintering and turning green,6 different alfalfa varieties( including Longmu806,Gongnong No. 1,Aohan,Wega 7F,WL319 HQ,Caoyuan No. 3) were used as plant materials. There were 4 treatments in this study include snow-cover of 0,30%,70% and natural snow-cover( used as control). Nutrient content and antioxidant enzyme activity of root were measured before and after overwintering period. The rate of plant returning green and growth rate after greening were also measured after turning green. The result showed that the snow cover was the guarantee of alfalfa safely overwintering and turning green. The 54. 5-77. 9 cm snowfall was the optimum thickness of snow for safe overwintering. Alfalfa improved the overwintering ability by enhancing the root nutrients and antioxidant enzyme activity,and it was affected by snow cover. In addition total nitrogen and soluble sugar increased by 61% and 60% respectively,soluble protein reduced by8%,SOD and CAT reduced by 20% and 9% respectively than that before the overwintering under 70% of natural snow-cover. There were differences between overwintering ability of 6 different alfalfa varieties,in which Caoyuan No. 3 has more grass production and Wega 7F has stronger overwintering ability.

Spatiotemporal characteristics and driving mechanisms of land use/land cover(LULC)changes in the Jinghe River Basin,China

Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and transfer rate of LULC in the Jinghe River Basin(JRB),China using LULC data from 2000 to 2020.Through trajectory analysis,knowledge maps,chord diagrams,and standard deviation ellipse method,we examined the spatiotemporal characteristics of LULC changes.We further established an index system encompassing natural factors(digital elevation model(DEM),slope,aspect,and curvature),socio-economic factors(gross domestic product(GDP)and population),and accessibility factors(distance from railways,distance from highways,distance from water,and distance from residents)to investigate the driving mechanisms of LULC changes using factor detector and interaction detector in the geographical detector(Geodetector).The key findings indicate that from 2000 to 2020,the JRB experienced significant LULC changes,particularly for farmland,forest,and grassland.During the study period,LULC change trajectories were categorized into stable,early-stage,late-stage,repeated,and continuous change types.Besides the stable change type,the late-stage change type predominated the LULC change trajectories,comprising 83.31% of the total change area.The period 2010-2020 witnessed more active LULC changes compared to the period 2000-2010.The LULC changes exhibited a discrete spatial expansion trend during 2000-2020,predominantly extending from southeast to northwest of the JRB.Influential driving factors on LULC changes included slope,GDP,and distance from highways.The interaction detection results imply either bilinear or nonlinear enhancement for any two driving factors impacting the LULC changes from 2000 to 2020.This comprehensive understanding of the spatiotemporal characteristics and driving mechanisms of LULC changes offers valuable insights for the planning and sustainable management of LULC in the JRB.

Estimation of the Carbon Sequestration Dynamics of Senegal’s Great Green Wall Based on Land Cover over the Past Three Decades

The severe drought observed in the Sahel during 1970s, 1980s and 1990s has deeply affected the population as well as the economies and the eco-systems of this climatic area. The GGW Initiative spearheaded by Africa Union in 2007 proposed to combat the land degradation and desertification by planting a wall of trees stretching from Dakar to Djibouti. A reforestation was then conducted in the Senegal’s GGW since 2006 as part as other areas in the Sahel. This paper aims to evaluate the carbon sequestration dynamics in the sites of the Senegal’s GGW over the last three decades. The method consists firstly of analyzing the evolution of land cover and land use dynamics based on ESA-CCI LC satellite data. There is an improvement of the surface areas of tree and shrub savanna of 11.40% (Tessekere), 8.25% (Syer) and 2.70% (Loughere-Thioly). The regreening of the different localities and a positive dynamic observed is explained by the return to normal rainfall and to reforestation actions, agroforestry practices, better management of natural resources undertaken. However, some non-reforested sites showed an opposite trend despite of the normal rainfall. Secondly, the results on land mapping are used as a proxy for the assessment of carbon stocks. The dynamic observed in vegetation cover since the beginning of the reforestation made it possible to sequester 5.8 million tons of carbon representing respectively 2.31% of African GGW. This gain in stored carbon is equivalent to 21.2 million tons of CO2 captured in the atmosphere. Through this study, it appears that carbon storage becomes significant 8 to 10 years after the start of reforestation. An urbanization without respect for the environmental factors could be a danger for the climate (case of Ballou).

Application of Cellular Automata and Markov Chain model for urban green infrastructure in Kuala Lumpur,Malaysia

Kuala Lumpur of Malaysia,as a tropical city,has experienced a notable decline in its critical urban green infrastructure(UGI)due to rapid urbanization and haphazard development.The decrease of UGI,especially natural forest and artificial forest,may reduce the diversity of ecosystem services and the ability of Kuala Lumpur to build resilience in the future.This study analyzed land use and land cover(LULC)and UGI changes in Kuala Lumpur based on Landsat satellite images in 1990,2005,and 2021and employed the overall accuracy and Kappa coefficient to assess classification accuracy.LULC was categorized into six main types:natural forest,artificial forest,grassland,water body,bare ground,and built-up area.Satellite images in 1990,2005,and 2021 showed the remarkable overall accuracy values of 91.06%,96.67%,and 98.28%,respectively,along with the significant Kappa coefficient values of 0.8997,0.9626,and 0.9512,respectively.Then,this study utilized Cellular Automata and Markov Chain model to analyze the transition of different LULC types during 1990-2005 and 1990-2021 and predict LULC types in 2050.The results showed that natural forest decreased from 15.22%to 8.20%and artificial forest reduced from 18.51%to 15.16%during 1990-2021.Reductions in natural forest and artificial forest led to alterations in urban surface water dynamics,increasing the risk of urban floods.However,grassland showed a significant increase from 7.80%to 24.30%during 1990-2021.Meanwhile,bare ground increased from 27.16%to 31.56%and built-up area increased from 30.45%to 39.90%during 1990-2005.In 2021,built-up area decreased to 35.10%and bare ground decreased to 13.08%,indicating a consistent dominance of built-up area in the central parts of Kuala Lumpur.This study highlights the importance of integrating past,current,and future LULC changes to improve urban ecosystem services in the city.

The Effect of Vineyard Cover Crop on Main Monomeric Phenols of Grape Berry and Wine in Vitis viniferal L. cv. Cabernet Sauvignon

This study was conducted to determine the effect of cover crop inter-row in vineyard on main mono-phenol content of grape berry and wine. Three such cover crops, two perennial legumes （white clover and alfalfa） and a perennial gramineous grass （tall fescue） were sown in vineyard. The main phenolic compounds of mature grape berry and wines vinified under the same conditions were extracted with ethyl acetate and diethyl ether and analyzed by high- performance liquid chromatography （HPLC） by comparing to soil tillage. A total of ten phenolic compounds were identified and quantified in the different grape berry and wines, including nonflavonoids （hydroxybenzoic and hydroxycinnamic acids） and flavonoids （flavanols and flavonols）. The concentration of flavonoid compounds （409.43 to 538.63 mg kg^-1 and 56.16 to 81.30 mg L^-1） was higher than nonflavonoids （76.91 to 98.85 mg kg^-1 and 30.65 to 41.22 mg L^-1） for Cabernet Sauvignon grape and wine under different treatments, respectively. In the flavonoid phenolics, Catechin was the most abundant in the different grapes and wines, accounting for 74.94 to 79.70% and 48.60 to 50.62% of total nonanthocyanin phenolics quantified, respectively. Compared to soil tillage, the sward treatments showed a higher content of main mono-phenol and total nonanthocyanin phenolics in grapes and wines. There were significant differences between two cover crop treatments （tall fescue and white clover） and soil tillage for the content of benzoic acid, salicylic acid, caffeic acid, catechin, and total phenolics in the grape berry （P 〈 0.05 or P〈0.01）. The wine from tall fescue cover crop had the highest gallic acid, caffeic acid and catechin. Cover crop system increased the total nonanthocyanin phenolics of grapes and wines in order of the four treatments： tall fescue, white clover, alfalfa, and soil tillage （control）. Cover crop in vineyard increased total phenols of grape berry and wine, and thus improved the quality of wine evidently.

Forward Calculation of 2-D and 3-D Structures with a Cover by the Boundary Element Method while Using Electrical Methods

This paper develops the boundary element method, the authors employ two-layered earth Green 's functions as the weighting functions of residual and derive boundary integral equations. The forward problems of point sources on 2 - D and 3-D structures with an influencing cover are solved by this method. The results show that this method markedly improves the original boundary element method. The features of the improved method are greater numerical accuracy and much smaller systems of equations and thus considerable savings for the storage capacity of computers, allowing us to solve the above problems with only ordinary microcomputers. The results in this paper extend the scope of applying the boundary element method while using electrical methods for geophysical prospecting.

Pattern Change of Urban Green Space in Beijing from 2000 to 2010

With the rapid urbanization in Beijing, the vegetated surfaces have been increasingly replaced by impervious built surfaces. A clear recognition on the changes in green spaces pattern is vital for urban administrators and planners to optimize the urban development areas and define the ecological protection red lines. Based on the SPOT images and field investigation data of urban green spaces within the sixth ring road of Beijing in 2000, 2005 and 2010, the study investigated the dynamic changes of urban green spaces in this area, by means of GIS techniques and landscape ecology methods. The results indicated that green spaces in Beijing have decreased by 207 km2 from 2000 to 2010 at the expense of agricultural lands and waters. Although there has been some increases in urban forests and grasslands, it cannot compensate the rapid decrease of urban green spaces. The land cover types conversion occurred mainly in the areas between the fifth and sixth ring roads while the zones encircled by the fourth ring road had a little change. In addition, landscape metrics such as number of patches(NP) and shape index(SHAPE) increased, but the mean nearest-neighbor distance(MNN), aggregation index(AI) and patch cohesion index(COHESION) decreased during the period of 2000-2010. Also green landscapes became considerably isolated and fragmented. The study disclosed the obvious changes of green space size, composition and layout in urban districts of Beijing City from 2000 to 2010, and highlighted that construction of urban green space should consider not only the geometric or aesthetic effect, but also the increase of vertical green volume and optimization of spatial layout to fully develop the ecological service functions of green spaces.

ANALYSIS OF RECTANGULAR MICROSTRIP PATCH ANTENNA COVERED WITH N-DIELECTRIC LAYERS

A generalized spectral Green’s function formulation of N-layer substrate structure is given with three dimension sources, which is a set of closed form formulas. A full-wave analysis model for rectangular microstrip antennas covered with N-dielectric layers has been established by using the above spectral Green’s function. The unknown surface current density on the niicrostrip patch for such structure is found as a solution of an integral equation. The input VSWR and radiation patterns of the antenna are also obtained. The numerical results have been verified by the experimental results.

Landscape Application of Ground Covers in Beijing Highway

Ground cover is a necessary component of highway green space, and as a background color of landscape, it enriches landscape hierarchy, reflects regional characteristics, and reduces maintenance cost. By analyzing application of ground covers in some sections of 6 highways in Beijing, China, selection standards, application species, and planting designs of ground covers in highway green spaces of Beijing were explored, so as to enrich the application species, optimize landscape designs, and enhance the application of under-bridge ground covers.

Wave Motion in an Ice Covered Ocean Due to Small Oscillations of a Submerged Thin Vertical Plate

In this paper we study the problem of generation of surface waves produced due to a） rolling of the plate and b） presence of a line source in front of a fixed vertical plate. The amplitudes of radiated waves at large distance from the plate, in both cases, are obtained by a suitable application of Green＇s integral theorem. These are then studied graphically for various values of the ice cover parameter.

绿化覆盖率对城市绿地破碎度与地表温度的关系的影响

优化绿地空间配置(如破碎度)是改善城市热环境的有效途径。然而绿地破碎度对城市热环境的影响可能随绿化覆盖率的变化而变化,对改善城市热环境提出了巨大挑战,但相关研究十分缺乏。以长沙市为例,利用Landsat地表温度表征城市热环境,使用解译于高分2号遥感影像的城市绿地图在1 m像元尺度量化绿化覆盖率和绿地破碎度(用绿地边界密度表征)。以419个1 km格网为分析单元,应用分段线性回归揭示绿化覆盖率与绿地破碎度间的非线性关系,识别绿化覆盖率阈值并以此为标准将419个1 km格网划分为高绿化覆盖率区和低绿化覆盖率区。以1 km格网平均地表温度为因变量,绿化覆盖率、绿地破碎度、水体覆盖率和裸地覆盖率为自变量从研究区、高绿化覆盖率区和低覆盖率区3个方面建立多元线性回归模型阐明绿地破碎度对地表温度的影响。最后进行方差分解分析绿化覆盖率、绿地破碎度和其他土地覆盖率对地表温度的独立和联合影响。结果显示,1)绿地破碎度随绿化覆盖率的增加先增加后降低,阈值为44.9%。2)整个研究区,4个指标可解释69.1%的地表温度变异,地表温度随绿化覆盖率、水体覆盖率、裸地覆盖率和绿地破碎度的增加显著降低。3)低绿化覆盖率下绿地破碎度显著影响地表温度,高绿化覆盖率下绿地破碎度对地表温度呈不显著正影响。4)在研究区和不同绿化覆盖率区域,绿化覆盖率对地表温度的独立影响均高于绿地破碎度的独立影响。建议长沙城市绿地规划管理在提高绿化覆盖率的同时可提高低绿化覆盖率区域绿地破碎度以改善城市热环境。

Uncertainty Analysis of Spatial Autocorrelation of Land-Use and Land-Cover Data within Pipestem Creek in North Dakota

A major threat to biodiversity in North Dakota is the conversion of forested land to cultivable land, especially those that act as riparian buffers. To reverse this trend of transformation, a validation and prediction model is necessary to assess the change. Spatial prediction within a Geographic Information System (GIS) using Kriging is a popular stochastic method. The objective of this study was to predict spatial and temporal transformation of a small agricultural watershed—Pipestem Creek in North Dakota;USA using satellite imagery from 1976 to 2015. To enhance the difference between forested land and non-forested land, a spectral transformation method—Tasseled-Cap’s Greenness Index (TCGI) was used. To study the spatial structure present in the imagery within the study period, semivariograms were generated. The Kriging prediction maps were post-classified using Remote Sensing techniques of change detection to obtain the direction and intensity of forest to non-forest change. TCGI generated higher values from 1976 to 2000 and it gradually reduced from 2000 to 2011 indicating loss of forested land.

Scattering of water waves by thin vertical plate submerged below ice-cover surface

The present paper is concerned with scattering of water waves from a vertical plate, modeled as an elastic plate, submerged in deep water covered with a thin uniform sheet of ice. The problem is formulated in terms of a hypersingular integral equation by a suitable application of Green＇s integral theorem in terms of difference of potential functicns across the barrier. This integral equation is solved by a collocation method using a finite series involving Chebyshev polynomials. Reflection and transmission coefficients are obtained numerically and presented graphically for various values of the wave number and ice-cover parameter.

Cultivated-land change in Mu Us Sandy Land of China before and after the first-stage grain-for-green policy

Mu Us Sandy Land(MUSL) of China, as a typical eco-fragile and farming-pastoral transitional region, shows great vulnerability to disturbances from cultivation activity. In this region, the conflict between cultivation activity and environmental protection has not attracted great importance until the implementation of China's Grain-for-Green Policy(CGGP) since2000. Here, using Landsat5 TM/Landsat7 ETM+ images from 1990, 2000, and 2010, we monitor the cultivation activity and land-use/cover changes(LUCC) resulting from cultivation activity in the MUSL region. Based on the data from images, we developed a series of databases of cultivated activity-induced LUCC and use them to discuss comparatively the spatio-temporal evolution trends of cultivation activity before and after CGGP implementation. These results provide evidence for managers to evaluate the implementation effectiveness of governmental policy and the influence of cultivation activity on the ecological environment of the MUSL region.

污水处理厂生化反应池加设混凝土顶盖工艺设计

地上式污水处理厂生化反应池加设混凝土顶盖设计是一项系统性工作,合理的顶盖设计是后期安全、便捷运行及景观效果良好的基础。以西安市鱼化污水处理厂生化反应池混凝土顶盖设计为例,探讨顶盖巡检通道设置、主要设备及管路布置、覆土绿化等方面设计时需考虑的关键内容。实际运行效果表明,通过合理利用顶盖空间设置主次巡检通道、布置设备、管路及增加覆土绿化,创造了便利的巡检、维护条件,可取得良好的工程绿化及密封除臭效果,可为供类似污水处理项目参考借鉴。

覆盖区矿产调查钻探查证技术方法研究

覆盖区矿产勘查是新一轮找矿突破战略行动的重要内容之一.采用更加绿色和有效的钻探技术,快速获取隐伏基岩信息与样品,是覆盖区找矿亟待总结和推广的工作.本研究基于绿色勘查理念,采用便携式浅层钻探装备与技术,以及空气反循环钻进工艺,在大兴安岭东南缘宝山浅覆盖区铜多金属矿勘查中开展钻探试验,实现了快速穿透覆盖层获取隐伏基岩信息、查证物探异常并采集地球化学样品的效果,同步结合孔内成像等技术,为填制覆盖区隐伏岩石地层单元分布范围和界线等提供了基础资料.试验结果表明,基于浅层绿色钻探技术,结合孔内成像,并为野外地球化学快速分析提供测试样品的多方法组合,可以有效解决浅覆盖区找矿难题,在矿产勘查过程中具有很好的推广价值.

填闲作物还田方式对烟田土壤轻重组有机碳的影响

为了提高多年连作烟田的土壤肥力,改善土壤生态环境,在烤烟冬闲期种植油菜、冬牧70、光叶紫花苕等3种作物,同时以冬季空闲不种植任何作物为对照,采取2种方式(掩青和收割)进行处理,通过测定不同处理不同土层的土壤轻、重组有机碳含量、比例及储量,探讨填闲作物收割和掩青处理对烟田土壤轻重组有机碳的影响。结果表明,不同填闲作物和不同还田方式下土壤总有机碳、重组有机碳、轻组有机碳含量均随着土壤深度的增加而降低。与对照相比,填闲作物掩青处理能够显著增加土壤总有机碳、重组有机碳、轻组有机碳含量,尤其是冬牧70在20~40 cm土层增加比较显著,分别增加了22.3%、21.98%、27.78%;填闲作物收割处理会降低土壤轻组有机碳比例和土壤轻组有机碳储量,而掩青处理则会增加土壤轻组有机碳比例和轻组有机碳储量,其中冬牧70掩青在0~20 cm土层增加比较明显,分别增加了18.14%、40.03%。填闲作物掩青处理增加了烟田土壤的含水量和持水量、降低了土壤容重以及增加土壤轻重组有机碳储量。综合来看,冬牧70掩青处理效果最好,能显著增加土壤总有机碳和轻重组有机碳含量,油菜次之。