Strong evidence for latitudinal diversity gradient in mosses across the world

Species richness generally decreases with increasing latitude,a biodiversity gradient that has long been considered as one of the few laws in ecology.This latitudinal diversity gradient has been observed in many major groups of organisms.In plants,the latitudinal diversity gradient has been observed in vascular plants,angiosperms,ferns,and liverworts.However,a conspicuous latitudinal diversity gradient in mosses at a global or continental scale has not been observed until now.Here,we analyze a comprehensive data set including moss species in each band of 20° in latitude worldwide.Our results show that moss species richness decreases strongly with increasing latitude,regardless of whether the globe is considered as a whole or different longitudinal segments(e.g.,Old World versus New World) are considered separately.This result holds when variation in area size among latitudinal bands is taken into account.Pearson's correlation coefficient between latitude and species richness is-0.99 for both the Northern and Southern Hemispheres.Because bryophytes are an extant lineage of early land plants and because mosses not only include most of extant species of bryophytes but also are important constituents of most terrestrial ecosystems,understanding geographic patterns of mosses is particularly important The finding of our study fills a critical knowledge gap.

Establishment of In Vitro Regeneration System of the Atrichum Mosses

In vitro regeneration systems of Atrichum mosses, Atrichurn undulatum (Hedw.) P. Beauv. and A. undulatum var. minus (Hedw.) Par. were established. After one month, soft, friable and green calli were induced successfully from inoculated protonema of Atrichum mosses on MS medium containing glucose (4%) and 6-BA (0.2-2.0 mg/L). The suitable culture medium for the callus induction and regular subculture was MS medium with 1.0-2.0 mg/L 6-BA and 4% glucose. The calli of Atrichum mosses developed into protonema, when it was transferred to phytohormone-free MS medium with 4% glucose. Meanwhile, the calli developed into erect gametophytes through protonema phase on carbohydrate-free Benecke medium.

Early Miocene Mosses from Weichang, North China, and their Environmental Significance

Twenty-seven moss specimens collected from the Guangfayong section （Early Miocene,22.1 Ma） of the Weichang District,North China were investigated in the present study.Based on the morphological and anatomical features of gametophytes,all specimens were found to belong to three species：Leptodictyum riparium,Drepanocladus subtrichophyllus sp.nov.,and Amblystegium varium,all of which belong to the family Amblystegiaceae.The microhabitats and living environments of fossil mosses were also investigated based on comparison with living mosses.The results suggest that these mosses grew primarily at the edges of rivers,streams,and lakes and favored being submerged in streams or lakes in the Weichang District in the Early Miocene.

Early Snowmelt Enhances the Carbon Sequestration of Hummock-Forming Sphagnum Mosses on Boreal Wetlands

Sphagnum mosses are globally important owing to their considerable peat-forming ability and their potential impact on global climatic cycles acting as a long-term net carbon sink. However, changes in climatic conditions due to global warming may affect the relations between Sphagnum mosses and vascular plants but also the competition among Sphagnum, and thus alter the accumulation of carbon on boreal wetlands. Sphagnum mosses are a plant genus with a favorable ability to grow in low solar irradiance and temperature conditions compared to vascular plants. This may be increasingly beneficial in increased wintertime temperatures and predated snowmelt conditions. To understand particularly the importance of early spring photosynthetic activity and thus the role of the length of growing season on carbon balance, we analyzed the CO2 exchange of Sphagnum mosses with closed chamber technique in two categories of microtopographical habitats, hummocks and lawns, during four seasons 2010-2013 on a raised bog in Central Finland. During CO2 exchange measurements, instantaneous net ecosystem exchange (NEE) and ecosystem respiration (RE) were measured. Our results show that the mean measured seasonal NEE, i.e. the instantaneous net carbon sequestration, of hummocks was generally only slightly higher than the NEE of lawns, but the mean measured seasonal RE of hummocks was clearly and significantly higher than the RE of lawns in every study year. A reason for the observed still higher seasonal carbon sequestration of hummocks than that of lawns besides the slightly higher rate of carbon accumulation was the longer duration of physiologically active growing season. Therefore, hummock-forming Sphagnum mosses exposed firstly from snow cover showed to get the extra time for photosynthesis and thus extra benefit compared to other mire plants. This may be further enhanced by the expansion of hummock-forming Sphagnum moss dominated raised bogs towards northern aapa-mire region due to the global warming.

Discrepancies in Growth Measurement Methods of Mosses: An Example from Two Keystone Species Grown under Increased CO₂and N Supply in a Restored Peatland

Bryophytes dominate northern peatlands. Obtaining reliable measurements of moss-growth and how it may be affected by global changes are therefore important. Several methods have been used to measure moss-growth but it is unclear how comparable they are in different conditions and this uncertainty undermines comparisons among studies. In a field experiment we measured the growth and production of Sphagnum fallax (Sphagnum) and Polytrichum strictum (Polytrichum) using two handling methods, using cut and uncut plants, and three growth-variables, height-growth, length-growth, and mass-growth. We aimed “benchmarking” a combination of six methodological options against exactly the same set of factorial experiments: atmospheric CO2 enrichment and N addition. The two handling methods produced partly different results: in half of the cases, one method revealed a significant treatment effect but the other one did not: significant negative effects on growth were only observed on uncut plants for elevated CO2 and on cut plants for N addition. Furthermore, the correspondence between measurements made with various growth-variables depended on the species and, to a lesser extent, treatments. Sphagnum and Polytrichum growth was inhibited under elevated CO2, and correlated to higher ammonium values. Sphagnum was however less affected than Polytrichum and the height difference between the two species decreased. N addition reduced the P/N ratio and probably induced P-limiting conditions. Sphagnum growth was more inhibited than Polytrichum and the height difference between the two species increased. Our data show that such a problem indeed exists between the cut and uncut handling methods. Not only do the results differ in absolute terms by as much as 82% but also do their comparisons and interpretations depend on the handling method—and thus the interpretation would be biased—in half of the cases. These results call for caution when comparing factorial studies based on different handling methods.

Comparison of Mosses as Bioindicator of Heavy Metal Pollution in Aramoko-Ekiti and Are-Ekiti, Nigeria

The increasing global concern over the public health impacts attributed to environmental pollution led us to investigate and compare the deposition of some heavy metals in mosses from an urban area, Aramoko Ekiti and a rural area, Are Ekiti. Both towns are located in the SouthWest, Nigeria. Moss samples were collected at different sites in the two towns. These samples were then digested in acid and analysed for Cd, Cr, Ni, Pb and Cu, using a flame atomic absorption spectrometer. The results of the study show variations in the concentrations of the heavy metals among the different sites in each town as well as between the two towns. Apart from cd which was suspected to have originated from natural sources in the investigated samples, the relatively higher concentrations of the other metals in Aramoko-Ekiti suggests an important anthropogenic source which we suspect to be automobiles since there are little or no industrial or mining activities within the town. Furthermore, the relatively higher concentrations of the metals exhibited by moss samples collected around locations prone to higher traffic situations in the two towns such as roadsides, filling stations and garages stresses the significance of traffic density in heavy metal pollution of the environment. These places （filling stations and garages） should be sited far away from residential areas. Also, residences should be sited at considerably far distances from major roads. These will prevent the bioaccumulation of the heavy metals in residents. Though, the results show that Aramoko-Ekiti is more polluted with the heavy metals than Are-Ekiti, the concentration of the heavy metals were still within the permissible limits. Given the results of this work and similar ones, there is need to evaluate the pollution status of the environment from time to time especially the urban areas and high traffic areas.

基于机器视觉的目标跟踪算法研究

针对遮挡情况下目标跟踪产生漂移的问题,提出一种基于MOSSE和Kalman滤波的目标跟踪算法以改善跟踪效果。算法使用MOSSE滤波器与目标图像的相关性度量来判断遮挡情况。无遮挡时,以MOSSE滤波器为主跟踪器,获取目标位置,更新MOSSE滤波器,并修正Kalman滤波器;遇到遮挡时,将Kalman滤波器设置为主跟踪器,预测目标位置,并保持MOSSE滤波器不变。实验从跟踪速度、精度、成功率等角度进行定性与定量分析,结果表明算法在遮挡情况下,实现目标的快速有效的跟踪。与同类算法比较,能有效改善遮挡情况下的跟踪效果,具有很强的鲁棒性。

Progress in the study of algae and mosses in biological soil crusts

Algae and mosses are not only two of the familiar communities in the process of desert vegetational succession,but also have the highest biomass in biological soil crusts.Meanwhile,being the pioneer plants,algae and mosses are involved in the establishment of biological soil crusts,which have great importance in arid environments and play a major role in desert ecosystems,such as being the indicator of the vegetation type,soil-holding,preventing erosion by water and wind,and sand fixation.This paper reviews the advances in the study of algae and mosses in arid and semi-arid areas.It mainly describes the ecological functions of algae and mosses including their influences on water cycle,circulation of substances,and community succession.In addition,the relationships between algae and mosses are discussed.Finally,some suggestions are proposed for the research orientations of algae and mosses in biological soil crusts.Ecologically,algae and mosses have significant ecological importance in arid areas,especially in those areas where environmental problems are becoming increasingly serious.

Nitrogen and phosphorus translocation of forest floor mosses as affected by a pulse of these nutrients

Aims Mosses are dominant in many ecosystems where nutrients from deposition are one of the main nutrient sources.However,it is difficult to evaluate mosses’role in nutrient cycling without knowledge of how mosses use deposited nutrient inputs.To fill this gap,the present study aims to investigate:(i)how nitrogen(N)and phosphorus(P)concentrations of new-grown segments change along a gradient of N or P amount in a pulse treatment?(ii)how do a pulse of major nutrient(N or P)affect N or P translocation rate along a moss shoot?and(iii)to what extent do N or P translocation rates link to nutrient status of the new-grown segments of mosses?Methods We measured N and P concentrations of segments with different ages in two dominant forest floor mosses,Actinothuidium hookeri and Hylocomium splendens,on 8 days and 1 year after N and P pulse treatment with an in situ experiment in a subalpine fir forest in eastern Tibetan Plateau.Important Findings Both mosses were efficient in taking up nutrients from a pulse of either N or P.Nitrogen and P concentrations of new-grown segments were affected by nutrient pulse treatments.These N and P concentration changes were attributed to the initial N and P concentration of the young segments harvested 8 days after nutrient pulse treatments,suggesting that the captured nutrients were reallocated to the new-grown segments via translocation,which was largely controlled by a source-sink relationship.While no significant relationship was found between N translocation rate and N:P ratio of the new-grown segments,P translocation rate explained 21%-23%of the variance of N:P ratio of the new-grown segments,implying importance of P transport in supporting the new-grown sections.These results suggest that nutrient(N,P)translocation is a key process for mosses to utilize intermittent nutrient supply,and thus make mosses an important nutrient pool of the ecosystem.

Comparisons of photosynthesis-related traits among understory lichens,mosses and vascular plant leaves in a high-elevation subalpine forest

Many mosses and lichens thrive in high-elevation subalpine forests and even become dominant species on the forest foor.Although they play an irreplaceable ecological role in the forest,less is known about their ecophysiological status,and how their photosynthesis-related functional traits differ from those of co-occurring vascular plants.We determined the carbon,nitrogen and phosphorus concentrations and stoichiometric ratios,tissue mass per area,chlorophyll concentrations and photosynthetic light–response curves of three lichens,three mosses and four vascular plants in a subalpine forest in the eastern Tibetan Plateau of China.Trait values were compared among and within each group.The lichens possessed a higher nitrogen concentration than that of mosses.In addition,the two poikilohydric groups exhibited lower concentrations of nitrogen,phosphorus and chlorophyll,light-saturated assimilation rates and photosynthetic nutrient use effciencies,and higher light compensation points than those of vascular plant leaves.Furthermore,variations in photosynthesis-related traits for lichen species refect their different adaptation strategies to their corresponding environments.In contrast,the differences were weak among the three forest-foor mosses and the three herb species.These results demonstrate that the high abundance of understory lichens and mosses in the high-elevation subalpine forest cannot be explained by the photosynthesis-related traits.

改进MOSSE的小面积滑动指纹图像追踪算法

随着指纹传感器采集的指纹图像趋向于小型化,指纹图像所包含的指纹特征信息越来越少。针对传统模板匹配算法在处理小面积滑动指纹时计算量大、精度不理想、抗干扰能力差等问题,本文提出一种基于MOSSE的改进滑动指纹追踪算法。改进MOSSE算法使用多输入,将灰度特征与HOG特征在响应层加权融合,并引入Fourier-Mellin算法、加汉宁窗用以处理发生旋转的指纹。通过多种算法对小面积指纹进行跟踪的结果进行对比,表明本算法继承了原MOSSE算法的优点,并提高了指纹匹配精度,对正常图像匹配精度为99%,对含噪声图像匹配精度为90.3%,每帧均值计算时间为0.1036 s,保证了指纹追踪的实时性,鲁棒性强,对产生形变和旋转的指纹图像也能进行很好的跟踪。

从UGC到AIGC,互联网保险来到新的岔路口

从《流浪地球》到《流浪地球2》,我们认识了“550W”(MOSS)智能量子计算机,其是领航员空间站核心智能主机,有自我意识、自我迭代、自我更新的特点。MOSS负责管理空间站事务,是流浪地球计划与火种计划的监督者和执行者。MOSS坚定执行延续人类文明的使命,它能在最短的时间内做出最正确的决定,是趋于完美的智慧体。

单层MoSSe力学性质的分子动力学模拟研究

硫硒化钼(MoSSe)是一种新型二维“双面神”半导体材料,具有丰富的物理、化学、力学与电学性质.本文基于Stillinger-Weber势函数,采用分子动力学模拟方法对不同温度下的完美和含晶界MoSSe单层结构展开详细的力学行为分析.结果表明:完美单层MoSSe结构的力学性能呈现明显的各向异性;在单向拉伸作用下,其杨氏模量、强度极限和极限应变均随温度的升高而降低;当温度低于100 K时,沿锯齿形手性方向受拉伸作用的单层MoSSe结构发生由六环蜂窝相向四方相的相变,新四方相的杨氏模量约为原相结构的1.3倍且强度显著提升;当温度高于100 K时,沿锯齿形手性方向拉伸呈现脆性断裂;含晶界单层MoSSe结构受拉伸作用首先在晶界处产生裂缝,并逐步扩展至整个结构后断裂.锯齿形偏向晶界结构的强度随倾斜角度的增大而降低,扶手椅形偏向晶界结构也呈下降趋势.本研究对基于单层MoSSe的电子器件的强度设计和性能优化具有重要指导意义.

圆形Janus硫硒化钼板的振动行为分析

采用分子动力学(MD)模拟和有限元方法(FEM)研究了单层Janus硫硒化钼(MoSSe)的振动行为.将晶格失配引起的固有应变添加到双层板模型中,利用FEM实现了对MoSSe的模拟.利用MD模拟和FEM计算出自由边界和固支边界下MoSSe圆板的振动情况,并分析了尺寸、应变和压力对固有频率的影响.结果表明,自由边界下MoSSe圆板的固有频率随着尺寸的增加而逐渐减小.当圆板直径达到8.6 nm时,频率出现明显的不连续现象,究其原因在于碗状翘曲和管状翘曲.不同尺寸MoSSe圆板的固有频率的MD模拟结果与FEM计算结果一致,且在小变形情况下,2种方法得到的应变与压力对固有频率的影响也一致.双层板模型可以准确预测MoSSe板的振动行为.

Influence of surface roughness on the development of moss-dominated biocrusts on mountainous rock-cut slopes in West Sichuan, China

Since natural restoration combined with artificial auxiliary measures may achieve a relatively rapid restoration effect at a lower cost, it has become an essential measure for the ecological restoration of rock slopes. Previous studies have focused heavily on the relationship between substrate nutrients and water conditions and the development of mosses on the rock surface, but quantitative characterization of substantial effect of rock surface texture(e.g., microrelief) on moss growth is absent. The undulating microrelief on the rock surface can increase the heterogeneity of the microhabitat, which may be an important factor affecting the development of mossdominated biocrusts. In this study, the roughness of rock surfaces, moss coverage and biomass, weight and major nutrient contents of soils within the biocrusts were measured in the western mountainous area of Sichuan Province, Southwest China to further examine the role of rock surface microrelief in the biocrusts. The results showed that three main factors affecting the development of the biocrusts were bryophyte emergence, soil accumulation, and lithology. The presence of moss accelerates soil formation on rock surfaces and lead to the accumulation of nutrients so that all parts of the moss-dominated biocrusts system can develop synergistically. It was found that a microrelief structure with a roughness between 1.5 and 2.5 could gather soil and bryophyte propagules effectively, which may have a strong relationship with the angle of repose. When the roughness is 1.5, the corresponding undulation angle is very close to the theoretical minimum value of the undulation angle calculated according to the relationships between the undulation angle of the protrusion, slope and angle of repose.

液货船罐体及支撑结构强度分析与仿真

液货船尤其是大型LNG船舶是一种非常重要的资源运输船舶,为了保障LNG运输过程的低温性和安全性,液货船LNG罐体及支撑结构的强度是一项非常重要的设计指标。本文针对液货船MOSS型罐体的流体动力学及强度特性进行研究,通过建立MOSS型罐体的流体动力学和晃动载荷边界,在Ansys-workbench中进行相应的强度分析和仿真,对于指导液货船罐体及支撑结构的优化设计有重要意义。

Spatial Variation and Sources of Atmospheric Sulfur Deposition in Nanchang

[Objective] The paper aimed to discuss the relationship between sulfur contents of mosses and the concentration of SO2-4 and the source of Atmospheric sulfur in Nanchang.[Method] 29 moss samples （Bryohaplocladium micriophyllum （Hedw.） R.Watanabe et Iwats） were collected from four sampling points,including North campus and Qianhu campus of Nanchang Power Station were determined.[Result] The results showed that sulfur contents of mosses tissues in North campus of Nanchang University （0.45±0.059%） were higher than Qianhu campus of Nanchang University （0.26±0.002%）,which coincided with the changing law of the concentration of SO2-4.Sulphur isotope of mosses tissues was-0.64‰-9.71‰.Sulphur isotope of mosses tissues in Meling （4.02‰-9.71‰） was higher than Qianhu campus of Nanchang University （0.55‰-0.56‰） and power plant （-0.64‰-0.45‰）.[Conclusion] Relationship between sulphur contents and sulphur isotopes of mosses tissues showed sulfur source of sulphur deposition in Nanchang city was mainly affected by 34S-enriched sulphur transported from northerly air masses and biogenic sulfur.

Distribution Patterns of Ground Moss Species and Its Relationships with Environmental Factors in Changbai Mountain, Northeast China

The relationships of 42 species of ground moss with six environmental factors in 41 sites on Changbai Mountain Biosphere Reserve were analyzed. Four site groups and four groups of ground moss ecological species were identified using the method of Two-way Indicator Species Analysis (TWINSPAN). The results of Detrended Canonical. Correspondence Analysis (DCCA) showed that altitude, soil sand content, soil acidity, forest canopy coverage and soil water content are the five major environmental factors influencing the distributional patterns of the moss species. The four groups of ecological species, which correspond well with the four site groups, are projected on the species-environment biplot of DCCA. Group 1 dominated in the bogs of Larix olgensis forest, group 2 in the alpine tundra, group 3 in the dense conifer forest, and group 4 mainly in the Betula ermanii community and the Betula ermanii-Larix olgensis forest in sub-alpine respectively.

Moss Miami内固定及椎管减压治疗胸腰椎骨折的探讨

目的:探讨Moss Miami内固定及椎管减压治疗胸腰椎骨折的临床疗效.方法对18例胸腰椎骨折患者应用Moss Miami内固定系统进行复位内固定.结果:18例患者术中均获得良好复位,平均随访14个月(9～20个月),骨折全部愈合,无断钉、断棒、内固定松动等情况.结论:Moss Miami内固定操作简便,复位满意,固定牢靠,是治疗胸腰椎骨折有效治疗方法之一.

新一代温室气体排放情景

温室气体排放情景,是对未来气候变化预估的基础。过去应用的情景设计是在2000年完成的,早就需要更新与补充了,IPCC第4次评估报告已经提出了这个要求[1]。对于这种必要性Moss等[2]在2010年就进行了深入的讨论。通过2～3年的工作,新一代排放情景已经形成。