基于垂直带谱的太白山区山地植被遥感信息提取

遥感数据因其全覆盖的优势被广泛应用于山地植被信息的调查和研究。为了实现山区植被类型的高精度提取,本文以太白山区为实验区,结合山地植被的垂直地带性分布规律,利用太白山植被垂直带谱、高分辨率遥感影像（GF1/GF2/ZY3）和1:1万的数字表面模型（Digital Surface Model, DSM）数据,进行了多层次、多尺度的影像分割,构建了具有植被垂直带谱信息的地形约束因子,并据此进行样本选择和面向对象的分类,分类总精度达92.9%,kappa系数达到0.9160。该方法相比于未辅以垂直带谱信息的分类,总精度提高了10%。研究结果表明,分类过程中加入具有垂直带谱信息的地形约束因子,能显著地提高样本选择的效率和准确率,为后续的植被分类提供了精度的保证。通过人机交互的方式,将垂直带谱知识应用到分类中,可以有效地提高山地植被分类的精度。     

Digital extraction of altitudinal belt spectra in the West Kunlun Mountains using SPOT-VGT NDVI and SRTM DEM

In this paper, a digital identification method for the extraction of altitudinal belt spectra of montane natural belts is presented. Acquiring the sequential spectra of digital altitudinal belts in mountains at an acceptable temporal frequency and over a large area requires extensive time and work if traditional methods of field investigation are to be used. Such being the case, often the altitudinal belts of a whole mountain or the belts at a regional scale are represented by single points. However, single points obviously cannot accurately reflect the spatial variety of altitudinal belts. In this context, a digital method was developed to extract the spectra of altitudinal belts from remote sensing data and SRTM DEM in the West Kunlun Mountains. By means of the 1km resolution SPOT-4 vegetation 10-day composite NDVI, the horizontal distribution of altitudinal belts were extracted through supervised classification, with a total classification accuracy of 72.23%. Then, a way of twice-scan was used to realize the automatic transition of horizontal maps to vertical belts. The classification results of remote-sensing data could thus be transformed automatically to sequential spectra of digital altitudinal belts. The upper and lower lines of the altitudinal belts were then extracted by vertical scanning of the belts. Relationships between the altitudinal belts based on the montane natural zones concerning vegetation types and the geomorphological altitudinal belts were also discussed. As a tentative method, the digital extraction method presented here is effective at digitally identifying altitudinal belts, and could be helpful in rapid information extraction over large-scale areas.     

喜马拉雅山脉与我国东部中低山区冰蚀地貌对比研究

我国东部中低山区第四纪冰川的存在与否一直存在争议,但冰川必然对山体进行冰蚀作用形成冰蚀地貌。为了分析我国东部中低山区的山体地貌是否具有冰蚀特征,该文选取了现代冰川集中发育区-喜马拉雅山脉作为冰蚀地貌的研究对象,通过宏观分析,除了由缩口、三角脊、残弧组成的冰斗系统外,还发现冰蚀作用过程存在避谷、吞脊、切壁、穿梁等特殊习性。分析认为冰蚀过程主要受制于雪线高程、积雪高程与坡向坡角三方面因素的控制。以此为基础,对我国东部的江西庐山、山东蒙山、大兴安岭主峰黄岗梁三个地区的山体地貌进行对比分析,发现这些山区的山体地貌与喜马拉雅山脉的冰蚀地貌具有一致性。文章从冰蚀过程的角度确认了我国东部中低山区存在第四纪冰川的事实。     

喜马拉雅山与我国东部中低山区冰蚀地貌对比研究

我国东部中低山区第四纪冰川的存在与否一直存在争议,但冰川必然对山体进行冰蚀作用形成冰蚀地貌。为了分析我国东部中低山区的山体地貌是否具有冰蚀特征,该文选取了现代冰川集中发育区—喜马拉雅山脉作为冰蚀地貌的研究对象,通过宏观分析,除了由缩口、三角脊、残弧组成的冰斗系统外,还发现冰蚀作用过程存在避谷、吞脊、切壁、穿梁等特殊习性。分析认为冰蚀过程主要受制于雪线高程、积雪高程与坡向坡角三方面因素的控制。以此为基础,对我国东部的江西庐山、山东蒙山、大兴安岭主峰黄岗梁三个地区的山体地貌进行对比分析,发现这些山区的山体地貌与喜马拉雅山脉的冰蚀地貌具有一致性。文章从冰蚀过程的角度确认了我国东部中低山区存在第四纪冰川的事实。     

CHARACTERISTICS OF PERIGLACIAL GEOMORPHOLOGY IN THE SOURCE AREA OF THE HUANGHE RIVER

There widely occur stretches of permafrost at more than 3,800-4,200 meters above sea level in the source area of the Huanghe (Yellow) River. The periglacial geomorphology develops quite well, including frozen disintegration geomorphology, freezing and thawing geomorphology in cold environments, periglacial dune, buried ices and fossil periglacial phenomena. In light of the relation between stratigraphy and periglacial phenomena, three periglacial periods can be divided, which are the Middle Pleistocene periglacial period, the Late Pleistocene periglacial period and modern periglacial period.     

Cryotic climate conditions and their eventual implication in the high-mountain surface of the Nevado de Toluca volcano,Mexico

The state of the cryosphere in tropical regions is of great importance because the temperature around the glaciers, permafrost and snow cover always fluctuates near the melting point. These thermal conditions and their high sensitivity to climate change cause the accelerated disappearance of these elements; therefore, it is important to know the climatic factors that regulate them, as well as the physical characteristics of each cryospheric element. Unlike glaciers, permafrost and snow cover have not been widely studied. In recent decades, the study of the glacial and periglacial environment has been carried out in intertropical mountains. However, despite the altitude of their relief and the frequent occurrence of snowfall in tropical high mountains, the conditions that determine such events have been barely analyzed; and in the case of Mexico, the volume of snowfall and its thickness have not been quantified either, as well as their corresponding duration. Consequently, this work is aimed to analyze the temperature and precipitation conditions that determine the snowfall at the higher part of the Nevado de Toluca volcano; at the same time, the conditions of the cryotic climate and their possible implication on the surface are studied. The analysis of data from 1965 to 2016, using frequency statistics, allowed to realize that snowfall occurs with low intensity, its accumulation being less than 10 cm thick and 10 mm of snow water equivalent, which causes the snowpack to stay only a few weeks on average. At the same time, it was determined that there is a significant increase in the number of freeze-thaw cycles. Therefore, due to the climate conditions and their influence on the mountain surface, it is probable that the bedrock is subject to a greater gelifraction dynamics, and the unconsolidated soil surface increases; the combination of the above could cause a greater geomorphological dynamic over time, particularly due to debris flows, and by water and wind erosion of the surface. This work is intended to serve as a reference for the high mountain environment in the intertropical regions.     

基于BEMD分解的地貌分类研究

地貌是指地势高低起伏的变化,即地表的形态。地貌划分对气温、降水、太阳辐照等诸多应用领域都有着重要作用。本文选择空间分辨率为90 m的福建省的数字高程模型(DEM)数据作为地理信号,运用二维经验模态分解(BEMD)进行分解处理,得到多个具有不同尺度、不同物理意义的本征模函数(BIMF1-BIMF3)以及对应余量ORIG。这些BIMF分量对应不同尺度的微观地形,ORIG余量表现为该研究区的地貌分布趋势,体现了平原、丘陵与山地的大致分布区域。运用变点分析法确定最佳计算单元,利用地形起伏度对各个信号区域进行一级分类,依据绝对高度进行二级分类,最后将一级分类与二级分类相结合,实现对地形的分类,这一分类过程体现了研究地区地貌组合复杂的特征。结果表明:①叠加BIMF分量,提取出分量和大于74 m的区域为高频信号区域。该区域以小起伏度的低山为主,并伴随有丘陵和小起伏度中山。②ORIG余量中余量高度小于等于340 m的区域,去除其中包含的高频信号区域后为低频信号区域,该区域以平原、丘陵为主。③剩余区域定义为中频信号区域,该区域的地貌以平丘陵和小起伏的山地为主。研究成果表明福建地貌可分为7种主要类型:低频平原,低频丘陵,中频丘陵,高频丘陵,中频小起伏低山,高频小起伏低山,高频小起伏中山。     

面向自然资源监测监管的分类体系设计

长期以来,我国采用分类管理的方式管理不同类型的自然资源,在自然资源监测监管中造成了部分自然资源重复统计、权属不明等问题,在湿地、林地等自然资源中表现尤其明显。为了系统性地进行自然资源监测监管,需要对自然资源进行整体性地、统一性地分类,建立一个综合性的自然资源分类体系。本文遵循“山水林田湖草”是一个生命共同体的理念,从这一理论思想出发,整理单门类自然资源整体和个体之间的关系,分析国内外的分类编码体系,从法理、学理和管理不同角度研究整理自然资源分类现状,综合考虑地表覆盖层的监测监管要求,采用树状分类法和交叉分类法重新构建了三级分类的自然资源分类体系框架,为构建自然资源监测监管体系提供必要的基础支撑,为完善生态文明建设,为国民经济健康持续发展提供重要的基础保障。     

宽甸县水土流失灾害与防治对策

宽甸县处于新构造运动强烈上升区,境内峰峦叠嶂,山势陡峻,沟深谷狭,暴雨频繁,地质环境十分脆弱;加之森林大量砍伐,陡坡开荒严重,垦植指数过高,超载养蚕放牧,滥采乱挖猖獗,使生态环境遭到严重破坏,水土流失程度日益加剧。严重的水土流失,导致水库淤积,河道堵塞,土层变薄,地力下降,洪水泛滥,灾害频繁,给国民经济和社会发展造成巨大损失。本文阐述了宽甸山区水土流失的形成因素和危害现状,并因地制宜提出了水土流失灾害的防治对策     

Degradation of High Mountain Ecosystems in Northern Europe

Data material of a long-term high mountain ecosystem research project was used to interpret the grazing impact of reindeers. In central Norway investigations were conducted to both, areas where reindeer grazing is excluded, and areas where intensive pasturing is present for a long period of time.The comparative analysis of grazing impact was based on similar environmental conditions. The results were transposed to northern Norway where dramatic overgrazing had been exceeding the carrying capacity. Using landscape ecological mappings, especially of vegetation and soils, the impact of reindeer grazing in different areas became obvious. Non-grazed lichen-dominated ecosystems of the snow-free locations functioned sensitively near the limit of organism survival. These localities were most influenced by grazing as they offer the winter forage to the reindeers. So, intensive grazing in central Norway led to landscape degradation by destruction of the vegetation and superinduced by soil erosion. Those features were comparable to the situation in northern Norway, where a broad-scale destruction of the environment combined with a depression of the altitudinal belts had occurred due to overgrazing. Functioning principles of intact high mountain systems were explained and used to interpret the environmental background for the understanding of degradation phenomena. Finally, the use of a new model calculating the carrying capacity of high mountain landscape was discussed.     

Regional-scale identification of three-dimensional pattern of vegetation landscapes

The altitudinal pattern of vegetation is usually identified by field surveys,however,these can only provide discrete data on a local mountain.Few studies identifying and analyzing the altitudinal vegetation pattern on a regional scale are available.This study selected central Inner Mongolia as the study area,presented a method for extracting vegetation patterns in altitudinal and horizontal directions.The data included a vegetation map at a 1∶1 000 000 scale and a digital elevation model at a 1∶250 000 scale.The three-dimensional vegetation pattern indicated the distribution probability for each vegetation type and the transition zones between different vegetation landscapes.From low to high elevations,there were five vegetation types in the southern mountain flanks,including the montane steppe,broad-leaved forest,coniferous mixed forest,montane dwarf-scrub and sub-alpine shrub-meadow.Correspondingly,only four vegetation types were found in the northern flanks,except for the montane steppe.This study could provide a general model for understanding the complexity and diversity of mountain environment and landscape.     

Influence of vegetation on runoff and sediment in wind-water erosion crisscross region in the upper Yellow River of China

All characteristics of vegetation,runoff and sediment from 1960 to 2010 in the Xiliu Gully Watershed,which is a representative watershed in wind-water erosion crisscross region in the upper reaches of the Yellow River of China,have been analyzed in this study.Based on the remote sensing image data,and used multi-spectral interpretation method,the characteristics of vegetation variation in the Xiliu Gully Watershed have been analyzed.And the rules of precipitation,runoff and sediment's changes have been illuminated by using mathematical statistics method.What′s more,the influence mechanism of vegetation on runoff and sediment has been discussed by using the data obtained from artificial rainfall simulation test.The results showed that the main vegetation type was given priority to low coverage,and the area of the low vegetation coverage type was reducing year by year.On the country,the area of the high vegetation coverage type was gradually increasing.In a word,vegetation conditions had got better improved since 2000 when the watershed management project started.The average annual precipitation of the river basin also got slightly increase in 2000–2010.The average annual runoff reduced by 37.5%,and the average annual sediment reduced by 73.9% in the same period.The results of artificial rainfall simulation tests showed that the improvement of vegetation coverage could increase not only soil infiltration but also vegetation evapotranspiration,and then made the rainfall-induced runoff production decrease.Vegetation root system could increases the resistance ability of soil to erosion,and vegetation aboveground part could reduce raindrop kinetic energy and splash soil erosion.Therefore,with the increase of vegetation coverage,the rainfall-induced sediment could decrease.     

Floristics and soil characteristics of Ohud mountain,AlMadinah AlMunawarah,Western Saudi Arabia

Ohud mountain is one of the main important historic sites in the Arab Peninsula, and it is distinguishable over the rest of the mountains in the region. No extensive floristic survey has been carried out on Ohud mountain because of the rugged topography of this mountain. The current study investigates the floristic diversity and the correspondence of environmental factors of the phytogeographical distribution of plants, based on the floristic analysis of the present region. The research question is about the relationships between the species diversity and the human impacts of populated area at lowlands around Ohud mountain. A total of 59 species belonging to 56 genera and 28 families were recorded. Asteraceae had the highest contribution, about 12% of the total plant species. The analysis of the life forms demonstrated the prevalence of therophytes(68%) followed by chamaephytes(24%), indicating the adaptation of these life forms to hyperarid conditions. The chorological analysis indicated the predominance of the bi-regional taxa over the other phytochoria. Most of the recorded plant species belong to Saharo-Arabian and Sudano-Zambezian(24%) phytochoria. TWINSPAN analysis was performed to detect the indicator species of different vegetation groups and confirmed by detrended correspondence analysis(DCA or DECORANA). It is concluded that species richness and diversity revealed clear variation along the mountain and among the studied sites. Plant species diversity and richness were more pronounced in the intermediate portion of the elevation gradients across the mountain, with a decrease in the high altitudinal belts. The decrease was also recorded at the lower altitudes, where human impacts clearly affected vegetation; leading to a decrease in alpha diversity. In addition, the beta diversity among moderately highlands and lowlands was considerably high indicating the heterogeneous species composition among the studied sites along mountain elevations. The general pattern of vegetation groups distribution is controlled by a number of environmental factors; such as latitude, longitude, elevation, organic matter and some anions and cations. A Canonical Correspondence Analysis(CCA) ordination revealed that the vegetation structure has a strong association with the latitude of the mountain followed by organic matter and Magnesium. It is recommended that the populated area should be subjected to restoration of mountain ecosystem that might be degraded by human activities.     

贵州省不同地貌形态类型土壤侵蚀强度变化的定量分析

如何揭示不同地貌形态类型区土壤侵蚀强度变化,尤其是在生态环境比较脆弱的喀斯特区域,是地方生态保护战略实施亟需研究的关键问题之一。本文基于ALOS、ZY-3、GF-1、Landsat和GDEMV2遥感影像数据,以及2762条野外采样验证数据,参照国家在喀斯特与非喀斯特地区土壤侵蚀不同分类标准,实现10 m×10 m分辨率的贵州省2010年和2015年土壤侵蚀空间信息数据提取。进而结合贵州省地貌数据,通过构建贵州省土壤侵蚀的时空分析模型,实现对不同地貌形态类型,尤其是喀斯特区域和非喀斯特区域的土壤侵蚀强度的时空变化进行定量分析。结果显示：在2010—2015年,贵州省中—高海拔区域土壤侵蚀变化的动态度高于低海拔区域,土壤侵蚀强度总体呈下降趋势,下降总面积达6468.13 km2。喀斯特区域的土壤侵蚀变化广度高于非喀斯特区域的土壤侵蚀变化广度,而且变化趋势基本上是从高一级的侵蚀强度向低一级的侵蚀强度变化。高盆地、中山、高中山土壤侵蚀强度减弱趋势明显高于其他地貌类型的趋势,但高中山仍是喀斯特与非喀斯特区土壤侵蚀增强变化较为明显的区域。这说明自21世纪以来,在贵州喀斯特区域实施的生态修复工程和生态环境保护政策在土壤侵蚀防治过程中发挥了主导性作用,在今后贵州省进行土壤侵蚀防治的过程中,除了喀斯特区域的防治外,还需要同时注意非喀斯特区域的防治。     

三北工程区植被恢复对土壤风蚀的影响及植被恢复潜力研究

三北地区是我国重要的生态屏障,分析2000—2019年三北防护林体系建设工程（简称：三北工程）区植被恢复时空变化状况,厘定人类活动与气候要素对植被恢复的贡献,探究植被恢复对土壤风蚀影响,评估植被恢复潜力空间,可为三北防护林体系建设工程未来规划管理和科学施策提供参考。本文在选取植被覆盖度和植被净初级生产力表征植被恢复状况基础上,利用地面数据,结合模型模拟,定量评估了2000—2019年三北防护林体系建设工程区植被恢复程度及其对土壤风蚀的影响,并对植被恢复潜力进行探究。研究结果表明：(1) 2000—2019年植被恢复程度高、较高的面积,占总面积的35.29%和13.16%,主要分布在黄土高原区及北部区域和风沙区与东北华北平原农区的部分地区。人类活动与气候因素对植被恢复贡献率为10.45%和89.55%;(2)土壤风蚀以轻度侵蚀和微度侵蚀为主,呈逐年下降趋势,剧烈侵蚀面积减少了66.45%,防风固沙服务得到进一步提升。植被恢复程度与土壤风蚀模数呈负相关关系,植被恢复程度较好有助于降低土壤风蚀模数;(3)三北工程区森林、草地和荒漠生态系统仍有8.16%的恢复潜力,内蒙古高原北部部分地区、哈顺...     

中国“数字黄土地貌”分类体系探讨

黄土地貌属中国典型地貌之一,其分类体系是制图的基础。过去各种黄土地貌分类研究方案由于标准不统一,在实际应用中没有形成公认的地貌分类系统。本文将形态和成因有机地结合在一起,采用分层分级方法,借助于地理信息系统技术,分析并提出适用于遥感影像数据(LandsatTM和ETM)的1:100万黄土地貌分类体系,拟定出相应的编码体系,建立了典型地貌的遥感图谱。该研究为利用中高分辨率卫星遥感数据编制中国1:100万黄土地貌类型图奠定了坚实的基础,该分类方案可充分反映黄土地貌的特征,也能与全国数字地貌分类方案保持一致,同时该分层分级分类方案可满足地貌类型的扩充性。     

The potential contribution of wildlife sanctuary to forest conservation: A case study from binsar wildlife sanctuary

Forest vegetation of a protected area(Binsar Wildlife Sanctuary) in Kumaun region(west Himalaya) was analysed for structure,composition and representativeness across three different altitudinal belts,lower(1,600-1,800 m a.s.l.),middle(1,900-2,100 m a.s.l.) and upper(2,200-2,400 m a.s.l.) during 2009-2011 using standard phytosociological methods.Four aspects(east,west,north and south) in each altitudinal belt were chosen for sampling to depict maximum representation of vegetation in the sanctuary.Population structure and regeneration behaviour was analysed seasonally for two years to show the establishment and growth of tree species.A total of 147 plant species were recorded from the entire region of which 27 tree species were selected for detailed study.Highest number was recorded at upper(18 species),and lowest at lower altitudinal belt(15 species).The relative proportion of species richness showed higher contribution of tree layer at each altitudinal belt.The population structure,based on the number of individuals,revealed a greater proportion of seedling layer at each altitudinal belt.The relative proportion of seedlings increases significantly along altitudinal belts(p<0.05) while opposite trends were observed in sapling and tree layers.The density of sapling and seedling species varied non-significantly across seasons(p>0.05).The density values decreased in summer and increased during rainy season.As far as the regeneration status is concerned,middle and upper altitudinal belts showed maximum number of species with fair regeneration as compared to lower altitudinal belt.Overall density diameter distribution of tree species showed highest species density and richness in the smallest girth class and decreased in the succeeding girth classes.This study suggests that patterns of regeneration behaviour would determine future structural and compositional changes in the forest communities.It is suggested that the compositional changes vis-à-vis role of ‘New’ and ‘Not regenerating’ species need priority attention while initiating conservation activities in the sanctuary.This study calls for exploring other less explored Wildlife Sanctuaries in the Himalaya and across the world,to achieve overall biodiversity status in these protected areas and thus to justify their role in conserving biodiversity in the region.     

土地类型多级地理格网分类体系框架的建设构想

土地类型研究在综合自然地理学中具有重要的地位和意义。该研究虽在国内外已取得很多成果以及制图实践,但仍然有3个问题有待解决：（1）如何对土地类型进行系统分级、分几级;（2）如何选择土地类型各级指标要素;（3）如何利用多源数据进行计算机自动跨尺度土地类型制图。针对上述问题,本文基于国家标准地理格网提出一种土地类型指标数据库建设方案,即构建4级标准地理格网模型,以各级格网单元作为指标表达载体,选择土地类型研究普遍采用的地带、地貌、土壤和植被4要素,进行多级标准地理格网指标库建设框架设计。通过设计与分析,指出多级地理格网分类体系有其物质基础,即地球科学各学科都具有多尺度研究特征,各学科所具有的分类体系层次性可用多级格网来表达,尤其是影响土地类型分类分级系统的地貌、土壤、植被3个要素间存在相互作用,决定了三者分类体系分级数目和各级格网单元尺度应一致或相近。因此,本文基于标准格网体系,给出了一个土地类型指标数据库建设框架,以期用于土地类型研究与制图格网数据库平台的构建,为进一步开展土地类型制图实践研究提供新思路。     

An overview of the geoenvironmental status of the Kullu Valley, Himachal Pradesh, India

The north-south trending Kullu valley between Rohtang in the north and Hansu in the south is a wide and open valley filled with Quaternary sediments along the main course of the Beas River. The valley in the middle is drained by the Beas River and numerous tributaries join it laterally. The tributary channels have deposited large alluvial fans at their mouths which form three distinct levels. The Beas River has deposited alluvial terraces, which are very distinct towards the lower reaches and form three to four levels. The upper slopes and high altitudinal areas are covered with periglacial and glacial deposits. The terrace, fan and hill slopes have provided an ideal geoenvironment for human activities including agriculture, horticulture, dense settlements and other civil establishments. The Kullu Valley is prone to various natural hazards, flash floods and cloudbursts that are very common in this valley due to its peculiar geomorphic condition, high relief of peripheral ridges and impact of monsoon winds. The studies carried out so far indicate that the losses caused by these phenomena both in terms of life and property are mainly due to unwise human interaction with the geoenvironment of the area. The paper gives an overview of the geoenvironmental status of the Kullu Valley and suggests the necessity of undertaking further detailed studies including resource mapping for balanced development of the area.     

基于“DEM-NDVI-土地覆盖分类”的天山博格达自然遗产地山地垂直带提取与变化分析

本文基于Landsat影像数据获取天山博格达自然遗产地土地覆盖分类,结合归一化植被指数（NDVI）和数字高程模型（DEM）构建“DEM-NDVI-土地覆盖分类”散点图分析研究区植被受海拔和坡向的水热空间变化影响的分布特征,通过概率统计分析提取博格达遗产地山地垂直带,并结合研究区的气温、降水数据和NDVI变化特征分析垂直带变化的原因。研究结果表明：① 本文利用“DEM-NDVI-土地覆盖分类”散点图,揭示了研究区1989年和2016年的NDVI值和分类类别随着海拔上升的变化特征,其中NDVI值随着海拔上升呈现“倒U形”变化,而不同分类类别在一定的海拔区间内呈现出聚集效应,且不同分类类别有明显的高程界限。② 1989年和2016年博格达遗产地山地垂直带分带上限分别为：1278 m和1185 m（温带荒漠草原带）、1784 m和1759 m（山地草原带）、2706 m和2730 m（山地针叶林带）、3272 m和3293 m（高山草甸带）、3636 m和3690 m（高山垫状植被带）。③ 博格达遗产地1989年和2016年山地垂直带受区域气温升高和降雨增加的影响有较为明显的改变,其中温带荒漠草原带最为敏感,其上限变化最大,向下收缩93 m;山地针叶林带的分布范围则向两侧扩张49 m;山地草甸带带宽基本保持不变,但整体上移了约20 m;冰雪带则受到全球气候变暖的影响向上退缩54 m。