Landscape spatial pattern mainly refers to the distribution of patches, which are different in size and shape in space owing to the interaction of various ecological activities. In landscape ecology study, landscape p...Landscape spatial pattern mainly refers to the distribution of patches, which are different in size and shape in space owing to the interaction of various ecological activities. In landscape ecology study, landscape pattern has been one of the key study areas. Water body landscape plays an important role in the development history of a city, but at present city water body landscape in many cities has been destroyed, hence protecting water body in the city is becoming more and more important. In order to protect city water body landscape reasonably, the precondition is to probe the dynamics of water body landscape. Based on historical data and remote sensing data, six indexes including patch number, patch area, landscape dominance index, fractal dimension, patch density and connectivity index etc. were used to analyze landscape pattern dynamics of water body in Kaifeng city since the end of the Qing Dynasty (in the 20th century). The results showed: (1) Since the end of the Qing Dynasty, landscape area of water body in Kaifeng city increased first and then decreased from 1898 to 2002AD; the landscape dominant degree had the same changing tendency with the area. (2) Patch number of water body landscape in Kaifeng city had an increase from 1898 to 2002, but maximum area of patch, minimum area of patch and average area of patch decreased, which resulted in an increase in landscape fragment degree. (3) Connectivity index decreased and fractal dimension increased from 1898 to 2002. The reasons for these changes were the repeated overflows and flooding of the Yellow River and the influence of human activities.展开更多
Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of t...Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of the typical region in the middle of the Yihe-Luohe river basin. These indices include patch number, mean patch area, fragment index, patch extension index, etc. The results showed that: (1) There was a rapid increase in the number of patch and total area from 1983 to 1999 in the study area. The fragment degree became very high. (2) The area of all the forest patch types had witnessed great changes. The fractal degree of each forest patch type became big from 1983 to 1999. The mean extension index of Robinia pseudoacacia forest, non-forest, shrub forest, sparse forest, and Quercus species forest increased rapidly, but that of economic forest became zero. The fractal dimension each showed that forest coverage has been promoted. (3) The changes of landscape patterns were different in different geomorphic regions. From 1983 to 1999 the vegetation cover area, the gross number and the density of patch, diversity and evenness of landscape were all reduced greatly in gullies and ravines, but the maximum area and the mean area of patch types were increased. In hilly region, both the forest cover area and the number of patch increased from 1983 to 1999, but the mean area of patch was reduced greatly. In mountain region, even though the area under forest canopy reduced from 1983 to 1999, the patch number was increased greatly, the mean area of all patch types was reduced, the extension index, diversity index and evenness index of landscape were all increased. Furthermore, because of different types of land use, human activity and terrain, the vegetation changes on northern and southern mountain slopes were different. According to these analyses, the main driving forces, such as the policies of management, market economy, influence of human activities etc. are brought out.展开更多
It is very significant for urban development and urban wetland protection and utilization to probe into the process and reasons of urban wetland landscape dynamics. Taking the information of remote sensing and detaile...It is very significant for urban development and urban wetland protection and utilization to probe into the process and reasons of urban wetland landscape dynamics. Taking the information of remote sensing and detailed land survey data as the basic information sources, with the help of RS and GIS, according to the principles and methods of landscape ecology, this paper analyzed wetland landscape pattern dynamics and its reasons in Kaifeng City, Henan Prov-ince of China, from 1987 to 2002. The results show that the total wetland area in Kaifeng City firstly reduced by 20.1% from 1987 to 1990 and then increased from 1990 to 2002, with an average annual growth rate of 3.3%. At the same time, landscape fragment degree and landscape dominance degree increased, respectively from 0.64 to 0.72 and from 0.3754 to 0.5563, but mean patch area, maximum patch area, patch fractal dimension reduced. As far as single landscape element concerned, from 1987 to 2002, patch area, patch number, patch density, patch shape and patch location changed in varying degrees in all wetland types in Kaifeng City, among which rice field changed most and others relatively less. In the recent 20 years, rice fields, lake wetlands, puddles and ponds had a higher stability, but river and bottomland wetlands were mostly transformed to land use types. The change of wetland landscape pattern was the result of the combined action of the Huanghe (Yellow) River, urban expansion, wide cultivation of rice, and rapid development of fishery. Among them human activities were the main driving factors for wetland landscape changes.展开更多
As a result of environmental degradation,urban green space has become a key issue for urban sustainable development.This paper takes Liaoyang City in Northeast China as an example to develop green space planning using...As a result of environmental degradation,urban green space has become a key issue for urban sustainable development.This paper takes Liaoyang City in Northeast China as an example to develop green space planning using the computational fluid dynamics (CFD) model,landscape ecological principles and Geographical Information System (GIS).Based on the influencing factors of topography,building density and orientation,Shou Mountain,Longding Mountain and the Taizi River were selected as the urban ventilation paths to promote wind and oxygen circulation.Oxygen concentration around the green spaces gradually decreased with wind speed increase and wind direction change.There were obvious negative correlation relationships between the oxygen dispersion concentration and urban layout factors such as the building plot ratio and building density.Comparison with the field measurements found that there was significant correlation relationship between simulated oxygen concentration and field measurements (R 2=0.6415,p<0.001),moreover,simulation precision was higher than 92%,which indicated CFD model was effective for urban oxygen concentration simulation.Only less than 10% areas in Liaoyang City proper needed more green space urgently to improve oxygen concentration,mainly concentrated in Baitai and west Wensheng districts.Based on land-scape ecology principle,green space planning at different spatial scales were proposed to create a green space network system for Liaoyang City,including features such as green wedges,green belts and parks.Totally,about 2012 ha of green space need to be constructed as oxygen sources and ventilation paths.Compared with the current green space pattern,proposed green space planning could improve oxygen concentration obviously.The CFD model and research results in this paper could provide an effective way and theory support for sustainable development of urban green space.展开更多
The present study is about the dynamics of the vegetation landscapes of the Mbere Valley’s National Park and its southern periphery (MVNP). The physical and human characteristics of this area, translated by an inter-...The present study is about the dynamics of the vegetation landscapes of the Mbere Valley’s National Park and its southern periphery (MVNP). The physical and human characteristics of this area, translated by an inter-twining of natural, anthropic and institutional factors, predispose its vegetation cover to a dynamic which can be progressive or regressive according to the dominant factor. The present study aims at reconstituting the various space-time variations of the MVNP vegetation cover and its periphery between 1987 and 2014, and at determining the processes and the factors having supported these space-time variations of vegetation cover. The methodological step consists of an association of fieldwork and remote sensing in order to characterize the vegetation cover, to reconstitute the evolution of the vegetation cover and to determine the main factors of the processes of this evolution or dynamic. The diachronic analysis shows that the dynamics of the vegetation cover was marked by a progressive evolution between 1987 and 1999, and a regressive evolution between 1999 and 2014. On the base of fieldwork observations and the socio-economic surveys, it arises that the dynamics of the vegetation cover of the valley of Mbere and its periphery is subjected to the combined influence of the natural conditions, from the recurring anthropic disturbances as well as the weight of regulatory measures.展开更多
Rapid, unplanned and uncontrolled urbanization causes disorganized growth. The patterns of urban development are changing natural landscapes and their dynamics. This has necessitated understanding of spatial patterns ...Rapid, unplanned and uncontrolled urbanization causes disorganized growth. The patterns of urban development are changing natural landscapes and their dynamics. This has necessitated understanding of spatial patterns of urbanization and prompted research. Urbanization being a dynamic phenomenon has been facing ambiguities regarding methods to study its dynamism. It has made operational, a wide-variety of spatial metrics methods utilizing multiple dates of remotely sensed data. The present work carries out the quantitative and qualitative analysis of urban growth of Srinagar by using Urban Landscape Analysis Tool (ULAT). Urbanized Area (UA), Urban Footprint (UF) and New Development (ND) maps are generated to quantify the degree of urbanization based on spatial density of built-up area. Comparative analysis of these maps in relation to the built-up spread pattern indicates that mostly the environs of the Srinagar city which includes mostly agricultural, vacant and marshy areas prominently in northern, western and southern areas contribute to the development of the city.展开更多
To tackle the problem of simultaneous localization and mapping(SLAM) in dynamic environments, a novel algorithm using landscape theory of aggregation is presented. By exploiting the coherent explanation how actors for...To tackle the problem of simultaneous localization and mapping(SLAM) in dynamic environments, a novel algorithm using landscape theory of aggregation is presented. By exploiting the coherent explanation how actors form alignments in a game provided by the landscape theory of aggregation, the algorithm is able to explicitly deal with the ever-changing relationship between the static objects and the moving objects without any prior models of the moving objects. The effectiveness of the method has been validated by experiments in two representative dynamic environments: the campus road and the urban road.展开更多
By using remote sensing images from three periods (1980, 1995, 2000) and with the support of GIS and RS, the spatial information of landscape elements of Jilin Province from 1980 to 2000 was interpreted and extracted....By using remote sensing images from three periods (1980, 1995, 2000) and with the support of GIS and RS, the spatial information of landscape elements of Jilin Province from 1980 to 2000 was interpreted and extracted. Using models of landscape indices such as diversity, fragmentation, and mean patch fractal dimension, dynamic spatio-temporal changes of landscape patterns of the province were analyzed. The results: ① cropland and forestland were the main landscape types, and forestland became a landscape matrix; ② in the study area, landscapes were distributed unevenly, and there was low heterogeneity, a simple ecosystem structure and a tendency of irrational landscape patterns. There were also simple spatial shapes of patches and strong self-similarities, and in terms of dynamic change analysis, patch shapes tended to be more simple; ③ from 1980 to 2000, holistic landscape fragmentation was low and changed slightly. As far as landscape elements were concerned, the fragmentation of grassland, water area, land for residential area and factory facilities was relatively low; land distribution for residential areas and factory facilities was dispersed; and cropland and forestland were most concentrated-an indication that the trend will continue. Comprehensive effects among human activity, local policy, regional climate and environmental change led to the results.展开更多
Competition used to be a steady,slow-moving phenomenon,dominated by the giant companies of the Western world.Two-thirds of the companies listed on the Fortune Global 500 in the 1960s were still there 15 years later.Ne...Competition used to be a steady,slow-moving phenomenon,dominated by the giant companies of the Western world.Two-thirds of the companies listed on the Fortune Global 500 in the 1960s were still there 15 years later.New competitors were easy to spot because they were well known,展开更多
Based on digital land use data from 1995 to 2000 and road data, the land use and landscape changes of Golmud, Qumaleb and Zhidoi are studied on a macro-scale. Land use and landscape changes in highway buffer zones and...Based on digital land use data from 1995 to 2000 and road data, the land use and landscape changes of Golmud, Qumaleb and Zhidoi are studied on a macro-scale. Land use and landscape changes in highway buffer zones and city expansion are special subjects. A new formula is used to define the exact degree of dynamic land use. To adequately define land use and landscape pattern changes, the buffer zones, illustrating the changes at different distances from the road, are recognized with ArcGIS 8.1 software. Prominent changes took place in land use and landscape patterns from 1995 to 2000, and the area of built-up land increased by 323.8%. The comprehensive degree of dynamic land use is 2.25, and the degree of dynamic land use of built-up land is the highest, followed by cultivated land. Woodland has the lowest value. The used degree index of land resources declined by 38.8 from 1995 to 2000. Landscape changed dramatically which influenced ecological processes immensely. Different from the corridor effect of other traffic routes, the corridor effect of this section of road is not obvious and its “point” radiation effect can be easily seen. The expanding range of Golmud City is confined to a 3 km buffer, while for Wudaoliang, it is 1 km. No land use change happened in the Nanshankou buffer.展开更多
High mobility group protein 1(HMGB1) is a multifunctional protein that interacts with DNA and chromatin to influence the regulation of transcription, DNA replication and repair and recombination. We show that HMGB1 al...High mobility group protein 1(HMGB1) is a multifunctional protein that interacts with DNA and chromatin to influence the regulation of transcription, DNA replication and repair and recombination. We show that HMGB1 alters the structure and stability of the canonical nucleosome(N) in a nonenzymatic,adenosine triphosphate-independent manner. As a result, the canonical nucleosome is converted to two stable, physically distinct nucleosome conformers. Although estrogen receptor(ER) does not bind to its consensus estrogen response element within a nucleosome, HMGB1 restructures the nucleosome to facilitate strong ER binding. The isolated HMGB1-restructured nucleosomes(N' and N'') remain stable and exhibit a number of characteristics that are distinctly different from the canonical nucleosome. These findings complement previous studies that showed(1) HMGB1 stimulates in vivo transcriptional activation at estrogen response elements and(2) knock down of HMGB1 expression by siR NA precipitously reduced transcriptional activation. The findings indicate that a major facet of the mechanism of HMGB1 action involves a restructuring of aspects of the nucleosome that appear to relax structural constraints within the nucleosome. The findings are extended to reveal the differences between ER and the other steroid hormone receptors. A working proposal outlines mechanisms that highlight the multiple facets that HMGB1 may utilize in restructuring the nucleosome.展开更多
Vegetation has positive effects on improving wind environment in residential areas which is important to the residents' pedestrian comfort. In order to reflect the impact of landscape on wind environment,a wind ex...Vegetation has positive effects on improving wind environment in residential areas which is important to the residents' pedestrian comfort. In order to reflect the impact of landscape on wind environment,a wind experiment was carried out in a typical residential area in Tsinghua University. Meanwhile,numerical simulation with reasonable plant models under the experimental boundary condition was held. By comparison between the experiment data and results of the simulation,wind direction of points in narrow passage and velocity of points in the first row facing the coming wind are almost accurate in simulation,but other points share big error percentage. The reason lies in the disturbing of wind model and settings of plant model. Moreover,by classifying measurement points according to relations between plants location and directions of coming wind,quantitative effects of vegetation are shown through simulations with plants and without plants. Plants directly facing the coming wind have most obvious function on decreasing the wind velocity,thus providing feasible scheme for vegetation design.展开更多
Landscape protection that, in the past, has been mainly concerned with its historical, artistic and cultural heritage, follows, nowadays, a systemic methodology that looks at landscape as a high level aggregate of spa...Landscape protection that, in the past, has been mainly concerned with its historical, artistic and cultural heritage, follows, nowadays, a systemic methodology that looks at landscape as a high level aggregate of spatial, ecologically different units that interact each other by exchanging energy and materials. Strategic environmental assessment, nowadays, has been adopted in Europe in landscape planning, whose task is to verify the compatibility of territory transformations with respect to their levels of criticality and vulnerability, to evaluate possible future scenarios as consequence of interventions by checking if they are in line with preservation and valorization of environmental. To this aim, we make here a short survey of three different simulation models that can be used as Decision Support System in landscape planning and management. They adopt tools of the Landscape Ecology and are based on GIS (Geographic Information System) technology. The first one consists of a planar graph, the so called ecological graph, whose construction needs the computation of suitable indices of environmental control, proper of Landscape Ecology, such as biodiversity, biological territorial capacity, connectivity. The planar graph, for the considered environmental system, returns a picture of its actual ecological health condition and provides very detailed indications and operational assistance for choosing among possible ecological sustainable interventions. The second one, based on the data used to construct the ecological graph, uses the least-cost path algorithm from GIS technology in order to build an ecological network to prevent and to reduce territorial fragmentation caused by intense processes of urbanisation and industrialisation. At last, an integrated GIS-based approach is developed combining an ecological graph model and a mathematical model based on a nonlinear differential equation of logistic-type with harvesting to perform qualitative predictions on the sustainability of a given territorial plan.展开更多
This paper systematically studied the landscape dynamic changes in Liangshui Natural Reserve (LNR) in Heilongjiang Province, northeast China during three periods (1950s, 1970s and 1990s), by applying landscape space m...This paper systematically studied the landscape dynamic changes in Liangshui Natural Reserve (LNR) in Heilongjiang Province, northeast China during three periods (1950s, 1970s and 1990s), by applying landscape space model------Markov model. The results indicated that the landscape structure in LNR changed and the types of landscape patches increased. The phenomena of increasing and reducing of landscape types happened at the same time and the matrix— natural Pinus koraiensis decreased year by year. The law of transformation of landscape types matches well with the results concluded from statistical data, survey data, and the developing process inherent succession of the forest. By analyzing landscape dynamic changes, some scientific management measures were put forward in this paper.展开更多
Background: In the contxt of ecosystem management, the present study aims to compare the natural and the present-day forested landscapes of a large territory in Quebec(Canada). Using contemporary and long-term fire cy...Background: In the contxt of ecosystem management, the present study aims to compare the natural and the present-day forested landscapes of a large territory in Quebec(Canada). Using contemporary and long-term fire cycles, each natural forst landscape is defined according to the variability of its structure and composition, and compared to the present-day landscape. This analysis was conducted to address the question of whether human activities have moved these ecosystems outside the range of natural landscape variability.Methods: The study encompassed a forested area of 175 000 km2 divided into 14 landscapes. Using a framework that integrates fire cycles, age structure and forest dynamics, we characterized the forest composition and age structures that resulted from three historical fire cycles(110,140, and 180 years) representative of the boreal forest of eastern Canada. The modeled natural landscapes were compared with present-day landscapes in regard to the proportion of old-growth forests(landscape level) and the proportion of late-successional forest stands(landscape level and potential vegetation type).Results: Four landscapes(39%) remain within their natural range of variability. In contrast, nine landscapes(54%)show a large gap between natural and present-day landscapes. These nine are located in the southern portion of the study area, and are mainly associated with Abies-Betula vegetation where human activities have contributed to a strong increase in the proportion of Populus tremuloides stands(early-successional stages) and a decrease of oldgrowth forest stands(more than 100 years old). A single landscape(7%), substantially changed from its potential natural state, is a candidate for adaptive-based management.Conclusion: Comparison of corresponding natural(reference conditions) and present-day landscapes showed that ten landscapes reflecting an important shift in forest composition and age structure could be considered beyond the range of their natural variability. The description of a landscape's natural variability at the scale of several millennia can be considered a moving benchmark that can be re-evaluated in the context of climate change.Focusing on regional landscape characteristics and long-term natural variability of vegetation and forest age structure represents a step forward in methodology for defining reference conditions and following shifts in landscape over time.展开更多
Land use changes are regarded as landscape pattern change driven by many interactive natural and social-economic factors. Different combination of physical geographical elements induced the difference of spatio-tempor...Land use changes are regarded as landscape pattern change driven by many interactive natural and social-economic factors. Different combination of physical geographical elements induced the difference of spatio-temporal pattern of land use change. There are four physical geographical regions in Mongolian Autonomou County of Qian Gorlos of Jilin Province. Based on spatial analysis and statistical analysis, we conclude that the primary pattern of land use and the tendency of land use changes are all different in four physical geographical regions. During 1987 - 1996, the dominant land use change processes were from grassland or forest to arableland, from unused land to paddy and grassland to unused land. Though land use change is mainly affected by social and economic condition in short period, the composite characters of physical geographical elements controls land use dynamic process. The relationship between land use dynamic process and the character of physical geographical units differ in different regions. Possible human impacts on land use change are explored with application of buffer areas of series distance along main roads and radius around main settlements. A few models are built to describe the relationship between land use spatial change rates and distance to road and settlements. According to our result, the relationship with the proximity to roads was a negative liner function, with the change rate decreasing rapidly when moving away from roads. Within a distance of less 7. skin from main traffic lines, land use changes occur red more. The bulk of grassland was apt to be opened up for cultivation around the settlements and the transformation from dryland to paddy occurred within the distance of 1km away from settlements.展开更多
The structure and dynamics of geosystems: plant of forest and bogs in the northwestern part of Western Siberia is considered by using the Kazym-Lyamin interfluve, based on the landscape-assessment map for the middle p...The structure and dynamics of geosystems: plant of forest and bogs in the northwestern part of Western Siberia is considered by using the Kazym-Lyamin interfluve, based on the landscape-assessment map for the middle part of the Khanty-Mansi Autonomous District. The study used the landscape structural-dynamical approach and the methods of studying the spatio-temporal dynamics of taiga geosystems. Theoretical and methodological research on the development of the landscape-assessment map for Asian Russia is high on the cartographic agenda of the V. B. Sochava Institute of geography SB RAS. The methodic research is to be used to Landsat-5 TM in GIS Multi-Spec and Qgis. An analysis is also made of the topographic, geomorphologic and forest 1:200,000 maps, the profiles characterize the lithology, field data of geobotanical and soil descriptions, and experimental permanent station operated. The landscape structure of this area and its hierarchical subordination are represented in the map legend in terms of groups of facies which are combined into regional-typological classification units: groups of geoms, classes, and types of natural environment. Landscape mapping and planning will help to timely prevent and forecast the magnitudes of disturbances to natural environment using and be as the basis for a package of optimal nature-conservation measures and target-oriented technogenic and anthropogenic impacts.展开更多
Kinesin is a molecular motor that can step processively on microtubules via the hydrolysis of ATP molecules.An important factor characterizing the processivity of the kinesin motor is its dissociation from the microtu...Kinesin is a molecular motor that can step processively on microtubules via the hydrolysis of ATP molecules.An important factor characterizing the processivity of the kinesin motor is its dissociation from the microtubule.Here,using all-atom molecular dynamics simulations,we studied the dissociation process of the kinesin head in weak-microtubulebinding or ADP state from tubulin on the basis of the available high-resolution structural data for the head and tubulin.By analyzing the simulated snapshots of the structure of the head-tubulin complex we provided detailed structural and dynamic information for the dissociation process.We found that the dissociation of the head along different directions relative to the tubulin exhibits very different dynamic behaviors.Moreover,the potential forms or energy landscapes of the interaction between the head and tubulin along different directions were determined.The studies have important implications for the detailed molecular mechanism of the dissociation of the kinesin motor and thus are critical to the mechanism of its processivity.展开更多
Primary radiation damage in hcp Zr,including both defect production in a single collision cascade and damage buildup through cascade overlap,is investigated using molecular dynamics(MD)simulations from a potential ene...Primary radiation damage in hcp Zr,including both defect production in a single collision cascade and damage buildup through cascade overlap,is investigated using molecular dynamics(MD)simulations from a potential energy landscape(PEL)perspective.It is found that the material’s response to an energetic particle can be understood as a trajectory in the PEL comprising a fast uphill journey and a slow downhill one.High-temperature-induced damage reduction and the difference in the radiation tolerance between metals and semiconductors can be both qualitatively explained by the dynamics of the trajectory associated with the topographic features of the system’s PEL.Additionally,by comparing irradiation and heating under a nearly identical condition,we find that large atomic displacements stemming from the extreme locality of the energy deposition in irradiation events are the key factor leading to radiation damage in a solid.Finally,we discuss the advantages of the PEL perspective and suggest that a combination of the PEL and the traditional crystallographic methods may provide more insights in future work.展开更多
Landscape is the visual impression formed in the mind of the aesthetic subject from what he sees at a certain viewpoint.A good viewpoint field is a place without visual barrier in the visual direction.Under the premis...Landscape is the visual impression formed in the mind of the aesthetic subject from what he sees at a certain viewpoint.A good viewpoint field is a place without visual barrier in the visual direction.Under the premise of analyzing aesthetic basis of expressway,starting from behavioral basis of dynamic vision,visual behavior characteristics of drivers at high speed are studied.On this basis,landscape experience tempo and rhythm determined by gaze locus under different linear characteristics are explored,and the impact of spatial alignment on gaze behavior and landscape experience is further analyzed.展开更多
文摘Landscape spatial pattern mainly refers to the distribution of patches, which are different in size and shape in space owing to the interaction of various ecological activities. In landscape ecology study, landscape pattern has been one of the key study areas. Water body landscape plays an important role in the development history of a city, but at present city water body landscape in many cities has been destroyed, hence protecting water body in the city is becoming more and more important. In order to protect city water body landscape reasonably, the precondition is to probe the dynamics of water body landscape. Based on historical data and remote sensing data, six indexes including patch number, patch area, landscape dominance index, fractal dimension, patch density and connectivity index etc. were used to analyze landscape pattern dynamics of water body in Kaifeng city since the end of the Qing Dynasty (in the 20th century). The results showed: (1) Since the end of the Qing Dynasty, landscape area of water body in Kaifeng city increased first and then decreased from 1898 to 2002AD; the landscape dominant degree had the same changing tendency with the area. (2) Patch number of water body landscape in Kaifeng city had an increase from 1898 to 2002, but maximum area of patch, minimum area of patch and average area of patch decreased, which resulted in an increase in landscape fragment degree. (3) Connectivity index decreased and fractal dimension increased from 1898 to 2002. The reasons for these changes were the repeated overflows and flooding of the Yellow River and the influence of human activities.
基金Prominent Youth Science Foundation of Henan Province No.0003+2 种基金 No.9920 Natural Science Foundation of Henan Province No. 0111070100
文摘Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of the typical region in the middle of the Yihe-Luohe river basin. These indices include patch number, mean patch area, fragment index, patch extension index, etc. The results showed that: (1) There was a rapid increase in the number of patch and total area from 1983 to 1999 in the study area. The fragment degree became very high. (2) The area of all the forest patch types had witnessed great changes. The fractal degree of each forest patch type became big from 1983 to 1999. The mean extension index of Robinia pseudoacacia forest, non-forest, shrub forest, sparse forest, and Quercus species forest increased rapidly, but that of economic forest became zero. The fractal dimension each showed that forest coverage has been promoted. (3) The changes of landscape patterns were different in different geomorphic regions. From 1983 to 1999 the vegetation cover area, the gross number and the density of patch, diversity and evenness of landscape were all reduced greatly in gullies and ravines, but the maximum area and the mean area of patch types were increased. In hilly region, both the forest cover area and the number of patch increased from 1983 to 1999, but the mean area of patch was reduced greatly. In mountain region, even though the area under forest canopy reduced from 1983 to 1999, the patch number was increased greatly, the mean area of all patch types was reduced, the extension index, diversity index and evenness index of landscape were all increased. Furthermore, because of different types of land use, human activity and terrain, the vegetation changes on northern and southern mountain slopes were different. According to these analyses, the main driving forces, such as the policies of management, market economy, influence of human activities etc. are brought out.
基金Under the auspices of Key Research Institution of Education Ministry (No. YRCSD-06B-06)
文摘It is very significant for urban development and urban wetland protection and utilization to probe into the process and reasons of urban wetland landscape dynamics. Taking the information of remote sensing and detailed land survey data as the basic information sources, with the help of RS and GIS, according to the principles and methods of landscape ecology, this paper analyzed wetland landscape pattern dynamics and its reasons in Kaifeng City, Henan Prov-ince of China, from 1987 to 2002. The results show that the total wetland area in Kaifeng City firstly reduced by 20.1% from 1987 to 1990 and then increased from 1990 to 2002, with an average annual growth rate of 3.3%. At the same time, landscape fragment degree and landscape dominance degree increased, respectively from 0.64 to 0.72 and from 0.3754 to 0.5563, but mean patch area, maximum patch area, patch fractal dimension reduced. As far as single landscape element concerned, from 1987 to 2002, patch area, patch number, patch density, patch shape and patch location changed in varying degrees in all wetland types in Kaifeng City, among which rice field changed most and others relatively less. In the recent 20 years, rice fields, lake wetlands, puddles and ponds had a higher stability, but river and bottomland wetlands were mostly transformed to land use types. The change of wetland landscape pattern was the result of the combined action of the Huanghe (Yellow) River, urban expansion, wide cultivation of rice, and rapid development of fishery. Among them human activities were the main driving factors for wetland landscape changes.
基金Under the auspices of National Key Technology Research and Development Program of China (No.2008BAJ10B01-01)National Natural Science Foundation of China (No.40801069)
文摘As a result of environmental degradation,urban green space has become a key issue for urban sustainable development.This paper takes Liaoyang City in Northeast China as an example to develop green space planning using the computational fluid dynamics (CFD) model,landscape ecological principles and Geographical Information System (GIS).Based on the influencing factors of topography,building density and orientation,Shou Mountain,Longding Mountain and the Taizi River were selected as the urban ventilation paths to promote wind and oxygen circulation.Oxygen concentration around the green spaces gradually decreased with wind speed increase and wind direction change.There were obvious negative correlation relationships between the oxygen dispersion concentration and urban layout factors such as the building plot ratio and building density.Comparison with the field measurements found that there was significant correlation relationship between simulated oxygen concentration and field measurements (R 2=0.6415,p<0.001),moreover,simulation precision was higher than 92%,which indicated CFD model was effective for urban oxygen concentration simulation.Only less than 10% areas in Liaoyang City proper needed more green space urgently to improve oxygen concentration,mainly concentrated in Baitai and west Wensheng districts.Based on land-scape ecology principle,green space planning at different spatial scales were proposed to create a green space network system for Liaoyang City,including features such as green wedges,green belts and parks.Totally,about 2012 ha of green space need to be constructed as oxygen sources and ventilation paths.Compared with the current green space pattern,proposed green space planning could improve oxygen concentration obviously.The CFD model and research results in this paper could provide an effective way and theory support for sustainable development of urban green space.
文摘The present study is about the dynamics of the vegetation landscapes of the Mbere Valley’s National Park and its southern periphery (MVNP). The physical and human characteristics of this area, translated by an inter-twining of natural, anthropic and institutional factors, predispose its vegetation cover to a dynamic which can be progressive or regressive according to the dominant factor. The present study aims at reconstituting the various space-time variations of the MVNP vegetation cover and its periphery between 1987 and 2014, and at determining the processes and the factors having supported these space-time variations of vegetation cover. The methodological step consists of an association of fieldwork and remote sensing in order to characterize the vegetation cover, to reconstitute the evolution of the vegetation cover and to determine the main factors of the processes of this evolution or dynamic. The diachronic analysis shows that the dynamics of the vegetation cover was marked by a progressive evolution between 1987 and 1999, and a regressive evolution between 1999 and 2014. On the base of fieldwork observations and the socio-economic surveys, it arises that the dynamics of the vegetation cover of the valley of Mbere and its periphery is subjected to the combined influence of the natural conditions, from the recurring anthropic disturbances as well as the weight of regulatory measures.
文摘Rapid, unplanned and uncontrolled urbanization causes disorganized growth. The patterns of urban development are changing natural landscapes and their dynamics. This has necessitated understanding of spatial patterns of urbanization and prompted research. Urbanization being a dynamic phenomenon has been facing ambiguities regarding methods to study its dynamism. It has made operational, a wide-variety of spatial metrics methods utilizing multiple dates of remotely sensed data. The present work carries out the quantitative and qualitative analysis of urban growth of Srinagar by using Urban Landscape Analysis Tool (ULAT). Urbanized Area (UA), Urban Footprint (UF) and New Development (ND) maps are generated to quantify the degree of urbanization based on spatial density of built-up area. Comparative analysis of these maps in relation to the built-up spread pattern indicates that mostly the environs of the Srinagar city which includes mostly agricultural, vacant and marshy areas prominently in northern, western and southern areas contribute to the development of the city.
基金Project(XK100070532)supported by Beijing Education Committee Cooperation Building Foundation,China
文摘To tackle the problem of simultaneous localization and mapping(SLAM) in dynamic environments, a novel algorithm using landscape theory of aggregation is presented. By exploiting the coherent explanation how actors form alignments in a game provided by the landscape theory of aggregation, the algorithm is able to explicitly deal with the ever-changing relationship between the static objects and the moving objects without any prior models of the moving objects. The effectiveness of the method has been validated by experiments in two representative dynamic environments: the campus road and the urban road.
基金Funded by the National Natural Science Foundation of China (No.40401003).
文摘By using remote sensing images from three periods (1980, 1995, 2000) and with the support of GIS and RS, the spatial information of landscape elements of Jilin Province from 1980 to 2000 was interpreted and extracted. Using models of landscape indices such as diversity, fragmentation, and mean patch fractal dimension, dynamic spatio-temporal changes of landscape patterns of the province were analyzed. The results: ① cropland and forestland were the main landscape types, and forestland became a landscape matrix; ② in the study area, landscapes were distributed unevenly, and there was low heterogeneity, a simple ecosystem structure and a tendency of irrational landscape patterns. There were also simple spatial shapes of patches and strong self-similarities, and in terms of dynamic change analysis, patch shapes tended to be more simple; ③ from 1980 to 2000, holistic landscape fragmentation was low and changed slightly. As far as landscape elements were concerned, the fragmentation of grassland, water area, land for residential area and factory facilities was relatively low; land distribution for residential areas and factory facilities was dispersed; and cropland and forestland were most concentrated-an indication that the trend will continue. Comprehensive effects among human activity, local policy, regional climate and environmental change led to the results.
文摘Competition used to be a steady,slow-moving phenomenon,dominated by the giant companies of the Western world.Two-thirds of the companies listed on the Fortune Global 500 in the 1960s were still there 15 years later.New competitors were easy to spot because they were well known,
基金The National Key Basic Research Special Fund, No.Gl 998040800 The Core Project of Institute of Geographic Sciences and Natural Resources Research of CAS for Knowledge Innovation, No. CXIOG-E01-01,No.CXIOG-A00-03-02.
文摘Based on digital land use data from 1995 to 2000 and road data, the land use and landscape changes of Golmud, Qumaleb and Zhidoi are studied on a macro-scale. Land use and landscape changes in highway buffer zones and city expansion are special subjects. A new formula is used to define the exact degree of dynamic land use. To adequately define land use and landscape pattern changes, the buffer zones, illustrating the changes at different distances from the road, are recognized with ArcGIS 8.1 software. Prominent changes took place in land use and landscape patterns from 1995 to 2000, and the area of built-up land increased by 323.8%. The comprehensive degree of dynamic land use is 2.25, and the degree of dynamic land use of built-up land is the highest, followed by cultivated land. Woodland has the lowest value. The used degree index of land resources declined by 38.8 from 1995 to 2000. Landscape changed dramatically which influenced ecological processes immensely. Different from the corridor effect of other traffic routes, the corridor effect of this section of road is not obvious and its “point” radiation effect can be easily seen. The expanding range of Golmud City is confined to a 3 km buffer, while for Wudaoliang, it is 1 km. No land use change happened in the Nanshankou buffer.
文摘High mobility group protein 1(HMGB1) is a multifunctional protein that interacts with DNA and chromatin to influence the regulation of transcription, DNA replication and repair and recombination. We show that HMGB1 alters the structure and stability of the canonical nucleosome(N) in a nonenzymatic,adenosine triphosphate-independent manner. As a result, the canonical nucleosome is converted to two stable, physically distinct nucleosome conformers. Although estrogen receptor(ER) does not bind to its consensus estrogen response element within a nucleosome, HMGB1 restructures the nucleosome to facilitate strong ER binding. The isolated HMGB1-restructured nucleosomes(N' and N'') remain stable and exhibit a number of characteristics that are distinctly different from the canonical nucleosome. These findings complement previous studies that showed(1) HMGB1 stimulates in vivo transcriptional activation at estrogen response elements and(2) knock down of HMGB1 expression by siR NA precipitously reduced transcriptional activation. The findings indicate that a major facet of the mechanism of HMGB1 action involves a restructuring of aspects of the nucleosome that appear to relax structural constraints within the nucleosome. The findings are extended to reveal the differences between ER and the other steroid hormone receptors. A working proposal outlines mechanisms that highlight the multiple facets that HMGB1 may utilize in restructuring the nucleosome.
基金Project(50878111) supported by the National Natural Science Foundation of ChinaProject(2006BAJ02A02) supported by the National Research Plan Project during the 11th Five-Year Plan Period
文摘Vegetation has positive effects on improving wind environment in residential areas which is important to the residents' pedestrian comfort. In order to reflect the impact of landscape on wind environment,a wind experiment was carried out in a typical residential area in Tsinghua University. Meanwhile,numerical simulation with reasonable plant models under the experimental boundary condition was held. By comparison between the experiment data and results of the simulation,wind direction of points in narrow passage and velocity of points in the first row facing the coming wind are almost accurate in simulation,but other points share big error percentage. The reason lies in the disturbing of wind model and settings of plant model. Moreover,by classifying measurement points according to relations between plants location and directions of coming wind,quantitative effects of vegetation are shown through simulations with plants and without plants. Plants directly facing the coming wind have most obvious function on decreasing the wind velocity,thus providing feasible scheme for vegetation design.
文摘Landscape protection that, in the past, has been mainly concerned with its historical, artistic and cultural heritage, follows, nowadays, a systemic methodology that looks at landscape as a high level aggregate of spatial, ecologically different units that interact each other by exchanging energy and materials. Strategic environmental assessment, nowadays, has been adopted in Europe in landscape planning, whose task is to verify the compatibility of territory transformations with respect to their levels of criticality and vulnerability, to evaluate possible future scenarios as consequence of interventions by checking if they are in line with preservation and valorization of environmental. To this aim, we make here a short survey of three different simulation models that can be used as Decision Support System in landscape planning and management. They adopt tools of the Landscape Ecology and are based on GIS (Geographic Information System) technology. The first one consists of a planar graph, the so called ecological graph, whose construction needs the computation of suitable indices of environmental control, proper of Landscape Ecology, such as biodiversity, biological territorial capacity, connectivity. The planar graph, for the considered environmental system, returns a picture of its actual ecological health condition and provides very detailed indications and operational assistance for choosing among possible ecological sustainable interventions. The second one, based on the data used to construct the ecological graph, uses the least-cost path algorithm from GIS technology in order to build an ecological network to prevent and to reduce territorial fragmentation caused by intense processes of urbanisation and industrialisation. At last, an integrated GIS-based approach is developed combining an ecological graph model and a mathematical model based on a nonlinear differential equation of logistic-type with harvesting to perform qualitative predictions on the sustainability of a given territorial plan.
基金the "Tenth Five-year Plan" National Key Projects in Science and Technology (Grant No. 2001BA510B02-02)
文摘This paper systematically studied the landscape dynamic changes in Liangshui Natural Reserve (LNR) in Heilongjiang Province, northeast China during three periods (1950s, 1970s and 1990s), by applying landscape space model------Markov model. The results indicated that the landscape structure in LNR changed and the types of landscape patches increased. The phenomena of increasing and reducing of landscape types happened at the same time and the matrix— natural Pinus koraiensis decreased year by year. The law of transformation of landscape types matches well with the results concluded from statistical data, survey data, and the developing process inherent succession of the forest. By analyzing landscape dynamic changes, some scientific management measures were put forward in this paper.
基金funded by the Ministère des Forêts,de la Faune et des Parcs du Québec(MFFP).The funds were used mainly for the salary of the authors working for the MFFP
文摘Background: In the contxt of ecosystem management, the present study aims to compare the natural and the present-day forested landscapes of a large territory in Quebec(Canada). Using contemporary and long-term fire cycles, each natural forst landscape is defined according to the variability of its structure and composition, and compared to the present-day landscape. This analysis was conducted to address the question of whether human activities have moved these ecosystems outside the range of natural landscape variability.Methods: The study encompassed a forested area of 175 000 km2 divided into 14 landscapes. Using a framework that integrates fire cycles, age structure and forest dynamics, we characterized the forest composition and age structures that resulted from three historical fire cycles(110,140, and 180 years) representative of the boreal forest of eastern Canada. The modeled natural landscapes were compared with present-day landscapes in regard to the proportion of old-growth forests(landscape level) and the proportion of late-successional forest stands(landscape level and potential vegetation type).Results: Four landscapes(39%) remain within their natural range of variability. In contrast, nine landscapes(54%)show a large gap between natural and present-day landscapes. These nine are located in the southern portion of the study area, and are mainly associated with Abies-Betula vegetation where human activities have contributed to a strong increase in the proportion of Populus tremuloides stands(early-successional stages) and a decrease of oldgrowth forest stands(more than 100 years old). A single landscape(7%), substantially changed from its potential natural state, is a candidate for adaptive-based management.Conclusion: Comparison of corresponding natural(reference conditions) and present-day landscapes showed that ten landscapes reflecting an important shift in forest composition and age structure could be considered beyond the range of their natural variability. The description of a landscape's natural variability at the scale of several millennia can be considered a moving benchmark that can be re-evaluated in the context of climate change.Focusing on regional landscape characteristics and long-term natural variability of vegetation and forest age structure represents a step forward in methodology for defining reference conditions and following shifts in landscape over time.
基金the auspices of the Knowledge Innovation Project of the Chinese Academy of sciences (KZCXI - Y - 02)the Key Ninth Five-Year P
文摘Land use changes are regarded as landscape pattern change driven by many interactive natural and social-economic factors. Different combination of physical geographical elements induced the difference of spatio-temporal pattern of land use change. There are four physical geographical regions in Mongolian Autonomou County of Qian Gorlos of Jilin Province. Based on spatial analysis and statistical analysis, we conclude that the primary pattern of land use and the tendency of land use changes are all different in four physical geographical regions. During 1987 - 1996, the dominant land use change processes were from grassland or forest to arableland, from unused land to paddy and grassland to unused land. Though land use change is mainly affected by social and economic condition in short period, the composite characters of physical geographical elements controls land use dynamic process. The relationship between land use dynamic process and the character of physical geographical units differ in different regions. Possible human impacts on land use change are explored with application of buffer areas of series distance along main roads and radius around main settlements. A few models are built to describe the relationship between land use spatial change rates and distance to road and settlements. According to our result, the relationship with the proximity to roads was a negative liner function, with the change rate decreasing rapidly when moving away from roads. Within a distance of less 7. skin from main traffic lines, land use changes occur red more. The bulk of grassland was apt to be opened up for cultivation around the settlements and the transformation from dryland to paddy occurred within the distance of 1km away from settlements.
文摘The structure and dynamics of geosystems: plant of forest and bogs in the northwestern part of Western Siberia is considered by using the Kazym-Lyamin interfluve, based on the landscape-assessment map for the middle part of the Khanty-Mansi Autonomous District. The study used the landscape structural-dynamical approach and the methods of studying the spatio-temporal dynamics of taiga geosystems. Theoretical and methodological research on the development of the landscape-assessment map for Asian Russia is high on the cartographic agenda of the V. B. Sochava Institute of geography SB RAS. The methodic research is to be used to Landsat-5 TM in GIS Multi-Spec and Qgis. An analysis is also made of the topographic, geomorphologic and forest 1:200,000 maps, the profiles characterize the lithology, field data of geobotanical and soil descriptions, and experimental permanent station operated. The landscape structure of this area and its hierarchical subordination are represented in the map legend in terms of groups of facies which are combined into regional-typological classification units: groups of geoms, classes, and types of natural environment. Landscape mapping and planning will help to timely prevent and forecast the magnitudes of disturbances to natural environment using and be as the basis for a package of optimal nature-conservation measures and target-oriented technogenic and anthropogenic impacts.
文摘Kinesin is a molecular motor that can step processively on microtubules via the hydrolysis of ATP molecules.An important factor characterizing the processivity of the kinesin motor is its dissociation from the microtubule.Here,using all-atom molecular dynamics simulations,we studied the dissociation process of the kinesin head in weak-microtubulebinding or ADP state from tubulin on the basis of the available high-resolution structural data for the head and tubulin.By analyzing the simulated snapshots of the structure of the head-tubulin complex we provided detailed structural and dynamic information for the dissociation process.We found that the dissociation of the head along different directions relative to the tubulin exhibits very different dynamic behaviors.Moreover,the potential forms or energy landscapes of the interaction between the head and tubulin along different directions were determined.The studies have important implications for the detailed molecular mechanism of the dissociation of the kinesin motor and thus are critical to the mechanism of its processivity.
文摘Primary radiation damage in hcp Zr,including both defect production in a single collision cascade and damage buildup through cascade overlap,is investigated using molecular dynamics(MD)simulations from a potential energy landscape(PEL)perspective.It is found that the material’s response to an energetic particle can be understood as a trajectory in the PEL comprising a fast uphill journey and a slow downhill one.High-temperature-induced damage reduction and the difference in the radiation tolerance between metals and semiconductors can be both qualitatively explained by the dynamics of the trajectory associated with the topographic features of the system’s PEL.Additionally,by comparing irradiation and heating under a nearly identical condition,we find that large atomic displacements stemming from the extreme locality of the energy deposition in irradiation events are the key factor leading to radiation damage in a solid.Finally,we discuss the advantages of the PEL perspective and suggest that a combination of the PEL and the traditional crystallographic methods may provide more insights in future work.
基金Sponsored by Jiangxi Social Science Planning Project(15YS39)National Natural Science Foundation of China(51608237)Jiangxi Natural Science Foundation(20161BAB216120)。
文摘Landscape is the visual impression formed in the mind of the aesthetic subject from what he sees at a certain viewpoint.A good viewpoint field is a place without visual barrier in the visual direction.Under the premise of analyzing aesthetic basis of expressway,starting from behavioral basis of dynamic vision,visual behavior characteristics of drivers at high speed are studied.On this basis,landscape experience tempo and rhythm determined by gaze locus under different linear characteristics are explored,and the impact of spatial alignment on gaze behavior and landscape experience is further analyzed.