Remote Sensing and Landscape Metrics-Based Forest Physical Degradation: Two-Decades Assessment in Gishwati-Mukura Biological Corridor in Rwanda, East-Central Africa

The management of forest corridors and related ecology is one of the effective strategies to minimize the adverse effects of forest degradation. It controls the connectivity of inhabitant species and the connection of the isolated patches. This study analyzed spatial and temporal forest physical degradation based on forest cover change and forest fragmentation in the Gishwati-Mukura biological corridor from 1990-2019. Remotely sensed datasets, Geographical Information System (GIS) and FRAGSTATS software were used to analyze the spatial and temporal physical degradation and changes in forest cover. The results indicated that the Gishwati-Mukura corridor experienced massive deforestation where approximately 7617.1 ha (64.22%) of forest cover was completely cleared out, which implies an annual forest loss of 262.6 ha·year-1 (2.21%) during 1990-2019. The forest cover transitions patterns and geostatistical analysis indicated that extensive deforestation was associated with intensive agriculture. The results demonstrated that agriculture has dramatically increased from 29.46% in 1990 to 57.22% in 2019, with an annual increase of 1.97%. Since Gishwati-Mukura has changed to National Park (NP), it lacks diversified scientific studies addressing the analysis of the remote and spatial patterns to investigate its physical degradation and landscape dynamics. This research study will serve as remote forest analysis gap-filling and as the cornerstone of numerous other research that will contribute to the improvement of the connectivity assessments along the Gishwati-Mukura corridor and other related ecosystems.

Reconciling Landscape Fragmentation and Hippopotamuses Population Decrease in Virunga National Park Wetland

Wetlands have been noted to be beneficial worldwide. Despite wetlands being a natural asset that is of great significance to the human community, they are threatened by human and natural events. In Virunga National Park (VNP) wetlands are the habitat of Hippopotamus (Hippopotamus amphibius) which are among the animal species threatened by extinction in VNP since the past few decades. As shown by the last studies the number of Hippos population declined for 96% for the period of less than 40 years. This study evaluated landscape fragmentation status and its implication on the decline of the hippos population in VNP wetland for the period from 1990 to 2018. This study’s land cover data was obtained using remote sensing techniques with the help of software package ERDAS IMAGINE v16.6 and ArcGIS v10.3. It was mapped and classified using the maximum likelihood supervised classification technique. The landscape was classified into seven classes, which included Cropland, Forest, grassland, wetland, scrubland, bare area, and water. Satellite data (Landsat) was used to evaluate NDVI and NDWI and finally the landscape patterns in the study were analyzed using Fragstats 4.2, which was also used to calculate landscape indices for the respective periods. The results obtained from the LULC, NDVI, NDWI and the landscape metrics showed that during the period of our study the VNP wetland was fragmented. A strong negative correlation between the number of hippos and the wetland’s LFI (Landscape Fragmentation Index) values showed that wetland fragmentation was one of the reasons of the decline of Hippos in the park.

A voxel-based fine-scale 3D landscape pattern analysis using laser scanner point clouds

The landscape pattern metrics can quantitatively describe the characteristics of landscape pattern and are widely used in various fields of landscape ecology.Due to the lack of vertical information,2D landscape metrics cannot delineate the vertical characteristics of landscape pattern.Based on the point clouds,a high-resolution voxel model and several voxel-based 3D landscape metrics were constructed in this study and 3D metrics calculation results were compared with that of 2D metrics.The results showed that certain quantifying difference exists between 2D and 3D landscape metrics.For landscapes with different components and spatial configurations,significant difference was disclosed between 2D and 3D landscape metrics.3D metrics can better reflect the real spatial structure characteristics of the landscape than 2D metrics.

Spatial pattern analysis of forest landscape in Changbai Mountain

Land use and land cover change is one of the important topics in the global change study with the development of satellite-based remote sensing technologies.This study employed 3D landscape pattern metrics to analyze the dynamics of land cover types around Heaven Lake in Changbai Mountain area from 2010 to 2015.The results indicated that forest land occupied the most proportion and increased from 61.9%in 2010 to 66%in 2015 due to government forest protection policy.The mean elevation of vegetation,including agriculture,fo-rest,grass and shrub was much lower compared with other land cover types(water,wetland,imperious land and bare land)in both 2010 and 2015.The elevation of agriculture land increased from 1700 m in 2010 to 1890 m in 2015 a decreased land proportion.Considering the adjacent relationship between the local agriculture land and forest land,the transformation from agriculture land to forest land was obvious in the lower elevation area.The study showed that the selected 3D landscape pattern metrics had the ability and efficiency to describe the spatiotemporal variations of mountainous landscape,and significant correlation existed between land cover and local terrain.

Assessing sediment connectivity and its spatial response on land use using two flow direction algorithms in the catchment on the Chinese Loess Plateau

Severe soil and water loss have led to widespread land degradation on the Loess Plateau in China.Exploring the relationship between land use and sediment connectivity can be beneficial to control soil erosion.In this study,three catchments in the Yanhe River Basin on the Loess Plateau were selected to analyse the relationship between land use and sediment connectivity using grey correlation method.Index of connectivity(IC)was employed to quantify sediment connectivity,including two flow direction algorithms(D8 and D-infinity)and two final targets of sediment transport(outlet and main channel of catchment).Then,11 landscape metrics were used to evaluate the land use spatial patterns of catchments.By comparing the IC value ranges,histograms and classes,and their relationship with remote sensing images of the two flow direction algorithms,we find that the D8 algorithm is more suitable for this study area.The results showed that the three catchments are characterized by high sediment connectivity in the grassland and forest close to the channel.In addition,the roads and bare land close to the channel also have high or medium sediment connectivity.Grey correlation analysis showed that landscape division index(DIVISION),fractal dimension index(FRACMN),aggregation index(AI),total class area,patch cohesion index(COHESION),and largest patch index(LPI)indices were the main factors that affect sediment connectivity at the class scale.At the landscape scale,the landscape shape index(LSI),Shannon’s diversity index(SHDI),and gully density have an essential effect on sediment connectivity.This condition provides a way to control the sediment connectivity in the watershed by transforming land use type or changing its spatial pattern,but specific adjustment measures have to be further explored.

An Approach to Environmental Planning and Sustainable Management of Watersheds and Municipalities in Southeastern Brazil

Diagnosis of fragmentation and landscape sustainability conditions are essential to environmental planning and sustainable management of natural resources. Land use spatial patterns and landscape structural indexes (landscape metrics, Urbanity Index— UI, and Landscape Vulnerability Index—LVI) have been proposed to assess biodiversity conservation and ecological sustainability, provided by impact of land use at Middle Mogi Gua&#231u watershed and its seventeen municipalities, in 2009. Land use typologies and structural indexes values were obtained based on screen digitizing of LandSat-5 imagery, for 2009. Cluster analysis and Permutational Multivariate Analysis of Variance were used to test the null hypothesis of equal degrees of fragmentation and sustainability conditions among municipalities in 2009, respectively. Land use spatial pattern showed a predominantly human occupation for watershed and its municipalities, with agricultural use as the main pressure factor. Municipalities were aggregated into three clusters related to forest fragmentation: one categorized by fifteen municipalities;the second cluster (municipality of Luiz Ant&#244nio) showing the best condition, and the third group (municipality of Araraquara) with extreme fragmentation condition. Landscape metrics related with shape, size, and core areas fragments intensify edge effects, and increase habitat isolation. The watershed showed a low naturalness and an intermediate degree of vulnerability. Ecological sustainability was different among municipalities (α = 0.05, F = 32.65 and p = 0.002), with two municipalities (Analandia and Luiz Ant&#244nio) presenting the best conditions. The most committed condition was observed, in municipalities of Rinc&#227o and Guatapará. For conservation policies to be effective must focus on the creation of ecological corridors around legally protected areas, besides creation of new legal reserves, with purpose to improve biodiversity conservation and ecological sustainability of Middle Mogi Gua&#231u watershed and its municipalities.

Spatiotemporal Dynamics of Urban Growth in Island Region from a Multi-scale Perspective: a Case Study of Zhoushan Island,China

The intensified conflict between island urbanization and lagging supervision deserves special attention worldwide.Zhoushan Island has been an outstanding center of marine economic development in China but also one of the areas most threatened by recent human activities.To cope with this challenge,the development of a retrospective understanding of the spatiotemporal dynamics of island urban growth is a key prerequisite.Detailed,multi-scales,long-term studies on island urban expansion are relatively rare.Remote sensing data,landscape metrics,and spatial statistics were used to characterize the urban landscape changes during the years from 1980 to 2013.Then,the potential determinants of island urban expansion were analyzed by integrating socioeconomic drivers,population factors,topographic variables,and policy guidance.The results indicate that Zhoushan Island has experienced a considerable urban expansion with an evident acceleration during the last period.Landscape changes in response to urban expansion varied with time,region,and scale.A general understanding of landscape metrics failed to reveal accurate dynamics for the urban landscape at a local level.At a block size of1 km,the urban landscape was more compact around the island urban center and the new developing zone,in contrast to the extensive and scattered pattern present across the entire region.Urban land primarily expanded from the urban center to the coastal regions due to topographic constraints and support from policy and economic benefits.The potential impact of the population factor decreased with urban growth,a finding that differs from several previous studies.The island urban dynamics observed in this study involved characteristics and differences that will guide future planning decisions and will provide a scientific case for urban development and sustainability with respect to islands and coastal regions in China.

Analysis of Rural Ecological Pattern Based on FRAGSTATS: A Case Study of Puxing Village in Pidu District

According to the plant information of Puxing Village, a typical village in Chengdu Plain, the GIS map was drawn to analyze the landscape ecology pattern by FRAGSTATS software. The results show that in the past 10 years, although urbanization had a great impact on the rural ecological pattern, it was still in a stable ecological environment. The comparison of the landscape index shows that the replacement of the vegetation community pattern leads to the conversion of the source population from the original farmland to laurel, and the increase of whole vegetation community under artificial intervention is the most important factor for the change of the vegetation community richness. At the same time, the pattern analysis at the horizontal level also reveals the obvious effect of the fast road as an artificial product for the enhancement of nearby vegetation community richness.

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

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

Urbanization between compactness and dispersion:designing a spatial model for measuring 2D binary settlement landscape configurations

Measuring spatial patterns is a crucial task in spatial sciences.Multiple indicators have been developed to measure patterns in a quantitative manner.However,most comparative studies rely on relative comparisons,limiting their explanatory power to specific case studies.Motivated by advancements in earth observation providing unprecedented resolutions of settlement patterns,this paper suggests a measurement technique for spatial patterns to overcome the limits of relative comparisons.We design a model spanning a feature space based on two metrics-largest patch index and number of patches.The feature space is defined as‘dispersion index’and covers the entire spectrum of possible two-dimensional binary(settlement)patterns.The model configuration allows for an unambiguous ranking of each possible pattern with respect to spatial dispersion.As spatial resolutions of input data as well as selected areas of interest influence measurement results,we test dependencies within the model.Beyond,common other spatial metrics are selected for testing whether they allow unambiguous rankings.For scenarios,we apply the model to artificially generated patterns representing all possible configurations as well as to real-world settlement classifications differing in growth dynamics and patterns.

Estimating landscape structure efects on pollination for management of agricultural landscapes

Background:The growing human population around the world is creating an increased demand for food.In agricultural landscapes,forests are cleared and turned into agricultural land to produce more food.Increasing the productivity of agricultural land per unit area may prevent extreme forest degradation.Since many agricultural products are dependent on pollinators,it is possible to increase crop production by increasing the pollination rate in the agricultural landscapes.Pollinators are highly dependent on forest patches in agricultural landscapes.Therefore,by creating new forest patches around agricultural felds,we can increase the pollination rate,and thus the crop production.In this regard,estimating the efects of diferent scenarios of forest fragmentation helps us to fnd an optimized pattern of forest patches for increasing pollination in an agricultural landscape.Methods:To investigate the efect of diferent forest fragmentation scenarios on pollination,we used simulated agricultural landscapes,including diferent forest proportions and degrees of fragmentation.Using landscape metrics,we estimated the relationship between pollination and landscape structure for each landscape.Results:Our results showed that for increasing pollination,two signifcant factors should be considered:habitat amount and capacity of small patches to supply pollination.We found that when the capacity of small patches in supplying pollination was low,fragmented patterns of forest patches decreased pollination.With increasing capacity,landscapes with a high degree of forest fragmentation showed the highest levels of pollination.There was an exception for habitat amounts(the proportion of forest patches)less than 0.1 of the entire landscape where increasing edge density,aggregation,and the number of forest patches resulted in increasing pollination in all scenarios.Conclusion:This study encourages agriculturists and landscape planners to focus on increasing crop production per unit area by pollinators because it leads to biodiversity conservation and reduces socio-economic costs of land-use changes.We also suggest that to increase pollination in agricultural landscapes by creating new forest patches,special attention should be paid to the capacity of patches in supporting pollinators.

Landscape structure and suitable habitat analysis for effective restoration planning in semi-arid mountain forests

Background:Suitable habitat and landscape structure play a pivotal role in the success of forest restoration projects.This study aimed to model the habitat suitability of wild almond(Amygdalus scoparia Spach)using three individual species distribution models(SDMs),i.e.,backpropagation artificial neural network(BP-ANN),maximum entropy(MaxEnt),generalized linear model(GLM),as well as the ensemble technique along with measuring the landscape metrics and analyzing the relationship between the distribution of the suitable habitat of the species in different landform classes in Fars Province,southern Iran.Results:There was no clear difference in the prediction performance of the models.The BP-ANN had the highest accuracy(AUC=0.935 and k=0.757)in modeling habitat suitability of A.scoparia,followed by the ensemble technique,GLM,and MaxEnt models with the AUC values of 0.890,0.887,and 0.777,respectively.The highest discrimination capacity was associated to the BP-ANN model,and the highest reliability was related to the ensemble technique.Moreover,evaluation of variable importance showed that the occurrence of A.scoparia was strongly dependent on climatic variables,particularly isothermality(Bio 3),temperature seasonality(Bio 4),and precipitation of driest quarter(Bio 17).Analysis of the distribution of species habitat in different landform classes revealed that the canyon,mountain top,upland drainage,and hills in valley classes had the highest suitability for the species establishment.Conclusions:Considering the importance of landform in the establishment of plant habitats,the combination of the outputs of the SDMs,landform,and the use of landscape metrics could provide both a clear view of habitat conditions and the possibility of analyzing habitat patches and their relationships that can be very useful in managing the remaining forests in semi-arid regions.The canyon,mountain top,and upland drainage classes were found to be the most important landforms to provide the highest suitable environmental conditions for the establishment of A.scoparia.Therefore,such landforms should be given priority in restoration projects of forest in the study area.

Quantifying local fire regimes using the Landsat data-archive:a conceptual framework to derive detailed fire pattern metrics from pixel-level information

Free and open access to the Landsat archive has enabled the detection and delineation of an unprecedented number of fire events across the globe.Despite the availability and potential of these data,few studies have analysed residual vegetation patterns and/or partial mortality of fire across the Canadian boreal forest,and those available,are either incomplete or inaccurate.Further,they all differ in the methods and spatial language,which makes it difficult for managers to interpret fire patterns over large areas.There is an urgent need for methods to help unify fire pattern observations across the Canadian boreal forest.This study explores the capacity of the Landsat data archive when coupled with a recently developed fire mapping approach and a robust spatial language to characterize and compare tree mortality patterns across the boreal plains ecozone,Canada.With 507 fires 2.5 Mha mapped,this study represents the most comprehensive analysis of mortality patterns for study area.Summaries from this demonstration generated an accurate characterization of the fire patterns the various ecoregions based on seven key fire metrics.The comparison between ecoregions revealed differences in the amount of residual vegetation,which in turn suggested various climate,topography and/or vegetation ecosystem drivers.

Urban growth dynamics and expansion forms in 11 Tanzanian cities from 1990 to 2020

With rapid urban expansion across Tanzania,there is a need to institute steps to address factors and forms as well as impacts and challenges associated with the observed trend.This study’s aim is to use spatial urban landscape indices to analyze the spatial changes in urban forms,patterns,and rates across 11 urban centers in Tanzania over a 30-year study period(1990–2020).During the past three decades,urban lands of 11 cities and town in Tanzania have grown by a total of 480 km2.Leapfrog growth was found as the most dominant form of urban expansion in Tanzania while Dodoma,the capital city of Tanzania,had the highest rate of urban expansion when compared to all other individual cities.The most robust and significant interaction of the AWMLEI and MLEI was found in Kigoma,Arusha,Mtwara,Mafinga,and Tunduma cities.In contrast,Mbeya agricultural city,Arusha the tourist city,Tabora,and Geita Lake zone areas did show their own peculiarities revealing an interesting spatial temporal variation in rate and form of expansion.The outcome of this study reveals that the influence and management of economic and socio-cultural opportunities will be an effective tool for the determination of the rapidly expanding cities and towns of Tanzania.

路网扩张对董志塬景观生态的影响

Road network expansion can result in the fragmentation of ecological landscapes due to the transformation of landscape processes and patterns.However,knowledge about these processes and patterns is scarce.In this study,the road network and landscape patterns in the Dongzhi tableland of the Chinese Loess Plateau(CLP) between 2005 and 2020 were characterized,and their spatial relationships were analyzed.The results showed that(1) the kernel density estimation(KDE) method is useful in characterizing road network density.When the bandwidth value is four,the boundary of the road network kernel can be distinguished clearly.(2) The road network in the tableland expanded greatly over the past 15 years,and the total area of road kernels in the Dongzhi tableland increased from 55.73 km~2 in 2005 to 223.55 km~2 in 2020.(3) High-density road networks were generally distributed on cultivated and constructed lands where the slopes were generally 0°–5°,while low-and medium-density road networks were mostly distributed in grassland areas where the slopes were greater than 5°.(4) Road network density is closely related to the coverage of cultivated and constructed lands.The results of this study are helpful in understanding the potential impact of road network evolution on the landscape at a regional scale.

Impact of deforestation on habitat connectivity thresholds for large carnivores in tropical forests

Introduction:Deforestation significantly impacts large carnivores that depend on large tracts of interconnected forest habitat and that are sensitive to human activities.Understanding the relationship between habitat use and spatial distribution of such species across human modified landscapes is critical when planning effective conservation strategies.This study assessed the presence of potential landscape connectivity thresholds resulting from habitat fragmentation associated with different deforestation patterns using a scale-based approach that links species-specific home ranges with the extent of anthropogenic activities.The objectives were(1)to quantify the spatial and temporal distribution of natural vegetation for five common deforestation patterns and(2)to evaluate the connectivity associated with these patterns and the existence of potential thresholds affecting jaguar dispersal.The Bolivian lowlands,located within jaguar conservation units,were analysed with landscape metrics to capture the spatial and temporal changes within deforested areas and to determine potential impact on jaguar connectivity and connectivity thresholds for dispersal.Results:Over the period of 1976–2005,the amount of natural vegetation has decreased by more than 40%in all locations with the biggest changes occurring between 1991 and 2000.Landscape spatial structure around jaguar locations showed that jaguars used areas with mean proportion of natural areas=83.14%(SE=3.72%),mean patch density=1.16 patches/100 ha(SE=0.28 patches/100 ha),mean patch area=616.95 ha(SE=172.89 ha)and mean edge density=705.27 m/ha(SE=182.19 m/ha).We observed strong fragmentation processes in all study locations,which has resulted in the connectivity of jaguar habitat decreasing to<20%by 2005.A connectivity threshold zone was observed when the proportion of natural vegetation was less than 58.4%(SE=1.3).Conclusions:Assessing fragmentation and connectivity for carnivores within the extent of human-modified landscapes proved to be an effective way to understand the changes caused by deforestation and their potential effects on large carnivore habitats.Our study highlights the importance of scale-based approaches for assessing current conservation challenges to protect large carnivores.

Using the Lonsdorf model for estimating habitat loss and fragmentation effects on pollination service

One of the most important issues related to landscape ecology and ecosystem services is finding the pattern of habitat patches that offers the highest pollination in agricultural landscapes.In this regard,two processes of habitat loss and fragmentation strongly affect the relationship between pollination and the pattern of habitat patches.In the present study,we aimed to examine the effects of habitat loss and fragmentation on pollination separately.For this purpose,first,we generated different simulated agricultural landscapes,including two habitats of forest and agriculture.Then,according to the Lonsdorf model,we estimated the potential of the simulated landscapes in providing pollination in different scenarios.Finally,using statistical models,we estimated the effects of habitat loss and fragmentation on pollination at the landscape and farm levels.Our results showed that the effects of habitat loss and fragmentation on pollination were completely different at the landscape and farm levels.At the landscape level,fragmentation negatively affected pollination,but at the farm level,the maximum pollination rate was observed in the landscapes with a high degree of fragmentation.Regarding the habitat loss effects,our results showed that pollination decreased linearly at the landscape level as habitat amount decreased,but at the farm level,it decreased exponentially.The present study considered the level of analysis(i.e.,landscape and farm levels)as a critical factor affecting pollination changes caused by fragmentation.We showed that using the Lonsdorf model could lead to confusing results for the landscape ecologists and alert farmers who want to reduce the adverse effects of fragmentation on their products by creating new forest patches.Therefore,agriculturalists and landscape ecologists should consider that the pollination rate at the landscape and farm levels is completely different according to the model and provide contradictory results about the process of habitat loss effects on pollination.

Influence of the variation in rural population on farmland preservation in the rapid urbanization area of China

In the past 40 years,cultivated land has faced the continued anthropogenic interference,which has become a significant issue for cultivated land preservation during rapid urbanization.The purpose of this research was to reveal the spatio-temporal evolutionary characteristics of cultivated land and the correlation between rural population variation and farmland change in China.Fifty county-level administrative units in Zhejiang Province were selected as the study area wherein spatio-temporal evolution comparative analysis for every 5 years from 2000 to 2015 was conducted.This study used the pool method to estimate the impacts of the rural population variation,average slope,average elevation,rural residential disposable income,primary industry proportion,and road density on farmland utilization efficiency from the spatial perspective,which is represented by landscape metrics including the mean patch size,edge density,area weighted mean shape index,and area weighted mean patch fractal dimension.This study showed that the cultivated land landscape index continued to rise after 2000 and then started decreasing after 2010,indicating a reduction in human interference after 2010.The spatial variation of rural population of all county-level administrative units decreased from 2000 to 2010,and 62%of them began to increase after 2010.The regression analysis results showed that the spatial variation of rural population was significantly and negatively correlated with the cultivated land landscape while the rural residential disposable income,average slope and primary industry proportion were all significantly and positively related to the cultivated land landscape index.The results implied that the loss of the agricultural labor force and the difficulty of sloping farmlands adapting to mechanized farming were unconducive to farmland utilization efficiency improvement,and the increase in nonagricultural activities in rural areas would increase the difficulty of cultivated land preservation.Our analysis suggests that local governments should improve the production efficiency of fragmented land or strengthen the construction control of housing and facilities in rural areas according to their regional urbanization development situation.

A comparative study of spatiotemporal patterns of urban expansion in six major cities of the Yangtze River Delta from 1980 to 2015

Introduction:China has been experiencing dramatic urbanization in parallel with its eco-nomic boom over the past three to four decades.The Yangtze River Delta(YRD),as the most important engine in the Chinese economy,has pioneered in the rapid urbanization road of China since the late 19705.We quantifed and compared the spatiotemporal patterns of urban expansion in six major cities in the YRD urban agglomeration between 1980 and 2015.Outcomes:We found that Sha nghai,Nanjing,Hangzhou,Wuxi,Suzhou and Ningbo expanded by an annual rate of 5.4%,5.9%,9.6%,7.4%,6.3%and 8.1%from 1980 to 2015,suggesting larger cities generally possess lower growth rates.Spatiotemporal patterns of urban expansion are defined by multiple forces including physical conditions and urban planning and policy.The urbanization processes in Shanghai,Nanjing and Hangzhou gen-erally conformed with the difusion-coales cence theory as the number of patches(NP)and patch density(PD)of urbanized land peaked and the proportion of leapfrogging urban growth type began to decrease around 2005,which separating their urbanization processes into difusion phase before and coalescence phase after.In contrast,Suzhou,Wuxi and Ningbo is either in the diffusion or in the transition phase from diffusion to coalescence,not showing temporal dynamics of diffusion-coalescence phase across the study period,which might be related to the fact that the urban areas in these three cities were more dispersive in space than that of other cities.Conclusions:These spatially explicit findings are the fundamental cornerstone to understand the characteristics,drivers and consequences of urban expansion in the urban agglomera-tions,and then detect the feasibility of general urbanization theories and further advance in-depth theoretical understanding to support a sustainable urban future.

Assessment of Urban Climate Environment and Configuration of Ventilation Corridor:A Refined Study in Xi'an

Integrating urban spatial landscape(USL) parameters into refined climate environment assessment is important. By taking the central urban area(CUA) of Xi’an, China as an example, this study develops an evaluation method based on Urban Climatic Map(UCMap) technology. We define surface urban heat island intensity(SUHI) and surface ventilation potential coefficient(VPC), which can effectively reflect local urban climate. Based on SUHI and VPC,we analyze the influences of seven typical USL metrics including building height(BH), building density(BD), floor area ratio(FAR), sky view factor(SVF), frontal area index(FAI), surface roughness length(RL), and vegetation cover(VC). Then, we construct a comprehensive evaluation model and create an urban climate zoning map on a 100-m resolution. The climate optimization on the map is performed for configuration of possible ventilation corridors and identification of associated control indicators. The results show that the main factors affecting SUHI in the CUA of Xi’an are VC and BD, which explain 87.9% of the variation in SUHI, while VPC explains 50% of the variation in SUHI. The main factors affecting VPC are BH, FAR, FAI, and RL, all of which contribute to more than 95% of the variation in VPC. The evaluation model constructed by SUHI, VPC, and VC can divide the CUA into climate resource spaces, climate preservation spaces, climate sensitive spaces, and climate restoration spaces. On this basis, a ventilation corridor network of 3 level-1 corridors(each over 500 m wide), 6 level-2 corridors(each over 500 m wide) and 13 level-3 corridors(each over 50 m wide) is established. Meanwhile, the main quantitative control indicators selected from the USL metrics are proved to be capable of ensuring smooth implementation of the planned corridors at different levels.