关键词：
hyperspectral;inversion;leaf area index;LAI;retrieval
摘要：
The leaf area index (LAI) is an important vegetation parameter, which is used widely in many applications. Remote sensing techniques are known to be effective but inexpensive methods for estimating the LAI of crop canopies. During the last two decades, hyperspectral remote sensing has been employed increasingly for crop LAI estimation, which requires unique technical procedures compared with conventional multispectral data, such as denoising and dimension reduction. Thus, we provide a comprehensive and intensive overview of crop LAI estimation based on hyperspectral remote sensing techniques. First, we compare hyperspectral data and multispectral data by highlighting their potential and limitations in LAI estimation. Second, we categorize the approaches used for crop LAI estimation based on hyperspectral data into three types: approaches based on statistical models, physical models (i.e., canopy reflectance models), and hybrid inversions. We summarize and evaluate the theoretical basis and different methods employed by these approaches (e.g., the characteristic parameters of LAI, regression methods for constructing statistical predictive models, commonly applied physical models, and inversion strategies for physical models). Thus, numerous models and inversion strategies are organized in a clear conceptual framework. Moreover, we highlight the technical difficulties that may hinder crop LAI estimation, such as the “curse of dimensionality” and the ill-posed problem. Finally, we discuss the prospects for future research based on the previous studies described in this review.
摘要：
This article explores the relationship between the tourist's cognition of the landscape experience and the environmental conservation efforts at three distinct tourist sites in mountains of southwestern China. A total of 1500 on-site questionnaire surveys were distributed and 1142 valid questionnaires were used for statistical analysis. Results from multi-group path analysis showed that both cognition of the cultural landscape experience and cognition of the natural landscape experience had positive impacts on environmental conservation behaviors and behavior intentions of tourists. Results from comparative analysis among the three tourist sites indicated that cognition of the cultural landscape experience had a stronger power to predict senior environmental conservation behaviors and behavior intentions than cognition of the natural landscape experience, whereas cognition of the natural landscape experience had more power to predict general environmental conservation behaviors and behavior intentions than cognition of the cultural landscape experience. Furthermore, our findings benefit environmental management and sustainability at tourist sites.
摘要：
The purpose of this study is to develop an assessment framework of ecological security at the watershed scale to meet the need of watershed management, and to assess ecological security using this framework in the middle and lower reaches of Hanjiang River Basin (in Hubei Province, China). The states and their changes of ecological security in the study region are investigated with the support of ERDAS and ARC/INFO platform. The results show that the ecological security index (P) values in 1995 and 2000 were 0.685 and 0.699 respectively in the study region. While in 2005 and 2010, the P values were decreased to 0.657 and 0.624. In 1995, there were 5 counties with degree II state (the poor state) of ecological security, and 14 counties with degree III state (the common state). By 2000, the amount of counties with degree II decreased to 4 counties. And the number of counties with degree II is the same as 2000 in 2005. The result of 2010 shows there were 12 countries with degree III state as well as 7 counties with degree II state. The results of our case study of the Hanjiang River Basin reflect that the ES situation is very grim in the study area. The degree of ecological security developed in this study can be used as a useful tool for watershed managers and decision-makers.
期刊：
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS,2014年11(8):1394-1398 ISSN：1545-598X
通讯作者：
Li, Chang
作者机构：
[Li, Chang] Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Li, Chang] Minist Civil Affairs China, Key Lab Disaster Reduct & Emergency Response Engn, Beijing 100124, Peoples R China.;[Shi, Wenzhong] Hong Kong Polytech Univ, Joint Spatial Informat Res Lab, Hong Kong, Hong Kong, Peoples R China.;[Shi, Wenzhong] Wuhan Univ, Wuhan 430079, Peoples R China.
通讯机构：
[Li, Chang] C;Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.
关键词：
Generalized-line-based iterative transformation model (GLBITM);ground control lines (GCLs);imagery registration;iterative method with variable weights;polynomial model;posterior variance estimation
摘要：
Imagery registration and rectification is a process of transforming different sets of data into one coordinate system. A new model, i.e., the generalized-line-based iterative transformation model (GLBITM), is proposed by integrating the line-based transformation model (LBTM) and generalized point photogrammetry (GPP). First, the initial value of an affine transformation is acquired by LBTM. Then, on the basis of ground control lines (GCLs), not ground control points, the linear feature adjustment model with GPP is extended to a quadratic polynomial model and utilized to iteratively solve transformation coefficients. This process eliminates the translation amount and recalculates the scale and rotation coefficients. The authors suggest an iterative method with variable weights that is based on posterior variance estimation to improve quality control. A significant characteristic of the GLBITM is that the two endpoints of the corresponding GCLs are not necessarily conjugate points. The GLBITM integrates the advantages of the LBTM and GPP and avoids their respective shortfalls. Finally, this experiment verifies that the GLBITM gives correct, robust, and effective results that can be applied in high-resolution satellite imagery processing of multiple sensors, angles, and resolutions.
期刊：
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS,2014年11(1):210-214 ISSN：1545-598X
通讯作者：
Hao, Ming
作者机构：
[Zhang, Hua; Hao, Ming] China Univ Min & Technol, Sch Environm Sci & Spatial Informat, Xuzhou 221116, Peoples R China.;[Shi, Wenzhong] Hong Kong Polytech Univ, Dept Land Surveying & Geoinformat, Hong Kong, Hong Kong, Peoples R China.;[Li, Chang] Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.
通讯机构：
[Hao, Ming] C;China Univ Min & Technol, Sch Environm Sci & Spatial Informat, Xuzhou 221116, Peoples R China.
关键词：
Expectation-maximization (EM);level set method;remote sensing;unsupervised change detection
摘要：
The level set method, because of its implicit handling of topological changes and low sensitivity to noise, is one of the most effective unsupervised change detection techniques for remotely sensed images. In this letter, an expectation-maximization-based level set method (EMLS) is proposed to detect changes. First, the distribution of the difference image generated from multitemporal images is supposed to satisfy Gaussian mixture model, and expectation-maximization (EM) is then used to estimate the mean values of changed and unchanged pixels in the difference image. Second, two new energy terms, based on the estimated means, are defined and added into the level set method to detect those changes without initial contours and improve final accuracy. Finally, the improved level set method is implemented to partition pixels into changed and unchanged pixels. Landsat and QuickBird images were tested, and experimental results confirm the EMLS effectiveness when compared to state-of-the-art unsupervised change detection methods.
期刊：
The Scientific World Journal,2014年2014:810782 ISSN：2356-6140
通讯作者：
Zhang, Hailin
作者机构：
[Dai, Shengli] Cent China Normal Univ, Sch Publ Management, Wuhan 430079, Peoples R China.;[Dai, Shengli] Cent China Normal Univ, Local Governance & Local Dev Res Ctr Hubei, Wuhan 430079, Peoples R China.;[Zhang, Hailin] Cent China Normal Univ, Sch Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Zhang, Hailin] Cent China Normal Univ, Sch Urban & Environm Sci, 152 Luoyu Rd, Wuhan 430079, Peoples R China.
通讯机构：
[Zhang, Hailin] C;Cent China Normal Univ, Sch Urban & Environm Sci, 152 Luoyu Rd, Wuhan 430079, Peoples R China.
摘要：
Based on Theory of Evidence and reviewing research papers concerned, a concept model of knowledge sharing network among industrial cluster firms, which can be applied to assess knowledge sharing capacity, has been built. Next, the authors create a set of assessment index systems including twelve subindexes under four principle indexes. In this study, ten experts in the same field were invited to score all the indexes of knowledge sharing capacity concerning one certain industrial cluster. The research result shows relatively high knowledge network sharing capacity among the certain industrial cluster firms. Another conclusion is that the assessment method with Theory of Evidence is feasible to conduct such a research.
作者机构：
[Yu, Guangming; Wang, Sa; Tian, Xiaojuan; Yu, Qiwu; Zhou, Xia; Zhang, Shu; Wu, Lei; Fan, Yong; Jia, Huanhuan; He, Xiaoli] Cent China Normal Univ, Coll Urban & Environm Sci, Lab Global Change & Disasters, Wuhan 430079, Peoples R China.
通讯机构：
[Yu, Guangming] C;Cent China Normal Univ, Coll Urban & Environm Sci, Lab Global Change & Disasters, Wuhan 430079, Peoples R China.
关键词：
The regional human-environment system;Flood;Disaster-causing factor;Disaster-bearing factor;Disaster-regulating factor;Disaster-bearing capability;Limit
摘要：
A series of interesting questions will be proposed and tried to be answered in this paper such as: Is there a limit of disaster-bearing capability in a region human-environment system (HES) when the system is hit by an extreme flood disaster? If so, what does it mean and how can it be explained? An assumption, naming the regional limit of flood-bearing capability (LFBC), is suggested and proved to respond these questions in this study. The LFBC model consists of three factors, namely, the disaster-causing factor (DCF), disaster-bearing factor (DBF) and disaster-regulating factor (DRF). The DCF can be selected from the cause analysis of flood, the DBF can be extracted from analysis of flood risk and vulnerability, and the DRF is responding to the analysis of flood risk management and measures. The logical relations among the three factors are determined by the analysis of flood inundation-loss models. The limit of disaster-bearing capability in regional HES is introduced by the principles of threshold analysis in terms of large-scale system theory, and can be expressed as the regional inundated depth or the amount of water in a flood. The LFBC model is built up following this idea, and approaches of its application are stated with the support of remote sensing (RS) and geographical information system (GIS). Substantial changes in terms of system succession, such as reservoir resettlement, population migration and land use pattern change, would occur only when extreme flood beyond its limit of disaster-bearing capability in a regional HES. Otherwise, the difference can be use to measures the damage conditions. Combining the occurrence probability of extreme flood, the LFBC model could be used to provide the data support for flood damage assessment, regional disaster control and reduction countermeasures, and regional development planning.
作者机构：
[Liu, Muxing; Zhang, Hailin; Du, Wenzheng] Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Liu, Muxing] Hubei Prov Lab Geog Proc Anal & Modeling, Wuhan, Peoples R China.
通讯机构：
[Liu, Muxing] C;Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.
关键词：
analyse des images;dye tracer;image analysis;Macropores du sol;région du réservoir des Trois-Gorges;Soil macropores;stained area;surface colorée;Three Gorges Reservoir Area;traceur colorant
摘要：
Preferential flow in soil macropores plays an important role in runoff control and soil and water conservation. The aim of this study was to investigate the distribution of preferential flow paths in the soil profile of various altitudinal belts, analyze its variation among different soil horizons, and define the cause of soil macropores. A dye tracer method combined with photographic analysis was conducted for four hillslope sites in the Three Gorges Reservoir Area of China (TGRA). The results show that stained area proportion, as well as its vertical distribution in soil sections, presented varied patterns due to changes of forest vegetation and soil type with altitude. Stained area ratio of soil profiles increased, while stained depth decreased with increasing altitude. For soil sections in the subalpine belt, mid-mountain belt, and low-mountain belt of TGRA, stained area ratios were 62, 42, and 45%, and stained depths were 52.4, 56.4, and 69.5 cm, respectively. For brown earth covered with subalpine temperate deciduous broadleaved forest, stained area ratios were the largest, but dyed patches were concentrated in the humus horizon. For yellow earth covered with low-mountain warm coniferous forest, stained depth reached 69.5 cm, and stained patches existed in the total soil profile. Compared with forest soil, stained depth and stained area ratio of abandoned farmland in low-mountain belt were lower, and the depth of dye infiltration was even shallower.
摘要：
Honghu Lake, one of the seven largest fresh-water lakes in China, is well known for its ecological and economic importance, as well as its rapid changes in recent years. This study investigates the potential of using remote sensing to map and monitor aquatic vegetation changes in Honghu Lake on a large scale. Landsat TM/ETM+ images dated July 27, 2000, July 9, 2002, and July 17, 2008, and CBERS image dated August 12, 2005, are employed to map the aquatic vegetation distribution in the lake. A hybrid classification method, combining the power of the decision tree classifier, naive Bayes classifier, and supporting vector machine classifier is used to distinguish different wetland types. A novel polar coordinate map method is proposed to map the changes of aquatic vegetation on a large scale. The map demonstrates vegetation patch size changes and percentage changes in the whole lake directions during four periods. Validation using in situ surveys and historical ancillary data suggests that this approach could map the distribution and monitor the changes of aquatic vegetation on a large scale efficiently. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI:10.1117/1.JRS.7.073593]
作者机构：
[Zeng Qun] Cent China Normal Univ, Editorial Dept Journal, Wuhan 430079, Peoples R China.;[Zeng Qun; Zhao Yue] Cent China Normal Univ, Sch Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Tian Li-qiao; Chen Xiao-ling] Wuhan Univ, State Key Lab Informat Engn Surveying Mapping & R, Wuhan 430079, Peoples R China.;[Chen Xiao-ling] Jiangxi Normal Univ, Minist Educ, Key Lab Poyang Lake Wetland & Watershed Res, Nanchang 330022, Peoples R China.
通讯机构：
[Tian Li-qiao] W;Wuhan Univ, State Key Lab Informat Engn Surveying Mapping & R, Wuhan 430079, Peoples R China.
关键词：
水色遥感;大气校正;HJ-1A/1B卫星
摘要：
HJ-1A/1B卫星CCD传感器具有较高的空间、 时间分辨率, 在内陆湖泊水质遥感定量监测方面有很大潜力, 大气校正是制约其应用的关键问题之一。 以我国第一大淡水湖——鄱阳湖为研究区域, 结合2009年、 2011年两次现场实测数据对FLAASH, 6S, COST和QUAC四种大气校正结果进行对比分析, 并探讨各种大气校正算法对悬浮泥沙浓度反演精度的影响。 结果表明: (1)HJ-1A/1B卫星CCD的第1波段在水环境遥感应用时, 建议进行重新定标; 第2和3波段四种大气校正结果精度相对较高, 其中, FLAASH, 6S和COST三种大气校正算法精度都较高, QUAC精度偏低, 建议在可能的情况下对该算法进行有针对性的改进; (2)FLAASH, 6S, COST和QUAC四种大气校正算法第2和3波段比值结果与实测数据吻合度最好, 平均相对误差分别为8.2%, 9.5%, 7.6%和11.6%, 因此建议在鄱阳湖水域尽量采用第2和3波段比值作为反演因子; (3)以四种大气校正结果为基础, 与悬浮泥沙浓度直接建模, 结果发现, 四种模型反演精度均比用实测遥感反射率与实测悬浮泥沙浓度建立的模型反演结果要高, FLAASH, 6S和COST三种算法反演所得悬浮泥沙浓度精度都较高, 平均相对误差分别为: 10.0%, 10.2%和8.0%; QUAC略差, 平均相对误差为18.6%。 建议在泥沙浓度反演时采用大气校正结果与悬浮泥沙浓度直接建模, 可以有效降低利用实测光谱数据建模引起的大气校正误差的累积效应; (4)在精度要求不是特别高的前提下, 四种大气校正算法都可以采用, 但综合算法复杂程度、 精度、 稳定性等多种因素, 在辅助信息不全的情况下, COST大气校正算法更值得推荐。 HJ-1A/1B satellite CCD images have higher spatial and temporal resolution, making them of great potential in quantitatively monitoring the water quality of inland lakes. However, the atmospheric correction of the images restricts their application. Therefore, taking Poyang Lake, the biggest freshwater lake in China as study area , and using the in-situ data collected in 2009 and 2011, this paper compares the atmospheric correction results done by the four methods: FLAASH, 6S, COST and QUAC, and analyzes the influence of these atmospheric correction methods on the inversion accuracy of the total suspended sediments (TSS) concentration. The results indicate: (1) the band 1 (blue band) of HJ-1A/1B CCD satellite images should be recalibrated while being applied into water quality remote sensing. The accuracy of atmospheric correction done from band 2 (green band) and band 3 (red band) is higher than that of others , especially that of the correction done by FLAASH, 6S and COST is much higher while that of correction done by QUAC is lower. So the algorithms of QUAC should be pointedly improved. (2) The ratios done from band 2 and band 3 have a good match with in-situ data , with an average relative error of 8.2%, 9.5%, 7.6% and 11.6% respectively for FLAASH, 6S, COST and QUAC. Therefore, it would be better to use the ratio done from band 2 and band 3 as inversion factors in Poyang Lake. (3) It is found that the accuracy of directly building models by using the four atmospheric corrected results and the TSS concentration is higher than the models built by the in-situ remote sensing reflectance and the TSS concentration. The accuracy of the TSS concentration inverted by FLAASH, 6S and COST is much high with an average error of only 10.0%, 10.2% and 8.0% respectively, while the error inverted by QUAC is a little bit higher of being 18.6%. So it is suggested to build model with atmospheric correction results and the TSS concentration data, because it can avoid the cumulate error resulted from modeling by using the in-situ spectrum data. (4) Under a low requested situation, these four atmospheric correction algorithms can all be adopted; otherwise, the COST should be used in the case of lacking supplementary information.
关键词：
Yangtze River Delta;rapid urbanization region;LUCC;eco-service value;eco-economic coordination;early-warning
摘要：
On the basis of Landsat TM data of the Yangtze River Delta (YRD) Economic Zone in 1991, 2001 and 2008, this article, taking 90 counties in this region as study units, built spatial data transformation models, ecosystem service value (ESV) and coordination degree of eco-economic system (CDES) models. With the aid of ArcGIS9.3, mass grid and vector data has been processed for spatial analyses. ESV and CDES indexes have demonstrated the relationship between economic development and eco-environment system and its evolution characteristics in the researched areas. Furthermore, the indexes have also been used for functional zoning and pattern recognition. Some results can be shown as follows. Firstly, since 1991, land use in the YRD has greatly changed: urban land area has increased primarily from original paddy land, dry land, grassland, garden plot and other land. Secondly, the ESV model has proved the deterioration trend of the YRD ecological system from 1991 to 2001 and slower degradation trend during 2001–2008. Also, it is illustrated that land-use conversion from water area and paddy field to urban area and dry land could cause great damage to ecosystem stabilization. Thirdly, GDP in the central and southern parts of the YRD is higher than that in the northern part since 1991. GDP growth rate in the central part is higher than that in the northern part during 1991–2001. This growth rate in the central part is also higher than that in the southern and northern parts of the YRD from 2001 to 2008. Fourthly, the YRD could be categorized into 12 types of subregions in terms of CDES index. According to its spatial characteristic of CDES index value in the study area, eco-economic conflict area with low CDES value which is located in the central part is surrounded by eco-coordinated areas with high CDES values. This illustrates a core-periphery spatial structure exists in the YRD. During 1991–2001, the CDES value implied the convergent deterioration trend of eco-economic system in the study area; while it gradually stepped into coexistence of divergent deterioration and coordination during 2001–2008. Finally, this paper analyzed five subregions in the YRD, including initially degrading zone, initially coordinative zone, continuously degrading zone, coordination-declined zone and coordination-promoted zone, based on eco-economic coordination and evolution patterns. And these subregions can be recognized and categorized by spatial transformation model.
摘要：
Miscanthus has been rated as one of the most promising bioenergy crops due to its potential for biomass production. The sustainable production of Miscanthus for bioenergy feedstock partly depends on the varieties that are efficient in terms of nutrient use for the production of biomass. In this study, 23 Miscanthus accessions, collected from wide range of geographic regions, were established early in March 2010 in Wuhan, China. The feedstock was sampled for nutrient concentration determination late in November 2010 and 2011 (at physiological maturity), and harvested early in February 2011 and 2012 (after a killing frost) to evaluate the biomass yield, nutrient concentration and removal. Across these two years, the biomass yield was negatively related to the latitude of the original collection sites. A significant increase in biomass production was observed in the second growth year relative to that in the first growth year among almost all of the Miscanthus accessions. The accessions of MS267 and MS321 only yielded 1.32 and 1.91 ton ha(-1) in 2010, respectively, but the biomass yield increased dramatically to 11.23 and 22.76 ton ha(-1) in 2011, leading to greater nutrient removal by the final harvest and thus the requirement of much more fertilizer in the following years. The accessions MS92, MS145, MS262, MS436 and MS438 established poor biomass yields, averaging <1 ton ha(-1) in the first two years, which suggests that they may be unsuitable for planting in the present environment. Significant differences between accessions were found for the nutrient concentration at maturity and after frost. Notable differences in the nutrient concentration after frost and nutrient removal were presented among the Miscanthus accessions. In addition, the significant difference conferred the possibility of achieving a desirable cultivar with significant biomass yield and relative nutrient removal by harvest. The accessions MS434, MS461 and MS296 had consistently high biomass yield and relatively low nutrient removal, demonstrating desirable characteristics as a low-input bioenergy crop. The results are important for guiding the agronomical practices of nutrient management and genetic improvement for nutrient-use efficiency to increase biomass production with low fertilizer input. (C) 2013 Elsevier B.V. All rights reserved.
摘要：
Paleoenvironmental history in the monsoonal margin in the northeast Tibetan Plateau provides important clue to the regional climate. Previous researches have been limited by either poor chronology or low resolution. Here we present a high-resolution pollen record from a 40.92-m-long sediment core (DLH) taken from Dalianhai, a terminal lake situated in the Gonghe Basin, the northeast Tibetan Plateau for reconstructing the vegetation and climate history since the last deglacial on the basis of a chronology controlled by 10 AMS ~(14)C dates on plant remains preserved in the core sediments. The pollen assemblages in DLH core can be partitioned into 6 pollen zones and each zone is mainly characterized by the growth and decline of tree or herb pollen percentage. During the periods of 14.8–12.9 ka and 9.4–3.9 ka, the subalpine arboreal and local herbaceous pollen increased, indicating the subalpine forest developed in the surrounding mountains and a desert steppe or typical steppe developed in Gonghe Basin under a relatively moister climate. During the periods of 15.8–14.8 ka, 12.9–9.4 ka and 3.9–1.4 ka, the forest shrank or disappeared according to different degrees of aridity, and the desert steppe degraded to a more arid steppe desert in the basin, indicating a dry climate. After 1.4 ka, vegetation type around Dalianhai was mainly dominated by steppe suggested by increased Artemisia. Our results suggested the climate history in this region was dry from 15.8–14.8 ka, humid from 14.8–12.9 ka and dry from 12.9–9.4 ka, after which the climate was humid during 9.4–3.9 ka, followed by dry conditions during 3.9–1.4 ka and humid conditions in the last 1.4 ka. The change of pollen percentage and the evolution of palaeovegetation in Dalianhai since the last deglacial were similar to those recorded in Qinghai Lake. The forest expanded in the mountains around Dalianhai during the Bolling-Allerod period, shrank during the Younger Dryas and the early Holocene, then it developed and reached its maximum in the mid-Holocene. During the late Holocene, the vegetation began to shrink till disappearance. However, the timing of forest expansion in the Holocene lagged behind that of Qinghai Lake, and this spatial heterogeneity was probably caused by the different forest species between these two places. The maximum of forest development in the mid-Holocene was inconsistent with the period of stronger summer monsoon in the early Holocene indicated by stalagmite records, the reason might be related to the complexity of vegetation response to a large-scale climatic change.
