Mapping multiple tree species classes using a hierarchical procedure with optimized node variables and thresholds based on high spatial resolution satellite data     

Yaoliang Chen  Shuai Zhao  Zhuli Xie  Erxue Chen 《地理信息系统科学与遥感》2020,57(4):526-542

ABSTRACT

Tree species distribution mapping using remotely sensed data has long been an important research area. However, previous studies have rarely established a comprehensive and efficient classification procedure to obtain an accurate result. This study proposes a hierarchical classification procedure with optimized node variables and thresholds to classify tree species based on high spatial resolution satellite imagery. A classification tree structure consisting of parent and leaf nodes was designed based on user experience and visual interpretation. Spectral, textural, and topographic variables were extracted based on pre-segmented images. The random forest algorithm was used to select variables by ranking the impact of all variables. An iterating approach was used to optimize variables and thresholds in each loop by comprehensively considering the test accuracy and selected variables. The threshold range for each selected variable was determined by a statistical method considering the mean and standard deviation for two subnode types at each parent node. Classification of tree species was implemented using the optimized variables and thresholds. The results show that (1) the proposed procedure can accurately map the tree species distribution, with an overall accuracy of over 86% for both training and test stages; (2) critical variables for each class can be identified using this proposed procedure, and optimal variables of most tree plantation nodes are spectra related; (3) the overall forest classification accuracy using the proposed method is more accurate than that using the random forest (RF) and classification and regression tree (CART). The proposed approach provides results with 3.21% and 7.56% higher overall land cover classification accuracy and 4.68% and 10.28% higher overall forest classification accuracy than RF and CART, respectively.  相似文献   

浅水流动计算中—阶有限体积法Osher格式的实现   总被引：11，自引：6，他引：11       下载免费PDF全文

谭维炎  胡四一 《水科学进展》1994,5(4):262-270

近年来,一阶有限体积法Osher格式已在二维浅水明流的一批模型问题和应用实例中获得成功。本文首次讨论其算法实现的种种问题。核心是建立单元水力模型-阶梯流,在数学上可用一类特殊的黎曼问题来描述。将该问题化作气体动力学中的黎曼问题近似求解,然后对结果加以校正。还在理论分析和数值试验的基础上详细讨论了各种外部边界条件、内部边界和动边界的处理,构成完整的算法。  相似文献   

放射性地层学的探讨     

朱永红 《地质科技情报》1993,12(2):44-46

探讨了放射性地层的划分原则和单位、界线、放射性地层对比、放射性异常的概念以及放射性地层工作程序和研究方法,提出在区调中开展放射性地层研究的建议。  相似文献   

草原农垦区土地沙质荒漠化过程的生物学机制   总被引：11，自引：1，他引：10  

赵文智  何志斌  李志刚 《地球科学进展》2003,18(2):257-262

以沙质荒漠化正处在发展过程的河北坝上地区和沙质荒漠化严重的科尔沁沙地流沙治理区为例,结合国内外已有的研究成果,探讨草原沙质荒漠化的主要生物学机制。指出在草原农垦区开垦和过度放牧引起的土壤细颗粒物质、养分损失,促进了灌木侵入。灌木侵入又加剧了土壤养分、水分空间格局的改变,在灌丛周围形成一个包括微生物在内的土壤肥力富集区,即灌丛"土壤肥岛",而在丛间发生土壤风蚀和水蚀,导致斑块状流沙甚至大面积流沙的出现。诱发荒漠化的不合理耕作、灌溉、盐渍化、过度放牧等过程同样影响菌根菌的密度和接种成功率,从而降低草地生产力。在草原地区的流沙上建立各种固沙植被不仅使流沙地土壤养分、水分异质性加强,而且使沙地景观异质性增加。还提出用土壤颗粒分形维数来表征土地沙质荒漠化的程度,以空间上不同样点土壤属性变异系数（方差与平均值之比）作为沙质荒漠化土壤属性异质性的测度。  相似文献   

RGMAP系统在1:5万矿调中的应用     

杨在峰  王君良  刘红云 《新疆地质》2003,21(Z1):48-51

采用数字填图系统(RGMAP)开展区域地质矿产调查,已成为今后工作的必须手段.针对15万矿调中路线地质矿产调查、化探异常查证、矿(化)点踏查和检查评价等传统的矿产调查工作内容,就如何充分利用数字填图系统提供的数据模型与"3S"技术平台,提高矿调工作效率与精度,结合野外数据采集与室内数据综合应用进行了尝试性地探讨.  相似文献   

有序样品聚类的最优分割应用程序开发   总被引：2，自引：0，他引：2  

范迪富 《江苏地质》2004,28(1):22-26

在地层划分、蚀变、矿化、圈定矿体的研究中，有序样品聚类的最优分割法——数学处理方法是一个十分有效的方法，而该方法的数据处理是一个复杂而繁琐的过程。为了有志于地质研究的爱好者，根据最优分割的数学处理原理，将最优分割法编制成易于为非计算机专业人员所利用的处理软件，并免费共享。该程序使用方便，操作简单，只要按文中说明加以编辑，即可投入使用。  相似文献   

On container versus time based inspection policies in invasive species management     

Amitrajeet A. Batabyal  Peter Nijkamp 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(5):340-347

We study the problem of precluding biological invasions caused by ships transporting internationally traded goods in containers between different regions of the world. Using the long run expected net cost (LRENC) of inspections as the apposite managerial objective, we address the following important question: given that inspection is a cyclical activity, is the LRENC lower when a port manager’s inspector inspects cargo upon the arrival of a specified number of containers (container policy) or is this LRENC lower when this inspector inspects cargo at fixed points in time (temporal policy)? We construct a queuing theoretic model and show that in an inspection cycle, irrespective of whether the inspection policy choice is made on the basis of an explicit optimization exercise or on the basis of rules of thumb, the container policy is superior to the temporal policy because the container policy results in lower LRENC from inspection activities.  相似文献   

强垂直温度梯度条件下强对流天气分析与潜势预报   总被引：9，自引：0，他引：9  

许爱华詹丰兴  刘晓晖王欢 《气象科技》2006,34(4):376-380

采用19年3~9月常规探空观测资料,对南昌ΔT850-500≥27℃这种强垂直温度梯度与江西强对流天气过程的关系进行了相关分析,并将区域强对流天气、局部强对流天气、无强对流天气的3类情况下的中低层气压、温度、湿度、风场及稳定度进行分类合成分析,结果表明:当南昌ΔT850-500≥27℃时,且有天气系统作为触发条件时,江西强对流天气发生的概率达85%;中低层低槽和切变等影响系统、江南华南暖湿气流、河套地区的冷空气都有利于江西强对流天气出现。对典型个例的探空曲线和对流有效位能分析表明:强垂直温度梯度结合中低层高湿度是强对流天气发生的重要条件。在强对流天气潜势预报中,强垂直温度梯度有时比对流有效位能更有指示性。根据上述分析结果,建立了相应的预报流程,并在业务试用中取得较好的效果。  相似文献   

Estimating contributions of sources of soil CO2 at the shallower layer in a Japanese larch forest area     

Wei LIU Jun MORIIZUMI Hiromi YAMAZAWA Takao IIDA 《中国地球化学学报》2006,25(B08):198-198

Soils contain about twice the amount of carbon presented in the atmosphere, so a small change in the soil carbon will influence atmospheric chemistry and heat balance. The soil carbon ultimately exchanged with the atmospheric CO2 as soil CO2, which mainly exists at the depth of 0-20 cm. The transport of soil CO2 is affected by the sources of soil CO2. Thus, separation of the contributions of sources of soil CO2 is a fundamental need to understand and predict implications of environmental change on soil carbon cycling and sequestration. It is a complicated task, so that a number of different methodological approaches such as component integration, root removal, and gap analyses have been developed. However, these methods could not avoid changing soil characteristics such as air-filled porosity, soil temperature and soil water contents. Consequently, fractional contributions of respiration of living root and decomposition of soil organic matter to the total soil CO2 cannot be estimated correctly. In this study, based on mass balance theory of both concentrations and δ^13C of soil CO2, a trenching method with a stable-isotope technique was used to determine both soil CO2 sources at the depth of 3-13 cm in a Japanese larch forest area during 30 May to 7 October 2005 and fractional contributions of these sources. Experimental results showed that the amount of atmospheric CO2 invaded the soil air was not significantly variable while its percent rate in the total soil CO2 had significantly temporal variations with the lower values between 5 August and 1 September. The litter-layer decomposition was very small. The soil CO2 derived from the respiration of living root and the decomposition of soil organic matter showed significantly temporal variations with increase from 30 May to 5 Aug. and decrease from 1 September to 7 October, 2005; and it accounted for 82%-98% of the total soil CO2 in which the respiration of living root was in the range from 32% to 62%.  相似文献   

Factors influencing determination of shale classification indices and their correlation to mechanical properties     

Hisham T. Eid 《Geotechnical and Geological Engineering》2006,24(6):1695-1713

The influence of sample preparation procedure on the measured classification indices such as clay-size fraction, liquid limit, and plastic limit of shales was investigated. Shale samples covering a wide range of composition and plasticity were tested using standard and modified preparation procedures to yield quantitative data required for this investigation. The study specifies the range of shale plasticity in which the measured values of clay-size fraction and liquid limit are sensitive to hydrometer specimen size and rehydration time, respectively. The study also revealed that the degree of shale particle disaggregation has an important influence on the measured clay-size fraction and liquid limit. This influence is maximized for shales with intermediate plasticity and can be interpreted in terms of particle size and shape. Correlations were established between classification indices derived from standard and modified sample preparation procedures. It is recommended to use these correlations to adjust shale classification indices derived from standard sample preparation procedures usually utilized by commercial laboratories. Such correlations help in creating a universally followed procedure for better estimation of shale engineering properties and reliable interpretation of case histories involving shale formations.  相似文献