Evaluation of different machine learning methods for land cover mapping of a Mediterranean area using multi-seasonal Landsat images and Digital Terrain Models     

《International Journal of Digital Earth》2013,6(6):492-509

Land cover monitoring using digital Earth data requires robust classification methods that allow the accurate mapping of complex land cover categories. This paper discusses the crucial issues related to the application of different up-to-date machine learning classifiers: classification trees (CT), artificial neural networks (ANN), support vector machines (SVM) and random forest (RF). The analysis of the statistical significance of the differences between the performance of these algorithms, as well as sensitivity to data set size reduction and noise were also analysed. Landsat-5 Thematic Mapper data captured in European spring and summer were used with auxiliary variables derived from a digital terrain model to classify 14 different land cover categories in south Spain. Overall, statistically similar accuracies of over 91% were obtained for ANN, SVM and RF. However, the findings of this study show differences in the accuracy of the classifiers, being RF the most accurate classifier with a very simple parameterization. SVM, followed by RF, was the most robust classifier to noise and data reduction. Significant differences in their performances were only reached for thresholds of noise and data reduction greater than 20% (noise, SVM) and 25% (noise, RF), and 80% (reduction, SVM) and 50% (reduction, RF), respectively.  相似文献   

Eucalyptus Trees – Ageratina adenophora Complex System: A New Eco‐environmental Protection Model          下载免费PDF全文

Xinhui Huang  Changqun Duan  Guosheng Zhang  Shugang Lu  Chang'e Liu  Denggao Fu  Hongbo Shao 《洁净——土壤、空气、水》2014,42(5):682-689

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石河子垦区蟠桃越冬不同覆盖方式的安全性对比试验     

杨举芳  樊新燕  季枫  向导  李宝林  李新建 《沙漠与绿洲气象(新疆气象)》2012,6(2)

通过在石河子垦区2个年度开展的草帘膜覆盖法、纸箱塑料膜覆盖法、玉米杆覆土覆盖法等保护蟠桃越冬的对比试验,分析不同覆盖方法覆盖物内外温、湿度资料与冻害发生状况,初步得到：覆盖后蟠桃树周边所处的极端最低温度要高于-22℃~-24℃,相对湿度保持在70~90%才能较好地保证蟠桃树安全越冬。玉米杆覆土覆盖法是三种方法中保证蟠桃越冬效果最好,但又是花费最高的方法。  相似文献   

Winter rainfall interception by two mature open‐grown trees in Davis,California     

Qingfu Xiao  E. Gregory McPherson  Susan L. Ustin  Mark E. Grismer  James R. Simpson 《水文研究》2000,14(4):763-784

A rainfall interception measuring system was developed and tested for open‐grown trees. The system includes direct measurements of gross precipitation, throughfall and stemflow, as well as continuous collection of micrometeorological data. The data were sampled every second and collected at 30‐s time steps using pressure transducers monitoring water depth in collection containers coupled to Campbell CR10 dataloggers. The system was tested on a 9‐year‐old broadleaf deciduous tree (pear, Pyrus calleryana ‘Bradford’) and an 8‐year‐old broadleaf evergreen tree (cork oak, Quercus suber) representing trees having divergent canopy distributions of foliage and stems. Partitioning of gross precipitation into throughfall, stemflow and canopy interception is presented for these two mature open‐grown trees during the 1996–1998 rainy seasons. Interception losses accounted for about 15% of gross precipitation for the pear tree and 27% for the oak tree. The fraction of gross precipitation reaching the ground included 8% by stemflow and 77% by throughfall for the pear tree, as compared with 15% and 58%, respectively, for the oak tree. The analysis of temporal patterns in interception indicates that it was greatest at the beginning of each rainfall event. Rainfall frequency is more significant than rainfall rate and duration in determining interception losses. Both stemflow and throughfall varied with rainfall intensity and wind speed. Increasing precipitation rates and wind speed increased stemflow but reduced throughfall. Analysis of rainfall interception processes at different time‐scales indicates that canopy interception varied from 100% at the beginning of the rain event to about 3% at the maximum rain intensity for the oak tree. These values reflected the canopy surface water storage changes during the rain event. The winter domain precipitation at our study site in the Central Valley of California limited our opportunities to collect interception data during non‐winter seasons. This precipitation pattern makes the results more specific to the Mediterranean climate region. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Evaluation of actual evapotranspiration measured by large-scale weighing lysimeters in a humid alpine meadow,northeastern Qinghai-Tibetan Plateau     

Licong Dai  Ruiyu Fu  Xiaowei Guo  Xun Ke  Yangong Du  Fawei Zhang  Yikang Li  Dawen Qian  Huakun Zhou  Guangmin Cao 《水文研究》2021,35(4):e14051

The accurate estimation of evapotranspiration (ET) is essential for assessing water availability and requirements of regional-scale terrestrial ecosystems, and for understanding the hydrological cycle in alpine ecosystems. In this study, two large-scale weighing lysimeters were employed to estimate the magnitude and dynamics of actual evapotranspiration in a humid alpine Kobresia meadow from January 2018 to December 2019 on the northeastern Qinghai-Tibetan Plateau (QTP). The results showed that daily ET_a averaged 2.24 ± 0.10 mm day ⁻¹ throughout the study period, with values of 3.89 ± 0.14 and 0.81 ± 0.06 mm day⁻¹ during the growing season and non-growing season, respectively. The cumulative ET_a during the study period was 937.39 mm, exceeding precipitation (684.20 mm) received at the site during the same period by 37%, suggesting that almost all precipitation in the lysimeters was returned to the atmosphere by evapotranspiration. Furthermore, the cumulative ET_a (805.04 mm) was almost equal to the maximum potential evapotranspiration estimated by the FAO-56 reference evapotranspiration (ET₀) (801.94 mm) during the growing season, but the cumulative ET_a (132.25 mm) was 113.72% less than the minimum equilibrium ET_eq) (282.86 mm) during the non-growing season due to the limited surface moisture in frozen soil. The crop coefficient (K_c) also showed a distinct seasonal pattern, with a monthly average of 1.01 during the growing season. Structural equation model (SEM) and boosted regression tree (BRT) show that net radiation and air temperature were the most important factors affecting daily ET_a during the whole study period and growing season, but that non-growing season ET_a was dominated by soil water content and net radiation. The daily K_c was dominated by net radiation. Furthermore, both ET_a and K_c were also affected by aboveground biomass.  相似文献   

融合城市行道树特征选取模型的自适应深度学习分类     

乔莲花  刘民士 《测绘通报》2020,(6):77-80

针对城市行道树的学习多分类问题，本文在综合分析城市行道树多分类特征的基础上，提出一种融合特征自动选取模型的自适应深度学习方法。基于随机森林法，学习行道树的特征重要性，通过特征消除方法舍弃不重要的特征，实现城市行道树多分类特征自动选取；在城市行道树分类特征工程提取的基础上，构建了城市行道树多分类问题的自适应深度学习方法，并采用交叉验证与参数搜索方法，对所提出的深度学习模型进行改进。试验结果表明，本文所提出的融合特征自动选取模型的自适应深度学习方法具有良好性能，解决了城市行道树多分类预测的准确性与泛化问题。  相似文献   

Measurement of biogenic sulfur emissions from soils and vegetation: Application of dynamic enclosure methods with Natusch filter and GC/FPD analysis   总被引：3，自引：0，他引：3  

B. Lamb  H. Westberg  G. Allwine  L. Bamesberger  A. Guenther 《Journal of Atmospheric Chemistry》1987,5(4):469-491

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Relationship of minimum winter temperature and temperature seasonality to the northern range limit and species richness of trees in North America     

Hong QIAN  ZHANG Yangjian  Robert E.RICKLEFS  Xianli WANG 《地理学报(英文版)》2022,32(2):280-290

Biologists have considered both winter coldness and temperature seasonality as major determinants of the northern limits of plants and animals in the Northern Hemisphere,which in turn drive the well-known latitudinal diversity gradient.However,few studies have tested which of the two climate variables is the primary determinant.In this study,we assess whether winter coldness or temperature seasonality is more strongly associated with the northern latitudinal limits of tree species and with tree species richness in North Amedca.Tree species were recorded in each of 1198 quadrats of 110 km × 110 km in North America.We used correlation and regression analyses to assess the relationship of the latitude of the northern boundary of each species,and of species richness per quadrat,with winter coldness and temperature seasonality.Species richness was analyzed within 38 longitudinal,i.e.,north-south,bands (each being ＞1100 km long and 110 km wide).The latitudes of the north-ern range limits of tree species were three times better correlated with minimum temperatures at those latitudes than with temperature seasonality.On average,minimum temperature and temperature seasonality together explained 81.5％ of the variation in the northern range limits of the tree species examined,and minimum temperature uniquely explained six-fold (33.7％versus 5.8％) more of this variation than did temperature seasonality.Correlations of tree species richness with minimum temperatures were stronger than correlations with tempera-ture seasonality for most of the longitudinal bands analyzed.Compared to temperature sea-sonality,winter coldness is more strongly associated with species distributions at high lati-tudes,and is likely a more important driver of the latitudinal diversity gradient.  相似文献   

A data mining based approach to predict spatiotemporal changes in satellite images     

W. Boulila  I.R. Farah  K. Saheb Ettabaa  B. Solaiman  H. Ben Ghézala 《International Journal of Applied Earth Observation and Geoinformation》2011

The interpretation of remotely sensed images in a spatiotemporal context is becoming a valuable research topic. However, the constant growth of data volume in remote sensing imaging makes reaching conclusions based on collected data a challenging task. Recently, data mining appears to be a promising research field leading to several interesting discoveries in various areas such as marketing, surveillance, fraud detection and scientific discovery. By integrating data mining and image interpretation techniques, accurate and relevant information (i.e. functional relation between observed parcels and a set of informational contents) can be automatically elicited.  相似文献   

THE MOST PERFECT EXAMPLE OF AN ALIEN ECOLOGY EVER CONSTRUCTED     

《The Professional geographer》2013,65(4):471-477

Much science-fiction literature is based upon the creation and exploration of alternative environments. Stanley G. Weinbaum's short story, “Parasite Planet,”introduces an unusual environment that may be wrong in the light of recent evidence on Venus but still stimulates the geographical imagination.  相似文献