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Mapping Corn Seedling Using Spectral, Morphological Features and Hough Transformation from UAV Images
YANG Xinyu, LI Peijun
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 843-853.   DOI: 10.13209/j.0479-8023.2023.064
Abstract127)   HTML    PDF(pc) (17602KB)(52)       Save
Using spectral features, morphological features and Hough transformation from UAV images, a method of mapping corn seedling is proposed. First, spectral features and morphological features are extracted from UAV images and then are separately classified using an improved one-class random forest for mapping of corn seedling. Second, Hough transform is used to extract the corn seedling rows from the classification results with morphological features. Third, the corn seedling classification results with spectral features and the corn seedling rows from Hough transform are combined to obtain the final seedling mapping result. The proposed mapping method is evaluated in two study areas. The results demonstrated that the proposed method, effectively combines morphological features and Hough transform in mapping of corn seedling, thus obtaining better results compared with the existing methods.
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Responses of Soil Inorganic Nitrogen to Warming and Altered Precipitation in an Alpine Meadow on the Qinghai-Tibetan Plateau
WU Dandan, JING Xin, LIN Li, YANG Xinyu, ZHANG Zhenhua, HE Jinsheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 959-966.   DOI: 10.13209/j.0479-8023.2016.061
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Based on the warming and altered precipitation experiment platform at Haibei research station, this study investigated the responses of soil inorganic nitrogen to warming and altered precipitation in the growing season in alpine meadow. The results show that 1) warming significantly decreasesNH4+-N by 47.5% (p=0.001) and NO3-N by 85.4% (p=0.021); 2) effect of decreased precipitation on soil inorganic nitrogen is unequal to the effect of increased precipitation, increased precipitation significantly increasesNH4+-N by 74.7% (p=0.046) and NO3-N by 154% (p=0.017), while decreases precipitation tends to reduce NH4+-N, but has no significant effect on NO3-N; 3) NH4+-N and NO3-N are positively correlated with soil moisture, but has no correlations with soil temperature. Thus, soil moisture induced by warming and altered precipitation, is the main factor affecting inorganic nitrogen availability in the growing season. This study suggests that inorganic nitrogen availability will increase in tandem with increasing soil moisture, under the background of climate change in alpine meadow on the Qinghai-Tibetan Plateau.

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