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摘要
In present model on land use and land cover change (LUCC) research, the fusion of multiple scales has been less considered. To solve this problem, a decision tree model (DTM) synthesizing multi-scale features was proposed in this paper; additionally, the simulation result was compared to those from the typical data mining methods. Firstly, the space was subdivided to land use unit with appropriate grid cell size of 9.5 km2, which was used as simulation unit, and land use intensity (LUI), landscape shape index (LSI), and dominant land use type (DLT) were selected as inner indices, proportion of construction land (POC) and neighborhood average intensity of land use (NAI) were selected as neighborhood index, and the city-suburb index (CSI) was selected as global index. All the indicators of three scales were used as the property terms of the DTM. Then, taking the multi-scale evaluation indices of land use in Nanjing City, Jiangsu Province in 1995 as the test properties of the space instance, in accordance with the method of natural split point, land use intensity was classified into 4 levels, i.e. highest, higher, lower, lowest; and taking the actual levels of land use intensity in 2000 as the prediction of land-use-intensity type (PLT), the DTM was generated based on the sample sets of 816 space instances by using 10-fold iterative method. And the obtained model after the training was expressed to a tree structure. Thirdly, by using spatial and statistical analysis of GIS, the corresponding index values of feature attributes at different scales and conceptual levels were extracted and calculated from land use data. Further, the semantic information at a high abstraction level in different scales was constructed, and the law restraints to the model with the features of different scales were expressed. Based on the land use data in 2000, the simulated classification of land use intensity in 2005 was conducted by using the previous generated DTM. And then, by performing 10-fold cross-training for the 1995 and 2000 sample sets of land use change, the simulated land use intensity in 2005 was obtained and compared with the actual land use intensity in 2005. Finally, the simulated result was compared to those from the Naive Bayes (NB) method, the back propagation neural network (BPNN) method and the support vector machine (SVM) method in model simulation accuracy. The comparative experiments showed that the simulation accuracy of the DTM proposed in this paper was 88.97%, which was higher than the NB, BPNN and SVM methods whose simulation accuracies were respectively 84.44%, 87.13% and 83.46%. Since the simulation results from the DTM could be expressed as a tree structure with semantic clarity, when compared to the NB and SVM models, the DTM had better explanation; on the other hand, the DTM was easy to be constructed and expanded. In conclusion, the proposed DTM with synthesized multi-scale features in this study has similar or better accuracy compared with typical data mining methods, has the advantage of high computing efficiency, is easy to be extended and explained and can be reused at other places, and hence can contribute to support decision in LUCC management.
