Classification of rare land cover types: Distinguishing annual and perennial crops in an agricultural catchment in South Korea

PLoS One. 2018 Jan 25;13(1):e0190476. doi: 10.1371/journal.pone.0190476. eCollection 2018.

Abstract

Many environmental data are inherently imbalanced, with some majority land use and land cover types dominating over rare ones. In cultivated ecosystems minority classes are often the target as they might indicate a beginning land use change. Most standard classifiers perform best on a balanced distribution of classes, and fail to detect minority classes. We used the synthetic minority oversampling technique (smote) with Random Forest to classify land cover classes in a small agricultural catchment in South Korea using modis time series. This area faces a major soil erosion problem and policy measures encourage farmers to replace annual by perennial crops to mitigate this issue. Our major goal was therefore to improve the classification performance on annual and perennial crops. We compared four different classification scenarios on original imbalanced and synthetically oversampled balanced data to quantify the effect of smote on classification performance. smote substantially increased the true positive rate of all oversampled minority classes. However, the performance on minor classes remained lower than on the majority class. We attribute this result to a class overlap already present in the original data set that is not resolved by smote. Our results show that resampling algorithms could help to derive more accurate land use and land cover maps from freely available data. These maps can be used to provide information on the distribution of land use classes in heterogeneous agricultural areas and could potentially benefit decision making.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Conservation of Natural Resources / methods*
  • Crops, Agricultural / classification*
  • Ecosystem
  • Republic of Korea

Grants and funding

This study is part of the International Research Training Group TERRECO (GRK 1565/1) funded by the German Science Foundation (DFG) and the National Research Foundation of Korea. This publication was funded by the German Research Foundation (DFG) and the University of Bayreuth in the funding programme Open Access Publishing. Bumsuk Seo acknowledges the support by the Agenda Program of the Rural Development Administration (PJ00997802) in South Korea. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.