Table 1. Top 20 most frequent words in each research area classified by text mining and co-word analysis

Research area	Top 20 most frequent words
1st	Species, landscape, habitat, population, conservation, biodiversity, abundance, disturbance, season, individual, diversity, movement, composition, connectivity, fragmentation, protected area, wildlife, edge, animal, usa
2nd	Concentration, deforestation, plant, stand, emission, erosion, pollution, transportation, content, sediment, watershed, treatment, biomass, wood, logging, catchment, tropical forest, load, runoff, harvesting
3rd	Random forest, accuracy, technique, algorithm, prediction, performance, dataset, machine, vehicle, classification, image, machine learning, detection, technology, support vector machine, svm, speed, imagery, machine learning model, random forest model
4th	Elevation, aspect, rainfall, landslide, auc, logistic regression, curve, county, ndvi, altitude, normalized difference vegetation index, training, validation, sensitivity, rf model, lithology, iran, hazard, susceptibility, roc