Trees Forests and forestry 48 Shrubs 32 Forest ecology 30 History 24 Diseases and pests 23 Ecology 19 more ... Environmental aspects 18 Plants 18 Symbolic aspects 15 Identification 13 Growth 12 Religious aspects 12 Ecophysiology 11 Climatic changes 10 Tree planting 10 Botany 9 Social aspects 9 Woody plants 9 Breeding 8 Effect of air pollution on 8 Ornamental trees 8 Wood 8 Wounds and injuries 8 Arboles 7 Forest genetics 7 Forest management 7 Timber 7 Arboriculture 6 Biotechnology 6 less ...