Ecology E ́cologie 31 Ecología 26 Ecologie 24 Zeitschrift 18 Environment 11 Environmental policy 10 O ̈kologie 10 Biology 9 Pollution 9 Environnement 8 42.90 ecology: general 7 Environmental protection 7 Human ecology 7 Biologie 5 Conservation of natural resources 5 Environmental Pollution 5 Environmental sciences 5 Microbial ecology 5 Microbiology 5 Nature 5 Pe ́riodiques 5 Protection 5 Animal ecology 4 Entomology 4 Geography 4 Insects 4 Medio ambiente 4 Natural history 4 Religious aspects 4