Human ecology Human geography 52 Nature 41 Environmental policy 29 Environmental sciences 18 Ecology 15 Environmental ethics 15 History 15 Human beings 15 Sustainable development 15 Environmental protection 12 Natural resources 12 Ecofeminism 10 Environmentalism 10 Conservation of natural resources 9 Forests and forestry 9 Social ecology 9 Economic development 8 Effect of human beings on 8 Pollution 8 World history 7 Biodiversity 6 Effect of environment on 6 Environmental education 6 Feminist theory 6 Forest policy 6 Imperialism 6 Philosophy 6 Sustainability 6 Agricultural ecology 5