Ecology-- Biodiversity-- Conservation-- Ecosystems 135 Ecology 103 Ecosystem 92 Ecosystems 80 Biodiversity 32 Ecosystem management 28 Climatic changes 23 Marine ecology 22 Environmental management-- Ecosystems 20 Environment 19 Marine ecology-- Ocean ecology-- Sea ecology 18 Biodiversity conservation 17 Management 17 Forest ecology 16 Natural resources 16 Aquatic ecology 15 Pollution 15 Human ecology 14 Sustainable development 14 Biology 13 Ecology-- Biodiversity-- Conservation-- Ecosystems - Encyclopedia-- Dictionary 13 Environmental chemistry-- Ecosystems 13 Environmental management 13 Environmental management--Ecosystems 13 Freshwater ecology 13 ecosystem 12 Biotic communities 11 Ecosystem services 11 Environmental economics 11 Nature 11