Woody plants Trees 12 Plants 11 Forests and Forest Trees (Biology and Ecology) 8 Forest ecology 4 Forests 4 Soil Biology 4 Agroforestry and Multipurpose Trees: Community, Farm and Social Forestry 3 Animal Ecology 3 Biodiversity 3 Ecosystems 3 Forest trees 3 Horticultural Crops, (New March 2000) 3 Nitrogen fixation 3 Plant Ecology 3 Pollution and Degradation 3 Agroforestry 2 Aquatic Biology and Ecology 2 Biochemistry and Physiology of Microorganisms, (New March 2000) 2 Biological Resources (General) 2 Biological Resources (Plant) 2 Climatic changes 2 Crops 2 Environmental impact 2 Erosion 2 Erosion: Soil and Water Conservation 2 Field Crops, (New March 2000) 2 Forest plants 2 Forests and forestry 2 Grasslands 2