ALKALINE SOIL
DENITRIFICATION
DERELICT LAND
DESERTIFICATION
FLORA
FOREST CONSERVATION
FOREST RESOURCES
FROZEN SOIL
LAND
LAND DEGRADATION
LAND ECONOMICS
LAND RECLAMATION
LAND SUBSIDENCE
LAND-USE CHANGE
NATIONAL PARKS AND RESERVES
NATURAL MONUMENTS
NITROGEN FIXATION
PARKS
PHOTOSYNTHESIS
PLANT ECOLOGY
PLANT PROTECTION
PLANT RESOURCES
RANGE MANAGEMENT
SALINE SOIL
SANDY SOIL
SOIL CONSERVATION
SOIL EROSION
SOIL FERTILITY
SOIL IMPROVEMENT
SOIL MANAGEMENT
SOIL RESOURCES
SOIL SURVEYS
SOILS
SUBSURFACE SPACE
TROPICAL PLANTS
VEGETATION
WINDBREAKS