Topics: water cycle, nitrogen cycle, food chain, food web, carbon cycle, energy, thermodynamics, ammonification, biomes, freshwater biome, aquatic biome

Topics: Botany, Ecology, ecological concepts, Ecosystem, Autotrophs, Heterotrophs, Phagotrophs, Osmotrophs, Energy Flow, Food Chain, Food Web, Biogeochemical Cycle, Water Cycle, hydrologic cycle, Carbon cycle, Atmospheric Carbon Cycle, Terrestrial biological carbon cycle, Oceanic carbon cycle, Nitrogen cycle, Nitrogen fixation, Nitrogen Assimilation, Ammonification, Nitrification, Denitrification, Marine nitrogen cycle, Oxygen cycle, Phosphorus cycle, Phosphorous, Sulfur cycle, sulfur, Competition, Mutualism, Predation, Parasitism, Commensalism, Ammensalism, niche, succession, biomes

Topics: Habitat, Biomes, tropical forest, Temperate forest, coniferous forest, fauna, grassland

Topics: Natural Environment, Animal Production, earth science, environment, geological activity, oceans, rivers, streams, lakes, ponds, climate change, atmosphere, atmospheric layers, global warming, climate, weather, life ecosystems, biomes, biogeochemical cycles, wilderness, Environmental degradation, population growth, agriculture, water management, greenhouse gas emission, Gas effect, emissions, pollution, air pollution, water pollution, land pollution, erosion, coastal erosion, glaciers, floods, freezing, thawing, wind erosion, gravitational erosion, exfoliation, soil structure, soil composition, vegetation cover, topography, agricultural practices, deforestation, urbanization, airborne dust pollution, desertification, Stratospheric Ozone, ozone hole, Antarctica Ozone Theory