- High temperature denatures enzymes and decreases the growth of plants. Low temperatures decrease enzyme activity and freezing temperatures inactivate enzymes. Most plants live in moderate temperature zones.
- Water is needed for enzyme activity, transport, photosynthesis, support, and many other things. There is a low diversity of plants in deserts and polar regions.
- Light is important for photosynthesis and flowering. Dark areas have small numbers of plants.
- Soil pH is important for absorption of nutrients. If soil is acidic, desertification can occur; the use of limestone can neutralise the soil. Salinity has an affect on the absorption through osmosis. High salinity causes plants to lose water through osmosis. Halophytes live in high salinity.
- Mineral nutrients are needed for many vital functions. Nitrogen is needed to manufacture proteins, enzymes, nucleotides, vitamins, and other compounds. Phosphorous is used in the formation of phospholipid and other structures.