Plant indicators
- The organisms are the measurement of the environment as they indicate environmental conditions of their respective habitats and thus serve as index of environmental conditions and commonly known as biological indicators.
- Plants are very useful indicators and are of great value as they are able to indicate the uses for which land may be best employed such as agricultural, forestation, grazing, etc.
- Many conditions of the environment are judged by the indicator species of communities. Some of them are as follows:
- Indicators of agriculture: The potential productivity of the land or particular habitat is measured with the help of forests and grasslands.
- Indicators of soil type: The sandy loam is indicated by deeply rooted and taller species like Andropogon scoparium and Ipomoea leptophylla. Similarly Woodfordia floribunda and Chloris virgata indicate high lime content in the soil. Saccharum munja and S. spontaneum indicate sandy desert. Rhododendron species indicate acid soils.
- Indicators of soil erosion and soil formation: Plant like Choris spinarum and Capparis spiaria are indicators of soil erosion where on Ziziphus rotundifolia is an indicator of soil formation.
- Indicators of soil water: Several plants like Enicostum littorale indicate well-drained soil.
- Indicators of minerals: Certain plants grow only in metal littorous soil. For example Viola calamine grows in soils rich in zinc, Stellaria setacea in mercury rich soil, Equisetum plebejum in soil containing gold.
- Indicators of pollution: Certain aquatic plants such as Utricularia, Chara and Wolffia indicate polluted water.
- Indicators of bogs and swamps: Typha, Phragmites, Juncus, Carex and some species of Polygonum indicate bogs and swamps.
- Indicators of saline and alkali soils: Rhizonphora, Sonneratia, Avceenia, Ceriops and Hevitiera indicate saline waterlogged soils. Plants like Salyrla foetida, Salicornia and Suaeda fruticosa are indicators of saline and alkali soils.