Plant indicators

Plant Indicators:- Plant indicators are also used to determine optimum use of land resources for forest, pasture, and agricultural crops. The occurrence, character and behaviour of a plant are thus indicator of the combined effect of all factors prevailing in a habitat. Since a plant species or plant community acts as a measure of environmental conditions, it is referred to as biological indicator or bio-indicator or phyto-indicator.

a. Plant indicators of forest:- Some plants indicate the characteristic types of forest and they grow in an area which is not disturbed. Narengaporphyrocoma is a grass which binds the soil. In such a soil sal (Shorearobustd) can be cultivated. Violaspecies in western Himalayas is a suitable indicator for plantation of Cedrusdeodara and Pinus.

b. Plant indicators for Soil types:- Many plants indicate the characteristic soils. For example, Casuarinaequisetifolia, Ipomoea grow in sandy soil. Sacchammmunja prefers to grow in sandy loams. Imperatacylindrica and Vetiveriazizanioides grow on clayey soils. Cotton prefers to grow in black soil.

c. Plants indicators for soil reaction:- Many plants indicate whether the soil is acidic or basic. For example, Rumexacetosa. Rhododendron, Polytrichum and Sphagnum indicate acidic soils.

d. Plant indicators for minerals:- Many plants indicate the presence of characteristic minerals in the soils. These plants are called metallocoles or metallophytes.

The following plants grow in the presence of specific metals:

i. Diamond:-Vallozia Candida grows in presence of diamond in Brazil.

ii. Gold:- Equisetum arvense, Lonicera confuse, Papaverlibonoticum, Alpiniaspeciosa, Thuja species indicate the presence of gold minerals in the soil.

iii. Silver:- Eriogoniumovalifolium indicates the presence of silver minerals in soils in U.S.A.

iv. Mercury:- Stellariasetacea grows in Spain in mercury rich soils.

v. Uranium:- Astragalus species grows in USA in uranium rich soils,

vi. Selenium:- Astragalus species, Neptuniaamplexicaulis, Stanleyapinnata, Onopsiscondensator, etc. grow in selenium rich habitat.

vii. Copper:- Viscariaalpina in Norway, Gymnoleaacutiloba in America, Gypsophila patrini in USSR grow on the soil rich in copper.

viii. Zinc:- Viola calaminara, V. lutea in Europe grow on the soil rich in zinc minerals.

ix. Boron:- Salsolanitrata, Eurotiacerutoides grow in boron rich soils.

x. Cobalt:- Silenecobalticola in Congo and Nyssa sylvatica grow in America in cobalt rich soils.