ATTRIBUTES OF THE PLANT COMMUNITIES

The attributes (characteristics) of a commit), are classified into three main groups: analytic. synthetic and physiognomic.

(a) Analytic characteristics

The characteristics which can be analyzed by quantitative or qualitative methods are called analytic characteristics. These may be qualitative or quantitative characteristics.

  1. Qualitative Characteristics

The disruptive characteristic’s which cannot be measured are called qualitative characteristics. These includes following characteristics.

(i)     Kinds of Species or Floristic Composition: A complete list of species is called floristic composition. It is essential for the study   of a stand.

(ii)    Stratification: The plants occurring together with a similar ecology in definite strata are called stratification. The size and number of these strata depends on the type of life form. Stratification of the community causes differences in requirement of trees, shrubs and herbs. They require different light intensity, temperature, moisture condition and organic content of the soil. Most temperate forest communities are composed of 3 – 4 strata.

  • Over story tree: The upper stratum consist of relatively large over storey trees.
  • Crown: Below these taller trees, there is a stratum of the crown or secondary under storey trees.
  • Herbaceous plants: Below the secondary trees there is one or more layers of herbaceous plants.
  • Mosses or lichens: Mosses or lichens may be present in the low layer on the ground.

(iii) Periodicity: The rhythmic phenomena related to seasonal changes is called periodicity. These changes are growth. flowering, pollination, ripening of- fruit and seed. Periodicity is controlled by different environmental factors like light, temperature etc.

(iv)   Vitality: The capacity of plants to complete its life cycle is called vitality. Some species have low vitality and die soon. Some have high vitality. They complete their life span.

(v) Sociability: The degree of aggregation of plants in nature is called sociability. Sociability depends on life form, mode of reproduction, habitat condition and competition.

  1. Quantitative characteristics

The characteristics which can be measured are called quantitative characteristics. These include:

(i)Density: The number of individuals of a specie in a unit area is called density.

(ii) Relative density: The proportion of a density of a specie to a stand as a whole is called relative density.

(iii) Abundance: The. estimation of individuals of a specie is called abundance.

(iv)  Cover: The ground covered or shaded by the above ground parts of plant is called cover. Cover also includes basal area. The ground actually covered by crown is called cover.

(v) Relative cover: The proportion of the cover of a species to sum of the all the plant of all the species is called relative cover.

(vi) Frequency: The degree of occurrence of individuals of a species within an area is called frequency.


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(vii) Relative frequency: The proportion of the total frequency_ of specie to the sum of the frequency of all the species in the area is Called relative frequency.

(viii)  Frequency classes: Dacron classes are formed on the basis of relative frequencies. There are live frequency classes.

(b) Synthetic characteristics

The generalization and integration of characteristics that derived from data of analytic qualities are called synthetic characteristics. In this case, data is arranged in tubular form. Then synthetic characteristics are studied. There are following synthetic characteristics:

(i)          Presence: It is the uniformity of specie occurs in number of
stands of the same type of community.

(ii)         Constancy: A specie that occurs in 90% or more of the stand is called constant specie.

(iii)        Fidelity: The relative occurrence of specie in an association or a group of related association is called fidelity.

(iv)   Dominance: The species which have high number and large
volume are called dominant species.

(c) Physiognomic characteristics

The general appearance or outlines of the stand or community are called physiognomic characteristics. It includes:

(I)      Physiognomy: The appearance of stand is called physiognomy.

(ii)      Pattern: The group of individuals with physiognomic contrast

(iii)    Life-form: The vegetative appearance of the plant body and its longevity is called life-from. There are five principle life form classes.

  • Phanerophytes: These plants include woody trees and shrubs. Their bud bearing shoots are elevated and exposed to the atmosphere. Example. Accaia sp.
  • Chamaeophytes: They include wood or semi woody perennial under shrubs. The bud is above the ground but less than 25 cm high. Example Salvia sp.
  • Hemi-cryptophytes: The perennating buds are half hidden in the surface of soil. Example cuphorbia.
  • Cryptophytes: Their buds are ill soil or under water, e.g. Hydrilla.
  • Therophytes: It includes all the annual plants. Their only perennating buds are present in seeds.

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