Process of Community Analysis: 4 Categories | Ecology

This article throws light upon the four categories of processes of Community Analysis. The categories of processes are: 1. Biological Spectrum or Life Form Analysis 2. Stratification 3. Quantitative Structures of Plant Community 4. Synthetic Characters of Plant Community.

Category # 1. Biological Spectrum or Life Form Analysis:

Danish Botanist Christen Raunkiaer (1903) at­tempted to describe the communities (higher plants) into five major life form classes viz.,

A. Phanerophytes:

These are trees, shrubs and climbers where the growing buds are located on the upright shoot much above the ground surface and they are the least protected.

There are four subgroups of phanerophytes depend­ing on the height of the plants:

(i) Mega-phanerophytes (for trees over 30 meters tall);

(ii) Meso-phanerophytes (for trees between 8 meters and 30 meters height);

(iii) Micro-phanerophytes (for trees between 2 and 8 meters height) and

(iv) Nano-phanerophytes (for shrubs smaller than 2 meters).

B. Chamaephyte:

These are the herbs or creep­ers whose buds are located close to the ground surface or up to a maximum height of 25 cm.

C. Hemicryptophytes:

These are mostly bien­nial or perennial herbs whose perennating buds are present just under the surface soil and remain protected there.

D. Cryptophytes or Geophytes:

These are plants having bulbs or rhizomatous stem lies under­neath the soil.

E. Therophytes:

These are annual herbs which only survive by seeds. According to Raunkiaer (1934), in general in normal vegetation of different habitats showed distinctive life-form pattern. Though there are some limitation in application of life-form classification, yet it is indicative of climatic condition of an area. The different life-form classes were depicted in Fig. 3.1.

Category # 2. Stratification:

All the plants in a community are not of the same size and do not occupy the same strata in multistoried structure. Thus the distribution of plants in vertical space is known as stratification. Depending on the vegetation types and climatic condition, the stratification may vary widely how­ever, in general the following strata could be recognised in a plant community (Fig. 3.2).

Category # 3. Quantitative Structures of Plant Community:

In the plant community different species are rep­resented by few or a large number of individuals aggregating in different vegetation units. It is es­sential to know the quantitative structure of the community, specially the numerical distribution and the space occupied by the individuals of different species.

Category # 4. Synthetic Characters of Plant Community:

Synthetic characters express the make-up of a community.

The chief synthetic characters are described below:

i. Fidelity:

The faithfulness of a species to its community is referred to as fidelity. While plants of low fidelity grow in several types of communities, a high fidelity plant occurs in only one kind in community. So, the charac­teristic species of a community has high fi­delity value but a low ecological amplitude. In other words, the species is tolerant to a nar­row range of environmental conditions.

The degrees of fidelity are usually expressed in the following manner:

Species belonging to F3, F4 and F5 classes are called characteristic or key species of a community.

ii. Presence and Constancy:

The uniformity of species over a number of sample plots or stands of the same type of community is ex­pressed in terms of presence or constancy. The term Constancy is used if the sample ar­eas are of equal size and Presence is used when the sample areas are of variable sizes.

iii. Physiognomy:

Physiognomy refers to the general appearance of plant community. Ma­jor plant communities of large area are classi­fied into component communities on the ba­sis of physiognomy. Component communi­ties recognized on the basis of physiognomy are named after the dominant forms of life, as for example forest grassland, desert com­munity, etc.