Presence and constancy - synthetic characters, Biology

Presence and Constancy - Synthetic Characters

Presence and constancy refer to how uniformly a species occurs in different stands in a community. For example, when a species is found in 15 out of the 20 stands in a community the presence or constancy is 75 per cent.

The terms presence and constancy are used in more or less in the same sense but they are however not synonyms. The term constancy is used when equal, measured sample areas are used for study, and presence is used when the area of sampling unit varies from stand to stand and especially when it is not measured. Many times, the sampling units do not have the same area, because of the nature of vegetation, as for example, small irregular stands in rock crevices or on sand deposits along a stream. Species in a community can be classified into five classes of constancy, according to the percentage of occurrence in sampling units or stands. These classes are:

Class I - 1-20% of the sampling units of a community

Class II - 21-40s of the sampling units of a community

Class III - 41-60% of the sampling units of a community

Class IV - 61-80% of the sampling units of a community

Class V - 81-100% of the sampling units of a community

You might have noticed that Classes IV and V include those species that occur in a large number of stands. The species that occur in over 80-90% or in more sampling units are called constant species. These species are important as they characterise and help to distinguish a community type. The species belonging to class IV and V indicate two possibilities:

  • The species have a wide ecological amplitude and are therefore capable of growing in various micro-habitats, and
  • The various sampling units are very similar in environmental conditions, so that species of narrow amplitude can grow in all of them.
Posted Date: 1/19/2013 7:59:35 AM | Location : United States

Related Discussions:- Presence and constancy - synthetic characters, Assignment Help, Ask Question on Presence and constancy - synthetic characters, Get Answer, Expert's Help, Presence and constancy - synthetic characters Discussions

Write discussion on Presence and constancy - synthetic characters
Your posts are moderated
Related Questions
Homo sapiens first appeared in the fossil record between 200,000 to 300,000 years ago, The fossils were the Swanscomb man from England and Steinheim man from Germany. a) The Swa

THEORY OF ORGANIC EVOLUTION - LAMARCKISM Theory of the inheritance of acquired characters or Lamarckism put forwarded by Jean Baptist de Lamarck (1809) in his book "

phylum platyhelminthes

Cheese Production Cheese production involves the conversion of the milk protein, k-casein to paracasein by a defined, limited hydrolysis, catalysed by chymosin (rennin). In the

M o n o c l o n a l antibodies: Hybridoma technology for production of monoclonal antibodies is one of the most important advancements in the f

Social Basis of Primitive Life: In the previous section, we gave you a glimpse of  how the primitive human beings faced the problems of day to day existence and found some so

Explain Functional property of Gelation/Viscosity  Mode of action  Protein-protein interactions produce matrix formations and setting Food system Salad dressings,

What are the results of Atrial Septal Defect ? Mortality for ASD closure has approached 0 per cent in most cardiac surgery centers. Late survival of patients who has ASD closu

The typological species concept was suggested by Plato more than 2000 years ago. According to this concept, the immense variety in nature can be reduced to a few "types". Individua

Define the Osazone Test or Phenylhydrazine Reaction? Compounds with -CO-CHOH group form crystalline osazones with phenyl hydrazine. These osazones have characteristic shapes an