Monsoon Deciduous Forest Biome: Location and Animal Life | Geography

In this article we will discuss about:- 1. Location of Monsoon Deciduous Forest Biome 2. Climate of Monsoon Deciduous Forest Biome 3. Plant Community and Structure 4. Animal Life 5. Man and Monsoon Deciduous Forest Biome.

Location of Monsoon Deciduous Forest Biome:

Normally, the tropical deciduous forests are found in the regions of monsoon climate but there are some departures from this close relationship and near correspondence between the regions of monsoon cli­mate and deciduous forest.

There are three major areas of tropical deciduous forest biome viz.:

(i) The Neotropics mainly West Indies,

(ii) Indo-Malaysian Zone (mainly in south and south-east Asia except equatorial ever­green rainforest areas) and

(iii) Eastern Africa and northern Australia.

Besides these major areas, some discontinuous localities of tropical deciduous forest biomes are also found in South Africa, Southern Bra­zil, South-Eastern U.S.A., Formosa (Taiwan), south­ern China and Japan.

Climate of Monsoon Deciduous Forest Biome:

This tropical deciduous forest biome is charac­terized by two distinct seasons viz. moist season and dry season.

There are three main seasons in a year in India and surrounding monsoonal areas such as Paki­stan, Bangladesh etc. e.g.:

(i) Dry warm summer season (March to June),

(ii) Warm humid summer season (July to October), and

(iii) Dry winter season (November to February).

Average temperature of warm dry summer season ranges between 27°C and 32°C but the maxi­mum temperature ranges between 38°C and 48°C dur­ing May and June. Warm humid summer season records average temperature between 20°C and 30°C. The temperature during dry winter season ranges between 10°C and 27°C. The length of dry season is more important than the total amount of precipitation in affecting vegetation in the tropical deciduous forest biome.

On an average, the mean annual rainfall is around 1500mm but there are much variations in temporal and spatial distribution of rainfall. Sometimes a few areas receive even less than 500 mm of mean annual rainfall. Even the temporal distribution of rainfall within a single year is highly variable because more than 80 percent of mean annual rainfall is re­ceived within 3 wet months of summer season (July, August and September).

Thus, the rainy season records much surplus water whereas dry winter and summer seasons have marked deficit water because dry season receives less than 25 mm of rainfall per month. There is maximum evaporation during warm dry summer months which results in desiccation of soils and marked reduction in soil-water. This seasonal regime of annual monsoonal rainfall gives deciduous character to the vegetations which shed their leaves (mostly trees and shrubs) during the transitional period between winter and summer season.

Plant Community and Structure of Monsoon Deciduous Forest Biome:

The number of plant species is less in the tropi­cal deciduous forest biome than the tropical evergreen rainforest biome. Since the density of plants is also lower in this biome than the rainforest biome and hence there is comparatively less competition among the plants for getting sunlight. The height of most of the trees ranges between 12m and 30m.

There are four strata or layers in the vertical structure of the tropical deciduous forests. The uppermost and the second strata consist of trees; the third stratum is formed by shrubs whereas the last and the fourth stratum or the ground stratum represents herbaceous plants.

Most of the trees are deciduous but the shrubs of the third stratum are evergreen. The trees are charac­terized by thick girth of stems, thick, rough and coarse bark and large hydromorphic leaves or small, hard xeromorphic leaves. The large hydromorphic leaves enable the trees to trap more and more rainfall during wet seasons but these large leaves are shed in dry periods to conserve moisture whereas small and hard xeromorphic leaves enable the trees to withstand dry weather and water deficiencies.

Though there are numerous climbers mainly lianas and epiphytes but their numbers are far less in the tropical deciduous forest biome than the tropical ever­green rainforest biome.

Sal (Shorea robusta) and teak trees of Indian deciduous forests form forest canopy but its shape is not like umbrella or cauliflower as is the case with the forest canopy of the rainforest biome. Bamboo is another important member of the Indian deciduous forests. Besides, there are numerous trees, climbers, shrubs and grasses which have spatial variations from one region of the tropical deciduous forests to the other region.

Animal Life of Monsoon Deciduous Forest Biome:

It may be pointed out that various dimensions of animal community of any habitat/ecosystem/biome including the number of species, their population and density, their life-forms and various activities, repro­duction and various types of biological interactions and above all species diversity largely depend on the composition and structure, richness or poorness, total biomass etc., of vegetation communities of the con­cerned biome.

It is a significant ecological principle that more is the development of stratification of the vertical structure of the vegetation community of a biome and greater the number of plant species, the more will be the number of animal species, their total population and species diversity.

This ecological prin­ciple holds good in the case of tropical evergreen rainforest biome. But there are comparatively lesser number of animals species in the monsoon deciduous forest biome than the rainforest biome because of comparatively less developed verti­cal strata and hence less diversification of animal species.

The seasonal character of vegetation commu­nity in terms of dense vegetation cover, full develop­ment of leaves and their evergreen form during rainy months (wet summer season, July to September) and shedding of leaves, drying of herbaceous plants etc. during dry season mainly during dry warm season has affected and determined the seasonal behaviour of animal communities particularly breeding and migrat­ing behaviour.

In other words, the seasonal character of the monsoon deciduous forests has been responsible for the seasonal regime in the breeding and reproduc­tion and migration of animals. For example, birds in east Africa breed twice during the two different seasons of a year. Indian dogs generally breed once a year mainly at the end of wet monsoon season (during October-November).

The animals of the tropical and sub-tropical dry deciduous forest biome range from very small animals (micro-organisms) to very large-bodied animals like elephants, horses, hippopotamus, ganda or rhinos, li­ons, forest buffalo together with a large population of birds of several species. This biome represents the largest number of domesticated mammals because of the development of agriculture. This biome also car­ries the largest number of human population of the world.

Man and Monsoon Deciduous Forest Biome:

The tropical and sub-tropical monsoon decidu­ous forest biome is one of the most disturbed ecosys­tems of the world. The forests have been adversely affected by both natural and anthropogenic processes. There are numerous cases of frequent forest fires every year kindled by either natural processes such as light­ning or anthropogenic factors such as inadvertent ac­tions of man (throwing of burning ends of ‘bidi’ or cigarettes by the herdsmen in the forest) or advertent and intentional actions of man (such as clearing of forests through deliberate burning for agricultural pur­poses under jhum cultivation which is very much preva­lent in India) and large-scale grazing.

The forests of the monsoon deciduous forest biome have been so rapidly destroyed within the last 50 years or so through the rapacious utilization of forest resources for commer­cial and industrial purposes and large-scale clearance through mass felling of trees for agricultural land that the vegetation cover has shrunk to a very critical size.

The rapid rate of deforestation has led to the initiation of several ecological and geological prob­lems. Several species of precious animals have now become endangered species because of destruction of their natural habitats. For example, lions and tigers and even elephants have become endangered species in India partly because of deforestation and partly by mass hunting of these animals. Similarly, Indian rhi­nos are facing extinction because of their mass killing.

The lions of Gir forest of Gujarat of India together with other animals like leopards, spotted deer, sambhar deer, Indian gazelle, nilgai, antelope, wild boar etc. are now endangered species because of enormous destruc­tion of the Gir Forest Ecosystem. The rapid rate of deforestation in the monsoon lands mainly in India has caused accelerated rate of soil loss through rill and gully erosion, siltation of river beds and consequent recurrent severe floods in the alluvial rivers.