Few example from Indian ecosystems: forest, grassland, freshwater, marine and estuarine (e-Text and Learn More)
1. Details of Module and its Structure
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Module Detail Subject Name <Ecosystem Ecology>
Paper Name <Ecology>
Module Name/Title <Fe w Examples of Indian Ecosystems>
Module Id <Module Id>
Pre-requisites <Knowledge on ecosystem structure and function >
Objectives <To study distribution and ecology of different forests, grasslands, aquatic ecosystems of India>
Keywords <Ecosystem >, < Food chain>, < Ecosystem distribution>
Structure of Module / Syllabus of a module (Define Topic / Sub-topic of module )
<Ecosystem> <Ecosystem concept>, <Hierarchy of ecosystem organization>,
<Ecosystem boundary>
<Topic name2> <Sub-topic Name2.1>, <Sub-topic Name2.2>
1. Introduction
The mainland of India lies between 8°4ʹ N and 37°6ʹ N latitude and 68°7ʹ E and 97°25ʹ E longitude.
It is completely in the northern hemisphere. India is the seventh largest country in the world with a
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
geographical area of 3,287,263 sq. km. Besides the main land there are two groups of islands;
Lakshadweep in the Arabian Sea and Andaman & Nicobar Islands in the Bay of Bengal. The country has almost all the important topographical features, viz; mountain, plateau, plain passing through rivers). The longitudinal and latitudinal expansion, spatial distance from sea, Himalayas and landforms influence the Indian climate. India experiences all kind of climatic conditions. The tropic of cancer passes through the middle part of India in east- west direction. The northern part of it is categorized under sub- tropical and temperate zone while the southern part of the tropic of cancer is categorized under the tropical zone. The Himalayas act as a barrier to the cold winds flowing down from Central Asia maintaining the most of the Indian subcontinent warmer than other locations of similar latitudes. There is a large variability in the amounts of rainfall perceived at different locations. India is an exceptional subcontinent due to vast variability in geographic area, topography and climate. These differences support diversity of ecosystems from the cold and Himalayan ranges to the seacoasts, from the wet north-eastern evergreen forests to the dry north- western arid deserts as well as many kinds of forests, wetlands, islands, estuaries and oceans. Each ecosystem has its own unique species. Including all ecosystems; India has approximately eight percent of the total biodiversity of the earth, hence recognized as one of mega diversity country among the 12 mega-diversity zones of the world and covers around 1,26,188 species (Khosboo 1995). In this chapter the distribution and ecology of different forests, grasslands, and aquatic ecosystems of India have been discussed.
2. Forests
It is very difficult to define ‘Forest’ due to variation in purpose of forest use and their scale. All around the world roughly 800 definitions to define the forests and wooded areas are in use (Lund 2012). Food and Agricultural Organization (FAO) defined forest as land area of more than 0.5 ha with trees higher than 5 m height and more than 10 percent tree cover, or trees capable to attain 5 m height under in situ condition, nevertheless it does not include the lands under agricultural or urban practices (FAO 2010). India first time defined forest during the Kyoto Protocol by adopting the definition of United Nations Framework Convention on Climate Change (UNFCCC).
Accordingly; forest is a land area having at least 0.05 ha land area and 15% tree cover with at least 2 m tree height. As per UNFCCC this definition includes the closed as well as open forests. These two forests differ in their tree cover. The tree cover between 10 to 40% is considered for open forest while more than 40% reflects closed forest. United Nations Environment Programme follows 40%
criteria of tree cover to define the forest (UNEP 2011).
Total forest cover in India is 78.92 million hectare which is 24.01 % of the total geographical area of the country (FSI 2011). It is less than the recommended forest cover (at least one third of the total geographical area of the country). The climax vegetation is represented by either forests or desert vegetation (Mishra, 1989). Primarily on the basis of temperature, Indian vegetation is categorized in four major zones; viz: (i) Alpine (mean annual temperature is below 7° C, mean January temperature under -17° C, winter is severe with much snow), (ii) Temperate (mean annual temperature between 7 and 17° C, mean January temperature between -1 and 10 ° C, winter is pronounced with frost and some snow), (iii) Subtropical (mean annual temperature ranges 17-24° C, mean January temperature ranges 10 to 18° C, winter is definite but not severe, frost is rare) and (iv) Tropical (mean annual temperature over 24° C, mean January temperature over 18° C, winter is none and no frost.
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
In 1968, Champion and Seth categorized the Indian forests into five major categories (Figure 1). (i) Tropical (ii) Montane subtropical (iii) Montane temperate (iv) Sub-alpine and (v) Alpine. Due to differences in annual temperature, rainfall and dry periods among t he forests; the forests types are futher divided into sub-types or groups (Figure 1, Table 1). Thus, India has a total of 16 forest vegetation types, presented in Table 1 (Champion and Seth 2005).
Figure 1. Forests types of India as per classification of Champion and Seth (1968).
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Table 1. Forest types of India showing mean annual minimum and maximum temperature, rainfall, dry periods, distribution and their major species (Sources: Champion and Seth 2005, Singh et al 2014).
Forest types Mean annual maximum and minimum Temperature (°C)
Rainfall (mm)
Dry periods (months)
Distribution Major species
1. Tropical wet evergreen
27-30 and 18- 23
>3000 3-4 Maha., Karn., T.N., Kerala, Andman, W.B., Assam, Orissa.
and throughout N.E.
Dipterocarpus grandiflorum, D.
costatus, Hoppea odorata, Shorea assmica, Artocarpus chaplasa, Mesua ferrea.
2. Tropical Semi- evergreen
28-30 and 19-23 2000- 2500
4-5 Maha., Goa,
Karn., Kerala, Andaman,
Assam, W.B., Orissa.
Xylia xylocarpus Terminallia
paniculata, T.
tomentosa
Schleichera oleosa Syzygium spp Cinnamomum spp.
3. Tropical moist deciduous
27-33 and 14-20 1200- 2500
3-7 M.P., Ch. gh., Maha., Karn., T.N., Kerala, Andaman and Nicobar, U.P.
Bihar, Orissa, W.B. Assam.
Tectona grandis, Terminalia spp, Pterocarpus
marsupium
Schleichera oleosa Shorea robusta, Lagerstroemia spp.
4. Littoral and swamp
29-33 and 18-24
475 - 3100
3-9 In coastal regions of W.B., Orissa, Andhra, T.N and Gujarat.
Manilkara littoralis, Casurina
equisetifolia, Rhizophora
mucronata, R.
candelaria,
Avicennia alba, Ceriops
roxburghiana.
5. Tropical dry deciduous
29-35 and 18-25 800- 1200
6-8 M.P., Gujrat , Maha., Andhra, Karn. T.N., Punjab, U.P.,
Shorea robusta, Tectona grandis, Anogeissus latifolia, Terminallia
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Bihar, Ch.gh., Jh.Kh., Orissa.
tomentosa,
Buchanania lanzan.
6. Tropical Thorn
31 -34 and 18- 25
200-800
7-10
Maha. Andhra , Karn., T.N., M.P.,U.P.,
Rajasthan, Gujrat, Punjab.
Acacia catechu, A leucopholea, A.
arabica,
Capparis deciduas, Prosopis spicigera, Zizyphus mauritiana, Z. nummularia.
7. Tropical dry evergreen
32-35 and 23-24 870- 1200
4-6 Karn.,
Andhra.,T.N.
Manilkara hexandra, Mimusops elengi, Dispyros ebenum, Memecylon edule and Drypetes sepiaria.
8. Subtropical broad leaved Hill
20-26 and 12 - 16
1000- 3000
4-7 Maha., Karn., T.N. Kerala, Rajasthan, M.P., Orissa, W.B, N.E.
Euginia wightiana, Memecylon sp, Quercus vercus, Q.serrata
Castanopsis
tribuloides C.indica., Alnus nepalensis.
9. Subtropical Pine
20-25 and 11-15 1000- 3000
3-7 Western and
Central Himalaya,
Punjab, U.K., Sikkim,
Megahlaya and Manipur.
Pinus roxburghii, P.
insularis, Quercus griffithii,
Rhododendron arboretum, Syzygium cumini.
10. Subtropical dry evergreen
500- 1000
Shiwalik hills, Western
Himalaya,
Jammu and
Punjab.
Olea cuspidata, Acacia modesta, Punica granatum, Dondonaea viscose.
11. Montane wet temperate
15-21 and 9-15 1500- 5000
2-5
T.N., Kerala, Eastern
Himalaya, W.B., Assam, N. E.
Ternstroemia gymnanthera, Eugenias calophyllifolia, Meliosma wightii, Rhododendron nilagiricum, Quercus lamellosa, Q.
pachphylla, Machilus edulis.
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Abbreviations: Maha = Maharastra, Karn = Karnataka, T.N. = Tamil Nadu, M.P. = Madhya Pradesh, U.K. = Uttrakhand, Jh.kh = Jharkhand, Ch.gh. = Chhattisgarh, Andhra =Andhra Pradesh, N.E. = North East, and U.P. = Uttar Pradesh.
A brief description on the sixteen forests types in India as described by Champion and Seth (1968) is given below:
(I) Tropical wet evergreen forests: These forests are similar to tropical rain forests, dominated by evergreen trees with close canopy. Evergreen trees are the climax vegetation. Number of species per hectare has been estimated in a range of 40 to 100. Legumes, myrtales,figs 12. Himalayan
moist temperate
17-18 and 7 -11 1000- 2500
2-5 Jammu and
Kashmir, Punjab, H.P ,
U.K., W.B.,
Assam and
Eastern Himalaya.
Abies densa, Cedrus spp, Picea spinulosa, Pinus wallichiana, Tsuga dumosa Quercus dilate, Q.
lamellose.
13. Himalayan dry te mperate
13-22 and
(-1.3) to 11
<1000 4-12
Jammu and
Kashmir, Punjab, H.P.,
U.K., Sikkim , N. E.
Cedrus deodara, Pinus geardiana , Juniperus
wallichina, Abies spectabilis, Quercus
ilex, Acer
pentapomicum.
14. Sub-alpine 9-13 and (-5.4) to (-1.3)
83-600
6-12 Jammu and
Kashmir, Punjab, H.P. ,
U.K., W. B., North East.
Abies spectabilis, , Pinus wallichiana, Betula utilis Rhododendron companulatum, Quercus
semecapifolia.
15. Moist-alpine scrub
Kashmir, U.K., Sikkim, Manipur.
Western
Himalaya and Eastern
Himalaya.
Rhododendron companulatum, R.wightii, R. molle, thomsoni.
Betula utilis, Sorbus foliolosa.
16. Dry alpine scrub
< 370
H.P, Kashmir, U.K.
Eurotia ceratoides, Juniperus
wallichiana, J.
communis, Artimisa maritima, A.
Sacrorum, Lonicera spp., and Potentilla spp.
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
and Dipterocarpus are locally dominant trees with Shorea as a common species of North India and Hopea of southern India. Distribution of these forests in India is shown in Figure 2. Major climatic conditions and species are described in Table 1. The tree height ranges between 75m and 100m. There is well developed stratification, having 4-5 strata (Mishra 1989).
(II) Tropical semi-evergreen forests:
These forests experience rainfall in between 2000 and 2500mm (Table 1). Such forests are occurring in Assam, Lusai, Kalimpong and Orrisa hills (Figure 2). In these forests top stories are dominated by the deciduous species while middle and lower stories are dominated by the evergreen species. Albizzia, Bombax, Cinnamomum, Dipterocarpus, Eugenia, Mangifera, Quercus, Terminalia and Xylia are the major genera (Singh et al 2014).
(III) Tropical moist deciduous forests: These forests are also dominated by the deciduous species. Understorey is predominated by the evergreen species. The height of trees varies from 30 to 40 m. Rainfall occurs around 1200-2500mm. Adina, Anogeissus, Calycopteris, Cedrela, Pongamia and Termilia are the common species.
(IV) Littoral and s wamp forests: Such forests are found in coastal regions of West Benga l, Orissa, Andhra Pradesh, Tamil Nadu and Gujarat (Table 1, Figure 2). The species are mainly evergreen, composed of mangrove and freshwater swamp forests (Singh et al 2014). The predominated species Rhizophora, Avicennia, Sonneratia species. As for as swamp forests is concerned, they occur in Valleys of Brahmaputra and the common trees are Barringtonia, Cephalanthus and Glochidion species. Flora of these forests are very poor (Mishra 1989).
(V) Tropical dry deciduous forests: The temperature and rainfall are major determinant factors for the distribution of these forests. The rainfall varies in the range of 800-1200mm (Table 1). They are also known as tropical monsoon forests occurring in areas of Vindhyan and South India; viz: Maharashtra, Uttar Pradesh, Bihar and Madhya Pradesh (Figure 2). These forests are entirely deciduous, may or may not have Teak and Sal or mixed deciduous vegetation locally dominated by Adina, Anogeissus, Diospyros, Hardwickia, Holarrhena and Terminalia species. The forests are stratified in three layers (Mishra 1989, Sagar et al 2003).
(VI) Tropical thorn forests: These forests are also known as xeric forests due to occurrence of very less rainfall which lies in a range of 200-800mm. The dry season is very long.
Maharashtra. Andhra Pradesh, Karnataka, Tamil Nadu, Madhya Pradesh, Uttar Pradesh, Rajasthan, Gujrat and Punjab are common areas for the occurrence of these forests (Table 1 and Figure 2). Deciduous with low thorny or dry deciduous scrub species of Acacia, Balanites, Euphorbia, Prosopis, Salvadora and Zizyphus predominate in such forests (Mishra 1989 and Singh et al 2014). The stratification is very poor.
(VII) Tropical dry evergreen forests: Occurrence of rainfall in these forests lies between 870 and 1200mm (Table 1). They are found on the eastern coast of Chennai (Figure 2).
Trees are mainly hard- leaved evergreen type having nearly 20m height dominated by Drypetes, Manilkara, Memecylon and Mimusops species. Stocking density is often very high.
(VIII) Sub-tropical broad-leaved hill forests: The vegetation is composed of mainly broad- leaved and evergreen with high forest trees. Such forests are usually seen on western and central Himalayas and on the hills of south India (Table 1 and Figure 2). In southern
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
India the Calolphyllum and Rhododendron species predominate while in eastern Himalayas Quercus predominate (Singh et al 2014). The tree height has been reported upto 35 m (Mishra 1989).
(IX) Sub-tropical pine forests: These forests mainly occur on hills and largely Pine forests extend in the western and central Himalayas between 1000 to 2000m (Figure 2).
Interestingly, Pinus roxburghii predominate in western Himalayas and Pinus kesiya in eastern Himalaya (Singh et al 2014). The forests are predominated by species of Pinus and Quercus. At moist zones of Garhwal region; Shorea-Anogeissus-Pinus association is apparent.
(X) Sub-tropical dry evergreen forests: They are low xerophytic, scrubs and open forests dominated by Acacia, Olea, Dodenea and many hardwood species. These forests are found on the hills of Shiwalik, Western Himalaya mainly Jammu and Punjab region (Table 1 and Figure 2).
(XI) Montane wet temperate forests: They are broad- leaved and closed evergreen forests without conifers. The development of buttress does not occur. Lianas and epiphytes are fewer with thinner stems of lianas. Lichens and mosses are abundant (Mishra 1989).
There is predominance of shoal forests with Terminalia, Ilex and Rhododendron species in southern India, while Quercus forests with Acer, Machilus and Rhododendro species predominate in eastern Himalaya (Singh et al 2014). The detailed distribution of these forests with major species and climatic conditions of these forests are indicated in (Table 1).
(XII) Himalayan moist te mperate forests: Also, they are broad- leaved evergreen forests with oakes and conifers. In general, these forests occur all along Himalaya at 1500- 3300m altitude in the regions of Jammu & Kashmir, Punjab, Himanchal Pradesh, uttrakhand, West Bengal, Assam and Eastern Himalayas (Figure 2). The tree heights are up to 50m. The main species are Abies, Cedrus, Picea, Tsuga (conifers), Acer, Quercus, Rhododendron and Ulmus (oakes). The species composition differs due to differences in altitudes and between western and eastern Himalayas. These forests experience tremendous anthropogenic pressure which could be due to occurrence of our hill stations in these regions.
(XIII) Himalayan dry temperate forests: Basically, they are the open forests with trees having 50 m heights. These forests are found along inner valleys of Himalayas (Figure 2) experiencing less than 1000mm rainfall. Predominance trees are coniferous species (Juniperous, Picea and Pinus).
(XIV) Sub-Alpine forests: These forests occur in the regions of Jammu & Kashmir, Punjab, Himanchal Pradesh, Uttrakhand, West Bengal and North East (Table 1 and Figure 2) at altitude of 2900-3500m. Temperature and precipitation in these forests are very poor (mean annual temperature 2 °C and precipitation 83-600mm). There is dominance of Abies, Betula and Rhododendron species (Singh et al 2014).
(XV) Moist –Alpine Scrub: They occur throughout the Himalaya, above timberline to 5500m altitude, particularly in the regions of Kashmir, Uttrakhand, Sikkim, Manipur, Western and Eastern Himalayas (Figure 2). The dominant genera are Betula, Juniperus, Rhododendron and Sorbus.
(XVI) Dry-Alpine forests: The forests are alpine xerophytic, occur in very low rainfall (370mm) areas at up to 5500m altitude in the regions of Himanchal Pradesh, Kashmir and Uttrakhand. Juniperous, Eurotia and Salix are dominant.
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
All of the above forests types are experiencing unpredictable anthropogenic activities, among them the dry deciduous forests are most threatened, hence the situation is more alarming for such grasslands. Because of high anthropogenic pressures in the past several decades, the dry deciduous forest cover is being converted into dry deciduous scrub, dry savanna and dry grasslands which are progressively species poor (Sagar and Singh 2005).
Figure 2. Major Forests types of India (Champion and Seth 2005) 3. Grasslands
Similar to forests, it is tough to define grassland, however it may be defined as natural vegetation dominated by native or natural and perennial grasses and other forbs species (Allen et al. 2011) suitable for forage production, there may or may not be trees, if trees are, then it should not be beyond more than three trees per hectare or 10% tree cover (FAO 2010). Natural grasslands are formed in areas having erratic and low annual precipitation just suitable for the growth of grasses.
Such low precipitation and occurrence of fire do not support the tree growth. The annual precipitation between 250 and 800 mm in temperate zone and upto 1500 mm in tropical zone support the luxuriant growth of grasslands (Mishra 1989). Further, the thin soil and dry cond ition of grassland restrict the tree survival (Rao et al 2012). Globally, the grasslands or grassland type
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
vegetations cover approximately 40% of Earth’s land area (Gibson 2009) and occupy nearly 24% of total vegetation cover (S hantz 1954), provides basic human needs (viz; food, fodder, medicines and thatching materials), supports maximum numbers of large herbivores and have high levels of productivity and utilization of energy (Kidder & Gierlowski-Kordesch 2005, Sage 2004). The Poaceae being a dominant family of grassland is the fourth largest family of the flowering plants. It includes around 11,000 species distributed in 700 genera (Chen et al. 2006). As for as Indian grassland is concerned, has highest genetic diversity of native grasses and legumes.
In India, grasslands occupy about 18% of the total land area and they are very heterogeneous in their distribution due to variability in climatic condition, soil and disturbance regimes. The grasses have greater tolerance to extremes of climate (greater arid ity, greater cold and wetter places than the trees. Further, the ecotypic differentiation and phenotypic plasticity facilitate many grasses to survive under extreme environments (Mishra 1989). The ecological status of Indian grasslands is debatable due to climax vegetation view point which would be either forests or desert vegetation.
Grasslands are existing because of biotic interferences (lopping, burning shifting cultivation and grazing of forests for the last several thousand years. Long-term agricultural practices converted majority of grasslands into agroclimax. In India, it is very painful to find virgin grassland (Mishra 1989). The Indian tropical grasslands are frequently known to as savanna (grasslands with scattered trees). Champion and Seth (1968) recognized three types of grasslands in India. Indian Council of Agricultural Research conducted grassland surveys during 1954 and 1962; accordingly categorized the Indian grasslands into five major types as illustrated in Table 2 (Dabadghao & Shankarnarayan 1973). Based on the floral characteristics, Whyte (1957) classified Indian grasslands into eight types. These grasslands are briefly described below and well indicated in Figure 3:
1. Schima-Dichanthium Type of grasslands generally grows on black soils. The major localities for its occurrence are western Hydrabad, Bombay, Madhya Pradesh, Bhopal, Southern-Eastern Uttar Pradesh, western Andhra Pradesh, Mysore, and Chennai.
Dichanthium annulatum, Chrysopogon fulvus, Themeda triandra and Sehimia sps. are the dominant species.
2. Dichantium-Cenchrus grassland well grows in sandy loam soils. Distribution localities are plains of Panjab, Delhi,Rajsthan, eastern Uttar Pradesh, Saurashtra, Kutch, northern Gujrat, Bengal, Bihar, Orissa, Northern Andhra Pradesh, eastern Hydrabad, Travancore-Cochin, western coast of Bombay and eastern Chennai., Cenchrus ciliaris, Dichanthium annulatum, Digitaria eriantha, Evolvulus sps, Leucaena leucocephala are the common species.
3. Phragmites-Saccharum dominates in marshy locations and occurs in tarai areas of Uttar Pradesh, Bihar, Bengal and Assam, swamps of Sunderban, Kaveri delta of Chennai. The common species are Arundo donax, Phragmitis karka, Saccharum spontaneum, Imperata cylindrical Desmostachya bipinnata.
4. Bothriochloa grasslands predominate in paddy tract and high rain- fall belt of Lonavala tract of Bombay. Bothriochloa odorata and Bothriochloa pertusa are the main species.
5. Cymbopogon grasslands mostly establish in low hilly areas of Western Ghats, Vindhya, Satpura, Aravali and Orrissa up to 1000m height. The major species are Cymbopogon coloratus, Heteropogon contortus and Crysopogon fulvus.
6. Arundinella grasslands are frequently occur at mountains, for example; high hills of Western Ghats, Nilgiris, lower Himalayan region in east Panjab, Himanchal Pradesh, Uttrakhand, Bihar, Bengal and Assam up to 2000 m height. Other species are Hetropogon sps., Themeda anathera and Chrysopogon aciculate.
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
7. Deyeuxia-Arundinella type is mix temperate climate grassland found in upper Himalayan region in eastern Panjab, Himanchal Pradesh, Jammu and Kashmir Uttrakhand, Bengal and Assam. There are many species of Brachypodium, Bromus and Festuca as co-dominant species at local sites.
8. Deschampsia- Deyeuxia type is a temperate alpine climate grassland grows in alpine and sub-alpine regions of the main Himalayas (Kashmir), eastern Panjab, Himanchal Pradesh, Uttrakhand, Bengal, Assam over 2000m height. Otherthan Deschampsia and Deyeuxia, the Festuca, Glyceria, Poa and Stipa are frequently occurring genera.
Figure 3. Distribution of major grasslands in India (Source: Whyte 1957).
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Table 2. Area coverage, elevation and distribution of major grasslands of India as suggested by Indian Council of Agricultural Research during the survey period from 1954 to 1962 (Dibadgho and Shankaranarayan 1973).
Compared to forests the situation of Indian grasslands is very horrible due to severe biotic pressure.
For an example; the number of grazing animals in arid and semi arid locations has been found to be 2-10 times greater than the capacity of the grassland to feed the animals (Singh et al. 2006). Other than global climate change (nutrient deposition, rising level of CO2, habitat fragmentation, invasion, over exploitation and increased level of pollution), due to high anthropogenic activities in the past decades, the grasslands of India are being progressively converted into the agricultural lands and many of them are in habitats, which are marginal for plant growth; that is, they are experiencing very poor species diversity (Champion and Seth 1968; Mishra 1989, Sagar and Verma 2010).
4. Aquatic ecosystems
It is amazing that only 3% of total water on earth is represented as fresh water and remaining 97%
is saltwater. Further, it is interesting that river and lakes cumulatively contain only 1% of the total freshwater and rest 99 % is present in form of frozen ice glacier and groundwater. Aquatic ecosystems are the most valued life-sustaining water resources. Throughout the world, they are the most productive and potential source of carbon sequestration (Panigrahy et al 2012). The strength of wetlands distributed in different states/union territories of India are presented in Figure 4. This indicated that the Gujrat has highest wetland coverage while the least coverage is represented by the Chandigarh. For our convenience the fresh water ecosystems have been divided into two major categories: (I) standing water or lentic ecosystem (viz: lakes and ponds) (II) flowing water or lotic ecosystems (river streams and springs). Irrespective of fresh and marine water on the land surface is designated as wetlands.
(A). Lentic (Lakes and ponds) ecosystem
The term ‘lentic’ (to make calm) is used for stagnant waters. Lakes and ponds are excellent examples of lentic ecosystem. Basically ponds and lakes have three distinct zones: the littoral, limnetic and profundal zones. The littoral zone is a shallow area adjacent to edge or shoreline of pond or lake. In the littoral zone, light reaches upto the bottom of the ponds and supports the rooted plant. Limnetic zone is the open water after the littoral zone. In this zone, light intensity supports
Parameters Schima- Dichanthium
Dichanthium- Cenchrus- Lasiurus
Phragmites- Sccachrum- Imperata
Themeda- Arundinaria
Temperate and alpine
Area coverage (Km2)
17,40,000 436,000 2,800,000 230,000 -
Elevation (m) 300-1200 150-300 300-500 350-1200 ˃2100
Distribution Central Indian plateau
Northern parts of Delhi
Gangetic plains
Jammu &
Kashmir
Cold deserts (areas of Himanchal Pradesh)
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
only phytoplankton (free floating microscopic algae and animal). Just below the limnetic zone; the deepest zone, found in larger lakes is the Profundal zone. The smaller lakes and ponds experience the absence of the profundal zone. As it is the deepest zone, and light does not reach up to this zone, therefore, only heterotrophs survive at this zone. Here, the available organic materials are decomposed by the anaerobic bacteria; as a result, the profundal zone is rich in minerals.
Figure 4. Wetland area covered by different states/union territories in India (Data source:
Panigrahy et. al. 2012).
Pond
Indian ponds are relatively small and shallow bodies of stored water with limited wind action. They may be called perennial if they retain water throughout the year or temporary/seasonal, if they do so seasonality. The vertical (50 cm to 250 cm in depth) and horizontal (0.02 ha to over 2.5 ha water surface area) sizes of ponds vary significantly. Contrasting to shallow or seasonal ponds, the bottom of the perennial ponds is devoid of sunlight and hence the ecosystems of such ponds are reasonably distinct from those of shallow or seasonal ponds. In general, the source of water for such pond is only heavy rainfall during the rainy season. As a result of ceasing of monsoon, the water level begins to decrease slowly; therefore, lack of water is very common at the time of pre- monsoon due to evaporation, seepage as well as transpiration by aquatic macrophytes and others present along the
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
sides of pond. Prevalence of thick sediment is characteristic of such ponds. In general, the pH varies in a range of 7.0–9.0, hence, alkaline in nature. The rate of photosynthesis is low due to presence of high turbidity in water owing to stirring of fishes at bottom. Moreover, the reduced dissolve oxygen at this surface reduces the population of plankton and fishes.
The flora and fauna of the ponds are phytoplankton of Myxophyceae, Chlorophyceae, Euglenophyceae along with Bacillariophyceae, aquatic macrophytes of flowering plants, ferns and macroscopic algae and zooplankton consisting of copepods, cladocerans and rotifers populations.
Ponds support diverse group of aquatic insects (water strider, water bug, mosquito larvae, and flies including the dragon fly. Ponds support fis hes, amphibian and birds (top consumer). Taking an example of Gujrat pond, pied Kingfisher (Ceryle rudis) feed on insects and fishes. Grey heron (Ardea cinerea) eats fishes, amphibians, insects, spiders, crabs, rodents, hatching turtles and small birds. The food-web of a typical pond ecosystem is presented in Figure 5.
Figure 5. Food web of a typical pond ecosystem.
Lake
An inland depression on the earth’s surface having depth ranging from few meters to approximately 150 m with standing water is defined as Lake (Vernberg & Vernberg 1970). It is entirely different
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
from the sea. Lake is deepest than the pond. It produces a barren wave swept shore nearby its periphery (Welch, 1952). Approximate numbers of lakes in various states and union territories of India are presented in Table. Majority of Indian lakes have been identified as Ramasar sites under Ramsar Conventionon due to its national and international importance. The Loktak Lake (‘lok’ = stream and ‘tak’ = the end), is a largest fresh water lake situated in Manipur of northeastern (NE) India. The Nambol, Nambul and Thongjarol rivers are the inlets of this Lake. This lake has many floating islands which support diverse mass of vegetation, soil and organic matter known as phumids. The Lokatak name has been derived from floating phumids (floating lake). It is the rare and single floating lake in the world.
Table 3. List of major lakes distributed in each states/ union territories of India. *Ramsar sites (threatened wetlands dedicated for conservation and sustainable utilization). **It is a brackish and the largest coastal lagoon of India as well as the second largest lagoon of the World.
States Number of lakes Major lakes
Andhra Pradesh 4 Pulicat lake
Assam 4 Deepor Beel*
Bihar 2 Kanwar lake
Chattishgarh 11 Dalpat Sagar
Gujrat 15 Thol lake
Haryana 9 Badkhal lake
Himanchal Pradesh 17 Maharana Pratap Sagar
Jammu & Kashmir 7 Pangong Tso, Wular* and Dal lakes
Jharkhand 10 Tilaiya Dam
Karnataka 12 Belandu lake
Kerala 8 Punnamada lake
Madhya Pradesh 4 Upper lake, Bhoj wetland*
Maharashtra 9 Shivajisagar lake
Manipur 1 Loktak lake*
Meghalaya 1 Umiam lake
Mizorum 2 Palak Dil lake
Odisha 3 Chilka lake**
Panjab 3 Kanji wetland*
Rajsthan 17 Rajsamand lake, Pushkar lake
Sikkim 4 Khecheopalri lake
Tamil Nadu 8 Ooty lake
Telangana 8 Osman Sagar, Durgam cheruvu (Secret lake)
Uttar Pradesh 9 Govind Vallabh Pant Sagar (largest man- made
lake), Belasagarlake, Surha Tal, Ramgarh Tal
Uttrakhand 5 Bhim Tal (Largest natural lake)
West Bengal 3 East Calcutta wetland (natural and man made)*
(B) Lotic ecosystem River
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Rivers and Streams are excellent examples of lotic (running) fresh water ecosystem. India is endowed with a total of 72 river basins covering nearly 45,000 km long riverine systems. Rivers are the collection of streams, deeper, longer and larger than the streams. The nature of lotic water ecosystem significantly differs between its source (origin) and its mouth (where it empties into another body of water). Many of the perennial rivers originate in springs and others from melting glaciers. The rivers have cool water and fast currents as reaches away from its origin. Lotic ecosystems exchange nutrients and energy at larger areas, compared to lentic ecosystems. These attributes are prevalent in river than the stream. Presence of currents and absence of thermal stratification in lotic ecosystems discriminate them from lentic ecosystem. The organisms of lotic water ecosystems vary largely from one lotic ecosystem to another due to differences in the strength of the currents. Headwater streams (smaller streams and sources of a rivers) are typically shallow, cool, rapidly flowing, and oxygen rich compared to down streams because down streams are wider, deeper, cloudy (contain suspended particulates), not as cool, slower flowing, and less oxygenated.
These conditions differentiate the species composition between rivers and streams as well as between headstreams and downstreams. For example; in slow current and deeper water areas, sand and silt deposition takes place on the bottom of the lotic ecosystems. In such zone; burrowing animals, rooter plants and swimming organisms flourish and survive, however, plankton occurs only in those zones where water is deep and the current is gentle.
River Ganga
The Ganga rises in the Gangotri glacier in the Himalayas at an elevation of about 7,010 m in the Uttarkashi district of Uttarakhand. The Ganga river basin is the largest of river of India. The total length of river is 2,525 km. The drainage area lying in India is 861404 sq. km which is nearly 26.2% of the total geographical area of the country, supports 43% of its human population as per 2001 census (MOEF 2009).
Many Indian rivers are experiencing serious threats to their degradation and The Ganga is one of them. Currently, the ecological flow (minimum flow of water in rivers and streams required for maintaining the ecology of aquatic ecosystems) of our Ganga river is disappointing. Politicians and Scientists have been advocating for Aviral Ganga’ (continuous Ganga) for more than the decades and since then approximately Rs 6,300-crore have been expended on the rejuvenation of River Ganga.
In Ganga River; Diatoms, green algae, blue-green algae and members of xanthophyceae predominate. Among the animals; the me mbers of Protozoans, Copepods, Rotifers, Cladocerans, Molluscs, Crustaceans, Insecta, Amphebians and fishes are common. Among the fishes; planktophagus, omnivorous, and strictly carnivorous are frequent. The turtles of the Ganga River are scavengers. Therefore, Gaga River is a unique aquatic ecosystem with simple to complex food chains (Figure 6) and food webs which vary from its origin to the end (Nautiyal 2010).
Gangetic dolphin (Platanista gangetica) and crocodiles (Gavialis gangeticus, Crocodilus palustris) are endangered species declared by IUCN. Their population is declining due to pollution overloading, overexploitation of resources, cause habitat fragmentation and reduction in its size limiting the gene flow (Srivastava 2009).
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Figure 6. A simple food chain of Ganga River.
Estuary
A water body where sea water (marine) and river water (fresh) meet and mix is appropriately known to Estuary. Due to mixing of fresh and marine water the estuaries have planktonic as well as detritus food webs. The amalgamation of fresh water and saline water is characterized as brackish water. When the rivers arrive at the sea, they drop their sediments in the quiet water of sea. The accumulation of sediments at the upper reaches of the mouth of sea results in delta (Smith 1996).
Water levels in an estuary rise and fall with the tides, whereas salinity fluctuates with tidal cycles, the times of years, and precipitation. Thus, tides determine the water level in estuary while, salinity is determined by the amount of river water and tides. These attributes regulate the structure and species composition of the Estuaries. Estuarine organisms are adapted to the daily, seasonal, and annual variation in temperature, salinity, and depth of light penetration. Estuaries are among the most fertile ecosystems in the world, often having a much greater productivity than either of the adjacent ocean (marine ecosystem) or the fresh water ecosystem. These are the good sources of marine fishes and approx 80 % commercial marine fishes are obtained by them (Singh et al 2014).
Mandovi estuary on the west coast of India in the state of Goa is better studied estuary of the country. During monsoon season, the river run-off is higher (~258 m3/s, measured at the head) than the post- and pre- monsoons (~6 m3/s). The tidal distance during the spring and tides are ~2.3 and 1.5 m, respectively (Vijith et al., 2009). Phytoplankton counts are generally higher in dry season than in wet season at the end of the monsoon. Actinocyclu., Dinophysis, Melosira, Navicula, Nitzschia. Peridinium and Rhizosolenia are common phytoplankton genera of Mandovi estuary.
Crustaceans, copepods and protozoa are dominant organisms. Diversity and biomass of
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Zooplanktons are lower in wet season and higher in dry season. For the survival of marine organisms of the Mandovi estuary; the presence of Mangrove forests at the bank of sanctuary acts as a protective measure. Interestingly, there are marine organisms (penaeid prawns) that often spend their partial life cycle in estuaries. They lay eggs in the open sea and their larvae migrate to an estuary to spend post larval stage and then the juveniles migrate to offshore (Fernandes et al., 2011).
Marine ecosystem Ocean
Globally; oceans cover approximately 70% of earth’s surface and characterized by saline (almost 3·5 % salts of the ocean water) and alkaline (pH 8·2) water. Similar to Lakes Ocean also shows vertical and horizontal stratification. Holistically, ocean is divided into two major regions ; (1) Pelagic region (whole water body) and (2) benthic region (bottom of the Ocean). Ggraphically, Ocean’s zones are presented in Figure 7 and for better understanding the vertical and horizontal strata of the ocean are shown in Figure 8.
Vertically, the pelagic region is divided into three strata:
(i) Photic zone (from the surface of ocean to nearly 200 m deep within the ocean) experiencing distinct gradients of light, temperature and salinity.
(ii) Mesopelagic zone (from 200m to 1000m deep); in this layer light penetration is very little and less temperature gradient, hence, less seasonal variation. It has very less oxyge n concentration but maximum nitrate and phosphate concentrations. Just below the photic zone; the heterotrophic organisms depend for their food on settling down organic debris from the upper layer. These heterotrophic organisms are predators, scavenger or filter feeder.
(iii) Bathypelagic zone (just beneath the mesopelagic layer) have varied depth due to global variation in location. This layer rages from 100 to 700m and 2000 to 4000m. This region is characterized by high darkness (except for bioluminance fishes), low temperature and high preassure.
Horizontally, the pelagic region is categorized into:
(i) Neretic province (shallow water zone) experiencing water lying over the continental shelf (“area of relatively shallow sea surrounding continent and lying on the edge of the continental plate”, Ricklefs and Miller 2000).
(ii) Ocean province (deep ocean zone). Open ocean harbor less organisms than the neritic zone due to light and nutrients scarcity. Only surface zone receives adequate sunlight which supports the growth of algae. Microscopic algae are the basic food source of zooplanktons which are further eaten by other organisms.
(iii) Abyssal pelagic or benthipelagic province (lies over the major plains of the ocean down to about 6000m.
The ocean bottom is known as benthic region. It is divided into four distinct zones having differences in the bottom life.
(i) Sublittoral or shelf zone; just lying below the neretic pelazic zone and above to the continental shelf. The margin of the ocean or the intertidal zone is recognized as littoral.
The tides on the coast are produced due to pulling of gravitational forces between sun and moon. Generally, the littoral is submerged and exposed by oceanic water due to the actions of waves and tides. The littoral organisms are well adopted to prevent themselves from tide and drying condition during low tide. Due to constant motion of surface layer, the sandy
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
coasts are highly unstable. Among the animals; hermit crab, nematodes, copepods and turbellarians are dominant while, sea lettuce as a free floating plant dominate. The rocks provide surface to plants and animals for anchorage. The burrows of the rocks provide shelter to hide some animals during low tide. The plants like; rockweed (many species of Fucus), and animals like; mussel and brancles are attached with the rocks.
(ii) Bathyal zone (covers the continental shelves and down to 4000m).
(iii) Abyssal zone (occupies the broad ocean plains below to 6000m. The abyssal plain of the oceans has undulating topography and exhibits high species diversity.
(iv) Hadal zone (bentic zone of oceanic trenches between 6000 and 10000m). It is the deepest places on earth plunge to as deep as 11,000 meters below the surface of the sea.
The water depth, distance from shore and drainage of river/ glacier into the ocean determine structure and function of the ocean ecosystem.
Figure 7. Graphical representation of Ocean zones
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Figure 8. Vertical and horizontal stratifications of ocean indicating different zones (Smith 1996) Mangroves
Mangrove is word used for a group of halophytic plant species or plant communities dominated by salt tolerant plant species (Smith 1996, Singh et al 2014). Such ecosystems occur in intertidal zones of sheltered shores, estuaries, creeks, lagoons, marshes and mud–flats along the coastlines.
Mangroves are formed due to absence of wave actions along the coasts. The mangrove swamp is also known by Mangal. Mangroves receive rainfall between 1000 to 3000 mm and temperature between 26 and 35 °C. They exhibit morphological, anatomical and physiological adaptations to cope with hostile environment. The soils of such ecosystems are water logged with high. Few of the common adaptations shown by the plants are presence of shallow, broadly spreading roots, buttress or prop roots arising from the trunk and braches, and few species show the pneumatophores and vivipary. Globally, 65 species of mangrove have been reported.
In India mangroves are found along the islands, major deltas, estuaries and backwaters of the east coasts (along the oceanic island groups of the Andaman and Nicobar). Mangroves occupy 4,628 sq km area of India or 0.14 % of the total geographical area of the country. Sunderbans and Mahanadi, Krishna and Godavari mangroves of Andhra Pradesh, and Muthupet and Pichavaram mangroves of Tamil Nadu, Gulf of Kutch and Khambat mangroves of Gujarat and Andaman and Nicobar Island mangroves are in India (Selvam 2003). The Sundarbans in West Bengal covers nearly half of
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
the total area under mangroves. The crabs make their home in muddy bottoms of mangrove forests. Another example of mangrove is Mandovi mangrove harboring Rhizophora mucronata, Bruguiera gymnorrhiza, Avicennia officinalis, and Acanthus illicifolius species. The mangroves provide the livelihood, immense ecological services to human well beings. Mangrove ecosystems, nevertheless detritus based, are reasonably high in primary production.
Mangrove forests primarily act as spawning, breeding and nursery for fishes, crabs, prawns, mollusks near shore. They function as “coastal stabilizers” and “shelter belt areas”. These structures protect the coasts and other areas from erosions and cyclonic destructions (Selvam 2003). The Indian mangroves are homes of many endangered species of crocodiles, snakes, tigers and birds (Singh et al 2014). Biotic pressures and natural calamities are threatening the species as well as ecosystems of mangroves, hence conservation and management of mangroves is needed for human as well as ecological well beings.
Sunderbans
The Sunderbans is one of the longest mangrove forests of the world. It is situated in the delta of Gnages–Bhramputra and Megna rivers, covering an area of nearly 16000km2. Interestingly, 60% of this is in Bangladesh and only 40% in India. It experiences a warm humid climate and annual rainfall between 1600 and 1800 mm. The rainfall is received from June to October during the south- west monsoon. The fresh water to the Sunderban is supplied by the Ganges and Brahmaputra throughout the year (Selvam 2003) that is why the salinity of the Sunderban is lower than the sea water (Singh et al 2014). Because of mild slope of the coast along with large tidal amplitude, the tidal water reaches up to 110 km inland. Due to this, the tidal mud flats facilitate the suitable platform for colonization of the mangrove plants and due course of time achieve a dense, tall and climax mangrove plant community.
The Sundarbans delta is rich in flora and fauna. It is home of large numbers of invertebrates, insects, fishes, mollusks, crustaceans, monkeys, and reptiles (Gopal and Chauhan 2006) and is the only habitat for the endangered Royal Bengal Tiger. Local peoples are dependent for their livelihood on this mangrove only. The Sunderban National Reserve has been included in world heritage site because of it’s alarmingly depletion. It is highly affected by rise in sea level due to global warming; many of the smaller islands of the region have already been submerged (Singh et al 2014).
Seagrasses
Plants completely submerged in salty water of the ocean are known as sea grasses. These plants only occur in shallow water up to a depth of 10m or up to a certain water depth receiving enough light for their efficient photosynthesis (Raven et al 2012). Luxuriant growth of sea grasses occur in waters of subtropical and tropical regions having calm temperature. The flat and rocky coastal wetlands that progressively slope towards the sea are suitable habitat for the growth of seaweed.
Seagrass communities are found along the eastern and western coasts of India as well as Andaman and Nicobar Islands. Seagrasses form a thick meadow on sandy and coral debris at the water bottoms and occasionally in the crevices of under water. The patchy areas of seagrasses provide more resources to fishes, crabs and starfish than the continuous area. Sea urchins severely change the above ground biomass of seagrass, thus the structure of individual seagrass plant and the seagrass density declines. Consequently, the sea urchins face the problem of their vulnerability to predation (Ricklefs and Miller 2000).
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Coral reef ecosystem
Coral reefs are formed in subtropical and tropical sea waters of shallow depth (approximately up to 25m depth) as a biological origin rather than geological origin. Carbonate secreting organisms (basically coral which is a small coelenterate) are main sources coral reefs, while corraline red algae, foraminifera and mollusks also contribute in the formation of coral reefs (Smith 1996, Pinet 2009, Singh et al 2014). This calcium carbonate secreted from the organisms harde ns around coral and joins it to the reef. The stable water provided by shallow continental shelves and submersed volcanoes acts as a strong foundation upon which the coral reefs are formed. The coral reefs are complex ecosystem having direct relationship between coral organisms and algae. The animal creates a colonial structure fixed in a skeleton of calcium carbonate or mass of it. Symbiotic algae zooxanthellae lie within the coral cells. Interestingly, only the external portion of reefs are alive and envelop it as skin subsequent to the death of organisms and their hard portions are added to reef structure (Pinet 2009).
Coral feefs are diversity rich ecosystem than any other ecosystem in the sea. Estimates suggested that around 3,000 species are known from a single reef of south east Asia and more than 1,000 species from a single Caribbean reef. Nevertheless, global estimate for the total coral reef number is yet unknown. Compared to coral reefs only tropical rainforests harbor around 30 million insects and have higher species number. Interestingly, due to presence of large number of fishes, the coral reefs have greater number of vertebrates than rainforest (Venkataram 2007). Light intensity, disturbances from waves, storms and overgrazing of algae by sea urchins determines the species diversity along the gradient of sea depth. Species diversity generally increases up to a depth of 20m and then decreases due to light limitation. Corals are partially photosynthetic and partially heterotrophic. At the day time, the zooxanthellae perform the photosynthesis and directly transfer the fixed energy to the coral tissue. Generally, photosynthetic coral grow well in shallow depth. During night time, coral polyps eat the zooplankton, and transfer the nutrients (basica lly phosphates and nitrates) to anthozoans as well as their symbiotic algae. Hence, the nutrients are recycled between the anthozoans and algae (Smith 1996). The presence of high diversity of organisms (a variety of bacteria, phytoplankton, crustose corraline algae, macroalgae, seagrass and sponges), the productivity of coral reefs is very high, that is why they are the highly productive ecosystem on the earth. The net productivity of coral reefs has been estimated in a range of 1500-5000g C m-2yr-1 (Smith 1996, Singh et al 2014).
Coral reefs are usually categorized into:
(i) Barrier reefs (Parallel shorelines and are separated from land by lagoon. For example; the Great Barrier Reef of Australia).
(ii) Fringing reefs (around islands or projects directly seaward from the sheshore).
(iii) Atolls (horseshoe – shaped reefs surrounding a lagoon).
India harbors all types of reef and the total coverage area of coral reefs has been estimated about 2,374.9 sq. km. The Indian reefs are distributed along the east and west coasts. Fringing reefs are in Gulf of Mannar and Palk Bay. Andaman and Nicobar Islands have fringing as well as barrier reefs while, atoll reefs occur in Lakshadweep.
Ecology Examples of few Indian ecosystems Concept of Indian Ecosystems
Globally, around 58% coral reefs have been degraded because of coastal development, overexploitation in addition to marine and land based pollution (Bryant et al., 1998). Therefore, it is seriously needed to protect such most threatened ecosystems by establishing marine reserves by adopting existing International laws (Roberts et al., 2002).
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