indian savannas
DESCRIPTION
Indian Savannas. A.S. Raghubanshi Banaras Hindu University. Indian Savanna/Grasslands. About 400 grass species, 139 endemic Pastoral nomadism- 200 tribes (6% of India’s total population) Grasses- multiuse species (fuel, fodder, thatching material, craft, rope, medicine, essential oils, etc) - PowerPoint PPT PresentationTRANSCRIPT
Indian Savannas
A.S. RaghubanshiBanaras Hindu University
Indian Savanna/Grasslands
• About 400 grass species, 139 endemic• Pastoral nomadism- 200 tribes (6% of India’s total
population)• Grasses- multiuse species (fuel, fodder, thatching
material, craft, rope, medicine, essential oils, etc)• Habitat for wildlife- insects, reptiles, amphibians,
birds (e.g. Lesser Florican), large mammals, wild cats, blackbuck, barasingha, chinkara, wild ass, etc.
Origin• Savannas of the Indian sub-continent are derived
primarily from woodlands through the action of humans (Singh, 1976; Singh e t al., 1983; Gadgil and Meher-Homji, 1985)
• Originated predominantly from woodland ecosystems through deforestation, shifting cultivation, and burning
• Without human disturbance, almost no natural grassland
• Maintained at a subclimax stage by repeated burning & grazing
Distribution & Types
• 8°N-30°N• Savanna types:
1. Sehima-Dichanthium2. Dichanthium-Cenchrus-Lasiurus3. Phragmites-Saccharum-Imperata4. Themeda-Arundinella5. Temperate Alpine
Indian Savanna Types(Dabadghao and Sankarnarayan, 1973)
Grassland Type Climatic Zone
Soil Areal extent(million Km2)
Distribution
Sehima-Dichanthium
Tropical Red, black laterite
1.74 Most of South India, Maharastra, MP, Chhattisgarh, some parts of U.P., Punjab, Gujarat and West Bengal
Dichanthium-Cenchrus-Lesiurus
Sub-tropical, Semi-arid
Alluvial 0.436 North Gujarat, Rajasthan excluding Arawalis, western UP, Delhi, Haryana, Punjab, parts of Jammu
Phragmites-Saccharum-Imperata
Humid, per-humid
various 2.8 Upper UP, NEH, Assam, West Bengal, North Bihar
Themeda-Arundinella
Sub-tropical
Forest hill soils
0.26 NEH, Himanchal Pradesh, J&K, Assam
Temperate-Alpine Temperate, Alpine
- - Himalayan Hill Ranges
Lasiurus sindicus (Sewan) found in western Rajasthan- wonder grass-very high protein content
Sehima-Dichanthium Type• Distribution: Tropical peninsular India, central Indian Plateau, Chhota
Nagpur Plateau, Arawali ranges• Topography: undulating to hilly• Rainfall: 300-6350mm• Maximum cover: 87%
Sehima-Dichanthium Type
• Grasses: Aristida setacea, Borthriochloa pertusa, Dichanthium annulatum, D. caricosum, Sehima nervosum
• Shrubs: Carissa auriculata, Mimosa rubicaulis, Ziziphus nummularia
• Trees: Acacia catechu, A. sandra, Anogessus latifolia, Dalbergia latifolia, Hardwickia binata, Tectona grandis, Terminalia tomentosa
Dichanthium-Cenchrus-Lasiurus• Distribution: subtropical and semi arid regions• Topography: mainly level, occasionally broken by spurs of southern hill
ranges or by sand dunes in Rajasthan• Rainfall: 100-750mm• Maximum cover: 57%
Dichanthium-Cenchrus-Lasiurus• Grasses: Cenchrus ciliaris, C. setigerus, Chrysopogon
monticola, Cynodon dactylon, Dactyloctenium sindicum, Dichanthium annulatum, Eleusine compressa, Lasiurus hirsutus, L. sindicus, Panicum antidotale, Sporobolus marginatus, S. pallidus
• Shrubs: Balanites aegyptica, Calotropis procera, Capparis decidua, Carissa auriculata, C. opaca, Dichrostachys cinerea, Prosopis cineraria, Tamarix dioica, Zizyphus nummularia
• Trees: Acacia catechu, A. leucophloea, A. senegal, Dalbergia sisoo, Prosopis cineraria, Salvadora oleoides
• Dichanthium dominant in protected areas• Cenchrus dominant with moderate grazing
Phragmites-Saccharum-Imperata• Distribution: Gangetic plains, Brahmaputra valley and plains of the Punjab• Topography: level, low lying, ill drained lands• Rainfall: up to 4000mm• Maximum cover: 57%
Phragmites-Saccharum-Imperata• Grasses: Bothriochloa intermedia, Desmostachya
bipinnata, Imperata cylindrica, Phragmites karka, Saccharum arundinaceum, S. bangalense, S. sponteneum, Sporobolus arabicus, S. indicus, Vetiveria zizanioides
• Shrubs: Calotropis gigantea, Clerodendron sp., Dandrocalamus strictus, Lantana camara, Leea indica, Vitex negundo
• Trees: Acacia arabica, Anogeissus latifolia, Butea monosperma, Hydrocarpus laurifolia, Pterocarpus dalbergioides, Tectona grandis, Terminalia procera, Vitex peduncularis
Themeda-Arundinella type• Distribution: northern and north-western montane tract• Topography: mountains ranging from 350-2100 m alt• Rainfall: 1000-2000mm• Maximum cover: 80%
Themeda-Arundinella type• Grasses: Arundinella bengalensis, A. nepalensis,
Bothriochloa intermedia, B. pertusa, Chrysopogon fulvus, C. cerrulatus, Cymbopogon jwarancusa, Eulaliopsis binnata, Heteropogon contortus, Panicum orientale, Themeda anathera
• Shrubs: Berberis lycium, Colebrookia oppositifolia, Daphne oleoides, Desmodium tiliaefolium, Indigofera gerardiana, I. pulchella, Myrsine africana, Prinsepia utilis, Punica granatum, Rhus cotinus, Woodfordia fruticosa
• Trees: Benthamidia capitata, Pinus roxburghii, Pristacia integerrima, Platanus orientalis, Prunus armeniaca, Quercus leucotricchophora, Robinia pseudoacacia
Temperate Alpine Type• Distribution: northern montane tract• Topography: mountains above 1500 and 2100m alt in the east and west,
respectively• Rainfall: 375-3750mm• Maximum cover: 80%
Temperate Alpine Type
• Grasses: Agropyron canaliculatum, Agrostis canina, Calamagrostris epigejos, Chrysopogon gryllus, Dactylis glomerata, Danthonia jacquemontii, Desmostachya bipinnata, Koeleria cristata, Phleum alpinus, Poa pratensis, Stipa sibirica
• Shrubs: Berberis umbellata,Cotoneaster microphylla, Spirarea lindleyana, Viburnum
• Trees: Cedrus deodara, Pinus vallichiana, Quercus leucotrichophora, Rhododendron arboreum
Climate Controls Distribution
• Sehima-Dichanthium – Tropical, dry sub humid
• Dichanthium-Cenchrus-Lasiurus
– Subtropical, semi arid
• Phragmites-Saccharum-Imperata
– Subtropical, moist sub humid
• Themeda-Arundinella– Subtropical, humid montane
Open Forest 28.99 Mha (8.82%)
EarthTrends 2003
Geological Shifts in Forest-Savanna Boundaries
• Palynological studies have shown an increase in the percentage of pollen of savanna species as early as 4000- 3500 BP, remaining almost constant up to the present (Singh et al. 1990; Caratini et al. 1991).
• A recent development of the savanna, linked to a decrease in rainfall.
Geological Shifts in Forest-Savanna Boundaries
• In contrast, Misra (1983) suggested that forests in India are favoured by present climatic conditions
• Pascal (1988) observed that plots protected from fires show increasing woody plant density
• New studies using stable carbon isotope ratio analysis show that change in ecosystem dominance occurred recently (roughly 2000 BP), and that forest has invaded an area occupied previously by a C4 plant community (savanna and cultivated grassland).
Deciduous Forest
Scrub Woodland
Thicket
Pseudosteppe
Scattered Shrubs Discontinuous ThicketShrub Savanna
Tree Savanna
Savanna Woodland
Fire
Tree removal
Furtherdegradation
Overexploitationand over grazing
Overexploitationand over grazing
Exploitation
Furtherexploitationand grazing
Furtherdegradation
Pandey & Singh 1991
Land Use Change
Forest Savanna
Pandey & Singh 1992
Pandey & Singh 1992
Lele & Hegde 1997)
Fine Root Production
• In a tropical forest ecosystem in South India, Sundarapandian & Swamy (1996) reported a similar strongly seasonal pattern in fine-root production, with maximum production occurring during the rainy season and minimum in the dry season.
Fire
• The mean annual canopy and belowground biomass of a Indian dry tropical savanna increases by 40 % and 12%, respectively.
• An increase in mean aboveground net production of 24 % and in belowground net production of 9 %.
• Fire increases the mean concentrations of N and P by 16% and 42% in vegetation and 18% and 17% in soil, respectively.
Effect of BurningSouth Indian Grasslands
NPP 5294-6962 g/m2/yr
Life Forms
• Phanerophytes: 3-10%• Therophytes & Cryptophytes dominate
– Therophytes abundant during rainy season, able to survive through seeds
– Cryptophytes withstand grazing: hidden sub surface position of their perennating buds
• Perennial Species: proportion increases along the gradient of increasing rainfall and grazing protection
Woody plants
• Mostly deciduous or nearly deciduous• The time of leaf fall appears to be related to
water stress• But new leaves emerge during dry phase
itself, much earlier than onset of rainy season
Phenology of Woody Components
The phenological clock of the forest is set during the interphase of winter and summer ensuring full advantage of the short rainy season that follows.
Ombrothermic diagram
fruiting
Flowering
leafing
Leaf-fall Fruit-fall
Solid symbols and curves are for initiation and open symbols and broken curves are for completion of various phenological events.
Sankaran and McNaughton (1999)• In Indian savanna grasslands, resistance to
compositional change was negatively correlated with diversity
• More diverse communities were more stable as measured by resistance to species turnover
• However, no such relationships were observed within communities
• Results are best explained by the ecological history and species characteristics of communities rather than by species diversity in itself
Issues
• Exotic species invasions– Lantana– Parthenium
• Climate Change– C3-C4 balance– Competitive ability
• Defining tree-savanna boundary– PFTs?
• Response to disturbance-PFTs
Current (%) Projected (%) Change (%)Moist savanna 32.52 0.56 -31.97Dry savanna 33.07 4.34 -28.73
Changes in Savanna Biomes under B2 scenario
Relationship of Lantana cover with Different Vegetation Parameters
Lantana cover (%)
0 20 40 60 80 100
Tre
e C
anao
py
cove
r (%
)
0
20
40
60
80
100
0 20 40 60 80 100
Sh
ann
on
H' f
or
Her
bac
eou
s la
yer
0.0
0.2
0.4
0.60.8
1.0
1.21.4
1.6
1.82.0
Lantana cover (%) Lantana cover (%)
0 20 40 60 80 100
Her
b C
ove
r (%
)
0
20
40
60
80
100 y = -0.71x + 83.844R2 = 0.574 P=<0.0001
y = -0.6113x + 71.44
R2 = 0.6991 ; P= 0.0004y = -0.0074x + 1.0603
R2 = 0.4047 : P = <0.0001
Indian Experimental Sites
• Vindhyan Highlands- Biodiversity Park Area, Banaras Hindu University
• Sariska Tiger Reserve- Rajasthan
Soil fertility AridityDry Humid
Eutrophic Ziziphus mauritania(Rhamnaceae)Acacia leucophloea(Mimosoideae)Butea monosperma(Papilionoideae)
Acacia catechu(Mimosoideae)Terminalia tomentosa(Combretaceae)Buchnania lanzan
Dystrophic Acacia nilotica (Mimosoideae)Balanites aegypticea(Balanitaceae)Cordia dichotoma (Boraginaceae)
Anogeissus latifolia(Combretaceae)Hardwickia binata(Caesalpinioideae)Holarrhena antidysenterica(Apocynaceae)
Grass
• Heteropogon contortus (more palatable), Chloris dolichostachya (less unpalatable)
• Questions– Do tree species’ seedlings differ in their ability to
compete with palatable and unpalatable grasses for different resources?
– If there are significant differences in the responsiveness of the tree species, can these be related to plant traits?
Add on Experiment• How tree seedlings grow in response to a number
of different grass species, representing more palatable species that dominate in moderately and undergrazed conditions and less palatable species that replace them in their local environment under heavy grazing?
• Growth response of the different tree species seedlings in competition with palatable and unpalatable grass species at both Indian sites.
• Heteropogon contortus (more palatable), Chloris dolichostachya (less unpalatable)
L1L0
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N0G2
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N1G2
2 m1.6 m1 m1.6 m
1.6 m
1 m
1.6 m
2 m
15.6 m
10.4 m
Block
W1DL0
N0G1
N1G2
N0G2
N1G0
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N0G1
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N1G1
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N1G1
N0G0
1.6 m
1 m
Thanks