Natural Vegetation in Rajasthan :

The state of Rajasthan is endowed with a wealth of a wide range of vegetaion. They can be discussed in two broad categories i.e. into two distinct groups – one comprising the arid vegetaion, falling into western part of the state while the other belonging to semi-arid to sub humid of eastern and southern Rajasthan.

A. Vegetation of Western Zone :

Being largely influenced by edaphic and biotic factors, the western Rajasthan is characterized by sparse vegetation. Vegetation of this arid tract has well adapted to existing arid conditions. The potential vegetation of this region has been modified due to intense biotic factors. The vegetation of western Rajasthan has been grouped under the following categories based on two prominent indices i.e. density and frequency. These have been used to identify the dominant and co-dominant species of vegetation.

1. Calligonum- Haloxylon- Leptadenia Type :  It is represented in the area of large stabilized longitudinal, parabolic and transverse dunes having the lowest rainfall zone (10 to 15cm). Only shrubs an under-shrubs which are well adapted to prevailing conditions are predominant in this tract. This region is represented by psammophytic Scrub Desert Vegetation. Phog is the major dominant shrub on the dunes in Barmer region while it is associated with Haloxylon in Jaisalmer tract.

2. Salvadoran Oleoides- Euphorbia Caducifolia Type :  A distinct habitat of good vegetation along runnels and scanty vegetation in small pockets of soil deposition is represented on the vast rocky plateau of Jaisalmer. Salvadora is the dominant species on this rocky areas with negligible soil cover, here euphorbia caducifilia (Thor) form the main associate. Many other lithophytes forming shrubs colonize the tract.

 3. Zizyphus Nummularia – Capparis Decidua Type : The exposed and buried pediments and gravelly plains of Jaisalmer with poor sandy loam or loamy and soil cover allow highly adapted species to colonize this habitat. Due to the adaptive capability to the adverse desertic conditions Ziziphus and Capparis are present here. In many regions, largely scattered stunted tree species of Prosopis and Acacia etc are prevalent. The limited associated species of the lithophytic Scrub Desert are also present.

4. Suaeda Fruticosa – Salsola Baryosma Type : This type of vegetation is generally present in low lying saline basin and depressional areas, with one percent slope. In western Rajasthan, these are located at Malhar (Jodhpur), Pachpadra, Uterlai, Thob (Barmer) Lawan, Pokhran etc. mostly Suaeda dominates these tracts.

 5. Prosopis – Capparis – Zizyphus Type : The region is dominated by Trees - Prosopis cineraria, Tecomella undulate etc. and Shrubs - Capparis deciduas, Calotropis procera etc. Large part of the flat plains in 25 to 30 cm rainfall zone is dominated by this type which covers the older alluvial plains and buried pediment plains. Due to cultivation the natural vegetation of this zone is highly modified.

 6. Prosopis – Tecomella Type : In the sandy undulating plains and ridges of low dunes with very deep soil profile in the district of Barmer, part of Churu and Sikar exhibit the prevalence of this type. As the farmers themselves conserve these plants so species have their predominance in arable lands also. Trees – Prosopis cineraria, Tecomella undulate, Salvadora oleoides, Balanties aegyptiaca. Shrubs – Calotropis procera, Leptadenia pyrotechnica, Lycium barbarum, Acaica jacquemontii, Clerodendrum phlomoides, Ziziphs nummularia, Mimosa Hamata.

7. Salvadora Oleoides – Prosopis Cineraria – Capparis Deciduas Type : The flat alluvial plains with heavy soils of sandy clay loam to clay, deep to very deep and moderately saline soils of district Pali, Jalore, southern Barmer, north eastern tract of Churu and Jhunjhunu support this type. Soil column and hardness of the pan is very much reflected by the growth of tree species. Trees – Salvadora sleoides, S. perisca, Tamarix articulate, Acacia nilotica, A. leucphloea, Balanites aegyptiaca. Shrubs – Indigofera oblongifolia, Calotropis proceera, Tamarix ereocoides, Cassia auriculata, Capparis deciduas, Zyziphus nummularia.

8. Acaia Nilotica Type : Deep buried pediment plains, flat alluvial plains with deep sandy clay loam soils but non-saline at the foot hills of Aravalli range in district Pali, Ajmer and part of Udaipur can be witnessed with the predominance of these two species. Trees – Acacia nilotica, Acacia cupressiformis, Azadirachta indica, Salvadora oleoides, S. persica, Tamarix articulate, Ziziphus mauritiana, Moringa oleifera, Albizia lebbeck and Ficus supp. Shrubs – Cassia auriculata, Capparis deciduas, Zyzyphus nummularia, Indigofera oblongifolia.

9. Acacia Senegal – Euphorbia Caducifolia Type : The granite and sand stone hills of Rajasthan are generally well vegetated while limestone and rhyolite hills support very poor vegetation. The protected hills in the rainfall zone of 20 to 35 cm support Acacia Senegal as the dominant forest type. Low hills / rocks, generally unprotected support Euphorbia caducifolia scrub. Trees – Acacia Senegal, Maytenus emarginatus, Anogeissus pendula, Moringa concanesis, Wrightia tinctoria. Shrubs – Euphorbia caducifotia, Capparis deciduas, Ziziphus nummularia, Grewia tenax, Cordia gharaf.

B. Vegetation of Eastern Zone :

 The Eastern Zone constitutes the plains, valleys, deeply buried or exposed pediment plains and the Aravalli range. The zone lies in the region which receives rainfall between 50 and 80 cm. The plains lie in the double cropping region and hence the existing vegetation is largely modified due to cultural interferences. Degraded vegetation is present on the rocky wastelands, which is a result of the high biotic impact.

1. Acacia Leucophloea – Prosopis. Cineraria – Acacia Nilotica Type : Acaica leucophloea dominates the shallow to moderately deep, buried and exposed plains whereas A. nilotica is the main species in the plains with deep soil in western part of Jaipur, Tonk, Alwar and Bhilwara district along with Jaisamand and Ajmer and north western Udaipur. Plains show sparse tree density as the region is extensively cultivated. Prominent Trees are – Acacia leucophlea, A. Senegal, A. nilotica, Aegle moremlos, Azadirachta indica Balanites aegyptiaca, Ficus bengalensis, F. religiosa, Propis cineraria Salvadora perisica, S. oleoides, Phonix sylvestris, Pithecellobium dulco Ziziphus mauritina, Mangifera indica, Madhuca indica. Prominent Shrubs are – Acac jacquemontii, Calotropis procera, Mimosa hamata, Capparis deciduas, zeylanica, C. sepiaria, Dichrostachys cinerea, Cassia auriculata, Lanta camera, Zizyphus nummularia.

 2. Acacia Nilotica Type: On the north east, east and south east of the Aravalli range the alluvial plains are largely under double cultivation and dominated by this type of specie. The density of trees is general limited due to cultivation but they exhibit good growth due to good irrigation. Dominate Trees – Acacia nilotica, A. cupressiformis, Azadirachta indica, Mangifra indica, Madhuca indica, Phoneix sylvestris, Ziziphus maauritiana, Ailantl excels, Ficus bengalensis, F. religiosa, Pithecellobium dulce, leucopholea, Cordia Environmental Background of Rajasthan 100 dichotoma, Prosopis cineraria. Dominant Shrubs – Zizyp nummularia, Capparis deciduas, C. zeylanica, Ficus palmate, Kirgan reticulate and Lantana camara.

3. Acacia Nilotica – Capparis Decidua Type: This vegetation type is present at dissected ravine terrain along the Chambal Valley covering Dholpur, Sawai Madhopur and Kota districts. This dissected upland has dry situation where as at all lower level, the flat land experiences fast flow of water.

 4. Butea Monosperma – Madhuca Indica – Ziziphus Mauritian Type : Banswara, Dungarpur, South Chittorgarh and Udaipur districts with undulating pediment plains and rocky valleys exhibit this type of vegetation. Here Madhuca indica and Zizphus maruitianna occur in place with deep soil deposition but Butea monosperma (Dhak) dominates the terrain. Dominant Shrubs are – Nyctanthes arbor-tristis, Holerrhena pubescens, Euphorbia neriifalia, E. vinulia, Dendrocalamus, Cassia auriculata, Dichrostachys cinera.

5. Tectona Grandis Type :This tract is largely dominated by tectona grandis (Teak) and its main associated species - Bosellia serrata and dalbargia latifoila. It is present in the hilly areas of south - eastern part of Udaipur, southern Chittorgarh and Banswara district. The regions with gentle slope mostly exhibit a good density of trees and shrubs species. Vegetation type changes with change in slope zones. On the Higher slopesBauhinia racemosa, Boswellia serrata, Emblica officinalis; Middle slopes- adina cordifolia, aegle mormelos; and Lower slopes - Holerrhena pulsescens, Euphorbia caducifolia etc. are seen.

6. Mangifera Indica- Syzygium Cumini Type : Some important species of this type distributed in this zone are: Butea monosperma, Anogeissus, Moringa concanensis, Anogeissus latifolia, Magnifera indica, Sterculia urens etc. This type of vegetation is present at Mount Abu and the composition of this vegetation is the reflection of the change in them due to the increase in altitude. The region supports dry deciduous, semi-deciduous and evergreen species of plants.

Vegetation serves several critical functions in the biosphere, at all possible spatial scales vegetation regulates the flow of numerous biogeochemical cycles, most critically those of water, carbon, and nitrogen; it is also of great importance in local and global energy balances.Such cycles are important not only for global patterns of vegetation but also for those of climate. Rajasthan has huge land of dry patches so need to conserve and increase the natural vegetation with efforts from both the community and government.