The state is located in the bio-geographic zone of 9b-north-east hills and possesses an extremely rich bio-diversity. The local flora and fauna bear a very close affinity and resemblance with floral and faunal components of indo-malayan and indo-chinese sub-regions.

There are 379- species of trees, 320- shrubs, 581- herbs, 165- climbers, 16- climbing shrubs, 35- ferns, 45- epiphytes and 4- parasites. Rare plants of tripura have been put to 18 numbers. There are 266 species of medicinal plants in the state (68- trees, 39- shrubs, 71- herbs and 88- climbers).

There are 90 mammal species in tripura and in the aquatic ecosystem 47 species of fish have been found. As per last census of wild life conducted in 1989, there are 39 numbers of leopard, 182 numbers of elephant and 92 numbers of bison in the state.

Aquatic ecosystems

About 2.22% of geographical area of the state constitute water bodies. Out of the total area of 22,921 ha under water, 20,493 ha makes aqua resource.

The main aqua resources of the state for fish production are ponds, tanks and mini barrages. The unit area of these water bodies is very small. They are rainfed having considerable depth of water for fish culture during monsoon period but remain shallow during winter. Some of these even dries up during summer. As a result, pisciculture in these water bodies is seasonal.

The gumti reservoir was spread over an area of 4,500 ha at the time of creation in 1975-76. The reservoir was the stock of diversified fishery resource upto early 1990s with natural propagation of indian major carp, exotic carp, minor carp, cat fishes and weed fishes, etc. Due to increasing siltation through raima and sarma rivers, the reservoir progressively lost its diversity year after year with decreasing water spread area. The condition of the reservoir nowadays may be called as endangered due to accumulation of silt. Weed infestation poses serious threat to the sustainable natural fishery resource of the state.

The rudrasagar lake in sonamura subdivision have water spread area of 240 ha. The lake has the potential for propagation and conservation of aquatic fauna and flora such as the self-propagation of wild catfishes, minor carps, weed fishes and turtles. Due to deforestation, use of agricultural pesticides and siltation, considerable destruction of aquatic fauna and flora of the resources has taken place. The lake is now considered endangered for its watershed and bioresource values.

Geology and soil

No survey has been conducted by geological survey of india in tripura. Ongc has conducted some studies in this regard. The geological features are described below in brief.

Five broad groups of soil are found in the state. Of these, red loam and sandy loam soils are most extensive (covering about 43 percent of the total geographical area of the state). This group is followed by reddish yellow brown sandy soils. This description is based on a report brought out by department of science, technology and environment (state of environment in Tripura, 1989).

The red loam and sandy soils are fairly mature and rich in nutrients and support luxuriant growth of forests. These soils, if devoid of vegetal cover and located on sloping ground, are susceptible to heavy erosion. Taxonomically these can be classified as alfisols comprising association of ultic hapludalfs and typic paleudalfs. The ph varies from 4.85 to 5.8. Organic carbon content is medium.

The reddish yellow brown sandy soils are also highly susceptible to erosion as they are associated with ridge tops and sloping flanks of hill ranges. As a result of continuos leaching under heavy rainfall conditions obtaining in tripura, these soils are rather poor in nutrients. Taxonomically these are alfisols (mainly ultic) mixed with erosion-affected inceptisols. Short cycle jhuming (shifting cultivation) is highly damaging to these soils.