BIODIVERSITY OF HERBAGE SPECIES UNDER SILVIPASTURE SYSTEM IN HUMID TROPIC ENVIRONMENT OF CHHATTISGARH

摘要

Silvipastoral system is dominating immovable tree component in the top storey andherbage plant species in the understorey. In a man-made silvipastoral system, tree species as well as improved grass and legume species are grown parallelly but over a period of time, the production and quality offorage get suffered due to invasion of local flora, particularly in typical wastelands of humid tropics.Chhattisgarh has humid tropical climate with mean annual rainfall between 1400 to 1600 mm and relative humidity 82 to 29 per cent during rains and summer, respectively. The mean monthly maximum and minimum temperature ranges from 27 to 13°C in winter and 42 to 28°C in summer. In central Chhattisgarh plain, lateritic wastelands are as uplands up to an extent of 20 per cent area in almost each block. These red lateritic soils are very poor in nutrients and are therefore, unable to sustain agricultural system and always suffer from soil-water and nutrient erosion during summer and rainy seasons by wind and rains, respectively.In a well-developed silvipastoral system, four MPTs viz., Dalbergia sissoo, Gmelina arborea, Pongamia pinnata and Terminalia arjuna were grown at 5x5 m spacing with Chrysopogon fulvus and Stylosanthes hamata. The structure and production share of herbagevegetation was studied after 10 years of establishment. Results of the study are presented in light of relationships among diversity, dominance and biomass production of understorey component.Phytosociological study revealed that Aschinomon indica, a weed species, was found dominanting in all the plots. The IVI values of Aschinomon indica were recorded as 144.32, 121.36, 109.61, 86.72 and 82.53 in control, G. arborea, T. arjuna, D. sissoo andP.pinnata plots, respectively. The similarity index was found 61.64 per cent. The highest dominance level of species was found in control plots (0.2585), followed by G. arborea (0.2046) and the lowest under P. pinnata (0.1273). Level of species diversity was found maximum under P. pinnata (1.0674), followed by T.arjuna (0.8752) and minimum in control plots (0.84). Association level between Stylosanthes hamata and Chrysopogon fulvus was recorded the highest under the closed canopy of D.sissoo (100 %) and the lowest in the open plots (57.1 4 %).The understorey pasture crops of Chrysopogon fulvus and Stylosanthes hamata got established during the initial growing stage in the silvipastoral system. As soon as the tree canopy developed, the invasion of local native flora interacted with the growingspecies and started to influence the quality and quantity of the established pasture crops.