The Role of Herb and Shrubs in the Cycling of Elements in a Tropical Dry Deciduous Forest in North-West India

Abstract

The Bala fort tropical dry deciduous forest in the Aravali ranges is located in Rajasthan state in North-West India (27^o4^’ to 28^o4^’ N and 76^o7^’ to 77^o13^’ E). These forests support a dense stratum of perennial herbs and shrubs under the relatively open tree canopy. Therefore, impact of a dominant herb and shrubs have been evaluated on the cycling of Sodium, Potassium, Calcium and Phosphorus in this forest. The percentage of Sodium was lower while that of other three elements was higher in the biomass of the selected species, in comparison to soil. Among the four plant species only the shrub Justicia adhatoda lost higher percentage of Sodium (0.268) than present in the soil (0.203). Grewia flavescens and Capparis sepiaria exhibited a tendency to retain Sodium in their plant body, however, through litter fall, the former returned higher amount of Sodium to soil. The herb, Achyranthes aspera exhibited unusually higher percentage of Potassium 4.464, 3.818 and 2.916 in leaves, stems and roots respectively than three shrub species. The percentage of Calcium was higher in the biomass and litter of shrubs than in the herb. Hence, the shrubs return large amount of Calcium to the soil than the herb. The herb Achyranthes aspera and the shrubs Justicia adhatoda and Grewia flavescens exhibited almost equal percentage of Phosphorus while Capparis sepiaria showed less percentage in biomass. The percentage of Phosphorus was higher in the litter of all the selected shrubs as compared to living biomass indicating its poor retranslocation during leaf shedding. On the basis of the standing crop, the herb Achyranthes aspera play important role in the nutrient cycling of Potassium and Phosphorus whereas the deciduous shrubs Justicia adhatoda and Grewia flavescens in Calcium and Phosphorus cycles. The deciduous shrubs Justicia adhatoda and Grewia flavescens contribute more than the evergreen shrub Capparis sepiaria in the nutrient cycling of this forest.