Evaluation of multipurpose tree species for managing degraded sodic land ecosystem in Indo-Gangetic alluvial plains

Afforestation on a highly degraded sodic soils at research farm of Central Soil Salinity Research Institute, Regional Research Station, Lucknow in north India representing large part of Indo-Gangetic plains in India has improved the ecosystem services including biomass production, soil amelioration and understorey vegetation during ten years. Of the ten species studied, above ground biomass of Prosopis juliflora was maximum at ten years (56.5 Mg ha(-1)). The highest mean annual increment (MAI) was estimated in P. juliflora followed by Acacia nilotica and Casuarina equisetifolia. However, the highest current annual increment (CAI) value was observed in Pongamia pinnata followed by A. nilotica and Terminalia arjuna. Highest understorey biomass yield was obtained under the canopy of A. nilotica but it was at par with P. juliflora and significantly higher over rest of the tree species studied. Highest improvement in soil physical indicators (bulk density and infiltration rate) and chemical indicators (pH, exchangeable sodium percentage) of alkaline soils was recorded under P. juliflora which was 20.12, 557.50, 9.23 and 48% higher over the initial and 9.02, 122.00, 7.29, and 43.20% higher over natural fallow, respectively. Amongst the underground herb species, Cynodon dactylon which is an indicator grass species for reclaimed sodic soils occupied highest intensity (70%) under P. juliflora and A. nilotica. Highest gain percent in terms of soil bulk density, infiltration rate, pH and organic carbon over the initial value was recorded in P. juliflora followed by C. equisetifolia and P. pinnata. Microbial biomass carbon was relatively higher under C. equisetifolia and P. juliflora than rest of the tree species.