Root structure, distribution and biomass in five multipurpose tree species of Western Himalayas

The tree root distribution pattern and biomass of seventeen year old trees of Grewia optiva, Morus alba, Celtis australis, Bauhinia variegata and Robinia pseudoacacia were studied by excavation method. B. variegata roots penetrated to a maximum depth of 4.78 m, whereas, M. alba roots were found down to 1.48 m depth. Lateral spread was minimum in B. variegata (1.10 m) and maximum in R. pseudoacacia (7.33 m). Maximum root biomass of 6.30 kg was found in R. pseudoacacia and minimum (2.43 kg) was found in M. alba. For four species viz., G. optiva, M. alba, C. australis and R. pseudoacacia, 68%-87% root biomass occurred within top 0-30 cm soil depth, but for B. variegata this was only 45%. The soil binding factor was maximum in G. optiva and minimum in B. variegata. Soil physico-chemical properties also showed wide variation. The study suggests that B. variegata with a deep root system is the most suitable species for plantation under agroforestry systems. R. pseudoacacia and G. optiva with deep root systems, more lateral spread and high soil binding factor are suitable for plantation on degraded lands for soil conservation.