Biomass production and nutrient dynamics in a multipurpose tree based black pepper production system

Abstract

A field study was undertaken on a 22-year-old black pepper production system at Livestock Research Station, Thiruvizhamkunnu, Kerala during 2009-10 to evaluate the growth, biomass production, Carbon sequestration and nutrient dynamics in six multipurpose trees used as pepper standards viz. Acacia auriculiformis, Artocarpus heterophyllus, Grevillea robusta, Macaranga peltata, Ailanthus triphysa and Casuarina equisetifolia. Diameter at breast height (DBH), total height and bole height varied significantly between the six species. Maximum DBH was registered by Grevillea robusta (23.06 cm) which was closely followed by Artocarpus heterophyllus (22.12 cm). Mean tree total volume and bole volume production also varied, maximum mean tree bole volume was recorded by Grevillea robusta (0.360 m3) followed by Artocarpus heterophyllus (0.280 m3) and Acacia auriculiformis (0.260 m3). The aboveground biomass was estimated from destructively sampled 12 trees of each species and the belowground biomass was estimated following root excavation of three average sized trees of each species. Species-wise variation in terms of total biomass, aboveground biomass and belowground biomass was observed. Among the black pepper support trees Grevillea robusta recorded highest total biomass production (366 Mg ha -1) followed by Acacia auriculiformis (331 Mg ha -1) and the lowest was recorded in Ailanthus triphysa which is 155 Mg ha-1. The above ground biomass ranged from 264 Mg ha-1 in the case of Grevillea robusta to lowest of 122 Mg ha-1 in the case of Macaranga peltata. Stem wood accounted for maximum contribution to the total biomass in all the species. Maximum root biomass was recorded in the case of Grevillea robusta (63 Mg ha-1) closely followed by Acacia auriculiformis (62 Mg ha-1) and the lowest in the case of Ailanthus triphysa (24 Mg ha-1). Percentage contribution of root biomass to the total biomass varied from 11 to 24 depending on the species. Among different pepper support tree system, the Grevillea robusta based pepper production system recorded highest biomass Carbon stock to the tune of 169.24 Mg C ha-1. However with regard to soil Carbon Acacia auriculiformis based pepper production system recorded highest value (71.39 Mg ha-1) followed by Macaranga peltata (68.64 Mg ha-1) based system while the treeless control plot recorded the lowest carbon stock (38.17 Mg ha-1). Study indicate the overall improvement in site productivity in multipurpose tree based production systems and careful selection of the tree species can bring substantial benefits both in economic and ecological terms to the farmer.