Impact of progressive and retrogressive land use changes on ecosystem multifunctionality: Implications for land restoration in the Indian Eastern Himalayan region.

Land use change, anthropogenic exploitation and climate change have impacted the flow of services in the Himalayan region. The dominant land uses in the region include natural forest, degraded forest, rubber (Hevea brasiliensis) plantations, Areca catechu plantations, Areca agroforestry and Piper agroforestry were considered for the study. A progressive shift in land use was defined as the conversion and restoration of a less productive system like degraded land to plantations or agroforestry systems. A land use shift was considered retrogressive when it entails the establishment of plantations after clearing natural forests or anthropogenic disturbance of natural forests resulting in forest degradation. The objectives of the current study were to estimate changes in soil properties, stand structure, tree biomass, fine root production and carbon storage following a progressive and retrogressive shift in land usage. The aboveground biomass (105.9 Mg ha-1 ) was highest in the natural forest, followed by Areca agroforestry (100.2 Mg ha-1 ) and least in the degraded forest (55.3 Mg ha-1 ). The aboveground biomass carbon (47.1 Mg ha-1 ) of Areca agroforestry was comparable with that of natural forest (51.3 Mg ha-1 ). The highest proportion of passive carbon concentrations was observed under Areca agroforestry, whereas the lowest (4.13 g kg-1 ) was found under Areca plantations in the 0-25 cm soil depth. With the progressive shift in land use from degraded forest to agroforestry, SOC stocks increased by 27.6 % and 3 % under Piper and Areca agroforests, respectively. SOC stocks decreased by 8.5 % with a shift in land use from natural forests to Areca plantations. The production of fine roots was maximum in the Areca agroforest (14.9 Mg ha-1 ) and lowest under rubber plantations (4.2 Mg ha-1 ). The results show that progressive shift from degraded forest to agroforestry can considerably increase carbon stocks, plant species diversity and multifunctionality than shift to monoculture plantations thereby supporting improved biodiversity and mitigation to climate change.