Forest degradation impacts on carbon stocks, tree density and regeneration status in banj oak forests of Central Himalaya

Abstract

Abstract The oak forests of the Himalaya are an important repository of carbon. Forest degradation, in terms of loss in biomass and carbon, is a more pressing problem than loss of forest area in the Himalaya. The altitudinal gradient between 1,000 m and 2,200 m is dominated by chir pine and banj oak forest. As a result of small‐scale chronic disturbances the structure and function of banj oak forest is rapidly changing, leaving few pristine patches. Forty permanent plots of 400 m 2 in four disturbance categories of Central Himalayas (1,400 m–2,300 m asl) were studied over 3 years (2015, 2016 and 2017) to understand the impact of disturbance on banj oak forests. The study indicates that tree biomass declined by 62% from undisturbed to degraded forests, carbon sequestration rate declined by 73% and was maximum for Moderately disturbed‐A forests, total soil carbon dropped by 79% and mycorrhizal sporocarps declined by 78% from undisturbed to degraded forests. There was an overall decline in tree density by 56% from undisturbed forests to degraded forests. In degraded forests, the invasion of pine, a species tolerant of disturbance, helps in maintaining the forest status but the population structure changes and significant decline in carbon sequestration rate and total biomass stocks (above ground biomass and below ground biomass) was observed. The study indicates that moderate level disturbance promotes better carbon sequestration rates, tree density and the survival of seedlings.