Pristine forest ecosystem is considered an enormous pool for carbon. Studies suggested that if these forests are continuously conserved, then they can be one of the biggest carbon sink.  

Nowadays, investigations on identifying the driving factors for carbon sequestration and accumulation become important to provide policy makers and forest managers with the information regarding species selection in forestry projects. 

Dr. Syed Moazzam Nizami, a Pakistani postdoc, and Prof. ZHANG Yiping’s team of Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences studied forest structure, stand dynamics and carbon density at two different sites of pristine evergreen broad-leaved forests of the Ailaoshan mountain nature reserve, south-western China.  

They investigated the woody species of the pristine forest (about 300 years old) during the years 2005–2010 to find out the carbon driving factors. 

They analyzed five-year (2005-2010) tree growth data from permanently established plots in the Ailaoshan mountain nature reserve, including species composition, density, stem diameter (diameter at breast height, DBH), height and carbon (C) density both in aboveground and belowground vegetation biomass.  

They found that on both sites in the pristine subtropical broad-leaved evergreen forests, overall 54 species belonging to 16 families were prevailing. Species density analysis showed overall 44 and 35 species were present on site 1 and site 2, respectively.  

Across the sites, estimation of the carbon density in above- and belowground vegetation biomass revealed significant difference with respect to time and sites.  

There was a direct relationship between tree density (i.e. number of trees per hectare), biomass and carbon accumulation at stand level. The dominant species (with high DBH) had high carbon accumulation potential and should be conserved. 

The principal component analysis (PCA) revealed that the density of the trees, their diameter increment and prevalence in nature reserves (being protected) are the main factors which drives carbon stocking and increment in pristine old forest this region. 

The researchers proposed that indigenous dominant species should be considered in future, in order to increase the carbon stock.

The study entitled “Evaluation of forest structure, biomass and carbon sequestration in subtropical pristine forests of SW China” has been published online in Environmental Science and Pollution Research.