PhytOC sequestration characteristics and phytolith carbon sink potential of karst Masson pine forest in southern...

Masson pine forest is an extremely important component of terrestrial ecosystems and plays a significant ecological function in forest carbon sink in China. Phytolith-occluded organic carbon (PhytOC) is the important long-term stable carbon sink mechanism in terrestrial ecosystems. To provide scientific bases for the accurate estimation of phytolith carbon sink and precise management of Masson pine forests, PhytOC sequestration and accumulation of the three typical forest ages of Masson pine in southern China karst area were studied in the present study. Although the sampling pots were still limited, PhytOC sequestration characteristics of the Masson pine forests were successfully clarified. The followed results and conclusions were obtained: 1) The range of PhytOC content, reserves, and sequestration rate of the Masson pine forests was 0.04-0.78 g·kg^-1, 0.44-16.93 kg·hm^-2, and 0.094-2.557 kg CO₂ hm^-2·a^-1, respectively. 2) Among the three forest ages of Masson pine, the mature forest had the highest accumulation of PhytOC, and the middle-aged forest had the highest sequestration rate of PhytOC. Compared with biomass, vegetation productivity more positively significantly affected the PhytOC sequestration. 3) Among the three organs, leaves had the highest PhytOC content and trunks had the highest PhytOC reserves, which all took significant functions in the sequestration and accumulation of PhytOC. 4) Artificial measures to promote vegetation productivity, such as thinning, artificial tending, and low-efficiency forest transformation, will significantly increase the PhytOC sequestration and accumulation of Masson pine forests.