Root: Shoot Ratio Predicts Total Tree Carbon Stock in Terrestrial Ecosystems: A Meta-Analysis

Abstract

Our study aims to determine the root: shoot (R/S) ratio in the terrestrial biome because it is an important predictor of global terrestrial carbon (C) stocks. Forests act as C sinks of the terrestrial ecosystem where the carbon pools of the terrestrial ecosystem are represented by tree biomass, (aboveground and belowground biomass), litters, woody debris and, soil organic matter. Among these C pools, the aboveground biomass harbors the major proportion of the terrestrial C pools. But industrialization, deforestation, and burning of fossil fuels have increased the carbon concentration in the atmosphere and disrupted the global carbon cycle. So, there are plenty of methods available for the estimation of terrestrial carbon, except for the root carbon. However, root: shoot ratio is a basic method for calculation of the root biomass from shoot biomass. Hence, we collected the reliable data on root: shoot ratio from published literatures using which we have developed an allometric equation (Y = -0.324+0.236X), where Y represents root biomass and X represents shoot biomass and thus the R/S value obtained was 0.236. Using this allometric equation we can harmlessly estimate the belowground biomass in no time. But this default value (0.236) varies with vegetation type, mean annual precipitation and temperature, tree size and age so using this value in the assessment of biomass and carbon would result into unreliable estimation. So, we also performed an in-situ sampling at the campus of Banaras Hindu University, Varanasi, India to measure the aboveground and belowground biomass using the allometric equation mentioned above and also found the potential tree species with greater aboveground and belowground biomass which can be more useful in sequestration of increased carbon dioxide concentration in the atmosphere.