Partitioning main carbon pools in a semi-deciduous rainforest in eastern Cameroon

Abstract

Tropical forests contribute to climate change mitigation by absorbing carbon from the atmosphere and storing this in biomass and soil organic matter. However, there is still considerable uncertainty about the above- and belowground quantity and distribution of carbon stocks in African forests. Here, we evaluate how different carbon pools (aboveground live biomass, aboveground dead biomass, belowground biomass) contribute to total carbon stocks, and how different carbon components (e.g. large trees, understorey trees, coarse woody debris, roots, soil organic carbon etc.) contribute to carbon pools and total carbon stocks. We evaluated data of extensive inventories within 30 1-ha plots spanning the terra-firme semi-deciduous forest in eastern Cameroon. Hence, the plots were placed at a mean distance of 1 km from the nearest plot and we analyzed the data using variation partitioning, linear regressions and correlation tests. We found that the terra-firme semi-deciduous forests store 283.97 ± 51.42 Mg C ha−1. The aboveground biomass pool, with a carbon stock of 180.99 ± 25.8 Mg C ha−1, mostly explained variation in total carbon stocks (R2 = 0.79). From all aboveground biomass components, carbon in large trees was most strongly correlated with total carbon stocks. The second most important carbon pool was belowground carbon (on average 85.06 ± 16.86 Mg C ha−1; R2 = 0.78), mainly explained by coarse root carbon. Carbon in dead biomass had only a small contribution to total carbon stocks (R2 = 0.04). Hence, our results indicate that aboveground live biomass is a good predictor for variation in total carbon storage within this semi-deciduous terra-firme forest. However, aboveground live carbon and belowground carbon and their interactions explained most of the variation in total carbon stock, indicating that a whole-ecosystem approach is necessary for a full understanding of the carbon cycle.