Fine roots dynamics in a tropical moist forest: Case of two forest groves in the Congo basin

The paper contributes new data on fine root production in tropical forests from the Teke Plateau, an underexplored area of Africa that is dominated by grove forests. Importantly, this study contributes to our understanding of the role of the successional age of vegetation and the impacts of water availability on ecosystem functions, which may assist in predicting how tropical vegetation will change in the future due to climate change driven rainfall changes and more direct human interventions. We used ingrowth cores to study the influence of the forest structure on fine roots production and turnover in two different forests types, a gallery forest (GF) and a hill-slope forest clump (HF) in the Teke Plateau in Congo. We found a significant higher fine root biomass in the 0-20 cm horizon between the GF and HF; however, for the 20-40 cm horizons no significant differences were found between the two forest types. Nevertheless, there is a huge difference on the whole profile (0-40 cm), with 9.45±8.23 kg m-2 for the GF and 4.26±1.28 kg m-2 for the HF (p < 0.05). The annual production of fine roots was 0.46±0.24 and 0.36±0.02 kg m-2 yr-1 in the GF and the HF for the horizon 0-20 cm, and of 0.21±0.19 and 0.20±0.08 g m-2 yr-1 for the horizon 20-40 cm. These differences are not significant (p > 0.05). The differences in fine root biomass between the two types of forest are not explained by differences in production, but by differences in turnover. This difference between the two forest types can be explained by differences in forest structure. The measured basal area was 16.68 m2· ha-1 and 6.66 m2 · ha-1 in the GF and the HF, respectively. We also noted a mean tree density of 640 stems per ha in the GF against 119 stems per ha in the HF.