Fine-root exploitation strategies differ in tropical old growth and logged-over forests in Ghana

Understanding the changes in root exploitation strategies during post-logging recovery is important for predicting forest productivity and carbon dynamics in tropical forests. We sampled fine (diameter < 2 mm) roots using the soil core method to quantify fine-root biomass and architectural and morphological traits to determine root exploitation strategies in an old growth forest and in a 54-yr-old logged-over forest influenced by similar parent material and climate. Seven root traits were considered: four associated with resource exploitation potential or an ‘extensive’ strategy (fine-root biomass, length, surface area, and volume), and three traits which reflect exploitation efficiency or an ‘intensive’ strategy (specific root area, specific root length, and root tissue density). We found that total fine-root biomass, length, surface area, volume, and fine-root tissue density were higher in the logged-over forest, whereas the old growth forest had higher total specific root length and specific root surface area than the logged-over forest. The results suggest different root exploitation strategies between the forests. Plants in the old growth forest invest root biomass more efficiently to maximize soil volume explored, whereas plants in the logged-over forest increase the spatial distribution of roots resulting in the expansion of the rhizosphere.