Patterns and controls on fine-root dynamics along a rainfall gradient in Ghana

Abstract

Fine-root biomass relates to environmental variables differently along a rainfall gradient in Ghana. Understanding changes in root dynamics in response to environmental factors is crucial for projections of climate change, yet information on controls of root dynamics is limited in the tropics. This study quantified fine-root dynamics along a rainfall gradient in Ghana, ranging from dry to wet evergreen forests. Fine-root biomass and necromass were estimated by the sequential coring method for a year and analyzed in relation to measured environmental factors (rainfall, soil moisture content, air temperature and soil temperature). Overall, fine-root biomass increased along the gradient with the highest estimate found in the wet forest site. Mean annual fine root production ranged from 276.60 to 348.95 gm−2 year−1 across the different forest types. Fine-root turnover rates ranged from 2.3 to 3.1 year−1, and roots tended to turn over faster in the dry than in the moist and wet forest sites. There was a non-linear but significant relationship between fine-root biomass and soil moisture content in the wet forest. None of the environmental factors related to fine-root biomass in the moist forest. However, there was a significant non-linear relationship between rainfall and fine-root biomass in the dry forest site. These results suggest that environmental factors influence fine-root biomass differently across the three forest types. Therefore, future studies should focus on a comprehensive measurement of environmental controls to deepen our understanding of fine root dynamics.