Litterfall and soil respiration as indicators of soil organic matter dynamics in clonal Eucalyptus plantations under seedling and coppice systems

Soil organic matter is the major carbon reservoir in forest plantations, litter deposition represents the main of carbon input to the soil, while soil respiration reflects the rate of transformation and release of this carbon to the atmosphere. This study evaluated, over one year, the coupled dynamics of monthly litter deposition and soil CO₂ emissions in eucalyptus plantations under two management systems, high forest and coppice, across regions with contrasting climatic conditions in Brazil. Monthly measurements were carried out in experimental areas located in Telêmaco Borba-PR and Bocaiuva-MG, allowing the assessment of the effects of management, climate, and clones on processes related to soil organic matter. The high forest system showed greater litter inputs at both sites, indicating higher surface carbon inputs. However, soil CO₂ emission patterns differed between regions. In Minas Gerais State, characterized by higher mean temperatures (> 25 ^oC) and water deficit (> 600 mm), soil CO₂ emissions were lower under coppice management, despite lower litter inputs, suggesting greater carbon retention in the soil under this system. In Paraná State, where rainfall is higher (>400 mm/month) and more stable, soil CO₂ emissions varied mainly among clones, and differences between management systems were less pronounced. These results demonstrate that soil organic matter dynamics in eucalyptus plantations are strongly driven by the interaction between forest management and climate. Coppice management may function as a more carbon-conservative system in water-limited environments, reinforcing the importance of integrated monitoring of litterfall and soil respiration to understand carbon cycling processes in planted forests.