Trade-off between forest productivity and carbon sequestration in soil
This article is part of a larger document. View the larger document here.Abstract
With the growing fraction of the world’s forests being intensively managed plantations, these ecosystems will increasingly be relied upon to provide other ecosystemservices, in addition to merchantable timber. Schemes proposing the use of managed forests to mitigate climate change by sequestering carbon, however, are yet to be tested for feasibility and cost. In the current study we will review literature on forest responses to key climate and management factors on the inputs and outputs to the soil C pool in the context of expected changes under management. Recent global reviews indicate that there are distinct tradeoffs in allocation of assimilated carbon to different plant parts with productivity, and that the greater aboveground productivity comes on the account of belowground allocation, particularly on account of fine roots. Despite the proportional decrease in belowground fluxes in proportion to GPP, the absolute respiration fluxes are higher in managed than unmanaged forests, resulting in greater soil C loss. The balance between annual soil C inputs (leaf and fine root production plus mortality of tissue) and losses (soil heterotrophic respiration) indicates that while the imbalance is global, it is greater in the more productive managed than unmanaged forests. This shift triggered by high productivity exaggerates the elevated respiration losses caused by the greater frequency of harvests and physical disturbance of soil, outlining the greater vulnerability of soil C in managed forests.