Quantification of carbon in forest necromass: state of the art

Abstract

Necromass plays an important ecological function, including organic matter deposition, which is crucial to carbon and nutrient cycling in forest ecosystems. Despite the devoted attention to the role of forest necromass in the global carbon cycle, international organizations, such as IPCC and FAO, have reported the absence of compatible data on carbon stocks in necromass for different typologies and regions. This paper reviews terminology, sampling methods, and measurement methodologies when quantifying carbon stock in forest necromass. We analyzed procedures in volume, biomass and carbon content obtainment worldwide and then particularly in Brazil. We discuss the problems associated with necromass spatial distribution and marked differences between terminologies and methods adopted among studies that address the quantification of necromass carbon. Disagreement in nomenclature, components and minimum diameter of inclusion hamper comparison of regional values. Therefore, standard terminology for studies on this purpose is proposed. Coarse woody and non-woody (litter) necromass are generally computed but fine woody necromass is disregarded in most inventories. We provide recommendations on specific sampling and measurement procedures, taking into account its spatial and size distribution for both necromass and litter.