Mass Balance of Organic Carbon in the Soils of Forested Watersheds from Northeastern North America

Abstract

The objective of this chapter is to establish the functional links between the organic carbon (C) dynamics in soils, the biogeochemical C cycle of forested watershed and the potential changes in the sequestration of atmospheric C by forest soils in response to changing climatic conditions. After an introductory statement on greenhouse gases and their effects on climate, the second part of the chapter describes the properties, functions and biogeochemical cycling of organic carbon (C) in forest soils. The third part of the chapter presents the results of an extensive review of organic C mass balance studies conducted in forested watersheds of northeastern North America. The soil and plant C pools and fluxes are quantified and results are compared to those obtained from other environments, such as southeastern United States and Western and Central Europe. The potential contribution of soils to the emission of greenhouse gases is critically discussed through an evaluation of the net role of soils on organic carbon (C) cycling and on its transport from terrestrial to aquatic environments. Based on the available data and evidences, it appears that the question as to whether soils from northern forests will behave as a net source or sink of C under a warmer climate cannot yet be answer unequivocally.