Attribution of net carbon change by disturbance type across forest lands of the conterminous United States.

S. S. Saatchi,B. H. Braswell,A. Fore,G. M. Domke,W. Salas,C. W. Woodall,T. R. H. Pearson,S. C. Hagen,N. L. Harris,B. F. Walters,Y. Yu,S. Brown

doi:10.1186/s13021-016-0066-5

Abstract

BackgroundLocating terrestrial sources and sinks of carbon (C) will be critical to developing strategies that contribute to the climate change mitigation goals of the Paris Agreement. Here we present spatially resolved estimates of net C change across United States (US) forest lands between 2006 and 2010 and attribute them to natural and anthropogenic processes.ResultsForests in the conterminous US sequestered −460 ± 48 Tg C year−1, while C losses from disturbance averaged 191 ± 10 Tg C year−1. Combining estimates of net C losses and gains results in net carbon change of −269 ± 49 Tg C year−1. New forests gained −8 ± 1 Tg C year−1, while deforestation resulted in losses of 6 ± 1 Tg C year−1. Forest land remaining forest land lost 185 ± 10 Tg C year−1 to various disturbances; these losses were compensated by net carbon gains of −452 ± 48 Tg C year−1. C loss in the southern US was highest (105 ± 6 Tg C year−1) with the highest fractional contributions from harvest (92%) and wind (5%). C loss in the western US (44 ± 3 Tg C year−1) was due predominantly to harvest (66%), fire (15%), and insect damage (13%). The northern US had the lowest C loss (41 ± 2 Tg C year−1) with the most significant proportional contributions from harvest (86%), insect damage (9%), and conversion (3%). Taken together, these disturbances reduced the estimated potential C sink of US forests by 42%.ConclusionThe framework presented here allows for the integration of ground and space observations to more fully inform US forest C policy and monitoring efforts.

Highlights

Locating terrestrial sources and sinks of carbon (C) will be critical to developing strategies that contribute to the climate change mitigation goals of the Paris Agreement
The objective of this study was to synthesize information from remote sensing observations of forest carbon stocks and disturbance with information collected by various United States (US) agencies into a framework that (1) more explicitly attributes C losses to major disturbance types; and (2) disaggregates net C change into relevant IPCC reporting categories of nonforest land converted to forest land, forest land converted to non-forest land, and forest land remaining forest land
Forest land remaining forest land lost 184 ± 10 Tg C year−1 to disturbance (13% from natural disturbance, 87% from harvest); these were compensated by net carbon gains of 452 ± 48 Tg C year−1, 75%

Summary

Introduction

Locating terrestrial sources and sinks of carbon (C) will be critical to developing strategies that contribute to the climate change mitigation goals of the Paris Agreement. The 2015 Paris Climate Change Agreement, with consensus from 192 signatories, calls for achieving a balance between anthropogenic emissions by sources and removals by sinks in the second half of this century [1]. If the ultimate aim of the Paris Agreement is to introduce practices that lead to reduced emissions and enhanced removals of C from the world’s managed forests, including in temperate and boreal biomes, a lack of disaggregated, spatially-explicit information could pose challenges over the coming years related to knowledge of where changes are occurring and where interventions are likely to be most effective

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