Ignoring detailed fast-changing dynamics of land use overestimates regional terrestrial carbon sequestration

S Q Zhao,Z Li,T L Sohl,S Liu

doi:10.5194/bg-6-1647-2009

Abstract

Abstract. Land use change is critical in determining the distribution, magnitude and mechanisms of terrestrial carbon budgets at the local to global scales. To date, almost all regional to global carbon cycle studies are driven by a static land use map or land use change statistics with decadal time intervals. The biases in quantifying carbon exchange between the terrestrial ecosystems and the atmosphere caused by using such land use change information have not been investigated. Here, we used the General Ensemble biogeochemical Modeling System (GEMS), along with consistent and spatially explicit land use change scenarios with different intervals (1 yr, 5 yrs, 10 yrs and static, respectively), to evaluate the impacts of land use change data frequency on estimating regional carbon sequestration in the southeastern United States. Our results indicate that ignoring the detailed fast-changing dynamics of land use can lead to a significant overestimation of carbon uptake by the terrestrial ecosystem. Regional carbon sequestration increased from 0.27 to 0.69, 0.80 and 0.97 Mg C ha−1 yr−1 when land use change data frequency shifting from 1 year to 5 years, 10 years interval and static land use information, respectively. Carbon removal by forest harvesting and prolonged cumulative impacts of historical land use change on carbon cycle accounted for the differences in carbon sequestration between static and dynamic land use change scenarios. The results suggest that it is critical to incorporate the detailed dynamics of land use change into local to global carbon cycle studies. Otherwise, it is impossible to accurately quantify the geographic distributions, magnitudes, and mechanisms of terrestrial carbon sequestration at the local to global scales.

Highlights

Quantifying the carbon exchange between the terrestrial biosphere and the atmosphere due to land use change is still the biggest uncertainty in regional and global carbon cycle studies (Houghton et al, 1999; Prentice, 2001; Canadell, 2002; Achard et al, 2004; Ramankutty et al, 2007)
To date, almost all regional to global carbon cycle studies have been driven by a static land use map or land use change statistics with decadal time intervals (e.g., Potter et al, 1993; Houghton et al, 1999; Sitch et al, 2003; Krinner et al, 2005) and have failed to capture the influences of detailed rapid land use change
We developed a data assimilation approach to inversely calculate spatially explicit model parameters from Moderate Resolution Imaging Spectroradiometer (MODIS) net primary production (NPP) (Turner at al., 2006)

Summary

Introduction

Quantifying the carbon exchange between the terrestrial biosphere and the atmosphere due to land use change is still the biggest uncertainty in regional and global carbon cycle studies (Houghton et al, 1999; Prentice, 2001; Canadell, 2002; Achard et al, 2004; Ramankutty et al, 2007). From 1850 to 2000, roughly 35% of global anthropogenic CO2 emissions resulted directly from land use changes (Houghton, 2003), whereas contemporary land use changes are considered to be the dominant driver for some regional terrestrial carbon sinks, contributing to a large portion of the current northern hemisphere terrestrial sink (Fang et al, 2001, 2005; Choi et al, 2002; Kauppi et al, 2006) These facts highlight the significance of including spatially explicit land use change information into the estimation of regional and global carbon exchange between the land and atmosphere.

Methods

Results

Conclusion