Terrestrial ecosystems in the southern United States (SUS) have experienced a complex set of changes in climate, atmospheric CO 2 concentration, tropospheric ozone (O 3), nitrogen (N) deposition, and land-use and land-cover change (LULCC) during the past century. Although each of these factors has received attention for its alterations on ecosystem carbon (C) dynamics, their combined effects and relative contributions are still not well understood. By using the Dynamic Land Ecosystem Model (DLEM) in combination with spatially explicit, long-term historical data series on multiple environmental factors, we examined the century-scale responses of ecosystem C storage and flux to multiple environmental changes in the SUS. The results indicated that multiple environmental changes shifted SUS ecosystems from a C source of 1. 20 ± 0. 56 Pg (1 Pg = 10 15 g) during the period 1895 to 1950, to a C sink of 2. 00 ± 0. 94 Pg during the period 1951 to 2007. Over the entire period spanning 1895-2007, SUS ecosystems were a net C sink of 0. 80 ± 0. 38 Pg. The C sink was primarily due to an increase in the vegetation C pool, whereas the soil C pool decreased during the study period. The spatiotemporal changes of C storage were caused by changes in multiple environmental factors. Among the five factors examined (climate, LULCC, N deposition, atmospheric CO 2, and tropospheric O 3), elevated atmospheric CO 2 concentration was the largest contributor to C sequestration, followed by N deposition. LULCC, climate, and tropospheric O 3 concentration contributed to C losses during the study period. The SUS ecosystem C sink was largely the result of interactive effects among multiple environmental factors, particularly atmospheric N input and atmospheric CO 2.
|Number of pages||21|
|State||Published - Jun 2012|
Bibliographical noteFunding Information:
This study has been supported by the US Department of Energy National Institute for Climate Change Research (NICCR) Program (DUKE-UN-07-SC-NICCR-1014), NASA Interdisciplinary Science Program (NNX10AU06G), NASA Terrestrial Ecology Program, Alabama Agricultural Experiment Station Research Program (AAES), and the Southern Forest Research Partnership. We would also thank Dr. Edward Rastetter and two anonymous reviewers who have provided thoughtful comments and suggestions, which led to a major improvement in the manuscript.
- Dynamic Land Ecosystem Model (DLEM)
- carbon storage and flux
- climate change
- land use change
- southern United States
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Environmental Chemistry