Drought in the Southern United States over the 20th century: Variability and its impacts on terrestrial ecosystem productivity and carbon storage

Guangsheng Chen, Hanqin Tian, Chi Zhang, Mingliang Liu, Wei Ren, Wenquan Zhu, Arthur H. Chappelka, Stephen A. Prior, Graeme B. Lockaby

Research output: Contribution to journalArticlepeer-review

100 Scopus citations


Drought is one of the most devastating natural hazards faced by the Southern United States (SUS). Drought events and their adverse impacts on the economy, society and environment have been extensively reported during 1895-2007. Our aim is thus to characterize drought conditions in the SUS and explore the impacts on terrestrial ecosystem function (i. e., net primary productivity (NPP) and net carbon exchange (NCE)). Standard precipitation index (SPI) was used to characterize drought intensity and duration, and a process-based ecosystem model was used to explore the relationship between drought and ecosystem function. Combining overall information on growing-season SPI, drought area and duration, we concluded there was no significant change in drought conditions for the SUS during 1895-2007. However, increased drought intensity was found for many areas in the east, resulting in significant decreases in NPP for these areas, with the largest decrease up to 40% during extreme droughts. Changes in precipitation patterns increased C emissions of 0.16 Pg (1 Pg = 10 15 g) in the SUS during 1895-2007. The west (dry region) acted as a C sink due to increased precipitation, while the east (water-rich region) acted as a C source due to increased drought intensity. Both NPP and NCE significantly increased along a gradient of declining drought intensity. Changes in precipitation resulted in C sources in forest, wetland, and cropland ecosystems, while C sinks in shrubland and grassland ecosystems. Changes in air temperature could either enhance or reduce drought impacts on NPP and NCE across different vegetation types.

Original languageEnglish
Pages (from-to)379-397
Number of pages19
JournalClimatic Change
Issue number2
StatePublished - Sep 2012

Bibliographical note

Funding Information:
Acknowledgements This study has been supported by the U.S. Department of Energy (DOE) NICCR Program (DUKE-UN-07-SC-NICCR-1014), NASA Interdisciplinary Science Program (NNX10AU06G), NASA Terrestrial Ecology Program, Alabama Agricultural Experiment Station research program, and the Southern Forest Research Partnership.

ASJC Scopus subject areas

  • Global and Planetary Change
  • Atmospheric Science


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