Net ecosystem productivity of temperate grasslands in northern China: An upscaling study

Authors

Li Zhang, Chinese Academy of Sciences, Beijing NormalUniversityFollow
Huadong Guo, Chinese Academy of Sciences
Gensou Jia, Institute of Atmospheric Physics, Chinese Academy of Sciences
Bruce K. Wylie, U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) CenterFollow
Tagir Gilmanov, South Dakota State UniversityFollow
Danny Howard, Stinger Ghaffarian Technologies (SGT), Contractor to USGS EROS Center
Lei Ji, ASRC InuTeq, Contractor to USGS EROS Center
Jingfeng Xiao, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire
Jing Li, Academy of Disaster Reduction and Emergency Management, Beijing NormalUniversity
Wenping Yuan, Cold and Arid Regions Environment and Engineering Research Institute, Chinese Academy of Sciences
Tianbao Zhao, Institute of Atmospheric Physics, Chinese Academy of Sciences
Shiping Chen, Institute of Botany, Chinese Academy of Sciences
Guangsheng Zhou, Chinese Academy of Meteorological Sciences
Tomomichi Kato, Laboratoire des Sciences du Climat et de l’Environnement

Date of this Version

2014

Citation

Agricultural and Forest Meteorology 184 (2014) 71– 81

Comments

This article is a U.S. government work, and is not subject to copyright in the United States.

Abstract

Grassland is one of the widespread biome types globally, and plays an important role in the terrestrial car-bon cycle. We examined net ecosystem production (NEP) for the temperate grasslands in northern China from 2000 to 2010. We combined flux observations, satellite data, and climate data to develop a piece-wise regression model for NEP, and then used the model to map NEP for grasslands in northern China. Over the growing season, the northern China’s grassland had a net carbon uptake of 158 ± 25 g C m−2during 2000–2010 with the mean regional NEP estimate of 126 Tg C. Our results showed generally higher grassland NEP at high latitudes (northeast) than at low latitudes (central and west) because of different grassland types and environmental conditions. In the northeast, which is dominated by meadow steppes, the growing season NEP generally reached 200–300 g C m⁻². In the southwest corner of the region, which is partially occupied by alpine meadow systems, the growing season NEP also reached 200–300 g C m⁻². In the central part, which is dominated by typical steppe systems, the growing season NEP generally varied in the range of 100–200 g C m⁻². The NEP of the northern China’s grasslands was highly variable through years, ranging from 129 (2001) to 217 g C m⁻²growing season−1 (2010). The large inter annual variations of NEP could be attributed to the sensitivity of temperate grasslands to climate changes and extreme climatic events. The droughts in 2000, 2001, and 2006 reduced the carbon uptake over the growing season by 11%, 29%, and 16% relative to the long-term (2000–2010) mean. Over the study period (2000–2010), precipitation was significantly correlated with NEP for the growing season (R²= 0.35, p-value < 0.1), indicating that water availability is an important stressor for the productivity of the temperate grasslands in semi-arid and arid regions in northern China. We conclude that northern temperate grasslands have the potential to sequester carbon, but the capacity of carbon sequestration depends on grassland types and environmental conditions. Extreme climate events like drought can significantly reduce the net carbon uptake of grasslands.