Effects of changes in precipitation on energy and water balance in a Eurasian meadow steppe

Ecological Processes

Luping Qu¹  Fangyuan Zhao²  Jingyan Chen³  Shicheng Jiang⁴  Gang Dong⁵  Changliang Shao⁵ 

[1] Forestry Post-Doctoral Station, Forest Ecology Stable Isotope Center, Forestry College, Fujian Agriculture and Forestry University;Institute of Applied Ecology, Chinese Academy of Sciences;Institute of Loess Plateau, Shanxi University;Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University;National Hulunber Grassland Ecosystem Observation and Research Station & Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences;

关键词: Energy balance;    Energy partition;    Precipitation change;    Eddy covariance;    Drought;   

DOI  :  10.1186/s13717-019-0170-z

来源: DOAJ

【 摘 要 】

Abstract Introduction Water such as precipitation is the most critical environment driver of ecosystem processes and functions in semi-arid regions. Frequency and intensity of drought and transient waterlogging are expected to increase in the meadow steppe in northeastern China. Using a 4-year dataset of eddy covariance flux measurements, ground measurements of biomass, phenology, and meteorological conditions, we investigated the changes in energy fluxes at multiple temporal scales and under different precipitation regimes. Results The meadow steppe was latent heat (LE) dominated when soil water content was > 0.3 m3 m−3, but switched to sensible heat (H) dominated status when soil water content fell below 0.3 m3 m−3. LE dominated the energy exchange of the meadow grasslands on a yearly basis. Intensive precipitation had a profound impact on water-energy balance that could reduce the damages of drought by elevating deep soil moisture. The influence of LE on waterlogging depended on timing, with increased LE at the beginning of growing season and decreased LE after waterlogging. Spring and summer droughts resulted in different energy partitioning between latent and sensible heat energies, with spring drought dramatically decreased the LE fraction due to the change in water. In contrast, summer drought had little impact on LE due to the sufficient water input from large precipitation events at the beginning of the growing season. Conclusions There existed great seasonal and interannual variabilities in energy balance and partitioning in the meadow steppe over the 4-year study period, which were strongly influenced by changes in precipitation. The water loss through latent heat was more sensitive to spring drought than to summer drought, while summer drought had negligible impact on LE. Waterlogging contributed to LE by enhancing its values during and after the waterlogged periods at the beginning of the growing season in a dry year, but lowering its value after the waterlogged periods in growing season.

【 授权许可】

Unknown