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Abstract:
Soil water supply and atmospheric humidity conditions play an important role in controlling plants' stomatal behavior and water use efficiency. Based on the fluxnet2015 dataset around the world, the water use efficiency (WUE) and carbon use efficiency (CUE) of five plant functional types(PFTs), namely crops (CRO), deciduous broad-leaved forest (DBF), evergreen coniferous forest (ENF), grassland (GRA) and shrub (SAV) are estimated under different level of water vapor pressure (VPD) and soil water content (SWC). The results showed that high VPD and the low SWC limit the level of GPP for all vagetation types, while high SWC could offset the negative effects caused by high VPD to some extent for certain types of vegetation (CRO, DBF). In general, the increase of VPD in vegetation dominated the changes in WUE and CUE. The major change of WUE caused by the rise of VPD was at about 50 μmol/mol, Compared to VPD, the effect of SWC limitation is smaller, and the change of WUE dominated by the decline of SWC is at 30μmol/mol. It is worth noting that the changes of CUE of SAV is different from other vegetation types in that the rise of VPD and the decrease of SWC promote the increase of CUE of SAV to some extent. The study could help to provide understanding for the role of plants in the carbon and water cycle of the ecosystem under extreme climate and build an efficient water management schedule.
