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- Wu, X. C., et al.
(author)
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Timing and Order of Extreme Drought and Wetness Determine Bioclimatic Sensitivity of Tree Growth
- 2022
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In: Earth's Future. - : American Geophysical Union (AGU). - 2328-4277. ; 10:7
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Journal article (peer-reviewed)abstract
- Tree resistance to extreme droughts and post-drought recovery are sensitive to the drought timing. However, how the bioclimatic sensitivity of tree growth may vary with the timing and order of extreme droughts and wetness is still poorly understood. Here, we quantified the bioclimatic sensitivity of tree growth in the period of 1951-2013 under different seasonal extreme drought/wetness regimes over the extra-tropical Northern Hemisphere, using 1,032 tree ring chronologies from 121 gymnosperm and angiosperm species. We found a negative asymmetry in tree growth under regimes with seasonal extreme droughts. With extreme drought, tree growth in arid and temperate dry regions is more negatively impacted by pre-growing-season (PGS) extreme droughts. Clade-wise, angiosperms are more sensitive to PGS water availability, and gymnosperms to legacy effects of the preceding tree growth conditions in temperate dry and humid regions. Our finding of divergent bioclimatic legacy effects underscores contrasting trends in forest responses to drought across different ecoregions and functional groups in a more extreme climate.
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- Fan, K. K., et al.
(author)
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The scenario-based variations and causes of future surface soil moisture across China in the twenty-first century
- 2021
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In: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 16:3
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Journal article (other academic/artistic)abstract
- Surface soil moisture (SSM) is a key factor for water and heat exchanges between land surface and the atmosphere. It is also important to water resources, agriculture, and ecosystems. In the backdrop of global warming, SSM variations and potential causes are not well-known at regional scales. Based on soil moisture (SM) data from GLDAS-Noah and 16 global climate models (GCMs) selected from 25 GCMs in CMIP5, we analyzed spatial distribution and temporal changes of SSM in China and quantified fractional contributions of four meteorological factors to the SSM variations. The selected models have the same direction of historic trends in SSM during 1981-2005 as those in the GLDAS SSM data which were also further used to calibrate the trends simulated by the 16 GCMs. Based on the calibration results for the 16 GCMs, future SSMs for nine regions were analyzed in mainland China under four Intergovernmental Panel on Climate Change emission scenarios. No significant changes were identified in SSM across most regions of mainland China under RCP2.6 scenario. However, there is a general wetting tendency in the arid regions and drying tendency across the humid regions under all the scenarios except RCP2.6. In general, the higher the global temperature raises, the more grids with significant increase or significant decrease in SSM. These findings contradicted prevailing view that wet regions get wetter and dry regions get drier. Attribution analysis indicates that precipitation acts as the major driver for SSM variations and contributes up to 43.4% of SSM variations across China. These results provide new insights into future SSM response to climate warming and a scientific basis to mitigation and adaptation works related to SSM in the future.
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| 4. |
- Gao, Ge, 1972, et al.
(author)
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Spatial and temporal characteristics of actual evapotranspiration over Haihe River basin in China
- 2012
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In: Stochastic Environmental Research and Risk Assessment. - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 26:5, s. 655-669
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Journal article (peer-reviewed)abstract
- Spatial and temporal characteristics of actualevapotranspiration over the Haihe River basin in Chinaduring 1960–2002 are estimated using the complementaryrelationship and the Thornthwaite water balance (WB)approaches. Firstly, the long-term water balance equation isused to validate and select the most suitable long-termaverage annual actual evapotranspiration equations for ninesubbasins. Then, the most suitable method, the Pike equation,is used to calibrate parameters of the complementaryrelationship models and the WB model at each station. Theresults show that the advection aridity (AA) model moreclosely estimates actual evapotranspiration than does theGranger and Gray (GG) model especially considering theannual and summer evapotranspiration when compared withtheWBmodel estimates. The results from theAA model andthe WB model are then used to analyze spatial and temporalchanging characteristics of the actual evapotranspirationover the basin. The analysis shows that the annual actualevapotranspirations during 1960–2002 exhibit similardecreasing trends in most parts of the Haihe River basin forthe AA and WB models. Decreasing trends in annual precipitationand potential evapotranspiration, which directlyaffect water supply and the energy available for actualevapotranspiration respectively, jointly lead to the decreasein actual evapotranspiration in the basin. A weakening of thewater cycle seems to have appeared, and as a consequence,the water supply capacity has been on the decrease, aggravatingwater shortage and restricting sustainable social andeconomic development in the region.
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